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Message-ID: <b08cb6806c2bf466210692be37ac562b744fc660.camel@az8.co>
Subject: Re: [PATCH v2 1/4] iio: gyro: add support for fxas21002c
From:   Afonso Bordado <afonsobordado@az8.co>
To:     Tomasz Duszynski <tduszyns@gmail.com>
Cc:     jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de,
        pmeerw@pmeerw.net, linux-iio@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Date:   Tue, 04 Sep 2018 20:23:57 +0100
In-Reply-To: <20180831153548.GA2679@arch>
References: <20180830211825.12202-1-afonsobordado@az8.co>
         <20180831153548.GA2679@arch>
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Sender: linux-kernel-owner@vger.kernel.org
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On Fri, 2018-08-31 at 17:35 +0200, Tomasz Duszynski wrote:
> On Thu, Aug 30, 2018 at 10:18:22PM +0100, Afonso Bordado wrote:
> > FXAS21002C is a 3 axis gyroscope with integrated temperature sensor
> > 
> > Signed-off-by: Afonso Bordado <afonsobordado@az8.co>
> > ---
> >  Changes in v2
> >    - Use ANSI C Comments
> >    - Minor cleanups
> >    - More dscriptive devicetree bindings
> > 
> >  drivers/iio/gyro/Kconfig      |  11 +
> >  drivers/iio/gyro/Makefile     |   1 +
> >  drivers/iio/gyro/fxas21002c.c | 367
> > ++++++++++++++++++++++++++++++++++
> >  3 files changed, 379 insertions(+)
> >  create mode 100644 drivers/iio/gyro/fxas21002c.c
> > 
> > diff --git a/drivers/iio/gyro/Kconfig b/drivers/iio/gyro/Kconfig
> > index 3126cf05e6b9..d71e33ea9fa4 100644
> > --- a/drivers/iio/gyro/Kconfig
> > +++ b/drivers/iio/gyro/Kconfig
> > @@ -73,6 +73,17 @@ config BMG160_SPI
> >  	tristate
> >  	select REGMAP_SPI
> > 
> > +config FXAS21002C
> > +	tristate "Freescale FXAS21002C Gyroscope"
> > +	depends on I2C
> > +	select REGMAP_I2C
> > +	help
> > +	  Say yes here to build support for the Freescale FXAS21002C
> > Gyroscope
> > +	  driver connected via I2C.
> > +
> > +	  This driver can also be built as a module. If so, the module
> > +	  will be called fxas21002c.
> > +
> >  config HID_SENSOR_GYRO_3D
> >  	depends on HID_SENSOR_HUB
> >  	select IIO_BUFFER
> > diff --git a/drivers/iio/gyro/Makefile b/drivers/iio/gyro/Makefile
> > index 295ec780c4eb..ec3e2aeae92a 100644
> > --- a/drivers/iio/gyro/Makefile
> > +++ b/drivers/iio/gyro/Makefile
> > @@ -12,6 +12,7 @@ obj-$(CONFIG_ADXRS450) += adxrs450.o
> >  obj-$(CONFIG_BMG160) += bmg160_core.o
> >  obj-$(CONFIG_BMG160_I2C) += bmg160_i2c.o
> >  obj-$(CONFIG_BMG160_SPI) += bmg160_spi.o
> > +obj-$(CONFIG_FXAS21002C) += fxas21002c.o
> > 
> >  obj-$(CONFIG_HID_SENSOR_GYRO_3D) += hid-sensor-gyro-3d.o
> > 
> > diff --git a/drivers/iio/gyro/fxas21002c.c
> > b/drivers/iio/gyro/fxas21002c.c
> > new file mode 100644
> > index 000000000000..261b73629544
> > --- /dev/null
> > +++ b/drivers/iio/gyro/fxas21002c.c
> > @@ -0,0 +1,367 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * FXAS21002C - Digital Angular Rate Gyroscope driver
> > + *
> > + * Copyright (c) 2018, Afonso Bordado <afonsobordado@az8.co>
> > + *
> > + * IIO driver for FXAS21002C (7-bit I2C slave address 0x20 or
> > 0x21).
