Nicera D3-323-AA is a PIR sensor for human detection. It has support for
raw data measurements and detection notification. The communication
protocol is custom made and therefore needs to be GPIO bit banged.

The device has two main settings that can be configured: a threshold
value for detection and a band-pass filter. The configurable parameters
for the band-pass filter are the high-pass and low-pass cutoff
frequencies and its peak gain. Map these settings to the corresponding
parameters in the `iio` framework.

The low-pass and high-pass cutoff frequencies are pairwise for the
different available filter types. Because of this, only allow to set the
low-pass cutoff frequency from `sysfs` and use that to configure the
corresponding high-pass cutoff frequency. This is sufficient to
unambiguously choose a filter type.

Raw data measurements can be obtained from the device. However, since we
rely on bit banging, it will be rather cumbersome with buffer support.
The main reason being that the data protocol has strict timing
requirements (it's serial like UART), and it's mainly used during
debugging since in real-world applications only the event notification
is of importance. Therefore, only add support for events (for now).

Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
---
 drivers/iio/proximity/Kconfig   |   9 +
 drivers/iio/proximity/Makefile  |   1 +
 drivers/iio/proximity/d3323aa.c | 868 ++++++++++++++++++++++++++++++++
 3 files changed, 878 insertions(+)
 create mode 100644 drivers/iio/proximity/d3323aa.c

diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
index a562a78b7d0d..6070974c2c85 100644
--- a/drivers/iio/proximity/Kconfig
+++ b/drivers/iio/proximity/Kconfig
@@ -32,6 +32,15 @@ config CROS_EC_MKBP_PROXIMITY
 	  To compile this driver as a module, choose M here: the
 	  module will be called cros_ec_mkbp_proximity.
 
+config D3323AA
+	tristate "Nicera (Nippon Ceramic Co.) D3-323-AA PIR sensor"
+	depends on GPIOLIB
+	help
+	  Say Y here to build a driver for the Nicera D3-323-AA PIR sensor.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called d3323aa.
+
 config HX9023S
 	tristate "TYHX HX9023S SAR sensor"
 	select IIO_BUFFER
diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile
index c5e76995764a..152034d38c49 100644
--- a/drivers/iio/proximity/Makefile
+++ b/drivers/iio/proximity/Makefile
@@ -6,6 +6,7 @@
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AS3935)		+= as3935.o
 obj-$(CONFIG_CROS_EC_MKBP_PROXIMITY) += cros_ec_mkbp_proximity.o
+obj-$(CONFIG_D3323AA)		+= d3323aa.o
 obj-$(CONFIG_HX9023S)		+= hx9023s.o
 obj-$(CONFIG_IRSD200)		+= irsd200.o
 obj-$(CONFIG_ISL29501)		+= isl29501.o
diff --git a/drivers/iio/proximity/d3323aa.c b/drivers/iio/proximity/d3323aa.c
new file mode 100644
index 000000000000..fa08b52636ba
--- /dev/null
+++ b/drivers/iio/proximity/d3323aa.c
@@ -0,0 +1,868 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Nicera D3-323-AA PIR sensor.
+ *
+ * Copyright (C) 2025 Axis Communications AB
+ */
+
+#include <linux/atomic.h>
+#include <linux/bitmap.h>
+#include <linux/cleanup.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+
+#define D3323AA_DRV_NAME "d3323aa"
+
+/*
+ * Register bitmap.
+ * For some reason the first bit is denoted as F37 in the datasheet, the second
+ * as F38 and so on. Note the gap between F60 and F64.
+ */
+#define D3323AA_REG_BIT_SLAVEA1		0	/* F37. */
+#define D3323AA_REG_BIT_SLAVEA2		1	/* F38. */
+#define D3323AA_REG_BIT_SLAVEA3		2	/* F39. */
+#define D3323AA_REG_BIT_SLAVEA4		3	/* F40. */
+#define D3323AA_REG_BIT_SLAVEA5		4	/* F41. */
+#define D3323AA_REG_BIT_SLAVEA6		5	/* F42. */
+#define D3323AA_REG_BIT_SLAVEA7		6	/* F43. */
+#define D3323AA_REG_BIT_SLAVEA8		7	/* F44. */
+#define D3323AA_REG_BIT_SLAVEA9		8	/* F45. */
+#define D3323AA_REG_BIT_SLAVEA10	9	/* F46. */
+#define D3323AA_REG_BIT_DETLVLABS0	10	/* F47. */
+#define D3323AA_REG_BIT_DETLVLABS1	11	/* F48. */
+#define D3323AA_REG_BIT_DETLVLABS2	12	/* F49. */
+#define D3323AA_REG_BIT_DETLVLABS3	13	/* F50. */
+#define D3323AA_REG_BIT_DETLVLABS4	14	/* F51. */
+#define D3323AA_REG_BIT_DETLVLABS5	15	/* F52. */
+#define D3323AA_REG_BIT_DETLVLABS6	16	/* F53. */
+#define D3323AA_REG_BIT_DETLVLABS7	17	/* F54. */
+#define D3323AA_REG_BIT_DSLP		18	/* F55. */
+#define D3323AA_REG_BIT_FSTEP0		19	/* F56. */
+#define D3323AA_REG_BIT_FSTEP1		20	/* F57. */
+#define D3323AA_REG_BIT_FILSEL0		21	/* F58. */
+#define D3323AA_REG_BIT_FILSEL1		22	/* F59. */
+#define D3323AA_REG_BIT_FILSEL2		23	/* F60. */
+#define D3323AA_REG_BIT_FDSET		24	/* F64. */
+#define D3323AA_REG_BIT_F65		25
+#define D3323AA_REG_BIT_F87		(D3323AA_REG_BIT_F65 + (87 - 65))
+
+#define D3323AA_REG_NR_BITS (D3323AA_REG_BIT_F87 - D3323AA_REG_BIT_SLAVEA1 + 1)
+#define D3323AA_THRESH_REG_NR_BITS                                             \
+	(D3323AA_REG_BIT_DETLVLABS7 - D3323AA_REG_BIT_DETLVLABS0 + 1)
+#define D3323AA_FILTER_TYPE_NR_BITS                                            \
+	(D3323AA_REG_BIT_FILSEL2 - D3323AA_REG_BIT_FILSEL0 + 1)
+#define D3323AA_FILTER_GAIN_REG_NR_BITS                                        \
+	(D3323AA_REG_BIT_FSTEP1 - D3323AA_REG_BIT_FSTEP0 + 1)
+
+#define D3323AA_THRESH_DEFAULT_VAL 56
+#define D3323AA_FILTER_GAIN_DEFAULT_VAL 2
+
+/*
+ * The pattern is 0b01101, but store it reversed (0b10110) due to writing from
+ * LSB on the wire (c.f. d3323aa_write_settings()).
+ */
+#define D3323AA_SETTING_END_PATTERN 0x16
+#define D3323AA_SETTING_END_PATTERN_NR_BITS 5
+
+/*
+ * Device should be ready for configuration after this many milliseconds.
+ * Datasheet mentions "approx. 1.2 s". Measurements show around 1.23 s,
+ * therefore add 100 ms of slack.
+ */
+#define D3323AA_RESET_TIMEOUT (1200 + 100)
+
+/*
+ * The configuration of the device (write and read) should be done within this
+ * many milliseconds.
+ */
+#define D3323AA_CONFIG_TIMEOUT 1400
+
+/* Number of IRQs needed for configuration stage after reset. */
+#define D3323AA_IRQ_RESET_COUNT 2
+
+/*
+ * High-pass filter cutoff frequency for the band-pass filter. There is a
+ * corresponding low-pass cutoff frequency for each of the filter types
+ * (denoted A, B, C and D in the datasheet). The index in this array matches
+ * that corresponding value in d3323aa_lp_filter_freq.
+ * Note that this represents a fractional value (e.g. the first value
+ * corresponds to 4 / 10 = 0.4 Hz).
+ */
+static const int d3323aa_hp_filter_freq[][2] = {
+	{ 4, 10 },
+	{ 3, 10 },
+	{ 3, 10 },
+	{ 1, 100 },
+};
+
+/*
+ * Low-pass filter cutoff frequency for the band-pass filter. There is a
+ * corresponding high-pass cutoff frequency for each of the filter types
+ * (denoted A, B, C and D in the datasheet). The index in this array matches
+ * that corresponding value in d3323aa_hp_filter_freq.
+ * Note that this represents a fractional value (e.g. the first value
+ * corresponds to 27 / 10 = 2.7 Hz).
+ */
+static const int d3323aa_lp_filter_freq[][2] = {
+	{ 27, 10 },
+	{ 15, 10 },
+	{ 5, 1 },
+	{ 100, 1 },
+};
+
+/*
+ * Register bitmap values for filter types (denoted A, B, C and D in the
+ * datasheet). The index in this array matches the corresponding value in
+ * d3323aa_lp_filter_freq (which in turn matches d3323aa_hp_filter_freq). For
+ * example, the first value 7 corresponds to 2.7 Hz low-pass and 0.4 Hz
+ * high-pass cutoff frequency.
+ */
+static const int d3323aa_lp_filter_regval[] = {
+	7,
+	0,
+	1,
+	2,
+};
+
+/*
+ * This is denoted as "step" in datasheet and corresponds to the gain at peak
+ * for the band-pass filter. The index in this array is the corresponding index
+ * in d3323aa_filter_gain_regval for the register bitmap value.
+ */
+static const int d3323aa_filter_gain[] = {
+	1,
+	2,
+	3,
+};
+
+/*
+ * Register bitmap values for the filter gain. The index in this array is the
+ * corresponding index in d3323aa_filter_gain for the gain value.
+ */
+static const u8 d3323aa_filter_gain_regval[] = {
+	1,
+	3,
+	0,
+};
+
+struct d3323aa_data {
+	struct completion reset_completion;
+	/*
+	 *  Since the setup process always requires a complete write of the
+	 *  _whole_ register bitmap, we need to synchronize it with a lock.
+	 */
+	struct mutex regmap_lock;
+	atomic_t irq_reset_count;
+	unsigned int irq;
+
+	struct device *dev;
+
+	/* Supply voltage. */
+	struct gpio_desc *gpiod_vdd;
+	/* Input clock or output detection signal (Vout). */
+	struct gpio_desc *gpiod_clk_vout;
+	/* Input (setting) or output data. */
+	struct gpio_desc *gpiod_data;
+
+	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
+
+	/*
+	 * Indicator for operational mode (configuring or detecting), i.e.
+	 * d3323aa_irq_detection() registered or not.
+	 */
+	bool detecting;
+};
+
+static int d3323aa_read_settings(struct iio_dev *indio_dev,
+				 unsigned long *regmap)
+{
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	size_t i;
+	int ret;
+
+	/* Bit bang the clock and data pins. */
+	ret = gpiod_direction_output(data->gpiod_clk_vout, 0);
+	if (ret)
+		return ret;
+
+	ret = gpiod_direction_input(data->gpiod_data);
+	if (ret)
+		return ret;
+
+	dev_dbg(data->dev, "Reading settings...\n");
+
+	for (i = 0; i < D3323AA_REG_NR_BITS; ++i) {
+		/* Clock frequency needs to be 1 kHz. */
+		gpiod_set_value(data->gpiod_clk_vout, 1);
+		udelay(500);
+
+		/* The data seems to change when clock signal is high. */
+		if (gpiod_get_value(data->gpiod_data))
+			set_bit(i, regmap);
+
+		gpiod_set_value(data->gpiod_clk_vout, 0);
+		udelay(500);
+	}
+
+	/* The first bit (F37) is just dummy data. Discard it. */
+	clear_bit(0, regmap);
+
+	/* Datasheet says to wait 30 ms after reading the settings. */
+	msleep(30);
+
+	return 0;
+}
+
+static int d3323aa_write_settings(struct iio_dev *indio_dev,
+				  const unsigned long *regmap)
+{
+	DECLARE_BITMAP(end_pattern, D3323AA_SETTING_END_PATTERN_NR_BITS);
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	size_t i;
+	int ret;
+
+	/* Bit bang the clock and data pins. */
+	ret = gpiod_direction_output(data->gpiod_clk_vout, 0);
+	if (ret)
+		return ret;
+
+	ret = gpiod_direction_output(data->gpiod_data, 0);
+	if (ret)
+		return ret;
+
+	dev_dbg(data->dev, "Writing settings...\n");
+
+	/* First bit (F37) is not used when writing the register map. */
+	for (i = 1; i < D3323AA_REG_NR_BITS; ++i) {
+		gpiod_set_value(data->gpiod_data, test_bit(i, regmap));
+
+		/* Clock frequency needs to be 1 kHz. */
+		gpiod_set_value(data->gpiod_clk_vout, 1);
+		udelay(500);
+		gpiod_set_value(data->gpiod_clk_vout, 0);
+		udelay(500);
+	}
+
+	/* Compulsory end pattern. */
+	bitmap_write(end_pattern, D3323AA_SETTING_END_PATTERN, 0,
+		     D3323AA_SETTING_END_PATTERN_NR_BITS);
+	for (i = 0; i < D3323AA_SETTING_END_PATTERN_NR_BITS; ++i) {
+		gpiod_set_value(data->gpiod_data, test_bit(i, end_pattern));
+
+		gpiod_set_value(data->gpiod_clk_vout, 1);
+		udelay(500);
+		gpiod_set_value(data->gpiod_clk_vout, 0);
+		udelay(500);
+	}
+
+	/* Datasheet says to wait 30 ms after writing the settings. */
+	msleep(30);
+
+	return 0;
+}
+
+static irqreturn_t d3323aa_irq_detection(int irq, void *dev_id)
+{
+	struct iio_dev *indio_dev = dev_id;
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	enum iio_event_direction dir;
+	int val;
+
+	val = gpiod_get_value(data->gpiod_clk_vout);
+	if (val < 0) {
+		dev_err_ratelimited(data->dev,
+				    "Could not read from GPIO clk-vout (%d)\n",
+				    val);
+		return IRQ_HANDLED;
+	}
+
+	dir = val ? IIO_EV_DIR_RISING : IIO_EV_DIR_FALLING;
+	iio_push_event(indio_dev,
+		       IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
+					    IIO_EV_TYPE_THRESH, dir),
+		       iio_get_time_ns(indio_dev));
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t d3323aa_irq_reset(int irq, void *dev_id)
+{
+	struct iio_dev *indio_dev = dev_id;
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	int count = atomic_inc_return(&data->irq_reset_count);
+
+	if (count == D3323AA_IRQ_RESET_COUNT)
+		complete(&data->reset_completion);
+
+	return IRQ_HANDLED;
+}
+
+static int d3323aa_reset(struct iio_dev *indio_dev)
+{
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	long time;
+	int ret;
+
+	/*
+	 * Datasheet says VDD needs to be low at least for 30 ms. Let's add a
+	 * couple more to allow VDD to completely discharge as well.
+	 */
+	gpiod_set_value(data->gpiod_vdd, 0);
+	msleep(30 + 5);
+
+	/*
+	 * After setting VDD to high, the device signals with
+	 * D3323AA_IRQ_RESET_COUNT falling edges on CLK/Vout that it is now
+	 * ready for configuration. Datasheet says that this should happen
+	 * within D3323AA_RESET_TIMEOUT ms. Count these two edges within that
+	 * timeout.
+	 */
+	atomic_set(&data->irq_reset_count, 0);
+	reinit_completion(&data->reset_completion);
+
+	ret = gpiod_direction_input(data->gpiod_clk_vout);
+	if (ret)
+		return ret;
+
+	dev_dbg(data->dev, "Resetting...\n");
+
+	gpiod_set_value(data->gpiod_vdd, 1);
+
+	/*
+	 * Datasheet doesn't mention this but measurements have shown that
+	 * CLK/Vout signal slowly ramps up during the first 1.5 ms after reset.
+	 * This means that the digital signal will have bogus values during this
+	 * period. Let's wait for this ramp-up before counting the "real"
+	 * falling edges.
+	 */
+	usleep_range(2000, 5000);
+
+	if (data->detecting) {
+		/*
+		 * Device had previously been set up and was in operational
+		 * mode. Thus, free that detection IRQ handler before requesting
+		 * the reset IRQ handler.
+		 */
+		free_irq(data->irq, indio_dev);
+		data->detecting = false;
+	}
+
+	ret = request_irq(data->irq, d3323aa_irq_reset, IRQF_TRIGGER_FALLING,
+			  dev_name(data->dev), indio_dev);
+	if (ret)
+		return ret;
+
+	time = wait_for_completion_killable_timeout(
+		&data->reset_completion,
+		msecs_to_jiffies(D3323AA_RESET_TIMEOUT));
+	free_irq(data->irq, indio_dev);
+	if (time == 0) {
+		return -ETIMEDOUT;
+	} else if (time < 0) {
+		/* Got interrupted. */
+		return time;
+	}
+
+	dev_dbg(data->dev, "Reset completed\n");
+
+	return 0;
+}
+
+static int d3323aa_setup(struct iio_dev *indio_dev, const unsigned long *regmap)
+{
+	DECLARE_BITMAP(read_regmap, D3323AA_REG_NR_BITS);
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	unsigned long start_time;
+	int ret;
+
+	ret = d3323aa_reset(indio_dev);
+	if (ret) {
+		if (ret != -ERESTARTSYS)
+			dev_err(data->dev, "Could not reset device (%d)\n",
+				ret);
+
+		return ret;
+	}
+
+	/*
+	 * Datasheet says to wait 10 us before setting the configuration.
+	 * Moreover, the total configuration should be done within
+	 * D3323AA_CONFIG_TIMEOUT ms. Clock it.
+	 */
+	usleep_range(10, 20);
+	start_time = jiffies;
+
+	ret = d3323aa_write_settings(indio_dev, regmap);
+	if (ret) {
+		dev_err(data->dev, "Could not write settings (%d)\n", ret);
+		return ret;
+	}
+
+	ret = d3323aa_read_settings(indio_dev, read_regmap);
+	if (ret) {
+		dev_err(data->dev, "Could not read settings (%d)\n", ret);
+		return ret;
+	}
+
+	if (time_is_before_jiffies(start_time +
+				   msecs_to_jiffies(D3323AA_CONFIG_TIMEOUT))) {
+		dev_err(data->dev, "Could not set up configuration in time\n");
+		return -EAGAIN;
+	}
+
+	/* Check if settings were set successfully. */
+	if (!bitmap_equal(regmap, read_regmap, D3323AA_REG_NR_BITS)) {
+		dev_err(data->dev, "Settings data mismatch\n");
+		return -EIO;
+	}
+
+	/* Now in operational mode. */
+	ret = gpiod_direction_input(data->gpiod_clk_vout);
+	if (ret) {
+		dev_err(data->dev,
+			"Could not set GPIO clk-vout as input (%d)\n", ret);
+		return ret;
+	}
+
+	ret = gpiod_direction_input(data->gpiod_data);
+	if (ret) {
+		dev_err(data->dev, "Could not set GPIO data as input (%d)\n",
+			ret);
+		return ret;
+	}
+
+	ret = request_irq(data->irq, d3323aa_irq_detection,
+			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+			  dev_name(data->dev), indio_dev);
+	if (ret) {
+		dev_err(data->dev, "Could not request IRQ for detection (%d)\n",
+			ret);
+		return ret;
+	}
+
+	bitmap_copy(data->regmap, regmap, D3323AA_REG_NR_BITS);
+	data->detecting = true;
+
+	dev_dbg(data->dev, "Setup done\n");
+
+	return 0;
+}
+
+static int d3323aa_get_hp_filter_freq(unsigned long *regmap, int *val,
+				      int *val2)
+{
+	size_t idx;
+	u8 regval;
+
+	regval = bitmap_read(regmap, D3323AA_REG_BIT_FILSEL0,
+			     D3323AA_FILTER_TYPE_NR_BITS);
+	for (idx = 0; idx < ARRAY_SIZE(d3323aa_lp_filter_regval); ++idx) {
+		if (d3323aa_lp_filter_regval[idx] == regval)
+			break;
+	}
+
+	if (idx == ARRAY_SIZE(d3323aa_lp_filter_regval))
+		return -EINVAL;
+
+	*val = d3323aa_hp_filter_freq[idx][0];
+	*val2 = d3323aa_hp_filter_freq[idx][1];
+
+	return 0;
+}
+
+static int d3323aa_get_lp_filter_freq(unsigned long *regmap, int *val,
+				      int *val2)
+{
+	size_t idx;
+	u8 regval;
+
+	regval = bitmap_read(regmap, D3323AA_REG_BIT_FILSEL0,
+			     D3323AA_FILTER_TYPE_NR_BITS);
+	for (idx = 0; idx < ARRAY_SIZE(d3323aa_lp_filter_regval); ++idx) {
+		if (d3323aa_lp_filter_regval[idx] == regval)
+			break;
+	}
+
+	if (idx == ARRAY_SIZE(d3323aa_lp_filter_regval))
+		return -EINVAL;
+
+	*val = d3323aa_lp_filter_freq[idx][0];
+	*val2 = d3323aa_lp_filter_freq[idx][1];
+
+	return 0;
+}
+
+static int d3323aa_set_lp_filter_freq(unsigned long *regmap, const int val,
+				      int val2)
+{
+	size_t idx;
+
+	/* Truncate fractional part to one digit. */
+	val2 /= 100000;
+
+	for (idx = 0; idx < ARRAY_SIZE(d3323aa_lp_filter_freq); ++idx) {
+		int integer = d3323aa_lp_filter_freq[idx][0] /
+			      d3323aa_lp_filter_freq[idx][1];
+		int fract = d3323aa_lp_filter_freq[idx][0] %
+			    d3323aa_lp_filter_freq[idx][1];
+		if (val == integer && val2 == fract)
+			break;
+	}
+
+	if (idx == ARRAY_SIZE(d3323aa_lp_filter_freq))
+		return -ERANGE;
+
+	bitmap_write(regmap, d3323aa_lp_filter_regval[idx],
+		     D3323AA_REG_BIT_FILSEL0, D3323AA_FILTER_TYPE_NR_BITS);
+
+	return 0;
+}
+
+static int d3323aa_get_filter_gain(unsigned long *regmap, int *val)
+{
+	size_t idx;
+	u8 regval;
+
+	regval = bitmap_read(regmap, D3323AA_REG_BIT_FSTEP0,
+			     D3323AA_FILTER_GAIN_REG_NR_BITS);
+	for (idx = 0; idx < ARRAY_SIZE(d3323aa_filter_gain_regval); ++idx) {
+		if (d3323aa_filter_gain_regval[idx] == regval)
+			break;
+	}
+
+	if (idx == ARRAY_SIZE(d3323aa_filter_gain_regval))
+		return -EINVAL;
+
+	*val = d3323aa_filter_gain[idx];
+
+	return 0;
+}
+
+static int d3323aa_set_filter_gain(unsigned long *regmap, const int val)
+{
+	size_t idx;
+
+	for (idx = 0; idx < ARRAY_SIZE(d3323aa_filter_gain); ++idx) {
+		if (d3323aa_filter_gain[idx] == val)
+			break;
+	}
+
+	if (idx == ARRAY_SIZE(d3323aa_filter_gain))
+		return -ERANGE;
+
+	bitmap_write(regmap, d3323aa_filter_gain_regval[idx],
+		     D3323AA_REG_BIT_FSTEP0, D3323AA_FILTER_GAIN_REG_NR_BITS);
+
+	return 0;
+}
+
+static void d3323aa_get_threshold(unsigned long *regmap, int *val)
+{
+	*val = bitmap_read(regmap, D3323AA_REG_BIT_DETLVLABS0,
+			   D3323AA_THRESH_REG_NR_BITS);
+}
+
+static int d3323aa_set_threshold(unsigned long *regmap, const int val)
+{
+	if (val > ((1 << D3323AA_THRESH_REG_NR_BITS) - 1))
+		return -ERANGE;
+
+	bitmap_write(regmap, val, D3323AA_REG_BIT_DETLVLABS0,
+		     D3323AA_THRESH_REG_NR_BITS);
+
+	return 0;
+}
+
+static int d3323aa_read_avail(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      const int **vals, int *type, int *length,
+			      long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+		*vals = (int *)d3323aa_hp_filter_freq;
+		*type = IIO_VAL_FRACTIONAL;
+		*length = 2 * ARRAY_SIZE(d3323aa_hp_filter_freq);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		*vals = (int *)d3323aa_lp_filter_freq;
+		*type = IIO_VAL_FRACTIONAL;
+		*length = 2 * ARRAY_SIZE(d3323aa_lp_filter_freq);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		*vals = (int *)d3323aa_filter_gain;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(d3323aa_filter_gain);
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int d3323aa_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	int ret;
+
+	guard(mutex)(&data->regmap_lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+		ret = d3323aa_get_hp_filter_freq(data->regmap, val, val2);
+		if (ret)
+			return ret;
+		return IIO_VAL_FRACTIONAL;
+	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		ret = d3323aa_get_lp_filter_freq(data->regmap, val, val2);
+		if (ret)
+			return ret;
+		return IIO_VAL_FRACTIONAL;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		ret = d3323aa_get_filter_gain(data->regmap, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int d3323aa_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
+	int ret;
+
+	guard(mutex)(&data->regmap_lock);
+
+	bitmap_copy(regmap, data->regmap, D3323AA_REG_NR_BITS);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+		/*
+		 * We only allow to set the low-pass cutoff frequency, since
+		 * that is the only way to unambigously choose the type of
+		 * band-pass filter. For example, both filter type B and C have
+		 * 0.3 Hz as high-pass cutoff frequency (see
+		 * d3323aa_hp_filter_freq).
+		 */
+		return -EINVAL;
+	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		ret = d3323aa_set_lp_filter_freq(regmap, val, val2);
+		if (ret)
+			return ret;
+		break;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		ret = d3323aa_set_filter_gain(regmap, val);
+		if (ret)
+			return ret;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return d3323aa_setup(indio_dev, regmap);
+}
+
+static int d3323aa_read_event(struct iio_dev *indio_dev,
+			      const struct iio_chan_spec *chan,
+			      enum iio_event_type type,
+			      enum iio_event_direction dir,
+			      enum iio_event_info info, int *val, int *val2)
+{
+	struct d3323aa_data *data = iio_priv(indio_dev);
+
+	guard(mutex)(&data->regmap_lock);
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		d3323aa_get_threshold(data->regmap, val);
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int d3323aa_write_event(struct iio_dev *indio_dev,
+			       const struct iio_chan_spec *chan,
+			       enum iio_event_type type,
+			       enum iio_event_direction dir,
+			       enum iio_event_info info, int val, int val2)
+{
+	struct d3323aa_data *data = iio_priv(indio_dev);
+	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
+	int ret;
+
+	guard(mutex)(&data->regmap_lock);
+
+	bitmap_copy(regmap, data->regmap, D3323AA_REG_NR_BITS);
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		ret = d3323aa_set_threshold(regmap, val);
+		if (ret)
+			return ret;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return d3323aa_setup(indio_dev, regmap);
+}
+
+static const struct iio_info d3323aa_info = {
+	.read_avail = d3323aa_read_avail,
+	.read_raw = d3323aa_read_raw,
+	.write_raw = d3323aa_write_raw,
+	.read_event_value = d3323aa_read_event,
+	.write_event_value = d3323aa_write_event,
+};
+
+static const struct iio_event_spec d3323aa_event_spec[] = {
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_RISING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE),
+	},
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_FALLING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE),
+	},
+};
+
+static const struct iio_chan_spec d3323aa_channels[] = {
+	{
+		.type = IIO_PROXIMITY,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY) |
+			BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) |
+			BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+		.info_mask_separate_available =
+			BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY) |
+			BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) |
+			BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+		.event_spec = d3323aa_event_spec,
+		.num_event_specs = ARRAY_SIZE(d3323aa_event_spec),
+	},
+};
+
+static int d3323aa_probe(struct platform_device *pdev)
+{
+	DECLARE_BITMAP(default_regmap, D3323AA_REG_NR_BITS);
+	struct d3323aa_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
+	if (!indio_dev)
+		return dev_err_probe(&pdev->dev, -ENOMEM,
+				     "Could not allocate iio device\n");
+
+	data = iio_priv(indio_dev);
+	data->dev = &pdev->dev;
+	platform_set_drvdata(pdev, indio_dev);
+
+	init_completion(&data->reset_completion);
+
+	ret = devm_mutex_init(data->dev, &data->regmap_lock);
+	if (ret)
+		return dev_err_probe(data->dev, ret,
+				     "Could not initialize mutex (%d)\n", ret);
+
+	/* Request GPIOs. */
+	data->gpiod_vdd = devm_gpiod_get(data->dev, "vdd", GPIOD_OUT_LOW);
+	if (IS_ERR(data->gpiod_vdd))
+		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_vdd),
+				     "Could not get GPIO vdd (%ld)\n",
+				     PTR_ERR(data->gpiod_vdd));
+
+	data->gpiod_clk_vout =
+		devm_gpiod_get(data->dev, "clk-vout", GPIOD_OUT_LOW);
+	if (IS_ERR(data->gpiod_clk_vout))
+		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_clk_vout),
+				     "Could not get GPIO clk-vout (%ld)\n",
+				     PTR_ERR(data->gpiod_clk_vout));
+
+	data->gpiod_data = devm_gpiod_get(data->dev, "data", GPIOD_OUT_LOW);
+	if (IS_ERR(data->gpiod_data))
+		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_data),
+				     "Could not get GPIO data (%ld)\n",
+				     PTR_ERR(data->gpiod_data));
+
+	ret = gpiod_to_irq(data->gpiod_clk_vout);
+	if (ret < 0)
+		return dev_err_probe(data->dev, ret, "Could not get IRQ (%d)\n",
+				     ret);
+
+	data->irq = ret;
+
+	/* Do one setup with the default values. */
+	bitmap_zero(default_regmap, D3323AA_REG_NR_BITS);
+	d3323aa_set_threshold(default_regmap, D3323AA_THRESH_DEFAULT_VAL);
+	d3323aa_set_filter_gain(default_regmap,
+				D3323AA_FILTER_GAIN_DEFAULT_VAL);
+	ret = d3323aa_setup(indio_dev, default_regmap);
+	if (ret)
+		return ret;
+
+	indio_dev->info = &d3323aa_info;
+	indio_dev->name = D3323AA_DRV_NAME;
+	indio_dev->channels = d3323aa_channels;
+	indio_dev->num_channels = ARRAY_SIZE(d3323aa_channels);
+
+	ret = devm_iio_device_register(data->dev, indio_dev);
+	if (ret)
+		return dev_err_probe(data->dev, ret,
+				     "Could not register iio device (%d)\n",
+				     ret);
+
+	return 0;
+}
+
+static void d3323aa_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct d3323aa_data *data = iio_priv(indio_dev);
+
+	if (data->detecting)
+		free_irq(data->irq, indio_dev);
+}
+
+static const struct of_device_id d3323aa_of_match[] = {
+	{
+		.compatible = "nicera,d3323aa",
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, d3323aa_of_match);
+
+static struct platform_driver d3323aa_driver = {
+	.probe = d3323aa_probe,
+	.remove = d3323aa_remove,
+	.driver = {
+		.name = D3323AA_DRV_NAME,
+		.of_match_table = d3323aa_of_match,
+	},
+};
+module_platform_driver(d3323aa_driver);
+
+MODULE_AUTHOR("Waqar Hameed <waqar.hameed@axis.com>");
+MODULE_DESCRIPTION("Nicera D3-323-AA PIR sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.39.5

On Fri, 9 May 2025 17:03:03 +0200
Waqar Hameed <waqar.hameed@axis.com> wrote:

> Nicera D3-323-AA is a PIR sensor for human detection. It has support for
> raw data measurements and detection notification. The communication
> protocol is custom made and therefore needs to be GPIO bit banged.
> 
> The device has two main settings that can be configured: a threshold
> value for detection and a band-pass filter. The configurable parameters
> for the band-pass filter are the high-pass and low-pass cutoff
> frequencies and its peak gain. Map these settings to the corresponding
> parameters in the `iio` framework.
> 
> The low-pass and high-pass cutoff frequencies are pairwise for the
> different available filter types. Because of this, only allow to set the
> low-pass cutoff frequency from `sysfs` and use that to configure the
> corresponding high-pass cutoff frequency. This is sufficient to
> unambiguously choose a filter type.
> 
> Raw data measurements can be obtained from the device. However, since we
> rely on bit banging, it will be rather cumbersome with buffer support.
> The main reason being that the data protocol has strict timing
> requirements (it's serial like UART), and it's mainly used during
> debugging since in real-world applications only the event notification
> is of importance. Therefore, only add support for events (for now).
> 
> Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Hi Waqar,

Biggest suggestion in here is hide those bitmaps. They are of interest
only at point of reading and writing. I wouldn't use them for device state
elsewhere as they make for much less readable code than using simple
fields in iio_priv() for the state elements and building up the bitmaps
only where needed.

Jonathan

> diff --git a/drivers/iio/proximity/d3323aa.c b/drivers/iio/proximity/d3323aa.c
> new file mode 100644
> index 000000000000..fa08b52636ba
> --- /dev/null
> +++ b/drivers/iio/proximity/d3323aa.c
> @@ -0,0 +1,868 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Driver for Nicera D3-323-AA PIR sensor.
> + *
> + * Copyright (C) 2025 Axis Communications AB
> + */
> +
> +#include <linux/atomic.h>
> +#include <linux/bitmap.h>
> +#include <linux/cleanup.h>
> +#include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/jiffies.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +
> +#include <linux/iio/events.h>
> +#include <linux/iio/iio.h>
> +
> +#define D3323AA_DRV_NAME "d3323aa"

Put that inline where used.  A define like this both implies that various values
must be the same when they need not be and means that we have to go find the
define to fine out what they are set to.  Just setting the strings directly
tends to end up more readable.

> +
> +/*
> + * Register bitmap.
> + * For some reason the first bit is denoted as F37 in the datasheet, the second
> + * as F38 and so on. Note the gap between F60 and F64.
> + */
> +#define D3323AA_REG_BIT_SLAVEA1		0	/* F37. */
> +#define D3323AA_REG_BIT_SLAVEA2		1	/* F38. */
> +#define D3323AA_REG_BIT_SLAVEA3		2	/* F39. */
> +#define D3323AA_REG_BIT_SLAVEA4		3	/* F40. */
> +#define D3323AA_REG_BIT_SLAVEA5		4	/* F41. */
> +#define D3323AA_REG_BIT_SLAVEA6		5	/* F42. */
> +#define D3323AA_REG_BIT_SLAVEA7		6	/* F43. */
> +#define D3323AA_REG_BIT_SLAVEA8		7	/* F44. */
> +#define D3323AA_REG_BIT_SLAVEA9		8	/* F45. */
Perhaps these can be represented as masks using GENMASK() rather than
bits.  A lot of this will be hidden away if you follow suggesting to
only expose that you are using a bitmap to bitbang in the read/write
functions.

> +#define D3323AA_REG_BIT_SLAVEA10	9	/* F46. */
> +#define D3323AA_REG_BIT_DETLVLABS0	10	/* F47. */
> +#define D3323AA_REG_BIT_DETLVLABS1	11	/* F48. */
> +#define D3323AA_REG_BIT_DETLVLABS2	12	/* F49. */
> +#define D3323AA_REG_BIT_DETLVLABS3	13	/* F50. */
> +#define D3323AA_REG_BIT_DETLVLABS4	14	/* F51. */
> +#define D3323AA_REG_BIT_DETLVLABS5	15	/* F52. */
> +#define D3323AA_REG_BIT_DETLVLABS6	16	/* F53. */
> +#define D3323AA_REG_BIT_DETLVLABS7	17	/* F54. */
> +#define D3323AA_REG_BIT_DSLP		18	/* F55. */
> +#define D3323AA_REG_BIT_FSTEP0		19	/* F56. */
> +#define D3323AA_REG_BIT_FSTEP1		20	/* F57. */
> +#define D3323AA_REG_BIT_FILSEL0		21	/* F58. */
> +#define D3323AA_REG_BIT_FILSEL1		22	/* F59. */
> +#define D3323AA_REG_BIT_FILSEL2		23	/* F60. */
> +#define D3323AA_REG_BIT_FDSET		24	/* F64. */
> +#define D3323AA_REG_BIT_F65		25
> +#define D3323AA_REG_BIT_F87		(D3323AA_REG_BIT_F65 + (87 - 65))
> +
> +#define D3323AA_REG_NR_BITS (D3323AA_REG_BIT_F87 - D3323AA_REG_BIT_SLAVEA1 + 1)
> +#define D3323AA_THRESH_REG_NR_BITS                                             \
> +	(D3323AA_REG_BIT_DETLVLABS7 - D3323AA_REG_BIT_DETLVLABS0 + 1)
> +#define D3323AA_FILTER_TYPE_NR_BITS                                            \
> +	(D3323AA_REG_BIT_FILSEL2 - D3323AA_REG_BIT_FILSEL0 + 1)
> +#define D3323AA_FILTER_GAIN_REG_NR_BITS                                        \
> +	(D3323AA_REG_BIT_FSTEP1 - D3323AA_REG_BIT_FSTEP0 + 1)

> +/*
> + * High-pass filter cutoff frequency for the band-pass filter. There is a
> + * corresponding low-pass cutoff frequency for each of the filter types
> + * (denoted A, B, C and D in the datasheet). The index in this array matches
> + * that corresponding value in d3323aa_lp_filter_freq.
> + * Note that this represents a fractional value (e.g. the first value
> + * corresponds to 4 / 10 = 0.4 Hz).
> + */
> +static const int d3323aa_hp_filter_freq[][2] = {
> +	{ 4, 10 },
> +	{ 3, 10 },
> +	{ 3, 10 },
> +	{ 1, 100 },
> +};
> +
> +/*
> + * Low-pass filter cutoff frequency for the band-pass filter. There is a
> + * corresponding high-pass cutoff frequency for each of the filter types
> + * (denoted A, B, C and D in the datasheet). The index in this array matches
> + * that corresponding value in d3323aa_hp_filter_freq.
> + * Note that this represents a fractional value (e.g. the first value
> + * corresponds to 27 / 10 = 2.7 Hz).
> + */
> +static const int d3323aa_lp_filter_freq[][2] = {
> +	{ 27, 10 },
> +	{ 15, 10 },
> +	{ 5, 1 },
> +	{ 100, 1 },
> +};
> +
> +/*
> + * Register bitmap values for filter types (denoted A, B, C and D in the
> + * datasheet). The index in this array matches the corresponding value in
> + * d3323aa_lp_filter_freq (which in turn matches d3323aa_hp_filter_freq). For
> + * example, the first value 7 corresponds to 2.7 Hz low-pass and 0.4 Hz
> + * high-pass cutoff frequency.
> + */
> +static const int d3323aa_lp_filter_regval[] = {
> +	7,
> +	0,
> +	1,
> +	2,
> +};
> +
> +/*
> + * This is denoted as "step" in datasheet and corresponds to the gain at peak
> + * for the band-pass filter. The index in this array is the corresponding index
> + * in d3323aa_filter_gain_regval for the register bitmap value.
> + */
> +static const int d3323aa_filter_gain[] = {
> +	1,
> +	2,
> +	3,
> +};
	1, 2, 3,
is fine for such a short list.

