Re: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer

[Jonathan Cameron <jic23@xxxxxxxxxx>]

On 22/04/15 13:45, Tirdea, Irina wrote:
> 
> 
>> -----Original Message-----
>> From: Jonathan Cameron [mailto:jic23@xxxxxxxxxx]
>> Sent: 18 April, 2015 21:07
>> To: Tirdea, Irina; linux-iio@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx; Hartmut Knaack; Lars-Peter Clausen; Peter Meerwald; Rob Herring; Pawel Moll; Mark Rutland; Ian
>> Campbell; Kumar Gala
>> Subject: Re: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer
>>
>> On 17/04/15 11:50, Irina Tirdea wrote:
>>> Add support for the Bosh BMC150 Magnetometer.
>>> The specification can be downloaded from:
>>> http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
>>> The chip contains both an accelerometer and a magnetometer.
>>> This patch adds support only for the magnetometer part.
>>>
>>> The temperature compensation formulas are based on bmm050_api.c
>>> authored by contact@xxxxxxxxxxxxxxxxxxx.
>>>
>>> Signed-off-by: Irina Tirdea <irina.tirdea@xxxxxxxxx>
>> Generally looks good, but a few odd bits and pieces...
> 
> Thanks for the review, Jonathan!
> 
>> Quite a few places you use regmap_update_bits to write with a mask of 0xFF
>> which seems odd..
>>
> The idea there is to not do unnecessary i2c_reads/writes if the value does not change:
> regmap_update_bits will check the cached value and only do the i2c transfer if the value 
> did not change.
Odd that regmap_write doesn't check the cache as well, or that we don't have a cleaner
means of doing this but fair enough. Cc'd Mark Brown in case he has any views on this.
>  
>> Various other bits inline.
>>> ---
>>>  drivers/iio/magnetometer/Kconfig       |   14 +
>>>  drivers/iio/magnetometer/Makefile      |    2 +
>>>  drivers/iio/magnetometer/bmc150_magn.c | 1060 ++++++++++++++++++++++++++++++++
>>>  3 files changed, 1076 insertions(+)
>>>  create mode 100644 drivers/iio/magnetometer/bmc150_magn.c
>>>
>>> diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
>>> index a5d6de7..008baca 100644
>>> --- a/drivers/iio/magnetometer/Kconfig
>>> +++ b/drivers/iio/magnetometer/Kconfig
>>> @@ -76,4 +76,18 @@ config IIO_ST_MAGN_SPI_3AXIS
>>>  	depends on IIO_ST_MAGN_3AXIS
>>>  	depends on IIO_ST_SENSORS_SPI
>>>
>>> +config BMC150_MAGN
>>> +	tristate "Bosch BMC150 Magnetometer Driver"
>>> +	depends on I2C
>>> +	select IIO_BUFFER
>>> +	select IIO_TRIGGERED_BUFFER
>>> +	help
>>> +	  Say yes here to build support for the BMC150 magnetometer.
>>> +
>>> +	  Currently this only supports the device via an i2c interface.
>>> +
>>> +	  This is a combo module with both accelerometer and magnetometer.
>>> +	  This driver is only implementing magnetometer part, which has
>>> +	  its own address and register map.
>>> +
>>>  endmenu
>>> diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
>>> index 0f5d3c9..e2c3459 100644
>>> --- a/drivers/iio/magnetometer/Makefile
>>> +++ b/drivers/iio/magnetometer/Makefile
>>> @@ -13,3 +13,5 @@ st_magn-$(CONFIG_IIO_BUFFER) += st_magn_buffer.o
>>>
>>>  obj-$(CONFIG_IIO_ST_MAGN_I2C_3AXIS) += st_magn_i2c.o
>>>  obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
>>> +
>>> +obj-$(CONFIG_BMC150_MAGN) += bmc150_magn.o
>>> diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
>>> new file mode 100644
>>> index 0000000..e970a0c
>>> --- /dev/null
>>> +++ b/drivers/iio/magnetometer/bmc150_magn.c
>>> @@ -0,0 +1,1060 @@
>>> +/*
>>> + * Bosch BMC150 three-axis magnetic field sensor driver
>>> + *
>>> + * Copyright (c) 2015, Intel Corporation.