> > + * Datasheet: https://www.nxp.com/docs/en/data-sheet/FXAS21002.pdf
> > + * TODO:
> > + *        ODR / Scale Support
> > + *        Devicetree
> > + *        Power management
> > + *        LowPass/HighPass Filters
> > + *        Buffers
> > + *        Interrupts
> > + *        Alarms
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/regmap.h>
> > +
> > +#define FXAS21002C_DRV_NAME "fxas21002c"
> > +
> > +#define FXAS21002C_MAX_TRANSITION_TIME_MS 61
> > +
> > +#define FXAS21002C_CHIP_ID             0xD7
> > +
> > +#define FXAS21002C_REG_STATUS          0x00
> > +#define FXAS21002C_REG_OUT_X_MSB       0x01
> > +#define FXAS21002C_REG_OUT_X_LSB       0x02
> > +#define FXAS21002C_REG_OUT_Y_MSB       0x03
> > +#define FXAS21002C_REG_OUT_Y_LSB       0x04
> > +#define FXAS21002C_REG_OUT_Z_MSB       0x05
> > +#define FXAS21002C_REG_OUT_Z_LSB       0x06
> > +#define FXAS21002C_REG_DR_STATUS       0x07
> > +#define FXAS21002C_REG_F_STATUS        0x08
> > +#define FXAS21002C_REG_F_SETUP         0x09
> > +#define FXAS21002C_REG_F_EVENT         0x0A
> > +#define FXAS21002C_REG_INT_SRC_FLAG    0x0B
> > +#define FXAS21002C_REG_WHO_AM_I        0x0C
> > +#define FXAS21002C_REG_CTRL_REG0       0x0D
> > +#define FXAS21002C_REG_RT_CFG          0x0E
> > +#define FXAS21002C_REG_RT_SRC          0x0F
> > +#define FXAS21002C_REG_RT_THS          0x10
> > +#define FXAS21002C_REG_RT_COUNT        0x11
> > +#define FXAS21002C_REG_TEMP            0x12
> > +
> > +#define FXAS21002C_REG_CTRL_REG1       0x13
> > +#define FXAS21002C_RST_BIT             BIT(6)
> > +#define FXAS21002C_ACTIVE_BIT          BIT(1)
> > +#define FXAS21002C_READY_BIT           BIT(0)
> > +
> > +#define FXAS21002C_REG_CTRL_REG2       0x14
> > +#define FXAS21002C_REG_CTRL_REG3       0x15
> > +
> > +#define FXAS21002C_DEFAULT_ODR_HZ      800
> > +
> > +/* 0.0625 deg/s */
> > +#define FXAS21002C_DEFAULT_SENSITIVITY IIO_DEGREE_TO_RAD(62500)
> > +
> > +#define FXAS21002C_TEMP_SCALE          1000
> > +
> > +enum fxas21002c_id {
> 
> It looks like your are not using this named enum anywhere
> in the code so perhaps drop the name. Besides the name
> collides with i2c_device_id table's name. Just a suggestion though.

I agree, changed in v3.

> > +	ID_FXAS21002C,
> > +};
> > +
> > +enum fxas21002c_operating_mode {
> > +	FXAS21002C_OM_BOOT,
> > +	FXAS21002C_OM_STANDBY,
> > +	FXAS21002C_OM_READY,
> > +	FXAS21002C_OM_ACTIVE,
> > +};
> > +
> > +struct fxas21002c_data {
> > +	struct i2c_client *client;
> > +	struct regmap *regmap;
> > +};
> > +
> > +static const struct regmap_range fxas21002c_writable_ranges[] = {
> > +	regmap_reg_range(FXAS21002C_REG_F_SETUP,
> > FXAS21002C_REG_F_SETUP),
> > +	regmap_reg_range(FXAS21002C_REG_CTRL_REG0,
> > FXAS21002C_REG_RT_CFG),
> > +	regmap_reg_range(FXAS21002C_REG_RT_THS,
> > FXAS21002C_REG_RT_COUNT),
> > +	regmap_reg_range(FXAS21002C_REG_CTRL_REG1,
> > FXAS21002C_REG_CTRL_REG3),
> > +};
> > +
> > +static const struct regmap_access_table fxas21002c_writable_table
> > = {
> > +	.yes_ranges = fxas21002c_writable_ranges,
> > +	.n_yes_ranges = ARRAY_SIZE(fxas21002c_writable_ranges),
> > +};
> > +
> > +static const struct regmap_range fxas21002c_volatile_ranges[] = {
> > +	regmap_reg_range(FXAS21002C_REG_STATUS,
> > FXAS21002C_REG_F_STATUS),
> > +	regmap_reg_range(FXAS21002C_REG_F_EVENT,
> > FXAS21002C_REG_INT_SRC_FLAG),
> > +	regmap_reg_range(FXAS21002C_REG_RT_COUNT,
> > FXAS21002C_REG_CTRL_REG1),
> > +};
> > +
> > +static const struct regmap_access_table fxas21002c_volatile_table
> > = {
> > +	.yes_ranges = fxas21002c_volatile_ranges,
> > +	.n_yes_ranges = ARRAY_SIZE(fxas21002c_volatile_ranges),
> > +};
> > +
> > +const struct regmap_config fxas21002c_regmap_config = {