> +
> +/*
> + * Register bitmap values for the filter gain. The index in this array is the
> + * corresponding index in d3323aa_filter_gain for the gain value.
> + */
> +static const u8 d3323aa_filter_gain_regval[] = {
> +	1,
> +	3,
> +	0,
> +};
> +
> +struct d3323aa_data {
> +	struct completion reset_completion;
> +	/*
> +	 *  Since the setup process always requires a complete write of the
> +	 *  _whole_ register bitmap, we need to synchronize it with a lock.
> +	 */
> +	struct mutex regmap_lock;
> +	atomic_t irq_reset_count;
> +	unsigned int irq;
> +
> +	struct device *dev;
> +
> +	/* Supply voltage. */
> +	struct gpio_desc *gpiod_vdd;
> +	/* Input clock or output detection signal (Vout). */

I'd rename. Vout kind of suggests a variable voltage. This seems to just
be a level signal.

> +	struct gpio_desc *gpiod_clk_vout;
> +	/* Input (setting) or output data. */
> +	struct gpio_desc *gpiod_data;
> +
> +	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
> +
> +	/*
> +	 * Indicator for operational mode (configuring or detecting), i.e.
> +	 * d3323aa_irq_detection() registered or not.
> +	 */
> +	bool detecting;
> +};
> +
> +static int d3323aa_read_settings(struct iio_dev *indio_dev,
> +				 unsigned long *regmap)
> +{
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	size_t i;
> +	int ret;
> +
> +	/* Bit bang the clock and data pins. */
> +	ret = gpiod_direction_output(data->gpiod_clk_vout, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = gpiod_direction_input(data->gpiod_data);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(data->dev, "Reading settings...\n");
> +
> +	for (i = 0; i < D3323AA_REG_NR_BITS; ++i) {
> +		/* Clock frequency needs to be 1 kHz. */
> +		gpiod_set_value(data->gpiod_clk_vout, 1);
> +		udelay(500);
> +
> +		/* The data seems to change when clock signal is high. */
> +		if (gpiod_get_value(data->gpiod_data))
> +			set_bit(i, regmap);
> +
> +		gpiod_set_value(data->gpiod_clk_vout, 0);
> +		udelay(500);
> +	}
> +
> +	/* The first bit (F37) is just dummy data. Discard it. */
> +	clear_bit(0, regmap);
> +
> +	/* Datasheet says to wait 30 ms after reading the settings. */
> +	msleep(30);
> +
> +	return 0;
> +}
> +
> +static int d3323aa_write_settings(struct iio_dev *indio_dev,
> +				  const unsigned long *regmap)

Rename regmap. regmap means some specific stuff in the kernel register_bm or something
like that avoids that potential confusion.

However, it would be much easier to read this driver if only this
function and the read one knew about the bitmap stuff.  Inside the reset
of the driver just store and pass around a structure with the various fields.
Then in here use that to build up the bitmap locally and write to the device.
The opposite in read which decodes the bitmap into those fields.

That will make for a more standard and easier to review driver.

> +{
> +	DECLARE_BITMAP(end_pattern, D3323AA_SETTING_END_PATTERN_NR_BITS);
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	size_t i;
> +	int ret;
> +
> +	/* Bit bang the clock and data pins. */
> +	ret = gpiod_direction_output(data->gpiod_clk_vout, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = gpiod_direction_output(data->gpiod_data, 0);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(data->dev, "Writing settings...\n");
> +
> +	/* First bit (F37) is not used when writing the register map. */
> +	for (i = 1; i < D3323AA_REG_NR_BITS; ++i) {
> +		gpiod_set_value(data->gpiod_data, test_bit(i, regmap));
> +
> +		/* Clock frequency needs to be 1 kHz. */
> +		gpiod_set_value(data->gpiod_clk_vout, 1);
> +		udelay(500);
> +		gpiod_set_value(data->gpiod_clk_vout, 0);
> +		udelay(500);
> +	}
> +
> +	/* Compulsory end pattern. */
> +	bitmap_write(end_pattern, D3323AA_SETTING_END_PATTERN, 0,
> +		     D3323AA_SETTING_END_PATTERN_NR_BITS);
 
Why not use a larger bitmap with padding for this end pattern
and just write this into that?  At which point this can all be one loop.

> +	for (i = 0; i < D3323AA_SETTING_END_PATTERN_NR_BITS; ++i) {
> +		gpiod_set_value(data->gpiod_data, test_bit(i, end_pattern));
> +
> +		gpiod_set_value(data->gpiod_clk_vout, 1);
> +		udelay(500);
> +		gpiod_set_value(data->gpiod_clk_vout, 0);
> +		udelay(500);
> +	}
> +
> +	/* Datasheet says to wait 30 ms after writing the settings. */
> +	msleep(30);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t d3323aa_irq_detection(int irq, void *dev_id)
> +{
> +	struct iio_dev *indio_dev = dev_id;
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	enum iio_event_direction dir;
> +	int val;
> +
> +	val = gpiod_get_value(data->gpiod_clk_vout);

Ideally I'd like a setup where we can wire the interrupt side of this
to one pin and the gpio needed for writing to another.  In practice
they may well be the same pin but that does introduced a bunch of races
and dependency on what the interrupt controller does when an irq
is disabled.

Using one pin as an irq and as a data line is prone to some nasty
corner cases though it works on some SoCs.


> +	if (val < 0) {
> +		dev_err_ratelimited(data->dev,
> +				    "Could not read from GPIO clk-vout (%d)\n",
> +				    val);
> +		return IRQ_HANDLED;
> +	}
> +
> +	dir = val ? IIO_EV_DIR_RISING : IIO_EV_DIR_FALLING;
> +	iio_push_event(indio_dev,
> +		       IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
> +					    IIO_EV_TYPE_THRESH, dir),
> +		       iio_get_time_ns(indio_dev));
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t d3323aa_irq_reset(int irq, void *dev_id)
> +{
> +	struct iio_dev *indio_dev = dev_id;
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	int count = atomic_inc_return(&data->irq_reset_count);
> +

As below. It should be easy enough to have a unified handler and avoid
the need to unregister / reregister the irq.

> +	if (count == D3323AA_IRQ_RESET_COUNT)
> +		complete(&data->reset_completion);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int d3323aa_reset(struct iio_dev *indio_dev)
> +{
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	long time;
> +	int ret;
> +
> +	/*
> +	 * Datasheet says VDD needs to be low at least for 30 ms. Let's add a
> +	 * couple more to allow VDD to completely discharge as well.
> +	 */
> +	gpiod_set_value(data->gpiod_vdd, 0);
> +	msleep(30 + 5);
> +
> +	/*
> +	 * After setting VDD to high, the device signals with
> +	 * D3323AA_IRQ_RESET_COUNT falling edges on CLK/Vout that it is now
> +	 * ready for configuration. Datasheet says that this should happen
> +	 * within D3323AA_RESET_TIMEOUT ms. Count these two edges within that
> +	 * timeout.
> +	 */
> +	atomic_set(&data->irq_reset_count, 0);
> +	reinit_completion(&data->reset_completion);
> +
> +	ret = gpiod_direction_input(data->gpiod_clk_vout);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(data->dev, "Resetting...\n");
> +
> +	gpiod_set_value(data->gpiod_vdd, 1);
> +
> +	/*
> +	 * Datasheet doesn't mention this but measurements have shown that
> +	 * CLK/Vout signal slowly ramps up during the first 1.5 ms after reset.
> +	 * This means that the digital signal will have bogus values during this
> +	 * period. Let's wait for this ramp-up before counting the "real"
> +	 * falling edges.
> +	 */
> +	usleep_range(2000, 5000);
> +
> +	if (data->detecting) {
> +		/*
> +		 * Device had previously been set up and was in operational
> +		 * mode. Thus, free that detection IRQ handler before requesting
> +		 * the reset IRQ handler.
> +		 */
> +		free_irq(data->irq, indio_dev);
> +		data->detecting = false;
> +	}
> +
> +	ret = request_irq(data->irq, d3323aa_irq_reset, IRQF_TRIGGER_FALLING,
> +			  dev_name(data->dev), indio_dev);

Can you keep to a single handler with a check on device state?  This
dance with releasing and requesting irqs is rather complex when all you need
to know is what the irq means and that is state the driver knows.


> +	if (ret)
> +		return ret;
> +
> +	time = wait_for_completion_killable_timeout(
> +		&data->reset_completion,
> +		msecs_to_jiffies(D3323AA_RESET_TIMEOUT));
> +	free_irq(data->irq, indio_dev);
> +	if (time == 0) {
> +		return -ETIMEDOUT;
> +	} else if (time < 0) {
> +		/* Got interrupted. */
> +		return time;
> +	}
> +
> +	dev_dbg(data->dev, "Reset completed\n");
> +
> +	return 0;
> +}
> +
> +static int d3323aa_setup(struct iio_dev *indio_dev, const unsigned long *regmap)
> +{
> +	DECLARE_BITMAP(read_regmap, D3323AA_REG_NR_BITS);
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	unsigned long start_time;
> +	int ret;
> +
> +	ret = d3323aa_reset(indio_dev);
> +	if (ret) {
> +		if (ret != -ERESTARTSYS)
> +			dev_err(data->dev, "Could not reset device (%d)\n",
> +				ret);
> +
> +		return ret;
> +	}
> +
> +	/*
> +	 * Datasheet says to wait 10 us before setting the configuration.
> +	 * Moreover, the total configuration should be done within
> +	 * D3323AA_CONFIG_TIMEOUT ms. Clock it.
> +	 */
> +	usleep_range(10, 20);
> +	start_time = jiffies;
> +
> +	ret = d3323aa_write_settings(indio_dev, regmap);
> +	if (ret) {
> +		dev_err(data->dev, "Could not write settings (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	ret = d3323aa_read_settings(indio_dev, read_regmap);
> +	if (ret) {
> +		dev_err(data->dev, "Could not read settings (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	if (time_is_before_jiffies(start_time +
> +				   msecs_to_jiffies(D3323AA_CONFIG_TIMEOUT))) {
> +		dev_err(data->dev, "Could not set up configuration in time\n");
> +		return -EAGAIN;
> +	}
> +
> +	/* Check if settings were set successfully. */
> +	if (!bitmap_equal(regmap, read_regmap, D3323AA_REG_NR_BITS)) {
> +		dev_err(data->dev, "Settings data mismatch\n");
> +		return -EIO;
> +	}
> +
> +	/* Now in operational mode. */
> +	ret = gpiod_direction_input(data->gpiod_clk_vout);
> +	if (ret) {
> +		dev_err(data->dev,
> +			"Could not set GPIO clk-vout as input (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	ret = gpiod_direction_input(data->gpiod_data);
> +	if (ret) {
> +		dev_err(data->dev, "Could not set GPIO data as input (%d)\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	ret = request_irq(data->irq, d3323aa_irq_detection,
> +			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,

Why both ways?  Add a comment.

