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

David Lechner
2025-09-11T19:23:43Z

On 9/10/25 2:57 AM, Petre Rodan wrote:
> 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

depends I2C || SPI

> 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;

Up to now, i2c is before spi. So would be consistent to keep
doing that.

> 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>

It doesn't look like the iio header is used. Maybe not device.h either.

> +
> +#include "bma220.h"
> +