> > +	.reg_bits = 8,
> > +	.val_bits = 8,
> > +
> > +	.max_register = FXAS21002C_REG_CTRL_REG3,
> > +	/* We don't specify a .rd_table because everything is readable
> > */
> > +	.wr_table = &fxas21002c_writable_table,
> > +	.volatile_table = &fxas21002c_volatile_table,
> > +};
> > +EXPORT_SYMBOL(fxas21002c_regmap_config);
> > +
> > +#define FXAS21002C_GYRO_CHAN(_axis) {				
> > 	\
> > +	.type = IIO_ANGL_VEL,						
> > \
> > +	.modified = 1,							
> > \
> > +	.channel2 = IIO_MOD_ ## _axis,					
> > \
> > +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			
> > \
> > +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |		
> > \
> > +				    BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
> > +	.address = FXAS21002C_REG_OUT_ ## _axis ## _MSB,		\
> > +}
> > +
> > +static const struct iio_chan_spec fxas21002c_channels[] = {
> > +	{
> > +		.type = IIO_TEMP,
> > +		.address = FXAS21002C_REG_TEMP,
> > +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > +				      BIT(IIO_CHAN_INFO_SCALE),
> > +	},
> > +	FXAS21002C_GYRO_CHAN(X),
> > +	FXAS21002C_GYRO_CHAN(Y),
> > +	FXAS21002C_GYRO_CHAN(Z),
> > +	IIO_CHAN_SOFT_TIMESTAMP(3),
> > +};
> > +
> > +static int fxas21002c_set_operating_mode(struct fxas21002c_data
> > *data,
> > +					 enum fxas21002c_operating_mode
> > om)
> > +{
> > +	int ret;
> > +	int mask;
> > +
> > +	switch (om) {
> > +	case FXAS21002C_OM_STANDBY:
> > +		mask = 0;
> > +		break;
> > +	case FXAS21002C_OM_READY:
> > +		mask = FXAS21002C_READY_BIT;
> > +		break;
> > +	case FXAS21002C_OM_ACTIVE:
> > +		mask = FXAS21002C_ACTIVE_BIT;
> > +		break;
> > +
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +
> > +	ret = regmap_write(data->regmap, FXAS21002C_REG_CTRL_REG1,
> > mask);
> > +	if (ret) {
> > +		dev_err(&data->client->dev,
> > +			"could not switch operating mode\n");
> > +		return ret;
> > +	}
> > +
> > +	msleep(FXAS21002C_MAX_TRANSITION_TIME_MS);
> > +
> > +	return 0;
> > +}
> > +
> > +static void fxas21002c_standby(void *_data)
> > +{
> > +	struct fxas21002c_data *data = _data;
> > +
> > +	fxas21002c_set_operating_mode(data, FXAS21002C_OM_STANDBY);
> > +}
> > +
> > +static int fxas21002c_reset(struct fxas21002c_data *data)
> > +{
> > +	int ret;
> > +
> > +	/*
> > +	 * On issuing a Software Reset command over an I2C interface,
> > +	 * the device immediately resets and does not send any
> > +	 * acknowledgment (ACK) of the written byte to the Master.
> > +	 *
> > +	 * This is documented in table 46 on the datasheet. Due to this
> > +	 * the write will fail with EREMOTEIO.
> > +	 */
> > +	ret = regmap_write(data->regmap,
> > +			   FXAS21002C_REG_CTRL_REG1,
> > FXAS21002C_RST_BIT);
> > +
> > +	if (ret != -EREMOTEIO) {
> > +		dev_err(&data->client->dev, "could not reset
> > device\n");
> > +		return ret;
> > +	}
> > +
> > +	regcache_mark_dirty(data->regmap);
> > +
> > +	/* Wait for device to boot up */
> > +	msleep(FXAS21002C_MAX_TRANSITION_TIME_MS);
> > +
> > +	return 0;
> > +}
> > +
> > +static int fxas21002c_verify_chip(struct fxas21002c_data *data)
> > +{
> > +	int ret;
> > +	int chip_id;
> > +
> > +	ret = regmap_read(data->regmap, FXAS21002C_REG_WHO_AM_I,
> > &chip_id);
> > +	if (ret) {
> > +		dev_err(&data->client->dev, "could not read device
> > id\n");
> > +		return ret;
> > +	}
> > +
> > +	if (chip_id != FXAS21002C_CHIP_ID) {
> > +		dev_err(&data->client->dev,
> > +			"unsupported chip id %02x\n", chip_id);
> > +		return -ENODEV;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int fxas21002c_read_oneshot(struct fxas21002c_data *data,
> > +				   struct iio_chan_spec const *chan,
> > int *val)
> > +{
> > +	int ret;
> > +	__be16 bulk_raw;
> > +
> > +	switch (chan->type) {
> > +	case IIO_ANGL_VEL:
