[PATCH v2 09/14] iio: accel: bma220: add i2c module

[Petre Rodan <petre.rodan@subdimension.ro>]

Add the bma220_i2c module.

Note that this 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>
---
no change
---
 drivers/iio/accel/Kconfig       |  9 +++++-
 drivers/iio/accel/Makefile      |  1 +
 drivers/iio/accel/bma220.h      |  1 +
 drivers/iio/accel/bma220_core.c | 18 ++++++++++++
 drivers/iio/accel/bma220_i2c.c  | 61 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 9b6c35b759481df5ff3c91856f8783357d25de80..b3c5b0b7a406ec0cec531a122af424cb8ec57703 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 56a9f848f7f913633bc2a628c1ac5c9190774b9d..fa440a85928398fee927081f605595ba9fbc4ad9 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 f9f4fa3daf33665f07f8bf073468dff070b46d74..384557d10d5613b7d829c6666f3da06de219277a 100644
--- a/drivers/iio/accel/bma220.h
+++ b/drivers/iio/accel/bma220.h
@@ -12,6 +12,7 @@
 #include <linux/regmap.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 4d8b65ea737a2d5fe74f98da13a582a80874a5af..191074d8618ea2638f69283781b8677921876681 100644
--- a/drivers/iio/accel/bma220_core.c
+++ b/drivers/iio/accel/bma220_core.c
@@ -175,6 +175,24 @@ const struct regmap_config bma220_spi_regmap_config = {
 };
 EXPORT_SYMBOL_NS_GPL(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_NONE,
+	.writeable_reg = bma220_is_writable_reg,
+};
+EXPORT_SYMBOL_NS_GPL(bma220_i2c_regmap_config, "IIO_BOSCH_BMA220");
+
 static irqreturn_t bma220_trigger_handler(int irq, void *p)
 {
 	int ret;
diff --git a/drivers/iio/accel/bma220_i2c.c b/drivers/iio/accel/bma220_i2c.c
new file mode 100644
index 0000000000000000000000000000000000000000..2b63949ea64ee11421e76a2e7c868a922d1f9a12
--- /dev/null
+++ b/drivers/iio/accel/bma220_i2c.c
@@ -0,0 +1,61 @@
+// 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))
+		return dev_err_probe(&client->dev, PTR_ERR(regmap),
+				     "failed to create regmap\n");
+
+	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