> +			  dev_name(data->dev), indio_dev);
> +	if (ret) {
> +		dev_err(data->dev, "Could not request IRQ for detection (%d)\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	bitmap_copy(data->regmap, regmap, D3323AA_REG_NR_BITS);
> +	data->detecting = true;
> +
> +	dev_dbg(data->dev, "Setup done\n");
> +
> +	return 0;
> +}

> +
> +static int d3323aa_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan, int val,
> +			     int val2, long mask)
> +{
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
> +	int ret;
> +
> +	guard(mutex)(&data->regmap_lock);
> +
> +	bitmap_copy(regmap, data->regmap, D3323AA_REG_NR_BITS);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> +		/*
> +		 * We only allow to set the low-pass cutoff frequency, since
> +		 * that is the only way to unambigously choose the type of
> +		 * band-pass filter. For example, both filter type B and C have
> +		 * 0.3 Hz as high-pass cutoff frequency (see
> +		 * d3323aa_hp_filter_freq).

This is somewhat unintiutive userspace inteface.  I'd try and do the best
possible in response to a userspace request.  So if the lp frequency is
already set to one of the values that matches requested hp then use that.
If it's not then pick the one that has best match lp (so nearest) on
assumption userspace is probably about to update the lp side anyway.

Slight fiddlier code than you have here, but a better attempt to figure
out what the users is after than rejecting writes.

> +		 */
> +		return -EINVAL;
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		ret = d3323aa_set_lp_filter_freq(regmap, val, val2);
> +		if (ret)
> +			return ret;
> +		break;
> +	case IIO_CHAN_INFO_HARDWAREGAIN:
> +		ret = d3323aa_set_filter_gain(regmap, val);
> +		if (ret)
> +			return ret;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return d3323aa_setup(indio_dev, regmap);

I'd bury this call in set_lp_filter() and set_fillter_gain() so they
actually do the setting.

> +}

> +
> +static int d3323aa_probe(struct platform_device *pdev)
> +{
> +	DECLARE_BITMAP(default_regmap, D3323AA_REG_NR_BITS);
> +	struct d3323aa_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return dev_err_probe(&pdev->dev, -ENOMEM,
> +				     "Could not allocate iio device\n");
> +
> +	data = iio_priv(indio_dev);
> +	data->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, indio_dev);

Should be unnecessary with the suggested change below.


> +
> +	init_completion(&data->reset_completion);
> +
> +	ret = devm_mutex_init(data->dev, &data->regmap_lock);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret,
> +				     "Could not initialize mutex (%d)\n", ret);

As already pointed out in other review - look at what dev_err_probe()
does.

> +
> +	/* Request GPIOs. */

This sort of code structure comment adds nothing useful. We can see
you are requesting gpios from the code.  As such, all it can do is
become wrong in future if code is reorganised.  Hence drop the comment.

> +	data->gpiod_vdd = devm_gpiod_get(data->dev, "vdd", GPIOD_OUT_LOW);

This seems to be a supply, not a gpio.  Use the regulator framework.
Make sure to request exclusive use though so you can turn it on and off.
_get_exclusive() etc should ensure no one else is using it.


> +	if (IS_ERR(data->gpiod_vdd))
> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_vdd),
> +				     "Could not get GPIO vdd (%ld)\n",
> +				     PTR_ERR(data->gpiod_vdd));
> +
> +	data->gpiod_clk_vout =
> +		devm_gpiod_get(data->dev, "clk-vout", GPIOD_OUT_LOW);
> +	if (IS_ERR(data->gpiod_clk_vout))
> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_clk_vout),
> +				     "Could not get GPIO clk-vout (%ld)\n",
> +				     PTR_ERR(data->gpiod_clk_vout));
> +
> +	data->gpiod_data = devm_gpiod_get(data->dev, "data", GPIOD_OUT_LOW);
> +	if (IS_ERR(data->gpiod_data))
> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_data),
> +				     "Could not get GPIO data (%ld)\n",
> +				     PTR_ERR(data->gpiod_data));
> +
> +	ret = gpiod_to_irq(data->gpiod_clk_vout);
> +	if (ret < 0)
> +		return dev_err_probe(data->dev, ret, "Could not get IRQ (%d)\n",
> +				     ret);
> +
> +	data->irq = ret;
> +
> +	/* Do one setup with the default values. */
> +	bitmap_zero(default_regmap, D3323AA_REG_NR_BITS);
> +	d3323aa_set_threshold(default_regmap, D3323AA_THRESH_DEFAULT_VAL);
> +	d3323aa_set_filter_gain(default_regmap,
> +				D3323AA_FILTER_GAIN_DEFAULT_VAL);
> +	ret = d3323aa_setup(indio_dev, default_regmap);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->info = &d3323aa_info;
> +	indio_dev->name = D3323AA_DRV_NAME
> +	indio_dev->channels = d3323aa_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(d3323aa_channels);
> +
> +	ret = devm_iio_device_register(data->dev, indio_dev);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret,
> +				     "Could not register iio device (%d)\n",
> +				     ret);
> +
> +	return 0;
> +}
> +
> +static void d3323aa_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct d3323aa_data *data = iio_priv(indio_dev);
> +
> +	if (data->detecting)
> +		free_irq(data->irq, indio_dev);

So this is an ordering mess.  You should never mix devm handling and
non devm handling - once something happens in probe that is non devm
you stop using devm_* from that point on.

The irq handling in here is complex, but not on fast paths. As such I'd
do devm_irq_request() and if you need to free it do so with devm_free_irq()
in the places where you immediately re request it.  However see above.
That should allow you to to drop this remove callabck.

> +}
> +
> +static const struct of_device_id d3323aa_of_match[] = {
> +	{
> +		.compatible = "nicera,d3323aa",
> +	},
> +	{}
	{ }

Is now standard format for these in IIO.

> +};
> +MODULE_DEVICE_TABLE(of, d3323aa_of_match);
> +
> +static struct platform_driver d3323aa_driver = {
> +	.probe = d3323aa_probe,
> +	.remove = d3323aa_remove,
> +	.driver = {
> +		.name = D3323AA_DRV_NAME,
> +		.of_match_table = d3323aa_of_match,
> +	},
> +};
> +module_platform_driver(d3323aa_driver);
> +
> +MODULE_AUTHOR("Waqar Hameed <waqar.hameed@axis.com>");
> +MODULE_DESCRIPTION("Nicera D3-323-AA PIR sensor driver");
> +MODULE_LICENSE("GPL");

On Sun, May 11, 2025 at 13:14 +0100 Jonathan Cameron <jic23@kernel.org> wrote:

[...]

> Hi Waqar,
>
> Biggest suggestion in here is hide those bitmaps. They are of interest
> only at point of reading and writing. I wouldn't use them for device state
> elsewhere as they make for much less readable code than using simple
> fields in iio_priv() for the state elements and building up the bitmaps
> only where needed.

Hi Jonathan!

Thank you for thorough (as usual) review!

[...]

>> +#define D3323AA_DRV_NAME "d3323aa"
>
> Put that inline where used.  A define like this both implies that various values
> must be the same when they need not be and means that we have to go find the
> define to fine out what they are set to.  Just setting the strings directly
> tends to end up more readable.

Sure, we can do that. (There are a bunch of IIO-drivers doing this, so I
just thought that was the "convention".)

>> +
>> +/*
>> + * Register bitmap.
>> + * For some reason the first bit is denoted as F37 in the datasheet, the second
>> + * as F38 and so on. Note the gap between F60 and F64.
>> + */
>> +#define D3323AA_REG_BIT_SLAVEA1		0	/* F37. */
>> +#define D3323AA_REG_BIT_SLAVEA2		1	/* F38. */
>> +#define D3323AA_REG_BIT_SLAVEA3		2	/* F39. */
>> +#define D3323AA_REG_BIT_SLAVEA4		3	/* F40. */
>> +#define D3323AA_REG_BIT_SLAVEA5		4	/* F41. */
>> +#define D3323AA_REG_BIT_SLAVEA6		5	/* F42. */
>> +#define D3323AA_REG_BIT_SLAVEA7		6	/* F43. */
>> +#define D3323AA_REG_BIT_SLAVEA8		7	/* F44. */
>> +#define D3323AA_REG_BIT_SLAVEA9		8	/* F45. */
> Perhaps these can be represented as masks using GENMASK() rather than
> bits.  A lot of this will be hidden away if you follow suggesting to
> only expose that you are using a bitmap to bitbang in the read/write
> functions.

Yes, that would be the natural thing to do when moving the bitmap stuff
to the read/write functions (as answered below).

[...]

>> +/*
>> + * This is denoted as "step" in datasheet and corresponds to the gain at peak
>> + * for the band-pass filter. The index in this array is the corresponding index
>> + * in d3323aa_filter_gain_regval for the register bitmap value.
>> + */
>> +static const int d3323aa_filter_gain[] = {
>> +	1,
>> +	2,
>> +	3,
>> +};
> 	1, 2, 3,
> is fine for such a short list.

Sure, I'll change the corresponding array below as well then.

>> +
>> +/*
>> + * Register bitmap values for the filter gain. The index in this array is the
>> + * corresponding index in d3323aa_filter_gain for the gain value.
>> + */
>> +static const u8 d3323aa_filter_gain_regval[] = {
>> +	1,
>> +	3,
>> +	0,
>> +};
>> +
>> +struct d3323aa_data {
>> +	struct completion reset_completion;
>> +	/*
>> +	 *  Since the setup process always requires a complete write of the
>> +	 *  _whole_ register bitmap, we need to synchronize it with a lock.
>> +	 */
>> +	struct mutex regmap_lock;
>> +	atomic_t irq_reset_count;
>> +	unsigned int irq;
>> +
>> +	struct device *dev;
>> +
>> +	/* Supply voltage. */
>> +	struct gpio_desc *gpiod_vdd;
>> +	/* Input clock or output detection signal (Vout). */
>
> I'd rename. Vout kind of suggests a variable voltage. This seems to just
> be a level signal.

>> +	struct gpio_desc *gpiod_clk_vout;

Yeah, it's a weird pin with multiple use-cases... I just named it
according to what the datasheet calls it. What about
`gpiod_clk_detection`?

>> +	/* Input (setting) or output data. */
>> +	struct gpio_desc *gpiod_data;
>> +
>> +	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
>> +
>> +	/*
>> +	 * Indicator for operational mode (configuring or detecting), i.e.
>> +	 * d3323aa_irq_detection() registered or not.
>> +	 */
>> +	bool detecting;
>> +};
>> +
>> +static int d3323aa_read_settings(struct iio_dev *indio_dev,
>> +				 unsigned long *regmap)
>> +{
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	size_t i;
>> +	int ret;
>> +
>> +	/* Bit bang the clock and data pins. */
>> +	ret = gpiod_direction_output(data->gpiod_clk_vout, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = gpiod_direction_input(data->gpiod_data);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_dbg(data->dev, "Reading settings...\n");
>> +
>> +	for (i = 0; i < D3323AA_REG_NR_BITS; ++i) {
>> +		/* Clock frequency needs to be 1 kHz. */
>> +		gpiod_set_value(data->gpiod_clk_vout, 1);
>> +		udelay(500);
>> +
>> +		/* The data seems to change when clock signal is high. */
>> +		if (gpiod_get_value(data->gpiod_data))
>> +			set_bit(i, regmap);
>> +
>> +		gpiod_set_value(data->gpiod_clk_vout, 0);
>> +		udelay(500);
>> +	}
>> +
>> +	/* The first bit (F37) is just dummy data. Discard it. */
>> +	clear_bit(0, regmap);
>> +
>> +	/* Datasheet says to wait 30 ms after reading the settings. */
>> +	msleep(30);
>> +
>> +	return 0;
>> +}
>> +
>> +static int d3323aa_write_settings(struct iio_dev *indio_dev,
>> +				  const unsigned long *regmap)
>
> Rename regmap. regmap means some specific stuff in the kernel register_bm or something
> like that avoids that potential confusion.
>
> However, it would be much easier to read this driver if only this
> function and the read one knew about the bitmap stuff.  Inside the reset
> of the driver just store and pass around a structure with the various fields.
> Then in here use that to build up the bitmap locally and write to the device.
> The opposite in read which decodes the bitmap into those fields.
>
> That will make for a more standard and easier to review driver.

Hm, maybe it would be easier to understand it if we remove the bitmap
from `struct d3323aa_data` and instead only store the relevant state
variables. We still would need to have the `regmap_lock` but to instead
protect all of the variables.

Let's go for that then! I actually don't have any strong arguments (or
opinions) against it.

