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

From: Peter Meerwald-Stadler
Date: Mon Jul 25 2016 - 04:37:24 EST


> > >> 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?

just pick one name, e.g. dmard06; the file name should NOT contain things
such as dmard0x or 050607 -- marketing is just too creative :) and
remember:
"There are two hard things in computer science: cache invalidation, naming
things, and off-by-one errors."

p.

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

--

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