> > +		ret = regmap_bulk_read(data->regmap, chan->address,
> > +				       &bulk_raw, sizeof(bulk_raw));
> > +		if (ret)
> > +			return ret;
> > +
> > +		*val = sign_extend32(be16_to_cpu(bulk_raw), 15);
> > +		return IIO_VAL_INT;
> > +	case IIO_TEMP:
> > +		ret = regmap_read(data->regmap, chan->address, val);
> > +		if (ret)
> > +			return ret;
> > +
> > +		return IIO_VAL_INT;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +}
> > +
> > +static int fxas21002c_read_raw(struct iio_dev *indio_dev,
> > +			       struct iio_chan_spec const *chan, int
> > *val,
> > +			       int *val2, long mask)
> > +{
> > +	struct fxas21002c_data *data = iio_priv(indio_dev);
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:
> > +		return fxas21002c_read_oneshot(data, chan, val);
> > +	case IIO_CHAN_INFO_SCALE:
> > +		switch (chan->type) {
> > +		case IIO_ANGL_VEL:
> > +			*val = 0;
> > +			*val2 = FXAS21002C_DEFAULT_SENSITIVITY;
> > +
> > +			return IIO_VAL_INT_PLUS_MICRO;
> > +		case IIO_TEMP:
> > +			*val = FXAS21002C_TEMP_SCALE;
> > +
> > +			return IIO_VAL_INT;
> > +		default:
> > +			return -EINVAL;
> > +		}
> > +	case IIO_CHAN_INFO_SAMP_FREQ:
> > +		if (chan->type != IIO_ANGL_VEL)
> > +			return -EINVAL;
> > +
> > +		*val = FXAS21002C_DEFAULT_ODR_HZ;
> > +
> > +		return IIO_VAL_INT;
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> > +
> > +static const struct iio_info fxas21002c_info = {
> > +	.read_raw		= fxas21002c_read_raw,
> > +};
> > +
> > +static int fxas21002c_probe(struct i2c_client *client,
> > +			    const struct i2c_device_id *id)
> > +{
> > +	int ret;
> > +	struct iio_dev *indio_dev;
> > +	struct fxas21002c_data *data;
> > +
> > +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	i2c_set_clientdata(client, indio_dev);
> > +	data = iio_priv(indio_dev);
> > +	data->client = client;
> > +
> > +	data->regmap = devm_regmap_init_i2c(client,
> > &fxas21002c_regmap_config);
> > +	if (IS_ERR(data->regmap)) {
> > +		ret = PTR_ERR(data->regmap);
> > +		dev_err(&client->dev,
> > +			"Failed to allocate regmap, err: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	indio_dev->dev.parent = &client->dev;
> > +	indio_dev->channels = fxas21002c_channels;
> > +	indio_dev->num_channels = ARRAY_SIZE(fxas21002c_channels);
> > +	indio_dev->name = id->name;
> > +	indio_dev->modes = INDIO_DIRECT_MODE;
> > +	indio_dev->info = &fxas21002c_info;
> > +
> > +	ret = fxas21002c_verify_chip(data);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	ret = fxas21002c_reset(data);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	ret = fxas21002c_set_operating_mode(data,
> > FXAS21002C_OM_ACTIVE);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	ret = devm_add_action(&client->dev, fxas21002c_standby, data);
> > +	if (ret < 0) {
> > +		fxas21002c_standby(data);
> > +		dev_err(&client->dev, "failed to add standby
> > action\n");
> > +		return ret;
> > +	}
> > +
> > +	ret = iio_device_register(indio_dev);
> > +	if (ret < 0)
> > +		dev_err(&client->dev, "failed to register iio
> > device\n");
> > +
> > +	return ret;
> > +}
> > +
> > +static const struct i2c_device_id fxas21002c_id[] = {
> > +	{"fxas21002c", ID_FXAS21002C},
> > +	{}
> > +};
> > +
> > +MODULE_DEVICE_TABLE(i2c, fxas21002c_id);
> > +
> > +static struct i2c_driver fxas21002c_driver = {
> > +	.driver = {
> > +		.name = FXAS21002C_DRV_NAME,
> > +	},
> > +	.probe		= fxas21002c_probe,
> > +	.id_table	= fxas21002c_id,
> > +};
> > +
> > +module_i2c_driver(fxas21002c_driver);
> > +
> > +MODULE_AUTHOR("Afonso Bordado <afonsobordado@az8.co>");
> > +MODULE_DESCRIPTION("FXAS21002C Digital Angular Rate Gyroscope
> > driver");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.18.0
> > 
> >