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

From: Aleksei Mamlin
Date: Mon Jul 25 2016 - 03:50:31 EST

On Sat, 23 Jul 2016 09:26:39 +0200
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:

> 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.

Jonathan, I found that dmard05, dmard06 and dmard07 chips are very similar
and have the same registers. There is not so many difference between chips,
dmard05 and dmard07 have 8 bit adc and dmard06 only 7 bit adc.

I want to add support of those chips in driver, but there is the question:
should driver be renamed to something like dmard050607 or just dmard05
as first chip in this series?

> >> ---
> >> .../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");
> >>
> >
>


--
Thanks and regards,
Aleksei Mamlin