Re: [PATCH 2/2] iio: accel: Add support for Domintech DMARD06 accelerometer

[Jonathan Cameron]

On 22/07/16 00:41, Peter Meerwald-Stadler wrote:
> 
>> This patch add support for Domintech DMARD06 accelerometer.
> 
> comments below
>  
>> Domintech DMARD06 is a low-g tri-axial digital accelerometer for
>> cost-sensitive consumer application.
>>
>> Signed-off-by: Aleksei Mamlin <mamlinav@xxxxxxxxx>
I don't have anything to add here. Nice fairly clean first version.
>> ---
>>  .../devicetree/bindings/iio/accel/dmard06.txt      |  17 ++
>>  drivers/iio/accel/Kconfig                          |  11 ++
>>  drivers/iio/accel/Makefile                         |   1 +
>>  drivers/iio/accel/dmard06.c                        | 219 +++++++++++++++++++++
>>  4 files changed, 248 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/iio/accel/dmard06.txt
>>  create mode 100644 drivers/iio/accel/dmard06.c
>>
>> diff --git a/Documentation/devicetree/bindings/iio/accel/dmard06.txt b/Documentation/devicetree/bindings/iio/accel/dmard06.txt
>> new file mode 100644
>> index 0000000..cc2231a
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/accel/dmard06.txt
>> @@ -0,0 +1,17 @@
>> +Device tree bindings for Domintech DMARD06 acceletometer
> 
> typo: accelerometer
> 
>> +
>> +Required properties:
>> + - compatible		: Should be "domintech,dmard06"
>> + - reg			: I2C address of the chip. Should be 0x1c
>> +
>> +Example:
>> +	&i2c1 {
>> +		/* ... */
>> +
>> +		accelerometer@1c {
>> +			compatible = "domintech,dmard06";
>> +			reg = <0x1c>;
>> +		};
>> +
>> +		/* ... */
>> +	};
>> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
>> index e4a758c..abc8536 100644
>> --- a/drivers/iio/accel/Kconfig
>> +++ b/drivers/iio/accel/Kconfig
>> @@ -40,6 +40,17 @@ config BMC150_ACCEL_SPI
>>  	tristate
>>  	select REGMAP_SPI
>>  
>> +config DMARD06
>> +	tristate "Domintech DMARD06 Digital Accelerometer Driver"
>> +	depends on OF || COMPILE_TEST
>> +	depends on I2C
>> +	help
>> +	  Say yes here to build support for the Domintech DMARD06 low-g
>> +	  tri-axial digital accelerometer connected via an I2C bus.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> +	  module will be called dmard06.
>> +
>>  config HID_SENSOR_ACCEL_3D
>>  	depends on HID_SENSOR_HUB
>>  	select IIO_BUFFER
>> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
>> index 71b6794..a96b269 100644
>> --- a/drivers/iio/accel/Makefile
>> +++ b/drivers/iio/accel/Makefile
>> @@ -7,6 +7,7 @@ obj-$(CONFIG_BMA180) += bma180.o
>>  obj-$(CONFIG_BMC150_ACCEL) += bmc150-accel-core.o
>>  obj-$(CONFIG_BMC150_ACCEL_I2C) += bmc150-accel-i2c.o
>>  obj-$(CONFIG_BMC150_ACCEL_SPI) += bmc150-accel-spi.o
>> +obj-$(CONFIG_DMARD06)	+= dmard06.o
>>  obj-$(CONFIG_HID_SENSOR_ACCEL_3D) += hid-sensor-accel-3d.o
>>  obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
>>  obj-$(CONFIG_KXSD9)	+= kxsd9.o
>> diff --git a/drivers/iio/accel/dmard06.c b/drivers/iio/accel/dmard06.c
