Add initial support for the new Goodix "Berlin" touchscreen ICs
over the I2C interface.

This initial driver is derived from the Goodix goodix_ts_berlin
available at [1] and [2] and only supports the GT9916 IC
present on the Qualcomm SM8550 MTP & QRD touch panel.

The current implementation only supports BerlinD, aka GT9916.

[1] https://github.com/goodix/goodix_ts_berlin
[2] https://git.codelinaro.org/clo/la/platform/vendor/opensource/touch-drivers

Reviewed-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/input/touchscreen/Kconfig             | 14 ++++++
 drivers/input/touchscreen/Makefile            |  1 +
 drivers/input/touchscreen/goodix_berlin_i2c.c | 69 +++++++++++++++++++++++++++
 3 files changed, 84 insertions(+)

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 950da599ae1a..cc7b88118158 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -419,6 +419,20 @@ config TOUCHSCREEN_GOODIX
 config TOUCHSCREEN_GOODIX_BERLIN_CORE
 	tristate
 
+config TOUCHSCREEN_GOODIX_BERLIN_I2C
+	tristate "Goodix Berlin I2C touchscreen"
+	depends on I2C
+	select REGMAP_I2C
+	select TOUCHSCREEN_GOODIX_BERLIN_CORE
+	help
+	  Say Y here if you have a Goodix Berlin IC connected to
+	  your system via I2C.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called goodix_berlin_i2c.
+
 config TOUCHSCREEN_HIDEEP
 	tristate "HiDeep Touch IC"
 	depends on I2C
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 2e2f3e70cd2c..7ef677cf7a10 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_CORE)	+= goodix_berlin_core.o
+obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_I2C)	+= goodix_berlin_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
 obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
diff --git a/drivers/input/touchscreen/goodix_berlin_i2c.c b/drivers/input/touchscreen/goodix_berlin_i2c.c
new file mode 100644
index 000000000000..6407b2258eb1
--- /dev/null
+++ b/drivers/input/touchscreen/goodix_berlin_i2c.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Goodix Berlin Touchscreen Driver
+ *
+ * Copyright (C) 2020 - 2021 Goodix, Inc.
+ * Copyright (C) 2023 Linaro Ltd.
+ *
+ * Based on goodix_ts_berlin driver.
+ */
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "goodix_berlin.h"
+
+#define I2C_MAX_TRANSFER_SIZE		256
+
+static const struct regmap_config goodix_berlin_i2c_regmap_conf = {
+	.reg_bits = 32,
+	.val_bits = 8,
+	.max_raw_read = I2C_MAX_TRANSFER_SIZE,
+	.max_raw_write = I2C_MAX_TRANSFER_SIZE,
+};
+
+/* vendor & product left unassigned here, should probably be updated from fw info */
+static const struct input_id goodix_berlin_i2c_input_id = {
+	.bustype = BUS_I2C,
+};
+
+static int goodix_berlin_i2c_probe(struct i2c_client *client)
+{
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init_i2c(client, &goodix_berlin_i2c_regmap_conf);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return goodix_berlin_probe(&client->dev, client->irq,
+				   &goodix_berlin_i2c_input_id, regmap);
+}
+
+static const struct i2c_device_id goodix_berlin_i2c_id[] = {
+	{ "gt9916", 0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, goodix_berlin_i2c_id);
+
+static const struct of_device_id goodix_berlin_i2c_of_match[] = {
+	{ .compatible = "goodix,gt9916", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, goodix_berlin_i2c_of_match);
+
+static struct i2c_driver goodix_berlin_i2c_driver = {
+	.driver = {
+		.name = "goodix-berlin-i2c",
+		.of_match_table = goodix_berlin_i2c_of_match,
+		.pm = pm_sleep_ptr(&goodix_berlin_pm_ops),
+	},
+	.probe = goodix_berlin_i2c_probe,
+	.id_table = goodix_berlin_i2c_id,
+};
+module_i2c_driver(goodix_berlin_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Goodix Berlin I2C Touchscreen driver");
+MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");

-- 
2.34.1

Hi Neil,

kernel test robot noticed the following build errors:

[auto build test ERROR on 6465e260f48790807eef06b583b38ca9789b6072]

