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

[Aleksei Mamlin <mamlinav@gmail.com>]

On Fri, 22 Jul 2016 00:41:39 +0200 (CEST)
Peter Meerwald-Stadler <pmeerw@pmeerw.net> 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@gmail.com>
> > ---
> >  .../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@gmail.com>
> > + *
> > + * 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()?
> 

I'll use it in next patch version

> 
> > +	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?
> 

You are right, this do the job for axis and temperature. Thanks

> 
> > +			*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@gmail.com>");
> > +MODULE_DESCRIPTION("Domintech DMARD06 accelerometer driver");
> > +MODULE_LICENSE("GPL v2");
> > 
> 
> -- 
> 
> Peter Meerwald-Stadler
> +43-664-2444418 (mobile)


-- 
Thanks and regards,
Aleksei Mamlin