>>> + *
>>> + * This code is based on bmm050_api.c authored by contact@xxxxxxxxxxxxxxxxxxx:
>>> + *
>>> + * (C) Copyright 2011~2014 Bosch Sensortec GmbH All Rights Reserved
>>> + *
>>> + * 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/delay.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/acpi.h>
>>> +#include <linux/gpio/consumer.h>
>>> +#include <linux/pm.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/iio/iio.h>
>>> +#include <linux/iio/sysfs.h>
>>> +#include <linux/iio/buffer.h>
>>> +#include <linux/iio/events.h>
>>> +#include <linux/iio/trigger.h>
>>> +#include <linux/iio/trigger_consumer.h>
>>> +#include <linux/iio/triggered_buffer.h>
>>> +#include <linux/regmap.h>
>>> +
>>> +#define BMC150_MAGN_DRV_NAME			"bmc150_magn"
>>> +#define BMC150_MAGN_IRQ_NAME			"bmc150_magn_event"
>>> +#define BMC150_MAGN_GPIO_INT			"interrupt"
>>> +
>>> +#define BMC150_MAGN_REG_CHIP_ID			0x40
>>> +#define BMC150_MAGN_CHIP_ID_VAL			0x32
>>> +
>>> +#define BMC150_MAGN_REG_X_L			0x42
>>> +#define BMC150_MAGN_REG_X_M			0x43
>>> +#define BMC150_MAGN_REG_Y_L			0x44
>>> +#define BMC150_MAGN_REG_Y_M			0x45
>>> +#define BMC150_MAGN_SHIFT_XY_L			3
>>> +#define BMC150_MAGN_REG_Z_L			0x46
>>> +#define BMC150_MAGN_REG_Z_M			0x47
>>> +#define BMC150_MAGN_SHIFT_Z_L			1
>>> +#define BMC150_MAGN_REG_RHALL_L			0x48
>>> +#define BMC150_MAGN_REG_RHALL_M			0x49
>>> +#define BMC150_MAGN_SHIFT_RHALL_L		2
>>> +
>>> +#define BMC150_MAGN_REG_INT_STATUS		0x4A
>>> +
>>> +#define BMC150_MAGN_REG_POWER			0x4B
>>> +#define BMC150_MAGN_MASK_POWER_CTL		BIT(0)
>>> +
>>> +#define BMC150_MAGN_REG_OPMODE_ODR		0x4C
>>> +#define BMC150_MAGN_MASK_OPMODE			GENMASK(2, 1)
>>> +#define BMC150_MAGN_SHIFT_OPMODE		1
>>> +#define BMC150_MAGN_MODE_NORMAL			0x00
>>> +#define BMC150_MAGN_MODE_FORCED			0x01
>>> +#define BMC150_MAGN_MODE_SLEEP			0x03
>>> +#define BMC150_MAGN_MASK_ODR			GENMASK(5, 3)
>>> +#define BMC150_MAGN_SHIFT_ODR			3
>>> +
>>> +#define BMC150_MAGN_REG_INT			0x4D
>>> +
>>> +#define BMC150_MAGN_REG_INT_DRDY		0x4E
>>> +#define BMC150_MAGN_MASK_DRDY_EN		BIT(7)
>>> +#define BMC150_MAGN_SHIFT_DRDY_EN		7
>>> +#define BMC150_MAGN_MASK_DRDY_INT3		BIT(6)
>>> +#define BMC150_MAGN_MASK_DRDY_Z_EN		BIT(5)
>>> +#define BMC150_MAGN_MASK_DRDY_Y_EN		BIT(4)
>>> +#define BMC150_MAGN_MASK_DRDY_X_EN		BIT(3)
>>> +#define BMC150_MAGN_MASK_DRDY_DR_POLARITY	BIT(2)
>>> +#define BMC150_MAGN_MASK_DRDY_LATCHING		BIT(1)
>>> +#define BMC150_MAGN_MASK_DRDY_INT3_POLARITY	BIT(0)
>>> +
>>> +#define BMC150_MAGN_REG_LOW_THRESH		0x4F
>>> +#define BMC150_MAGN_REG_HIGH_THRESH		0x50
>>> +#define BMC150_MAGN_REG_REP_XY			0x51
>>> +#define BMC150_MAGN_REG_REP_Z			0x52