>> new file mode 100644
>> index 0000000..433e430
>> --- /dev/null
>> +++ b/drivers/iio/accel/dmard06.c
>> @@ -0,0 +1,219 @@
>> +/*
>> + * IIO driver for Domintech DMARD06 accelerometer
>> + *
>> + * Copyright (C) 2016 Aleksei Mamlin <mamlinav@xxxxxxxxx>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/i2c.h>
>> +#include <linux/iio/iio.h>
>> +
>> +struct dmard06_data {
>> +	struct i2c_client *client;
>> +};
>> +
>> +#define DMARD06_DRV_NAME		"dmard06"
>> +
>> +/* Device data registers */
>> +#define DMARD06_CHIP_ID_REG		0x0f
>> +#define DMARD06_TOUT_REG		0x40
>> +#define DMARD06_XOUT_REG		0x41
>> +#define DMARD06_YOUT_REG		0x42
>> +#define DMARD06_ZOUT_REG		0x43
>> +
>> +/* Device ID value */
>> +#define DMARD06_CHIP_ID			0x06
>> +
>> +/* Device values */
>> +#define DMARD06_AXIS_MAX_VAL		64
>> +#define DMARD06_AXIS_SCALE_VAL		31250
>> +#define DMARD06_TEMP_CENTER_VAL		25
>> +
>> +static int dmard06_i2c_read(struct i2c_client *client, u8 reg, u8 *buf)
>> +{
>> +	int error;
> 
> 'error' is a bit pessimistic, how about 'ret'? :-)
> 
>> +
> 
> can't use i2c_smbus_read_byte_data()?
> 
>> +	error = i2c_master_send(client, &reg, 1);
>> +	if (unlikely(error < 0))
>> +		return error;
>> +
>> +	error = i2c_master_recv(client, buf, 1);
>> +	if (unlikely(error < 0))
>> +		return error;
> 
> not sure if it is worth to annotate unlikely() here -- i2c is slooow
> locking is needed if you really need two i2c_master calls
> 
>> +	return 0;
>> +}
>> +
>> +static int dmard06_read_chip_id(struct dmard06_data *dmard06)
>> +{
>> +	u8 buf;
>> +	u8 chip_id;
>> +	int error;
>> +
>> +	error = dmard06_i2c_read(dmard06->client, DMARD06_CHIP_ID_REG, &buf);
>> +	if (error) {
>> +		dev_err(&dmard06->client->dev, "Failed to read chip id: %d\n",
>> +			error);
>> +		return error;
>> +	}
>> +
>> +	chip_id = (buf & 0x00ff);
> 
> why? buf is u8 anyways
> 
>> +	if (chip_id != DMARD06_CHIP_ID) {
>> +		dev_err(&dmard06->client->dev, "Invalid chip id: %02x\n",
>> +			chip_id);
>> +		return -EINVAL;
> 
> often ENODEV is used for this case
> 
>> +	}
>> +
>> +	dev_info(&dmard06->client->dev, "Found DMARD%02x chip\n", chip_id);
> 
> we prefer silent probing of the driver, please don't clutter the log
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static int dmard06_read_raw(struct iio_dev *indio_dev,
>> +			    struct iio_chan_spec const *chan,
>> +			    int *val, int *val2, long mask)
>> +{
>> +	struct dmard06_data *dmard06 = iio_priv(indio_dev);
>> +	u8 buf;
>> +	bool reversed;
>> +	int error;
>> +	int tmp;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		error = dmard06_i2c_read(dmard06->client, chan->address, &buf);
>> +		if (error) {
>> +			dev_err(&dmard06->client->dev,
>> +				"Failed to read data %d\n", error);
>> +			return error;
>> +		}
>> +
>> +		reversed = (buf >> 7) & 1;
>> +		tmp = (int)((buf & 0x7f) >> 1);
> 
> 
>> +
>> +		switch (chan->type) {
>> +		case IIO_ACCEL:
> 
> wouldn't sign_extend32(buf >> 1, 6) do the job?