>> +{
>> +	DECLARE_BITMAP(end_pattern, D3323AA_SETTING_END_PATTERN_NR_BITS);
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	size_t i;
>> +	int ret;
>> +
>> +	/* Bit bang the clock and data pins. */
>> +	ret = gpiod_direction_output(data->gpiod_clk_vout, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = gpiod_direction_output(data->gpiod_data, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_dbg(data->dev, "Writing settings...\n");
>> +
>> +	/* First bit (F37) is not used when writing the register map. */
>> +	for (i = 1; i < D3323AA_REG_NR_BITS; ++i) {
>> +		gpiod_set_value(data->gpiod_data, test_bit(i, regmap));
>> +
>> +		/* Clock frequency needs to be 1 kHz. */
>> +		gpiod_set_value(data->gpiod_clk_vout, 1);
>> +		udelay(500);
>> +		gpiod_set_value(data->gpiod_clk_vout, 0);
>> +		udelay(500);
>> +	}
>> +
>> +	/* Compulsory end pattern. */
>> +	bitmap_write(end_pattern, D3323AA_SETTING_END_PATTERN, 0,
>> +		     D3323AA_SETTING_END_PATTERN_NR_BITS);
>  
> Why not use a larger bitmap with padding for this end pattern
> and just write this into that?  At which point this can all be one loop.

Will do! It will be natural to do that after moving the bitmap stuff and
only scope it here.

>> +	for (i = 0; i < D3323AA_SETTING_END_PATTERN_NR_BITS; ++i) {
>> +		gpiod_set_value(data->gpiod_data, test_bit(i, end_pattern));
>> +
>> +		gpiod_set_value(data->gpiod_clk_vout, 1);
>> +		udelay(500);
>> +		gpiod_set_value(data->gpiod_clk_vout, 0);
>> +		udelay(500);
>> +	}
>> +
>> +	/* Datasheet says to wait 30 ms after writing the settings. */
>> +	msleep(30);
>> +
>> +	return 0;
>> +}
>> +
>> +static irqreturn_t d3323aa_irq_detection(int irq, void *dev_id)
>> +{
>> +	struct iio_dev *indio_dev = dev_id;
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	enum iio_event_direction dir;
>> +	int val;
>> +
>> +	val = gpiod_get_value(data->gpiod_clk_vout);
>
> Ideally I'd like a setup where we can wire the interrupt side of this
> to one pin and the gpio needed for writing to another.  In practice
> they may well be the same pin but that does introduced a bunch of races
> and dependency on what the interrupt controller does when an irq
> is disabled.
>
> Using one pin as an irq and as a data line is prone to some nasty
> corner cases though it works on some SoCs.

Hm, that's an interesting idea. However, as you say there might then be
other issues to take care of.

On the other hand, the scope of the clock bit bang is quite small (only in
`*read/write_settings()`). So I guess we just leave it then?

>
>
>> +	if (val < 0) {
>> +		dev_err_ratelimited(data->dev,
>> +				    "Could not read from GPIO clk-vout (%d)\n",
>> +				    val);
>> +		return IRQ_HANDLED;
>> +	}
>> +
>> +	dir = val ? IIO_EV_DIR_RISING : IIO_EV_DIR_FALLING;
>> +	iio_push_event(indio_dev,
>> +		       IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
>> +					    IIO_EV_TYPE_THRESH, dir),
>> +		       iio_get_time_ns(indio_dev));
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t d3323aa_irq_reset(int irq, void *dev_id)
>> +{
>> +	struct iio_dev *indio_dev = dev_id;
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	int count = atomic_inc_return(&data->irq_reset_count);
>> +
>
> As below. It should be easy enough to have a unified handler and avoid
> the need to unregister / reregister the irq.

Alright (see longer response below).

>> +	if (count == D3323AA_IRQ_RESET_COUNT)
>> +		complete(&data->reset_completion);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int d3323aa_reset(struct iio_dev *indio_dev)
>> +{
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	long time;
>> +	int ret;
>> +
>> +	/*
>> +	 * Datasheet says VDD needs to be low at least for 30 ms. Let's add a
>> +	 * couple more to allow VDD to completely discharge as well.
>> +	 */
>> +	gpiod_set_value(data->gpiod_vdd, 0);
>> +	msleep(30 + 5);
>> +
>> +	/*
>> +	 * After setting VDD to high, the device signals with
>> +	 * D3323AA_IRQ_RESET_COUNT falling edges on CLK/Vout that it is now
>> +	 * ready for configuration. Datasheet says that this should happen
>> +	 * within D3323AA_RESET_TIMEOUT ms. Count these two edges within that
>> +	 * timeout.
>> +	 */
>> +	atomic_set(&data->irq_reset_count, 0);
>> +	reinit_completion(&data->reset_completion);
>> +
>> +	ret = gpiod_direction_input(data->gpiod_clk_vout);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_dbg(data->dev, "Resetting...\n");
>> +
>> +	gpiod_set_value(data->gpiod_vdd, 1);
>> +
>> +	/*
>> +	 * Datasheet doesn't mention this but measurements have shown that
>> +	 * CLK/Vout signal slowly ramps up during the first 1.5 ms after reset.
>> +	 * This means that the digital signal will have bogus values during this
>> +	 * period. Let's wait for this ramp-up before counting the "real"
>> +	 * falling edges.
>> +	 */
>> +	usleep_range(2000, 5000);
>> +
>> +	if (data->detecting) {
>> +		/*
>> +		 * Device had previously been set up and was in operational
>> +		 * mode. Thus, free that detection IRQ handler before requesting
>> +		 * the reset IRQ handler.
>> +		 */
>> +		free_irq(data->irq, indio_dev);
>> +		data->detecting = false;
>> +	}
>> +
>> +	ret = request_irq(data->irq, d3323aa_irq_reset, IRQF_TRIGGER_FALLING,
>> +			  dev_name(data->dev), indio_dev);
>
> Can you keep to a single handler with a check on device state?  This
> dance with releasing and requesting irqs is rather complex when all you need
> to know is what the irq means and that is state the driver knows.

We can do that. Ironically, I opted for separating them just for the
sake of simplicity, and thought it would be easier to understand this
way :)

>> +	if (ret)
>> +		return ret;
>> +
>> +	time = wait_for_completion_killable_timeout(
>> +		&data->reset_completion,
>> +		msecs_to_jiffies(D3323AA_RESET_TIMEOUT));
>> +	free_irq(data->irq, indio_dev);
>> +	if (time == 0) {
>> +		return -ETIMEDOUT;
>> +	} else if (time < 0) {
>> +		/* Got interrupted. */
>> +		return time;
>> +	}
>> +
>> +	dev_dbg(data->dev, "Reset completed\n");
>> +
>> +	return 0;
>> +}
>> +
>> +static int d3323aa_setup(struct iio_dev *indio_dev, const unsigned long *regmap)
>> +{
>> +	DECLARE_BITMAP(read_regmap, D3323AA_REG_NR_BITS);
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	unsigned long start_time;
>> +	int ret;
>> +
>> +	ret = d3323aa_reset(indio_dev);
>> +	if (ret) {
>> +		if (ret != -ERESTARTSYS)
>> +			dev_err(data->dev, "Could not reset device (%d)\n",
>> +				ret);
>> +
>> +		return ret;
>> +	}
>> +
>> +	/*
>> +	 * Datasheet says to wait 10 us before setting the configuration.
>> +	 * Moreover, the total configuration should be done within
>> +	 * D3323AA_CONFIG_TIMEOUT ms. Clock it.
>> +	 */
>> +	usleep_range(10, 20);
>> +	start_time = jiffies;
>> +
>> +	ret = d3323aa_write_settings(indio_dev, regmap);
>> +	if (ret) {
>> +		dev_err(data->dev, "Could not write settings (%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = d3323aa_read_settings(indio_dev, read_regmap);
>> +	if (ret) {
>> +		dev_err(data->dev, "Could not read settings (%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	if (time_is_before_jiffies(start_time +
>> +				   msecs_to_jiffies(D3323AA_CONFIG_TIMEOUT))) {
>> +		dev_err(data->dev, "Could not set up configuration in time\n");
>> +		return -EAGAIN;
>> +	}
>> +
>> +	/* Check if settings were set successfully. */
>> +	if (!bitmap_equal(regmap, read_regmap, D3323AA_REG_NR_BITS)) {
>> +		dev_err(data->dev, "Settings data mismatch\n");
>> +		return -EIO;
>> +	}
>> +
>> +	/* Now in operational mode. */
>> +	ret = gpiod_direction_input(data->gpiod_clk_vout);
>> +	if (ret) {
>> +		dev_err(data->dev,
>> +			"Could not set GPIO clk-vout as input (%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = gpiod_direction_input(data->gpiod_data);
>> +	if (ret) {
>> +		dev_err(data->dev, "Could not set GPIO data as input (%d)\n",
>> +			ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = request_irq(data->irq, d3323aa_irq_detection,
>> +			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
>
> Why both ways?  Add a comment.

Good point! I'll add a comment.

>
>> +			  dev_name(data->dev), indio_dev);
>> +	if (ret) {
>> +		dev_err(data->dev, "Could not request IRQ for detection (%d)\n",
>> +			ret);
>> +		return ret;
>> +	}
>> +
>> +	bitmap_copy(data->regmap, regmap, D3323AA_REG_NR_BITS);
>> +	data->detecting = true;
>> +
>> +	dev_dbg(data->dev, "Setup done\n");
>> +
>> +	return 0;
>> +}
>
>> +
>> +static int d3323aa_write_raw(struct iio_dev *indio_dev,
>> +			     struct iio_chan_spec const *chan, int val,
>> +			     int val2, long mask)
>> +{
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +	DECLARE_BITMAP(regmap, D3323AA_REG_NR_BITS);
>> +	int ret;
>> +
>> +	guard(mutex)(&data->regmap_lock);
>> +
>> +	bitmap_copy(regmap, data->regmap, D3323AA_REG_NR_BITS);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
>> +		/*
>> +		 * We only allow to set the low-pass cutoff frequency, since
>> +		 * that is the only way to unambigously choose the type of
>> +		 * band-pass filter. For example, both filter type B and C have
>> +		 * 0.3 Hz as high-pass cutoff frequency (see
>> +		 * d3323aa_hp_filter_freq).
>
> This is somewhat unintiutive userspace inteface.  I'd try and do the best
> possible in response to a userspace request.  So if the lp frequency is
> already set to one of the values that matches requested hp then use that.
> If it's not then pick the one that has best match lp (so nearest) on
> assumption userspace is probably about to update the lp side anyway.
>
> Slight fiddlier code than you have here, but a better attempt to figure
> out what the users is after than rejecting writes.

To be honest, I wasn't super keen on doing this either and figured you
would have some suggestions on it. It was the easiest way to just set a
policy instead :)

Your suggestion is reasonable. Let's do that!

>> +		 */
>> +		return -EINVAL;
>> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
>> +		ret = d3323aa_set_lp_filter_freq(regmap, val, val2);
>> +		if (ret)
>> +			return ret;
>> +		break;
>> +	case IIO_CHAN_INFO_HARDWAREGAIN:
>> +		ret = d3323aa_set_filter_gain(regmap, val);
>> +		if (ret)
>> +			return ret;
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return d3323aa_setup(indio_dev, regmap);
>
> I'd bury this call in set_lp_filter() and set_fillter_gain() so they
> actually do the setting.

Alright, let's do that then.

>
>> +}
>
>> +
>> +static int d3323aa_probe(struct platform_device *pdev)
>> +{
>> +	DECLARE_BITMAP(default_regmap, D3323AA_REG_NR_BITS);
>> +	struct d3323aa_data *data;
>> +	struct iio_dev *indio_dev;
>> +	int ret;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
>> +	if (!indio_dev)
>> +		return dev_err_probe(&pdev->dev, -ENOMEM,
>> +				     "Could not allocate iio device\n");
>> +
>> +	data = iio_priv(indio_dev);
>> +	data->dev = &pdev->dev;
>> +	platform_set_drvdata(pdev, indio_dev);
>
> Should be unnecessary with the suggested change below.

Yup, will be removed.

>
>> +
>> +	init_completion(&data->reset_completion);
>> +
>> +	ret = devm_mutex_init(data->dev, &data->regmap_lock);
>> +	if (ret)
>> +		return dev_err_probe(data->dev, ret,
>> +				     "Could not initialize mutex (%d)\n", ret);
>
> As already pointed out in other review - look at what dev_err_probe()
> does.

Yeah, will fix!

>
>> +
>> +	/* Request GPIOs. */
>
> This sort of code structure comment adds nothing useful. We can see
> you are requesting gpios from the code.  As such, all it can do is
> become wrong in future if code is reorganised.  Hence drop the comment.

Sure, let's drop it.

>> +	data->gpiod_vdd = devm_gpiod_get(data->dev, "vdd", GPIOD_OUT_LOW);
>
> This seems to be a supply, not a gpio.  Use the regulator framework.
> Make sure to request exclusive use though so you can turn it on and off.
> _get_exclusive() etc should ensure no one else is using it.

Alright, will do!

>> +	if (IS_ERR(data->gpiod_vdd))
>> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_vdd),
>> +				     "Could not get GPIO vdd (%ld)\n",
>> +				     PTR_ERR(data->gpiod_vdd));
>> +

[...]

