Re: [PATCH v3] iio: add driver for Freescale MMA9551L

[Hartmut Knaack <knaack.h@gmx.de>]

Vlad Dogaru schrieb am 17.11.2014 16:03:
> Add support for Freescale MMA9551L Intelligent Motion-Sensing Platform.
> The driver supports raw reads for acceleration and inclination, as well
> as configuring an inclination rate-of-change events.  The events can be
> used similarly to an Android sensor Tilt event.
> 
> The specifications can be downloaded from:
> http://www.freescale.com/files/sensors/doc/ref_manual/MMA955xLSWRM.pdf
> 
Looks very good. Just a few minor cleanup recommendations inline.
> Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
> Signed-off-by: Vlad Dogaru <vlad.dogaru@intel.com>
> ---
> Changes since v2:
>  - all three events can be enabled at the same time, each using a separate
>    GPIO line.
>  - simplify GPIO config code.
>  - style fixes as suggested by Jonathan.
> 
> Changes since v1:
>  - invert logic in mma9551_set_device_state().  Setting the sleep bit to 1 puts
>    the device into sleep.
>  - do not use scan_index for channels, since we don't support buffering.
>  - style fixes as suggested by Peter.
> 
>  drivers/iio/accel/Kconfig   |  10 +
>  drivers/iio/accel/Makefile  |   1 +
>  drivers/iio/accel/mma9551.c | 960 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 971 insertions(+)
>  create mode 100644 drivers/iio/accel/mma9551.c
> 
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 9b9be87..d80616d 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -105,4 +105,14 @@ config KXCJK1013
>  	  To compile this driver as a module, choose M here: the module will
>  	  be called kxcjk-1013.
>  
> +config MMA9551
> +	tristate "Freescale MMA9551L Intelligent Motion-Sensing Platform Driver"
> +	depends on I2C
> +	help
> +	  Say yes here to build support for the Freescale MMA9551L
> +	  Intelligent Motion-Sensing Platform Driver.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called mma9551.
> +
>  endmenu
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index a593996..de5b9cb 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_HID_SENSOR_ACCEL_3D) += hid-sensor-accel-3d.o
>  obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
>  obj-$(CONFIG_KXSD9)	+= kxsd9.o
>  obj-$(CONFIG_MMA8452)	+= mma8452.o
> +obj-$(CONFIG_MMA9551)	+= mma9551.o
>  
>  obj-$(CONFIG_IIO_ST_ACCEL_3AXIS) += st_accel.o
>  st_accel-y := st_accel_core.o
> diff --git a/drivers/iio/accel/mma9551.c b/drivers/iio/accel/mma9551.c
> new file mode 100644
> index 0000000..d677042
> --- /dev/null
> +++ b/drivers/iio/accel/mma9551.c
> @@ -0,0 +1,960 @@
> +/*
> + * Freescale MMA9551L Intelligent Motion-Sensing Platform driver
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * 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.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/slab.h>
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/events.h>
> +
> +#define MMA9551_DRV_NAME		"mma9551"
> +#define MMA9551_IRQ_NAME		"mma9551_event"
> +#define MMA9551_GPIO_NAME		"mma9551_int"
> +#define MMA9551_GPIO_COUNT		4
> +
> +/* Applications IDs */
> +#define MMA9551_APPID_VERSION		0x00
> +#define MMA9551_APPID_GPIO		0x03
> +#define MMA9551_APPID_AFE		0x06
> +#define MMA9551_APPID_TILT		0x0B