> 
>> +			*val = reversed ? (tmp - DMARD06_AXIS_MAX_VAL) : tmp;
>> +			return IIO_VAL_INT;
>> +		case IIO_TEMP:
>> +			*val = reversed ? -tmp : tmp;
>> +			return IIO_VAL_INT;
>> +		default:
>> +			return -EINVAL;
>> +		}
>> +	case IIO_CHAN_INFO_OFFSET:
>> +		switch (chan->type) {
>> +		case IIO_TEMP:
>> +			*val = DMARD06_TEMP_CENTER_VAL;
>> +			return IIO_VAL_INT;
>> +		default:
>> +			return -EINVAL;
>> +		}
>> +	case IIO_CHAN_INFO_SCALE:
>> +		switch (chan->type) {
>> +		case IIO_ACCEL:
>> +			*val = 0;
>> +			*val2 = DMARD06_AXIS_SCALE_VAL;
>> +			return IIO_VAL_INT_PLUS_MICRO;
>> +		default:
>> +			return -EINVAL;
>> +		}
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>> +static const struct iio_info dmard06_info = {
>> +	.driver_module	= THIS_MODULE,
>> +	.read_raw	= dmard06_read_raw,
>> +};
>> +
>> +#define DMARD06_ACCEL_CHANNEL(_axis, reg) {			\
> 
> maybe rename reg to _reg
> 
>> +	.type = IIO_ACCEL,					\
>> +	.address = reg,						\
>> +	.channel2 = IIO_MOD_##_axis,				\
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
>> +	.modified = 1,						\
>> +}
>> +
>> +#define DMARD06_TEMP_CHANNEL(reg) {				\
>> +	.type = IIO_TEMP,					\
>> +	.address = reg,						\
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
>> +			      BIT(IIO_CHAN_INFO_OFFSET),	\
>> +}
>> +
>> +static const struct iio_chan_spec dmard06_channels[] = {
>> +	DMARD06_ACCEL_CHANNEL(X, DMARD06_XOUT_REG),
>> +	DMARD06_ACCEL_CHANNEL(Y, DMARD06_YOUT_REG),
>> +	DMARD06_ACCEL_CHANNEL(Z, DMARD06_ZOUT_REG),
>> +	DMARD06_TEMP_CHANNEL(DMARD06_TOUT_REG),
>> +};
>> +
>> +static int dmard06_probe(struct i2c_client *client,
>> +			const struct i2c_device_id *id)
>> +{
>> +	int error;
>> +	struct iio_dev *indio_dev;
>> +	struct dmard06_data *dmard06;
>> +
>> +	dev_dbg(&client->dev, "I2C Address: 0x%02x\n", client->addr);
> 
> not needed
> 
>> +
>> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
>> +		dev_err(&client->dev, "I2C check functionality failed\n");
>> +		return -ENXIO;
>> +	}
>> +
>> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dmard06));
>> +	if (!indio_dev) {
>> +		dev_err(&client->dev, "Failed to allocate iio device\n");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	dmard06 = iio_priv(indio_dev);
>> +	dmard06->client = client;
>> +
>> +	error = dmard06_read_chip_id(dmard06);
>> +	if (error)
>> +		return error;
>> +
>> +	i2c_set_clientdata(client, indio_dev);
>> +	indio_dev->dev.parent = &client->dev;
>> +	indio_dev->name = DMARD06_DRV_NAME;
>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>> +	indio_dev->channels = dmard06_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(dmard06_channels);
>> +	indio_dev->info = &dmard06_info;
>> +
>> +	return devm_iio_device_register(&client->dev, indio_dev);
>> +}
>> +
>> +static const struct i2c_device_id dmard06_id[] = {
>> +	{ "dmard06", 0 },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(i2c, dmard06_id);
>> +
>> +static const struct of_device_id dmard06_of_match[] = {
>> +	{ .compatible = "domintech,dmard06" },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(of, dmard06_of_match);
>> +
>> +static struct i2c_driver dmard06_driver = {
>> +	.probe = dmard06_probe,
>> +	.id_table = dmard06_id,
>> +	.driver = {
>> +		.name = DMARD06_DRV_NAME,
>> +		.of_match_table = of_match_ptr(dmard06_of_match),
>> +	},
>> +};
>> +module_i2c_driver(dmard06_driver);
>> +
>> +MODULE_AUTHOR("Aleksei Mamlin <mamlinav@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("Domintech DMARD06 accelerometer driver");
>> +MODULE_LICENSE("GPL v2");
>>
>