url:    https://github.com/intel-lab-lkp/linux/commits/Neil-Armstrong/dt-bindings-input-document-Goodix-Berlin-Touchscreen-IC/20231002-145648
base:   6465e260f48790807eef06b583b38ca9789b6072
patch link:    https://lore.kernel.org/r/20231002-topic-goodix-berlin-upstream-initial-v7-3-792fb91f5e88%40linaro.org
patch subject: [PATCH v7 3/4] Input: goodix-berlin - add I2C support for Goodix Berlin Touchscreen IC
config: nios2-allmodconfig (https://download.01.org/0day-ci/archive/20231002/202310021730.epucKAC1-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231002/202310021730.epucKAC1-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310021730.epucKAC1-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   drivers/input/touchscreen/goodix_berlin_core.c: In function 'goodix_berlin_checksum_valid':
>> drivers/input/touchscreen/goodix_berlin_core.c:50:16: error: implicit declaration of function 'FIELD_GET' [-Werror=implicit-function-declaration]
      50 |         return FIELD_GET(GOODIX_BERLIN_COOR_DATA_CHECKSUM_MASK, cal_checksum) == r_checksum;
         |                ^~~~~~~~~
   drivers/input/touchscreen/goodix_berlin_core.c: In function 'goodix_berlin_get_ic_info':
>> drivers/input/touchscreen/goodix_berlin_core.c:284:1: warning: the frame size of 1140 bytes is larger than 1024 bytes [-Wframe-larger-than=]
     284 | }
         | ^
   cc1: some warnings being treated as errors


vim +/FIELD_GET +50 drivers/input/touchscreen/goodix_berlin_core.c

3fd649a6bbd95d Neil Armstrong 2023-10-02  15  
3fd649a6bbd95d Neil Armstrong 2023-10-02  16  /*
3fd649a6bbd95d Neil Armstrong 2023-10-02  17   * Goodix "Berlin" Touchscreen ID driver
3fd649a6bbd95d Neil Armstrong 2023-10-02  18   *
3fd649a6bbd95d Neil Armstrong 2023-10-02  19   * This driver is distinct from goodix.c since hardware interface
3fd649a6bbd95d Neil Armstrong 2023-10-02  20   * is different enough to require a new driver.
3fd649a6bbd95d Neil Armstrong 2023-10-02  21   * None of the register address or data structure are close enough
3fd649a6bbd95d Neil Armstrong 2023-10-02  22   * to the previous generations.
3fd649a6bbd95d Neil Armstrong 2023-10-02  23   *
3fd649a6bbd95d Neil Armstrong 2023-10-02  24   * Currently only handles Multitouch events with already
3fd649a6bbd95d Neil Armstrong 2023-10-02  25   * programmed firmware and "config" for "Revision D" Berlin IC.
3fd649a6bbd95d Neil Armstrong 2023-10-02  26   *
3fd649a6bbd95d Neil Armstrong 2023-10-02  27   * Support is missing for:
3fd649a6bbd95d Neil Armstrong 2023-10-02  28   * - ESD Management
3fd649a6bbd95d Neil Armstrong 2023-10-02  29   * - Firmware update/flashing
3fd649a6bbd95d Neil Armstrong 2023-10-02  30   * - "Config" update/flashing
3fd649a6bbd95d Neil Armstrong 2023-10-02  31   * - Stylus Events
3fd649a6bbd95d Neil Armstrong 2023-10-02  32   * - Gesture Events
3fd649a6bbd95d Neil Armstrong 2023-10-02  33   * - Support for older revisions (A & B)
3fd649a6bbd95d Neil Armstrong 2023-10-02  34   */
3fd649a6bbd95d Neil Armstrong 2023-10-02  35  
3fd649a6bbd95d Neil Armstrong 2023-10-02  36  static bool goodix_berlin_checksum_valid(const u8 *data, int size)
3fd649a6bbd95d Neil Armstrong 2023-10-02  37  {
3fd649a6bbd95d Neil Armstrong 2023-10-02  38  	u32 cal_checksum = 0;
3fd649a6bbd95d Neil Armstrong 2023-10-02  39  	u16 r_checksum;
3fd649a6bbd95d Neil Armstrong 2023-10-02  40  	u32 i;
3fd649a6bbd95d Neil Armstrong 2023-10-02  41  
3fd649a6bbd95d Neil Armstrong 2023-10-02  42  	if (size < GOODIX_BERLIN_COOR_DATA_CHECKSUM_SIZE)
3fd649a6bbd95d Neil Armstrong 2023-10-02  43  		return false;
3fd649a6bbd95d Neil Armstrong 2023-10-02  44  
3fd649a6bbd95d Neil Armstrong 2023-10-02  45  	for (i = 0; i < size - GOODIX_BERLIN_COOR_DATA_CHECKSUM_SIZE; i++)
3fd649a6bbd95d Neil Armstrong 2023-10-02  46  		cal_checksum += data[i];
3fd649a6bbd95d Neil Armstrong 2023-10-02  47  
3fd649a6bbd95d Neil Armstrong 2023-10-02  48  	r_checksum = get_unaligned_le16(&data[i]);
3fd649a6bbd95d Neil Armstrong 2023-10-02  49  
3fd649a6bbd95d Neil Armstrong 2023-10-02 @50  	return FIELD_GET(GOODIX_BERLIN_COOR_DATA_CHECKSUM_MASK, cal_checksum) == r_checksum;
3fd649a6bbd95d Neil Armstrong 2023-10-02  51  }
3fd649a6bbd95d Neil Armstrong 2023-10-02  52  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki