Add i2c module.
Note that the kernel module transparently shifts all register addresses
1 bit to the left, so all functions will operate based on the SPI memory
map.

Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
---
 drivers/iio/accel/Kconfig       |  9 ++++-
 drivers/iio/accel/Makefile      |  1 +
 drivers/iio/accel/bma220.h      |  1 +
 drivers/iio/accel/bma220_core.c | 19 ++++++++++
 drivers/iio/accel/bma220_i2c.c  | 62 +++++++++++++++++++++++++++++++++
 5 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 drivers/iio/accel/bma220_i2c.c

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 9b6c35b75948..b3c5b0b7a406 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -221,6 +221,7 @@ config BMA220
 	select REGMAP
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
+	select BMA220_I2C if I2C
 	select BMA220_SPI if SPI
 	help
 	  Say yes here to add support for the Bosch BMA220 triaxial
@@ -228,7 +229,13 @@ config BMA220

 	  To compile this driver as a module, choose M here: the
 	  module will be called bma220_core and you will also get
-	  bma220_spi if SPI is enabled.
+	  bma220_i2c if I2C is enabled and bma220_spi if SPI is
+	  enabled.
+
+config BMA220_I2C
+	tristate
+	select REGMAP_I2C
+	depends on BMA220

 config BMA220_SPI
 	tristate
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 56a9f848f7f9..fa440a859283 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_ADXL380_I2C) += adxl380_i2c.o
 obj-$(CONFIG_ADXL380_SPI) += adxl380_spi.o
 obj-$(CONFIG_BMA180) += bma180.o
 obj-$(CONFIG_BMA220) += bma220_core.o
+obj-$(CONFIG_BMA220_I2C) += bma220_i2c.o
 obj-$(CONFIG_BMA220_SPI) += bma220_spi.o
 obj-$(CONFIG_BMA400) += bma400_core.o
 obj-$(CONFIG_BMA400_I2C) += bma400_i2c.o
diff --git a/drivers/iio/accel/bma220.h b/drivers/iio/accel/bma220.h
index 5eefa9749d33..ae4b74514629 100644
--- a/drivers/iio/accel/bma220.h
+++ b/drivers/iio/accel/bma220.h
@@ -13,6 +13,7 @@
 #include <linux/iio/iio.h>

 extern const struct regmap_config bma220_spi_regmap_config;
+extern const struct regmap_config bma220_i2c_regmap_config;
 extern const struct dev_pm_ops bma220_pm_ops;

 int bma220_common_probe(struct device *dev, struct regmap *regmap, int irq);
diff --git a/drivers/iio/accel/bma220_core.c b/drivers/iio/accel/bma220_core.c
index e6dac2e1cf4d..fae84823d52b 100644
--- a/drivers/iio/accel/bma220_core.c
+++ b/drivers/iio/accel/bma220_core.c
@@ -225,6 +225,25 @@ const struct regmap_config bma220_spi_regmap_config = {
 };
 EXPORT_SYMBOL_NS(bma220_spi_regmap_config, "IIO_BOSCH_BMA220");

+/*
+ * Based on the datasheet the memory map differs between the SPI and the I2C
+ * implementations. I2C register addresses are simply shifted to the left
+ * by 1 bit yet the register size remains unchanged.
+ * This driver employs the SPI memory map to correlate register names to
+ * addresses regardless of the bus type.
+ */
+
+const struct regmap_config bma220_i2c_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.reg_shift = -1,
+	.max_register = BMA220_REG_SOFTRESET,
+	.cache_type = REGCACHE_MAPLE,
+	.writeable_reg = bma220_is_writable_reg,
+	.volatile_reg = bma220_is_volatile_reg,
+};
+EXPORT_SYMBOL_NS(bma220_i2c_regmap_config, "IIO_BOSCH_BMA220");
+
 static int bma220_data_rdy_trigger_set_state(struct iio_trigger *trig,
 					     bool state)
 {
diff --git a/drivers/iio/accel/bma220_i2c.c b/drivers/iio/accel/bma220_i2c.c
new file mode 100644
index 000000000000..8a1644aac287
--- /dev/null
+++ b/drivers/iio/accel/bma220_i2c.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Bosch triaxial acceleration sensor
+ *
+ * Copyright (c) 2025 Petre Rodan <petre.rodan@subdimension.ro>
+ *
+ * Datasheet: https://media.digikey.com/pdf/Data%20Sheets/Bosch/BMA220.pdf
+ * I2C address is either 0x0b or 0x0a depending on CSB (pin 10)
+ */
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include <linux/iio/iio.h>
+
+#include "bma220.h"
+
+static int bma220_i2c_probe(struct i2c_client *client)
+{
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init_i2c(client, &bma220_i2c_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "failed to create regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	return bma220_common_probe(&client->dev, regmap, client->irq);
+}
+
+static const struct of_device_id bma220_i2c_match[] = {
+	{ .compatible = "bosch,bma220" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bma220_i2c_match);
+
+static const struct i2c_device_id bma220_i2c_id[] = {
+	{ "bma220" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, bma220_i2c_id);
+
+static struct i2c_driver bma220_i2c_driver = {
+	.driver = {
+		.name = "bma220_i2c",
+		.pm = pm_sleep_ptr(&bma220_pm_ops),
+		.of_match_table = bma220_i2c_match,
+	},
+	.probe = bma220_i2c_probe,
+	.id_table = bma220_i2c_id,
+};
+module_i2c_driver(bma220_i2c_driver);
+
+MODULE_AUTHOR("Petre Rodan <petre.rodan@subdimension.ro>");
+MODULE_DESCRIPTION("Bosch triaxial acceleration sensor i2c driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_BOSCH_BMA220");
--
2.49.1

On Mon,  1 Sep 2025 22:47:30 +0300
Petre Rodan <petre.rodan@subdimension.ro> wrote:

> Add i2c module.
> Note that the kernel module transparently shifts all register addresses
> 1 bit to the left, so all functions will operate based on the SPI memory
> map.
> 
> Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>

Trivial comments inline

> diff --git a/drivers/iio/accel/bma220_i2c.c b/drivers/iio/accel/bma220_i2c.c
> new file mode 100644
> index 000000000000..8a1644aac287
> --- /dev/null
> +++ b/drivers/iio/accel/bma220_i2c.c
> @@ -0,0 +1,62 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Bosch triaxial acceleration sensor
> + *
> + * Copyright (c) 2025 Petre Rodan <petre.rodan@subdimension.ro>
> + *
> + * Datasheet: https://media.digikey.com/pdf/Data%20Sheets/Bosch/BMA220.pdf
> + * I2C address is either 0x0b or 0x0a depending on CSB (pin 10)
> + */
> +
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/i2c.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
> +
> +#include <linux/iio/iio.h>
> +
> +#include "bma220.h"
> +
> +static int bma220_i2c_probe(struct i2c_client *client)
> +{
> +	struct regmap *regmap;
> +
> +	regmap = devm_regmap_init_i2c(client, &bma220_i2c_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(&client->dev, "failed to create regmap\n");
> +		return PTR_ERR(regmap);

return dev_err_probe()

> +	}
> +
> +	return bma220_common_probe(&client->dev, regmap, client->irq);
> +}

>