>> +static void d3323aa_remove(struct platform_device *pdev)
>> +{
>> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> +	struct d3323aa_data *data = iio_priv(indio_dev);
>> +
>> +	if (data->detecting)
>> +		free_irq(data->irq, indio_dev);
>
> So this is an ordering mess.  You should never mix devm handling and
> non devm handling - once something happens in probe that is non devm
> you stop using devm_* from that point on.
>
> The irq handling in here is complex, but not on fast paths. As such I'd
> do devm_irq_request() and if you need to free it do so with devm_free_irq()
> in the places where you immediately re request it.  However see above.
> That should allow you to to drop this remove callabck.

Yes, we'll merge the IRQ handlers into one and thus we'll drop this
altogether.

>> +}
>> +
>> +static const struct of_device_id d3323aa_of_match[] = {
>> +	{
>> +		.compatible = "nicera,d3323aa",
>> +	},
>> +	{}
> 	{ }
>
> Is now standard format for these in IIO.
>
>> +};
>> +MODULE_DEVICE_TABLE(of, d3323aa_of_match);

Oh ok. I'll change it to:

static const struct of_device_id d3323aa_of_match[] = {
	{ .compatible = "nicera,d3323aa", },
	{ }
};

If that's more according to the style (I was relying on `clang-format`
here).

[...]

On Fri, May 16, 2025 at 19:16 +0200 Waqar Hameed <waqar.hameed@axis.com> wrote:

> On Sun, May 11, 2025 at 13:14 +0100 Jonathan Cameron <jic23@kernel.org> wrote:

[...]

>>> +
>>> +/*
>>> + * Register bitmap.
>>> + * For some reason the first bit is denoted as F37 in the datasheet, the second
>>> + * as F38 and so on. Note the gap between F60 and F64.
>>> + */
>>> +#define D3323AA_REG_BIT_SLAVEA1		0	/* F37. */
>>> +#define D3323AA_REG_BIT_SLAVEA2		1	/* F38. */
>>> +#define D3323AA_REG_BIT_SLAVEA3		2	/* F39. */
>>> +#define D3323AA_REG_BIT_SLAVEA4		3	/* F40. */
>>> +#define D3323AA_REG_BIT_SLAVEA5		4	/* F41. */
>>> +#define D3323AA_REG_BIT_SLAVEA6		5	/* F42. */
>>> +#define D3323AA_REG_BIT_SLAVEA7		6	/* F43. */
>>> +#define D3323AA_REG_BIT_SLAVEA8		7	/* F44. */
>>> +#define D3323AA_REG_BIT_SLAVEA9		8	/* F45. */
>> Perhaps these can be represented as masks using GENMASK() rather than
>> bits.  A lot of this will be hidden away if you follow suggesting to
>> only expose that you are using a bitmap to bitbang in the read/write
>> functions.
>
> Yes, that would be the natural thing to do when moving the bitmap stuff
> to the read/write functions (as answered below).

Since `bitmap_write()` needs an offset (and size), I didn't use
`GENMASK()` in v2 and thought it would be more clear this way. I'm still
open for suggestions though.

> >> +#define D3323AA_DRV_NAME "d3323aa"  
> >
> > Put that inline where used.  A define like this both implies that various values
> > must be the same when they need not be and means that we have to go find the
> > define to fine out what they are set to.  Just setting the strings directly
> > tends to end up more readable.  
> 
> Sure, we can do that. (There are a bunch of IIO-drivers doing this, so I
> just thought that was the "convention".)

I'm sometimes in less fussy mood.  One day I might just clean those up
so there is nothing to copy into new drivers!

>
> >> +	/* Input clock or output detection signal (Vout). */  
> >
> > I'd rename. Vout kind of suggests a variable voltage. This seems to just
> > be a level signal.  
> 
> >> +	struct gpio_desc *gpiod_clk_vout;  
> 
> Yeah, it's a weird pin with multiple use-cases... I just named it
> according to what the datasheet calls it. What about
> `gpiod_clk_detection`?

That sounds like it's detecting a clock.  Hmm.  
gpiod_clkin_detectout maybe?

> >> +static int d3323aa_write_settings(struct iio_dev *indio_dev,
> >> +				  const unsigned long *regmap)  
> >
> > Rename regmap. regmap means some specific stuff in the kernel register_bm or something
> > like that avoids that potential confusion.
> >
> > However, it would be much easier to read this driver if only this
> > function and the read one knew about the bitmap stuff.  Inside the reset
> > of the driver just store and pass around a structure with the various fields.
> > Then in here use that to build up the bitmap locally and write to the device.
> > The opposite in read which decodes the bitmap into those fields.
> >
> > That will make for a more standard and easier to review driver.  
> 
> Hm, maybe it would be easier to understand it if we remove the bitmap
> from `struct d3323aa_data` and instead only store the relevant state
> variables. We still would need to have the `regmap_lock` but to instead
> protect all of the variables.
> 
> Let's go for that then! I actually don't have any strong arguments (or
> opinions) against it.

Just don't use the term regmap and that all sounds fine as it won't
cause confusion against the stuff in drivers/base/regmap/


> >> +static irqreturn_t d3323aa_irq_detection(int irq, void *dev_id)
> >> +{
> >> +	struct iio_dev *indio_dev = dev_id;
> >> +	struct d3323aa_data *data = iio_priv(indio_dev);
> >> +	enum iio_event_direction dir;
> >> +	int val;
> >> +
> >> +	val = gpiod_get_value(data->gpiod_clk_vout);  
> >
> > Ideally I'd like a setup where we can wire the interrupt side of this
> > to one pin and the gpio needed for writing to another.  In practice
> > they may well be the same pin but that does introduced a bunch of races
> > and dependency on what the interrupt controller does when an irq
> > is disabled.
> >
> > Using one pin as an irq and as a data line is prone to some nasty
> > corner cases though it works on some SoCs.  
> 
> Hm, that's an interesting idea. However, as you say there might then be
> other issues to take care of.
> 
> On the other hand, the scope of the clock bit bang is quite small (only in
> `*read/write_settings()`). So I guess we just leave it then?

I'd give a very high chance that if the driver sees much use you will get
bug reports as we've seen for ADCs that do similar multiple uses of the
same line (one of which is as an interrupt).

Here we will probably just see spurious interrupts which will be mostly
harmless.  So fine as it stands.

On Sun, May 18, 2025 at 18:38 +0100 Jonathan Cameron <jic23@kernel.org> wrote:

>> >> +#define D3323AA_DRV_NAME "d3323aa"  
>> >
>> > Put that inline where used.  A define like this both implies that various values
>> > must be the same when they need not be and means that we have to go find the
>> > define to fine out what they are set to.  Just setting the strings directly
>> > tends to end up more readable.  
>> 
>> Sure, we can do that. (There are a bunch of IIO-drivers doing this, so I
>> just thought that was the "convention".)
>
> I'm sometimes in less fussy mood.  One day I might just clean those up
> so there is nothing to copy into new drivers!

A quick search tells that there are (at least) 105 of those:

  rgrep -A 30 "\.driver" drivers/iio/ | grep "\.name" | grep -v '"'
  
I was just about to write a small Python script to fix those, but just
wanted to confirm with you before spending more time on this. So if you
don't want to do this yourself, I can help your here :)

>>
>> >> +	/* Input clock or output detection signal (Vout). */  
>> >
>> > I'd rename. Vout kind of suggests a variable voltage. This seems to just
>> > be a level signal.  
>> 
>> >> +	struct gpio_desc *gpiod_clk_vout;  
>> 
>> Yeah, it's a weird pin with multiple use-cases... I just named it
>> according to what the datasheet calls it. What about
>> `gpiod_clk_detection`?
>
> That sounds like it's detecting a clock.  Hmm.  
> gpiod_clkin_detectout maybe?

No objections.

[...]

On Tue, 20 May 2025 13:27:54 +0200
Waqar Hameed <waqar.hameed@axis.com> wrote:

> On Sun, May 18, 2025 at 18:38 +0100 Jonathan Cameron <jic23@kernel.org> wrote:
> 
> >> >> +#define D3323AA_DRV_NAME "d3323aa"    
> >> >
> >> > Put that inline where used.  A define like this both implies that various values
> >> > must be the same when they need not be and means that we have to go find the
> >> > define to fine out what they are set to.  Just setting the strings directly
> >> > tends to end up more readable.    
> >> 
> >> Sure, we can do that. (There are a bunch of IIO-drivers doing this, so I
> >> just thought that was the "convention".)  
> >
> > I'm sometimes in less fussy mood.  One day I might just clean those up
> > so there is nothing to copy into new drivers!  
> 
> A quick search tells that there are (at least) 105 of those:
> 
>   rgrep -A 30 "\.driver" drivers/iio/ | grep "\.name" | grep -v '"'
>   
> I was just about to write a small Python script to fix those, but just
> wanted to confirm with you before spending more time on this. So if you
> don't want to do this yourself, I can help your here :)

It's probably not worth the churn on the ones that have the string repeated
multiple times.  However, perhaps any that are only using it for .name would
be good to tidy up?  Those are less a case of it being 'taste' vs it being silly
to have a define!

> 
> >>  
> >> >> +	/* Input clock or output detection signal (Vout). */    
> >> >
> >> > I'd rename. Vout kind of suggests a variable voltage. This seems to just
> >> > be a level signal.    
> >>   
> >> >> +	struct gpio_desc *gpiod_clk_vout;    
> >> 
> >> Yeah, it's a weird pin with multiple use-cases... I just named it
> >> according to what the datasheet calls it. What about
> >> `gpiod_clk_detection`?  
> >
> > That sounds like it's detecting a clock.  Hmm.  
> > gpiod_clkin_detectout maybe?  
> 
> No objections.
> 
> [...]
>

On Sun, May 25, 2025 at 10:30 +0100 Jonathan Cameron <jic23@kernel.org> wrote:

> On Tue, 20 May 2025 13:27:54 +0200
> Waqar Hameed <waqar.hameed@axis.com> wrote:
>
>> On Sun, May 18, 2025 at 18:38 +0100 Jonathan Cameron <jic23@kernel.org> wrote:
>> 
>> >> >> +#define D3323AA_DRV_NAME "d3323aa"    
>> >> >
>> >> > Put that inline where used.  A define like this both implies that various values
>> >> > must be the same when they need not be and means that we have to go find the
>> >> > define to fine out what they are set to.  Just setting the strings directly
>> >> > tends to end up more readable.    
>> >> 
>> >> Sure, we can do that. (There are a bunch of IIO-drivers doing this, so I
>> >> just thought that was the "convention".)  
>> >
>> > I'm sometimes in less fussy mood.  One day I might just clean those up
>> > so there is nothing to copy into new drivers!  
>> 
>> A quick search tells that there are (at least) 105 of those:
>> 
>>   rgrep -A 30 "\.driver" drivers/iio/ | grep "\.name" | grep -v '"'
>>   
>> I was just about to write a small Python script to fix those, but just
>> wanted to confirm with you before spending more time on this. So if you
>> don't want to do this yourself, I can help your here :)
>
> It's probably not worth the churn on the ones that have the string repeated
> multiple times.  However, perhaps any that are only using it for .name would
> be good to tidy up?  Those are less a case of it being 'taste' vs it being silly
> to have a define!

I think if you use it in multiple places, it should definitively be a
macro definition. I just sent some patches for those that only used it
once (I didn't include those with `KBUILD_MODNAME`. We can discuss if we
should also address those in that thread).

However, there are a bunch of drivers that _only_ use a macro definition
in `.name` and `indio_dev->name`, including this one. That _is_ more
than one place, so we should actually leave it? Or do you still think we
should have the same string literal in both places, as you originally
commented above?

On Tue, 27 May 2025 16:48:30 +0200
Waqar Hameed <waqar.hameed@axis.com> wrote:

> On Sun, May 25, 2025 at 10:30 +0100 Jonathan Cameron <jic23@kernel.org> wrote:
> 
> > On Tue, 20 May 2025 13:27:54 +0200
> > Waqar Hameed <waqar.hameed@axis.com> wrote:
> >  
> >> On Sun, May 18, 2025 at 18:38 +0100 Jonathan Cameron <jic23@kernel.org> wrote:
> >>   
> >> >> >> +#define D3323AA_DRV_NAME "d3323aa"      
> >> >> >
> >> >> > Put that inline where used.  A define like this both implies that various values
> >> >> > must be the same when they need not be and means that we have to go find the
> >> >> > define to fine out what they are set to.  Just setting the strings directly
> >> >> > tends to end up more readable.      
> >> >> 
> >> >> Sure, we can do that. (There are a bunch of IIO-drivers doing this, so I
> >> >> just thought that was the "convention".)    
> >> >
> >> > I'm sometimes in less fussy mood.  One day I might just clean those up
> >> > so there is nothing to copy into new drivers!    
> >> 
> >> A quick search tells that there are (at least) 105 of those:
> >> 
> >>   rgrep -A 30 "\.driver" drivers/iio/ | grep "\.name" | grep -v '"'
> >>   
> >> I was just about to write a small Python script to fix those, but just
> >> wanted to confirm with you before spending more time on this. So if you
> >> don't want to do this yourself, I can help your here :)  
> >
> > It's probably not worth the churn on the ones that have the string repeated
> > multiple times.  However, perhaps any that are only using it for .name would
> > be good to tidy up?  Those are less a case of it being 'taste' vs it being silly
> > to have a define!  
> 
> I think if you use it in multiple places, it should definitively be a
> macro definition. I just sent some patches for those that only used it
> once (I didn't include those with `KBUILD_MODNAME`. We can discuss if we
> should also address those in that thread).

I would disagree slightly.  If it is used in multiple places because there
is some inherent reason they should have same string then I absolutely agree.
If it's just because it's a convenient string that is used twice in places
that could have had different string then not so much.

> 
> However, there are a bunch of drivers that _only_ use a macro definition
> in `.name` and `indio_dev->name`, including this one. That _is_ more
> than one place, so we should actually leave it? Or do you still think we
> should have the same string literal in both places, as you originally
> commented above?

I'd prefer that for new code, but it is a less clear cut case than the ones
you have tidied up, so not worth the churn of tidying up unless people
are otherwise working on the relevant drivers.

Jonathan

>

On Sat, May 31, 2025 at 16:10 +0100 Jonathan Cameron <jic23@kernel.org> wrote:

[...]

>> I think if you use it in multiple places, it should definitively be a
>> macro definition. I just sent some patches for those that only used it
>> once (I didn't include those with `KBUILD_MODNAME`. We can discuss if we
>> should also address those in that thread).
>
> I would disagree slightly.  If it is used in multiple places because there
> is some inherent reason they should have same string then I absolutely agree.
> If it's just because it's a convenient string that is used twice in places
> that could have had different string then not so much.

Absolutely! If two places can end up with different strings, then they
shouldn't share the same variable in the first place. I was not as clear
as you with my one-sentence :)

>> However, there are a bunch of drivers that _only_ use a macro definition
>> in `.name` and `indio_dev->name`, including this one. That _is_ more
>> than one place, so we should actually leave it? Or do you still think we
>> should have the same string literal in both places, as you originally
>> commented above?
>
> I'd prefer that for new code, but it is a less clear cut case than the ones
> you have tidied up, so not worth the churn of tidying up unless people
> are otherwise working on the relevant drivers.

Sure, let's use string literals in this driver then.

Le 09/05/2025 à 17:03, Waqar Hameed a écrit :
> Nicera D3-323-AA is a PIR sensor for human detection. It has support for
> raw data measurements and detection notification. The communication
> protocol is custom made and therefore needs to be GPIO bit banged.
> 
> The device has two main settings that can be configured: a threshold
> value for detection and a band-pass filter. The configurable parameters
> for the band-pass filter are the high-pass and low-pass cutoff
> frequencies and its peak gain. Map these settings to the corresponding
> parameters in the `iio` framework.
> 
> The low-pass and high-pass cutoff frequencies are pairwise for the
> different available filter types. Because of this, only allow to set the
> low-pass cutoff frequency from `sysfs` and use that to configure the
> corresponding high-pass cutoff frequency. This is sufficient to
> unambiguously choose a filter type.
> 
> Raw data measurements can be obtained from the device. However, since we
> rely on bit banging, it will be rather cumbersome with buffer support.
> The main reason being that the data protocol has strict timing
> requirements (it's serial like UART), and it's mainly used during
> debugging since in real-world applications only the event notification
> is of importance. Therefore, only add support for events (for now).
> 
> Signed-off-by: Waqar Hameed <waqar.hameed-VrBV9hrLPhE@public.gmane.org>
> ---

Hi,

...

> +static int d3323aa_set_lp_filter_freq(unsigned long *regmap, const int val,
> +				      int val2)
> +{
> +	size_t idx;
> +
> +	/* Truncate fractional part to one digit. */
> +	val2 /= 100000;
> +
> +	for (idx = 0; idx < ARRAY_SIZE(d3323aa_lp_filter_freq); ++idx) {
> +		int integer = d3323aa_lp_filter_freq[idx][0] /
> +			      d3323aa_lp_filter_freq[idx][1];
> +		int fract = d3323aa_lp_filter_freq[idx][0] %
> +			    d3323aa_lp_filter_freq[idx][1];

Missing newline.

> +		if (val == integer && val2 == fract)
> +			break;
> +	}
> +
> +	if (idx == ARRAY_SIZE(d3323aa_lp_filter_freq))
> +		return -ERANGE;
> +
> +	bitmap_write(regmap, d3323aa_lp_filter_regval[idx],
> +		     D3323AA_REG_BIT_FILSEL0, D3323AA_FILTER_TYPE_NR_BITS);
> +
> +	return 0;
> +}

...

> +static int d3323aa_probe(struct platform_device *pdev)
> +{
> +	DECLARE_BITMAP(default_regmap, D3323AA_REG_NR_BITS);
> +	struct d3323aa_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return dev_err_probe(&pdev->dev, -ENOMEM,
> +				     "Could not allocate iio device\n");
> +
> +	data = iio_priv(indio_dev);
> +	data->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	init_completion(&data->reset_completion);
> +
> +	ret = devm_mutex_init(data->dev, &data->regmap_lock);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret,
> +				     "Could not initialize mutex (%d)\n", ret);

No need to repeat the error code in the message, when using dev_err_probe().

Same for all calls below.

> +
> +	/* Request GPIOs. */
> +	data->gpiod_vdd = devm_gpiod_get(data->dev, "vdd", GPIOD_OUT_LOW);
> +	if (IS_ERR(data->gpiod_vdd))
> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_vdd),
> +				     "Could not get GPIO vdd (%ld)\n",
> +				     PTR_ERR(data->gpiod_vdd));
> +
> +	data->gpiod_clk_vout =
> +		devm_gpiod_get(data->dev, "clk-vout", GPIOD_OUT_LOW);
> +	if (IS_ERR(data->gpiod_clk_vout))
> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_clk_vout),
> +				     "Could not get GPIO clk-vout (%ld)\n",
> +				     PTR_ERR(data->gpiod_clk_vout));
> +
> +	data->gpiod_data = devm_gpiod_get(data->dev, "data", GPIOD_OUT_LOW);
> +	if (IS_ERR(data->gpiod_data))
> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_data),
> +				     "Could not get GPIO data (%ld)\n",
> +				     PTR_ERR(data->gpiod_data));
> +
> +	ret = gpiod_to_irq(data->gpiod_clk_vout);
> +	if (ret < 0)
> +		return dev_err_probe(data->dev, ret, "Could not get IRQ (%d)\n",
> +				     ret);
> +
> +	data->irq = ret;
> +
> +	/* Do one setup with the default values. */
> +	bitmap_zero(default_regmap, D3323AA_REG_NR_BITS);
> +	d3323aa_set_threshold(default_regmap, D3323AA_THRESH_DEFAULT_VAL);
> +	d3323aa_set_filter_gain(default_regmap,
> +				D3323AA_FILTER_GAIN_DEFAULT_VAL);
> +	ret = d3323aa_setup(indio_dev, default_regmap);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->info = &d3323aa_info;
> +	indio_dev->name = D3323AA_DRV_NAME;
> +	indio_dev->channels = d3323aa_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(d3323aa_channels);
> +
> +	ret = devm_iio_device_register(data->dev, indio_dev);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret,
> +				     "Could not register iio device (%d)\n",
> +				     ret);
> +
> +	return 0;
> +}

...

CJ

On Sun, May 11, 2025 at 09:57 +0200 Christophe JAILLET <christophe.jaillet@wanadoo.fr> wrote:

[...]

> Hi,

Hi Christophe! Thank you for your review!

>
> ...
>
>> +static int d3323aa_set_lp_filter_freq(unsigned long *regmap, const int val,
>> +				      int val2)
>> +{
>> +	size_t idx;
>> +
>> +	/* Truncate fractional part to one digit. */
>> +	val2 /= 100000;
>> +
>> +	for (idx = 0; idx < ARRAY_SIZE(d3323aa_lp_filter_freq); ++idx) {
>> +		int integer = d3323aa_lp_filter_freq[idx][0] /
>> +			      d3323aa_lp_filter_freq[idx][1];
>> +		int fract = d3323aa_lp_filter_freq[idx][0] %
>> +			    d3323aa_lp_filter_freq[idx][1];
>
> Missing newline.

Sure, I'll add one.

>
>> +		if (val == integer && val2 == fract)
>> +			break;
>> +	}
>> +
>> +	if (idx == ARRAY_SIZE(d3323aa_lp_filter_freq))
>> +		return -ERANGE;
>> +
>> +	bitmap_write(regmap, d3323aa_lp_filter_regval[idx],
>> +		     D3323AA_REG_BIT_FILSEL0, D3323AA_FILTER_TYPE_NR_BITS);
>> +
>> +	return 0;
>> +}
>
> ...
>
>> +static int d3323aa_probe(struct platform_device *pdev)
>> +{
>> +	DECLARE_BITMAP(default_regmap, D3323AA_REG_NR_BITS);
>> +	struct d3323aa_data *data;
>> +	struct iio_dev *indio_dev;
>> +	int ret;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
>> +	if (!indio_dev)
>> +		return dev_err_probe(&pdev->dev, -ENOMEM,
>> +				     "Could not allocate iio device\n");
>> +
>> +	data = iio_priv(indio_dev);
>> +	data->dev = &pdev->dev;
>> +	platform_set_drvdata(pdev, indio_dev);
>> +
>> +	init_completion(&data->reset_completion);
>> +
>> +	ret = devm_mutex_init(data->dev, &data->regmap_lock);
>> +	if (ret)
>> +		return dev_err_probe(data->dev, ret,
>> +				     "Could not initialize mutex (%d)\n", ret);
>
> No need to repeat the error code in the message, when using dev_err_probe().
>
> Same for all calls below.

Ah, of course! I'll remove it. (There is actually another driver that is
doing this, I'll update that one as well...)

>
>> +
>> +	/* Request GPIOs. */
>> +	data->gpiod_vdd = devm_gpiod_get(data->dev, "vdd", GPIOD_OUT_LOW);
>> +	if (IS_ERR(data->gpiod_vdd))
>> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_vdd),
>> +				     "Could not get GPIO vdd (%ld)\n",
>> +				     PTR_ERR(data->gpiod_vdd));
>> +
>> +	data->gpiod_clk_vout =
>> +		devm_gpiod_get(data->dev, "clk-vout", GPIOD_OUT_LOW);
>> +	if (IS_ERR(data->gpiod_clk_vout))
>> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_clk_vout),
>> +				     "Could not get GPIO clk-vout (%ld)\n",
>> +				     PTR_ERR(data->gpiod_clk_vout));
>> +
>> +	data->gpiod_data = devm_gpiod_get(data->dev, "data", GPIOD_OUT_LOW);
>> +	if (IS_ERR(data->gpiod_data))
>> +		return dev_err_probe(data->dev, PTR_ERR(data->gpiod_data),
>> +				     "Could not get GPIO data (%ld)\n",
>> +				     PTR_ERR(data->gpiod_data));
>> +
>> +	ret = gpiod_to_irq(data->gpiod_clk_vout);
>> +	if (ret < 0)
>> +		return dev_err_probe(data->dev, ret, "Could not get IRQ (%d)\n",
>> +				     ret);
>> +
>> +	data->irq = ret;
>> +
>> +	/* Do one setup with the default values. */
>> +	bitmap_zero(default_regmap, D3323AA_REG_NR_BITS);
>> +	d3323aa_set_threshold(default_regmap, D3323AA_THRESH_DEFAULT_VAL);
>> +	d3323aa_set_filter_gain(default_regmap,
>> +				D3323AA_FILTER_GAIN_DEFAULT_VAL);
>> +	ret = d3323aa_setup(indio_dev, default_regmap);
>> +	if (ret)
>> +		return ret;
>> +
>> +	indio_dev->info = &d3323aa_info;
>> +	indio_dev->name = D3323AA_DRV_NAME;
>> +	indio_dev->channels = d3323aa_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(d3323aa_channels);
>> +
>> +	ret = devm_iio_device_register(data->dev, indio_dev);
>> +	if (ret)
>> +		return dev_err_probe(data->dev, ret,
>> +				     "Could not register iio device (%d)\n",
>> +				     ret);
>> +
>> +	return 0;
>> +}
>
> ...
>
> CJ