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

Peter Meerwald-Stadler
2016-07-21T22:41:43Z

> 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()?

> + 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@gmail.com>");
> +MODULE_DESCRIPTION("Domintech DMARD06 accelerometer driver");
> +MODULE_LICENSE("GPL v2");
>

--

Peter Meerwald-Stadler
+43-664-2444418 (mobile)