> +#define MMA9551_APPID_SLEEP_WAKE	0x12
> +#define MMA9551_APPID_RESET		0x17
> +#define MMA9551_APPID_NONE		0xff
> +
> +/* Command masks for mailbox write command */
> +#define MMA9551_CMD_READ_VERSION_INFO	0x00
> +#define MMA9551_CMD_READ_CONFIG		0x10
> +#define MMA9551_CMD_WRITE_CONFIG	0x20
> +#define MMA9551_CMD_READ_STATUS		0x30
> +
> +enum mma9551_gpio_pin {
> +	mma9551_gpio6 = 0,
> +	mma9551_gpio7,
> +	mma9551_gpio8,
> +	mma9551_gpio9,
> +	mma9551_gpio_max = mma9551_gpio9,
> +};
> +
> +/* Mailbox read command */
> +#define MMA9551_RESPONSE_COCO		BIT(7)
> +
> +/* Error-Status codes returned in mailbox read command */
> +#define MMA9551_MCI_ERROR_NONE			0x00
> +#define MMA9551_MCI_ERROR_PARAM			0x04
> +#define MMA9551_MCI_INVALID_COUNT		0x19
> +#define MMA9551_MCI_ERROR_COMMAND		0x1C
> +#define MMA9551_MCI_ERROR_INVALID_LENGTH	0x21
> +#define MMA9551_MCI_ERROR_FIFO_BUSY		0x22
> +#define MMA9551_MCI_ERROR_FIFO_ALLOCATED	0x23
> +#define MMA9551_MCI_ERROR_FIFO_OVERSIZE		0x24
> +
> +/* GPIO Application */
> +#define MMA9551_GPIO_POL_MSB		0x08
> +#define MMA9551_GPIO_POL_LSB		0x09
> +
> +/* Sleep/Wake application */
> +#define MMA9551_SLEEP_CFG		0x06
> +#define MMA9551_SLEEP_CFG_SNCEN		BIT(0)
> +#define MMA9551_SLEEP_CFG_SCHEN		BIT(2)
> +
> +/* AFE application */
> +#define MMA9551_AFE_X_ACCEL_REG		0x00
> +#define MMA9551_AFE_Y_ACCEL_REG		0x02
> +#define MMA9551_AFE_Z_ACCEL_REG		0x04
> +
> +/* Tilt application (inclination in IIO terms). */
> +#define MMA9551_TILT_XZ_ANG_REG		0x00
> +#define MMA9551_TILT_YZ_ANG_REG		0x01
> +#define MMA9551_TILT_XY_ANG_REG		0x02
> +#define MMA9551_TILT_XY_QUAD_SHIFT	0
> +#define MMA9551_TILT_YZ_QUAD_SHIFT	2
> +#define MMA9551_TILT_XZ_QUAD_SHIFT	4
> +#define MMA9551_TILT_ANGFLG		BIT(7)
This flag is part of the angular registers, so better move it up there.
> +#define MMA9551_TILT_QUAD_REG		0x03
This line should be put on top of the _QUAD_SHIFTs.
> +#define MMA9551_TILT_CFG_REG		0x01
> +#define MMA9551_TILT_ANG_THRESH_MASK	0x0f
This may be represented using GENMASK - just a matter of taste.
> +
> +/* Tilt events are mapped to the first three GPIO pins. */
> +enum mma9551_tilt_axis {
> +	mma9551_x = 0,
> +	mma9551_y,
> +	mma9551_z,
> +};
> +
> +/*
> + * A response is composed of:
> + * - control registers: MB0-3
> + * - data registers: MB4-31
> + *
> + * A request is composed of:
> + * - mbox to write to (always 0)
> + * - control registers: MB1-4
> + * - data registers: MB5-31
> + */
> +#define MMA9551_MAILBOX_CTRL_REGS	4
> +#define MMA9551_MAX_MAILBOX_DATA_REGS	28
> +#define MMA9551_MAILBOX_REGS		32
> +
> +#define MMA9551_I2C_READ_RETRIES	5
> +#define MMA9551_I2C_READ_DELAY	50	/* us */
> +
> +struct mma9551_mbox_request {
> +	u8 start_mbox;		/* Always 0. */
> +	u8 app_id;
> +	/*
> +	 * See Section 5.3.1 of the MMA955xL Software Reference Manual.
> +	 *
> +	 * Bit 7: reserved, always 0
> +	 * Bits 6-4: command
> +	 * Bits 3-0: upper bits of register offset
> +	 */
> +	u8 cmd_off;
> +	u8 lower_off;
> +	u8 nbytes;
> +	u8 buf[MMA9551_MAX_MAILBOX_DATA_REGS - 1];
> +} __packed;
> +
> +struct mma9551_mbox_response {
> +	u8 app_id;
> +	/*
> +	 * See Section 5.3.3 of the MMA955xL Software Reference Manual.
> +	 *
> +	 * Bit 7: COCO
> +	 * Bits 6-0: Error code.
> +	 */
> +	u8 coco_err;
> +	u8 nbytes;
> +	u8 req_bytes;
> +	u8 buf[MMA9551_MAX_MAILBOX_DATA_REGS];
> +} __packed;
> +
> +struct mma9551_version_info {
> +	__be32 device_id;
> +	u8 rom_version[2];
> +	u8 fw_version[2];
> +	u8 hw_version[2];
> +	u8 fw_build[2];
> +};
> +
> +struct mma9551_data {
> +	struct i2c_client *client;
> +	struct mutex mutex;
> +	int event_enabled[3];
> +	int irqs[MMA9551_GPIO_COUNT];
> +};
> +
> +static int mma9551_transfer(struct i2c_client *client,
> +			    u8 app_id, u8 command, u16 offset,
> +			    u8 *inbytes, int num_inbytes,
> +			    u8 *outbytes, int num_outbytes)
> +{
> +	struct mma9551_mbox_request req;
> +	struct mma9551_mbox_response rsp;
> +	struct i2c_msg in, out;
> +	u8 req_len, err_code;
> +	int ret;
> +	int retries;
These two int definitions could be consolidated in one line.
> +
> +	if (offset >= 1 << 12) {
> +		dev_err(&client->dev, "register offset too large\n");
> +		return -EINVAL;
> +	}
> +
> +	req_len = 1 + MMA9551_MAILBOX_CTRL_REGS + num_inbytes;
> +	req.start_mbox = 0;
> +	req.app_id = app_id;
> +	req.cmd_off = command | (offset >> 8);
> +	req.lower_off = offset;
> +
> +	if (command == MMA9551_CMD_WRITE_CONFIG)
> +		req.nbytes = num_inbytes;
> +	else
> +		req.nbytes = num_outbytes;
> +	if (num_inbytes)
> +		memcpy(req.buf, inbytes, num_inbytes);
> +
> +	out.addr = client->addr;
> +	out.flags = 0;
> +	out.len = req_len;
> +	out.buf = (u8 *)&req;
> +
> +	ret = i2c_transfer(client->adapter, &out, 1);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "i2c write failed\n");
> +		return ret;
> +	}
> +
> +	retries = MMA9551_I2C_READ_RETRIES;
> +	do {
> +		udelay(MMA9551_I2C_READ_DELAY);
> +
> +		in.addr = client->addr;
> +		in.flags = I2C_M_RD;
> +		in.len = sizeof(rsp);
> +		in.buf = (u8 *)&rsp;
> +
> +		ret = i2c_transfer(client->adapter, &in, 1);
> +		if (ret < 0) {
> +			dev_err(&client->dev, "i2c read failed\n");
> +			return ret;
> +		}
> +
> +		if (rsp.coco_err & MMA9551_RESPONSE_COCO)
> +			break;
> +	} while (--retries > 0);
> +
> +	if (retries == 0) {
> +		dev_err(&client->dev,
> +			"timed out while waiting for command response\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	if (rsp.app_id != app_id) {
> +		dev_err(&client->dev,
> +			"app_id mismatch in response got %02x expected %02x\n",
> +			rsp.app_id, app_id);
> +		return -EINVAL;
> +	}
> +
> +	err_code = rsp.coco_err & ~MMA9551_RESPONSE_COCO;
> +	if (err_code != MMA9551_MCI_ERROR_NONE) {
> +		dev_err(&client->dev, "read returned error %x\n", err_code);
> +		return -EINVAL;
> +	}
> +
> +	if (rsp.nbytes != rsp.req_bytes) {
> +		dev_err(&client->dev,
> +			"output length mismatch got %d expected %d\n",
> +			rsp.nbytes, num_outbytes);
Don't you mean rsp.req_bytes instead of num_outbytes here?
> +		return -EINVAL;
> +	}
> +
> +	if (num_outbytes)
> +		memcpy(outbytes, rsp.buf, num_outbytes);
> +
> +	return 0;
> +}
> +
> +static int mma9551_read_config_byte(struct i2c_client *client, u8 app_id,
> +				    u16 reg, u8 *val)
> +{
> +	return mma9551_transfer(client, app_id, MMA9551_CMD_READ_CONFIG,
> +				reg, NULL, 0, val, 1);
> +}
> +
> +static int mma9551_write_config_byte(struct i2c_client *client, u8 app_id,
> +				     u16 reg, u8 val)
> +{
> +	return mma9551_transfer(client, app_id, MMA9551_CMD_WRITE_CONFIG, reg,
> +				&val, 1, NULL, 0);
> +}
> +
> +static int mma9551_read_status_byte(struct i2c_client *client, u8 app_id,
> +				    u16 reg, u8 *val)
> +{
> +	return mma9551_transfer(client, app_id, MMA9551_CMD_READ_STATUS,
> +				reg, NULL, 0, val, 1);
> +}
> +
> +static int mma9551_read_status_word(struct i2c_client *client, u8 app_id,
> +				    u16 reg, u16 *val)
> +{
> +	int ret;
> +	__be16 v;
> +
> +	ret = mma9551_transfer(client, app_id, MMA9551_CMD_READ_STATUS,
> +			       reg, NULL, 0, (u8 *)&v, 2);
> +	*val = be16_to_cpu(v);
> +
> +	return ret;
> +}
> +
> +static int mma9551_update_config_bits(struct i2c_client *client, u8 app_id,
> +				      u8 reg, u8 mask, u8 val)
u16 was used for reg previously, would be more consistent to stick to it.
> +{
> +	int ret;
> +	u8 tmp, orig;
> +
> +	ret = mma9551_read_config_byte(client, app_id, reg, &orig);
> +	if (ret < 0)
> +		return ret;
> +
> +	tmp = orig & ~mask;
> +	tmp |= val & mask;
> +
> +	if (tmp == orig)
> +		return 0;
> +
> +	return mma9551_write_config_byte(client, app_id, reg, tmp);
> +}
> +
> +/*
> + * The polarity parameter is described in section 6.2.2, page 66, of the
> + * Software Reference Manual.  Basically, polarity=0 means the interrupt
> + * line has the same value as the selected bit, while polarity=1 means
> + * the line is inverted.
> + */
> +static int mma9551_gpio_config(struct i2c_client *client,
> +			       enum mma9551_gpio_pin pin,
> +			       u8 app_id, u8 bitnum, int polarity)
> +{
> +	u8 reg, pol_mask, pol_val;
> +	int ret;
> +
> +	if (pin > mma9551_gpio_max) {
> +		dev_err(&client->dev, "bad GPIO pin\n");
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Pin 6 is configured by regs 0x00 and 0x01, pin 7 by 0x02 and
> +	 * 0x03, and so on.
> +	 */
> +	reg = pin * 2;
> +
> +	ret = mma9551_write_config_byte(client, MMA9551_APPID_GPIO,
> +					reg, app_id);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "error setting GPIO app_id\n");
> +		return ret;
> +	}
> +
> +	ret = mma9551_write_config_byte(client, MMA9551_APPID_GPIO,
> +					reg + 1, bitnum);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "error setting GPIO bit number\n");
> +		return ret;
> +	}
> +
> +	switch (pin) {
> +	case mma9551_gpio6:
> +		reg = MMA9551_GPIO_POL_LSB;
> +		pol_mask = 1 << 6;
> +		break;
> +	case mma9551_gpio7:
> +		reg = MMA9551_GPIO_POL_LSB;
> +		pol_mask = 1 << 7;
> +		break;
> +	case mma9551_gpio8:
> +		reg = MMA9551_GPIO_POL_MSB;
> +		pol_mask = 1 << 0;
> +		break;
> +	case mma9551_gpio9:
> +		reg = MMA9551_GPIO_POL_MSB;
> +		pol_mask = 1 << 1;
> +		break;
> +	}
> +	pol_val = polarity ? pol_mask : 0;
> +
> +	ret = mma9551_update_config_bits(client, MMA9551_APPID_GPIO, reg,
> +					 pol_mask, pol_val);
> +	if (ret < 0)
> +		dev_err(&client->dev, "error setting GPIO polarity\n");
> +
> +	return ret;
> +}
> +
> +static int mma9551_read_version(struct i2c_client *client)
> +{
> +	struct mma9551_version_info info;
> +	int ret;
> +
> +	ret = mma9551_transfer(client, MMA9551_APPID_VERSION, 0x00, 0x00,
> +			       NULL, 0, (u8 *)&info, sizeof(info));
> +	if (ret < 0)
> +		return ret;
> +
> +	dev_info(&client->dev, "Device ID 0x%x, firmware version %02x.%02x\n",
> +		 be32_to_cpu(info.device_id), info.fw_version[0],
> +		 info.fw_version[1]);
> +
> +	return 0;
> +}
> +
> +/*
> + * Use 'false' as the second parameter to cause the device to enter
> + * sleep.
> + */
> +static int mma9551_set_device_state(struct i2c_client *client,
> +				    bool enable)
> +{
> +	return mma9551_update_config_bits(client, MMA9551_APPID_SLEEP_WAKE,
> +			  MMA9551_SLEEP_CFG,
> +			  MMA9551_SLEEP_CFG_SNCEN,
> +			  enable ? 0 : MMA9551_SLEEP_CFG_SNCEN);
This will fit exactly 80 chars, if indented the normal way.
> +}
> +
> +static int mma9551_read_incli_chan(struct i2c_client *client,
> +				   const struct iio_chan_spec *chan,
> +				   int *val)
> +{
> +	u8 quad_shift, quad_mask, angle, quadrant;
> +	u16 reg_addr;
> +	int ret;
> +
> +	switch (chan->channel2) {
> +	case IIO_MOD_X:
> +		reg_addr = MMA9551_TILT_YZ_ANG_REG;
> +		quad_shift = MMA9551_TILT_YZ_QUAD_SHIFT;
> +		break;
> +	case IIO_MOD_Y:
> +		reg_addr = MMA9551_TILT_XZ_ANG_REG;
> +		quad_shift = MMA9551_TILT_XZ_QUAD_SHIFT;
> +		break;
> +	case IIO_MOD_Z:
> +		reg_addr = MMA9551_TILT_XY_ANG_REG;
> +		quad_shift = MMA9551_TILT_XY_QUAD_SHIFT;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
> +				       reg_addr, &angle);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = mma9551_read_status_byte(client, MMA9551_APPID_TILT,
> +				       MMA9551_TILT_QUAD_REG, &quadrant);
> +	if (ret < 0)
> +		return ret;
> +
> +	angle &= ~MMA9551_TILT_ANGFLG;
> +	quad_mask = 0x03 << quad_shift;
> +	quadrant = (quadrant & quad_mask) >> quad_shift;
quad_mask is unnecessary. Just do:
	quadrant = (quadrant >> quad_shift) & 0x03;
> +
> +	if (quadrant == 1 || quadrant == 3)
> +		*val = 90 * (quadrant + 1) - angle;
> +	else
> +		*val = angle + 90 * quadrant;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int mma9551_read_accel_chan(struct i2c_client *client,
> +				   const struct iio_chan_spec *chan,
> +				   int *val, int *val2)
> +{
> +	u16 reg_addr;
> +	s16 raw_accel;
> +	int ret;
> +
> +	switch (chan->channel2) {
> +	case IIO_MOD_X:
> +		reg_addr = MMA9551_AFE_X_ACCEL_REG;
> +		break;
> +	case IIO_MOD_Y:
> +		reg_addr = MMA9551_AFE_Y_ACCEL_REG;
> +		break;
> +	case IIO_MOD_Z:
> +		reg_addr = MMA9551_AFE_Z_ACCEL_REG;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ret = mma9551_read_status_word(client, MMA9551_APPID_AFE,
> +				       reg_addr, &raw_accel);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = raw_accel;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int mma9551_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		switch (chan->type) {
> +		case IIO_INCLI:
> +			mutex_lock(&data->mutex);
> +			ret = mma9551_read_incli_chan(data->client,
> +						      chan, val);
No need to wrap this line.
> +			mutex_unlock(&data->mutex);
> +			return ret;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			mutex_lock(&data->mutex);
> +			ret = mma9551_read_accel_chan(data->client,
> +						      chan, val, val2);
> +			mutex_unlock(&data->mutex);
> +			return ret;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			*val = 0;
> +			*val2 = 2440;
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		default:
> +			return -EINVAL;
> +		}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int mma9551_read_event_config(struct iio_dev *indio_dev,
> +				     const struct iio_chan_spec *chan,
> +				     enum iio_event_type type,
> +				     enum iio_event_direction dir)
> +{
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +
> +	switch (chan->type) {
> +	case IIO_INCLI:
> +		/* IIO counts axes from 1, because IIO_NO_MOD is 0. */
> +		return data->event_enabled[chan->channel2 - 1];
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int mma9551_config_incli_event(struct iio_dev *indio_dev,
> +				      enum iio_modifier axis,
> +				      int state)
> +{
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	enum mma9551_tilt_axis mma_axis;
> +	int ret;
> +
> +	/* IIO counts axes from 1, because IIO_NO_MOD is 0. */
> +	mma_axis = axis - 1;
> +
> +	if (data->event_enabled[mma_axis] == state)
> +		return 0;
> +
> +	if (state == 0) {
> +		ret = mma9551_gpio_config(data->client, mma_axis,
> +					  MMA9551_APPID_NONE, 0, 0);
> +		if (ret < 0)
> +			return ret;
> +	} else {
> +		int bitnum;
> +
> +		/* Bit 7 of each angle register holds the angle flag. */
> +		switch (axis) {
> +		case IIO_MOD_X:
> +			bitnum = 7 + 8 * MMA9551_TILT_YZ_ANG_REG;
> +			break;
> +		case IIO_MOD_Y:
> +			bitnum = 7 + 8 * MMA9551_TILT_XZ_ANG_REG;
> +			break;
> +		case IIO_MOD_Z:
> +			bitnum = 7 + 8 * MMA9551_TILT_XY_ANG_REG;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		ret = mma9551_gpio_config(data->client, mma_axis,
> +					  MMA9551_APPID_TILT, bitnum, 0);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	data->event_enabled[mma_axis] = state;
> +
> +	return ret;
> +}
> +
> +static int mma9551_write_event_config(struct iio_dev *indio_dev,
> +				      const struct iio_chan_spec *chan,
> +				      enum iio_event_type type,
> +				      enum iio_event_direction dir,
> +				      int state)
> +{
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (chan->type) {
> +	case IIO_INCLI:
> +		mutex_lock(&data->mutex);
> +		ret = mma9551_config_incli_event(indio_dev,
> +						 chan->channel2, state);
> +		mutex_unlock(&data->mutex);
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int mma9551_write_event_value(struct iio_dev *indio_dev,
> +				     const struct iio_chan_spec *chan,
> +				     enum iio_event_type type,
> +				     enum iio_event_direction dir,
> +				     enum iio_event_info info,
> +				     int val, int val2)
> +{
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (chan->type) {
> +	case IIO_INCLI:
> +		if (val2 != 0 || val < 1 || val > 10)
> +			return -EINVAL;
> +		mutex_lock(&data->mutex);
> +		ret = mma9551_update_config_bits(data->client,
> +						 MMA9551_APPID_TILT,
> +						 MMA9551_TILT_CFG_REG,
> +						 MMA9551_TILT_ANG_THRESH_MASK,
> +						 val);
> +		mutex_unlock(&data->mutex);
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int mma9551_read_event_value(struct iio_dev *indio_dev,
> +				    const struct iio_chan_spec *chan,
> +				    enum iio_event_type type,
> +				    enum iio_event_direction dir,
> +				    enum iio_event_info info,
> +				    int *val, int *val2)
> +{
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	int ret;
> +	u8 tmp;
> +
> +	switch (chan->type) {
> +	case IIO_INCLI:
> +		mutex_lock(&data->mutex);
> +		ret = mma9551_read_config_byte(data->client,
> +					       MMA9551_APPID_TILT,
> +					       MMA9551_TILT_CFG_REG, &tmp);
> +		mutex_unlock(&data->mutex);
> +		if (ret < 0)
> +			return ret;
> +		*val = tmp & MMA9551_TILT_ANG_THRESH_MASK;
> +		*val2 = 0;
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_event_spec mma9551_incli_event = {
> +	.type = IIO_EV_TYPE_ROC,
> +	.dir = IIO_EV_DIR_RISING,
> +	.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +	.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE),
> +};
> +
> +#define MMA9551_ACCEL_CHANNEL(axis) {				\
> +	.type = IIO_ACCEL,					\
> +	.modified = 1,						\
> +	.channel2 = axis,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +}
> +
> +#define MMA9551_INCLI_CHANNEL(axis) {				\
> +	.type = IIO_INCLI,					\
> +	.modified = 1,						\
> +	.channel2 = axis,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),	\
> +	.event_spec = &mma9551_incli_event,			\
> +	.num_event_specs = 1,					\
> +}
> +
> +static const struct iio_chan_spec mma9551_channels[] = {
> +	MMA9551_ACCEL_CHANNEL(IIO_MOD_X),
> +	MMA9551_ACCEL_CHANNEL(IIO_MOD_Y),
> +	MMA9551_ACCEL_CHANNEL(IIO_MOD_Z),
> +
> +	MMA9551_INCLI_CHANNEL(IIO_MOD_X),
> +	MMA9551_INCLI_CHANNEL(IIO_MOD_Y),
> +	MMA9551_INCLI_CHANNEL(IIO_MOD_Z),
> +};
> +
> +static const struct iio_info mma9551_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = mma9551_read_raw,
> +	.read_event_config = mma9551_read_event_config,
> +	.write_event_config = mma9551_write_event_config,
> +	.read_event_value = mma9551_read_event_value,
> +	.write_event_value = mma9551_write_event_value,
> +};
> +
> +static irqreturn_t mma9551_event_handler(int irq, void *private)
> +{
> +	struct iio_dev *indio_dev = private;
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	int mma_axis, ret, i;
> +	u16 reg;
> +	u8 val;
> +
> +	mutex_lock(&data->mutex);
> +
> +	mma_axis = -1;
This value could be assigned already during declaration.
> +	for (i = 0; i < 3; i++)
> +		if (irq == data->irqs[i]) {
> +			mma_axis = i;
> +			break;
> +		}
> +
> +	if (mma_axis == -1) {
> +		/* IRQ was triggered on 4th line, which we don't use. */
> +		dev_warn(&data->client->dev,
> +			 "irq triggered on unused line %d\n", data->irqs[3]);
> +		goto out;
> +	}
> +
> +	switch (mma_axis) {
> +	case mma9551_x:
> +		reg = MMA9551_TILT_YZ_ANG_REG;
> +		break;
> +	case mma9551_y:
> +		reg = MMA9551_TILT_XZ_ANG_REG;
> +		break;
> +	case mma9551_z:
> +		reg = MMA9551_TILT_XY_ANG_REG;
> +		break;
> +	}
> +
> +	/*
> +	 * Read the angle even though we don't use it, otherwise we
> +	 * won't get any further interrupts.
> +	 */
> +	ret = mma9551_read_status_byte(data->client, MMA9551_APPID_TILT,
> +				       reg, &val);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"error %d reading tilt register in IRQ\n", ret);
> +		goto out;
> +	}
> +
> +	iio_push_event(indio_dev,
> +		       IIO_MOD_EVENT_CODE(IIO_INCLI, 0,
> +					  (mma_axis + 1),
> +					  IIO_EV_TYPE_ROC,
> +					  IIO_EV_DIR_RISING),
Why not put more parameters in every line? Would save some space.
> +		       iio_get_time_ns());
> +
> +out:
> +	mutex_unlock(&data->mutex);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int mma9551_init(struct mma9551_data *data)
> +{
> +	int ret;
> +
> +	ret = mma9551_read_version(data->client);
> +	if (ret)
> +		return ret;
> +
> +	/* Power on chip and enable doze mode. */
> +	ret = mma9551_update_config_bits(data->client,
> +			 MMA9551_APPID_SLEEP_WAKE,
> +			 MMA9551_SLEEP_CFG,
> +			 MMA9551_SLEEP_CFG_SCHEN | MMA9551_SLEEP_CFG_SNCEN,
> +			 MMA9551_SLEEP_CFG_SCHEN);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
Just return mma9551_update_config_bits().
> +}
> +
> +static int mma9551_gpio_probe(struct iio_dev *indio_dev)
> +{
> +	struct gpio_desc *gpio;
> +	int i, ret;
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +	struct device *dev = &data->client->dev;
> +
> +	for (i = 0; i < MMA9551_GPIO_COUNT; i++) {
> +		gpio = devm_gpiod_get_index(dev, MMA9551_GPIO_NAME, i);
> +		if (IS_ERR(gpio)) {
> +			dev_err(dev, "acpi gpio get index failed\n");
> +			return PTR_ERR(gpio);
> +		}
> +
> +		ret = gpiod_direction_input(gpio);
> +		if (ret)
> +			return ret;
> +
> +		data->irqs[i] = gpiod_to_irq(gpio);
> +		ret = devm_request_threaded_irq(dev, data->irqs[i],
> +				NULL, mma9551_event_handler,
> +				IRQF_TRIGGER_RISING | IRQF_ONESHOT,
> +				MMA9551_IRQ_NAME, indio_dev);
> +		if (ret < 0) {
> +			dev_err(dev, "request irq %d failed\n", data->irqs[i]);
> +			return ret;
> +		}
> +
> +		dev_dbg(dev, "gpio resource, no:%d irq:%d\n",
> +			desc_to_gpio(gpio), data->irqs[i]);
> +	}
> +
> +	return 0;
> +}
> +
> +static const char *mma9551_match_acpi_device(struct device *dev)
> +{
> +	const struct acpi_device_id *id;
> +
> +	id = acpi_match_device(dev->driver->acpi_match_table, dev);
> +	if (!id)
> +		return NULL;
> +
> +	return dev_name(dev);
> +}
> +
> +static int mma9551_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct mma9551_data *data;
> +	struct iio_dev *indio_dev;
> +	const char *name = NULL;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	data->client = client;
> +
> +	if (id)
> +		name = id->name;
> +	else if (ACPI_HANDLE(&client->dev))
> +		name = mma9551_match_acpi_device(&client->dev);
> +
> +	ret = mma9551_init(data);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_init(&data->mutex);
> +	memset(data->event_enabled, 0, sizeof(data->event_enabled));
What for? devm_iio_device_alloc already fills that memory region with zeros.
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->channels = mma9551_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(mma9551_channels);
> +	indio_dev->name = name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &mma9551_info;
> +
> +	ret = mma9551_gpio_probe(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "unable to register iio device\n");
> +		return ret;
> +	}
> +
> +	return 0;
What about an error-out-path for powering off the device if something fails after mma9551_init()?
> +}
> +
> +static int mma9551_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	mutex_lock(&data->mutex);
> +	mma9551_set_device_state(data->client, false);
> +	mutex_unlock(&data->mutex);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int mma9551_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +
> +	mutex_lock(&data->mutex);
> +	mma9551_set_device_state(data->client, false);
> +	mutex_unlock(&data->mutex);
> +
> +	return 0;
> +}
> +
> +static int mma9551_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct mma9551_data *data = iio_priv(indio_dev);
> +
> +	mutex_lock(&data->mutex);
> +	mma9551_set_device_state(data->client, true);
> +	mutex_unlock(&data->mutex);
> +
> +	return 0;
> +}
> +#else
> +#define mma9551_suspend NULL
> +#define mma9551_resume NULL
> +#endif
> +
> +static const struct dev_pm_ops mma9551_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(mma9551_suspend, mma9551_resume)
> +};
> +
> +static const struct acpi_device_id mma9551_acpi_match[] = {
> +	{"MMA9551", 0},
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, mma9551_acpi_match);
> +
> +static const struct i2c_device_id mma9551_id[] = {
> +	{"mma9551", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, mma9551_id);
> +
> +static struct i2c_driver mma9551_driver = {
> +	.driver = {
> +		   .name = MMA9551_DRV_NAME,
> +		   .acpi_match_table = ACPI_PTR(mma9551_acpi_match),
> +		   .pm = &mma9551_pm_ops,
> +		   },
> +	.probe = mma9551_probe,
> +	.remove = mma9551_remove,
> +	.id_table = mma9551_id,
> +};
> +
> +module_i2c_driver(mma9551_driver);
> +
> +MODULE_AUTHOR("Irina Tirdea <irina.tirdea@intel.com>");
> +MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("MMA9551L motion-sensing platform driver");
>