>>> +
>>> +#define BMC150_MAGN_REG_TRIM_START		0x5D
>>> +#define BMC150_MAGN_REG_TRIM_END		0x71
>>> +
>>> +#define BMC150_MAGN_XY_OVERFLOW_VAL		-4096
>>> +#define BMC150_MAGN_Z_OVERFLOW_VAL		-16384
>>> +
>>> +/* Time from SUSPEND to SLEEP */
>>> +#define BMC150_MAGN_START_UP_TIME_MS		3
>>> +
>>> +#define BMC150_MAGN_AUTO_SUSPEND_DELAY_MS	2000
>>> +
>>> +#define BMC150_MAGN_REGVAL_TO_REPXY(regval) (((regval) * 2) + 1)
>>> +#define BMC150_MAGN_REGVAL_TO_REPZ(regval) ((regval) + 1)
>>> +#define BMC150_MAGN_REPXY_TO_REGVAL(rep) (((rep) - 1) / 2)
>>> +#define BMC150_MAGN_REPZ_TO_REGVAL(rep) ((rep) - 1)
>>> +
>>> +enum bmc150_magn_axis {
>>> +	AXIS_X,
>>> +	AXIS_Y,
>>> +	AXIS_Z,
>>> +	RHALL,
>>> +	AXIS_XYZ_MAX = RHALL,
>>> +	AXIS_XYZR_MAX,
>>> +};
>>> +
>>> +enum bmc150_magn_power_modes {
>>> +	BMC150_MAGN_POWER_MODE_SUSPEND,
>>> +	BMC150_MAGN_POWER_MODE_SLEEP,
>>> +	BMC150_MAGN_POWER_MODE_NORMAL,
>>> +};
>>> +
>>> +struct bmc150_magn_trim_regs {
>>> +	s8 x1;
>>> +	s8 y1;
>>> +	__le16 reserved1;
>>> +	u8 reserved2;
>>> +	__le16 z4;
>>> +	s8 x2;
>>> +	s8 y2;
>>> +	__le16 reserved3;
>>> +	__le16 z2;
>>> +	__le16 z1;
>>> +	__le16 xyz1;
>>> +	__le16 z3;
>>> +	s8 xy2;
>>> +	u8 xy1;
>>> +} __packed;
>>> +
>>> +struct bmc150_magn_data {
>>> +	struct i2c_client *client;
>>> +	/*
>>> +	 * 1. Protect this structure.
>>> +	 * 2. Serialize sequences that power on/off the device and access HW.
>>> +	 */
>>> +	struct mutex mutex;
>>> +	struct regmap *regmap;
>>> +	s32 *buffer;
>>> +	struct iio_trigger *dready_trig;
>>> +	bool dready_trigger_on;
>>> +};
>>> +
>>> +static const struct {
>>> +	int freq;
>>> +	u8 reg_val;
>>> +} bmc150_magn_samp_freq_table[] = { {10, 0x00},
>>> +				    {2, 0x01},
>>> +				    {6, 0x02},
>>> +				    {8, 0x03},
>>> +				    {15, 0x04},
>>> +				    {20, 0x05},
>>> +				    {25, 0x06},
>>> +				    {30, 0x07} };
>>> +
>>> +enum bmc150_magn_presets {
>>> +	LOW_POWER_PRESET,
>>> +	REGULAR_PRESET,
>>> +	ENHANCED_REGULAR_PRESET,
>>> +	HIGH_ACCURACY_PRESET
>>> +};
>>> +
>>> +static const struct bmc150_magn_preset {
>>> +	u8 rep_xy;
>>> +	u8 rep_z;
>>> +	u8 odr;
>>> +} bmc150_magn_presets_table[] = {
>>> +	[LOW_POWER_PRESET] = {3, 3, 10},
>>> +	[REGULAR_PRESET] =  {9, 15, 10},
>>> +	[ENHANCED_REGULAR_PRESET] =  {15, 27, 10},
>>> +	[HIGH_ACCURACY_PRESET] =  {47, 83, 20},
>>> +};
>>> +
>>> +#define BMC150_MAGN_DEFAULT_PRESET REGULAR_PRESET
>>> +
>>> +static bool bmc150_magn_is_writeable_reg(struct device *dev, unsigned int reg)
>>> +{
>>> +	switch (reg) {
>>> +	case BMC150_MAGN_REG_POWER:
>>> +	case BMC150_MAGN_REG_OPMODE_ODR:
>>> +	case BMC150_MAGN_REG_INT:
>>> +	case BMC150_MAGN_REG_INT_DRDY:
>>> +	case BMC150_MAGN_REG_LOW_THRESH:
>>> +	case BMC150_MAGN_REG_HIGH_THRESH:
>>> +	case BMC150_MAGN_REG_REP_XY:
>>> +	case BMC150_MAGN_REG_REP_Z:
>>> +		return true;
>>> +	default:
>>> +		return false;
>>> +	};
>>> +}
>>> +
>>> +static bool bmc150_magn_is_volatile_reg(struct device *dev, unsigned int reg)
>>> +{
>>> +	switch (reg) {
>>> +	case BMC150_MAGN_REG_X_L:
>>> +	case BMC150_MAGN_REG_X_M:
>>> +	case BMC150_MAGN_REG_Y_L:
>>> +	case BMC150_MAGN_REG_Y_M:
>>> +	case BMC150_MAGN_REG_Z_L:
>>> +	case BMC150_MAGN_REG_Z_M:
>>> +	case BMC150_MAGN_REG_RHALL_L:
>>> +	case BMC150_MAGN_REG_RHALL_M:
>>> +	case BMC150_MAGN_REG_INT_STATUS:
>>> +		return true;
>>> +	default:
>>> +		return false;
>>> +	}
>>> +}
>>> +
>>> +static const struct regmap_config bmc150_magn_regmap_config = {
>>> +	.reg_bits = 8,
>>> +	.val_bits = 8,
>>> +
>>> +	.max_register = BMC150_MAGN_REG_TRIM_END,
>>> +	.cache_type = REGCACHE_RBTREE,
>>> +
>>> +	.writeable_reg = bmc150_magn_is_writeable_reg,
>>> +	.volatile_reg = bmc150_magn_is_volatile_reg,
>>> +};
>>> +
>> Why bother with this? It's only called in one place and then with a constant so you'll
>> always get the top option.
> 
> Indeed. I thought I will have multiple usages, but now it does not make sense anymore.
> I will remove it and use usleep_range instead.
> 
>>> +static void bmc150_magn_sleep(int sleep_time_ms)
>>> +{
>>> +	if (sleep_time_ms < 20)
>>> +		usleep_range(sleep_time_ms * 1000, 20000);
>>> +	else
>>> +		msleep_interruptible(sleep_time_ms);
>>> +}
>>> +
>>> +static int bmc150_magn_set_power_mode(struct bmc150_magn_data *data,
>>> +				      enum bmc150_magn_power_modes mode,
>>> +				      bool state)
>>> +{
>>> +	int ret;
>>> +
>>> +	switch (mode) {
>>> +	case BMC150_MAGN_POWER_MODE_SUSPEND:
>>> +		ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_POWER,
>>> +					 BMC150_MAGN_MASK_POWER_CTL, !state);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +		bmc150_magn_sleep(BMC150_MAGN_START_UP_TIME_MS);
>>> +		return 0;
>>> +	case BMC150_MAGN_POWER_MODE_SLEEP:
>>> +		return regmap_update_bits(data->regmap,
>>> +					  BMC150_MAGN_REG_OPMODE_ODR,
>>> +					  BMC150_MAGN_MASK_OPMODE,
>>> +					  BMC150_MAGN_MODE_SLEEP <<
>>> +					  BMC150_MAGN_SHIFT_OPMODE);
>>> +	case BMC150_MAGN_POWER_MODE_NORMAL:
>>> +		return regmap_update_bits(data->regmap,
>>> +					  BMC150_MAGN_REG_OPMODE_ODR,
>>> +					  BMC150_MAGN_MASK_OPMODE,
>>> +					  BMC150_MAGN_MODE_NORMAL <<
>>> +					  BMC150_MAGN_SHIFT_OPMODE);
>>> +	}
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static int bmc150_magn_set_power_state(struct bmc150_magn_data *data, bool on)
>>> +{
>>> +#ifdef CONFIG_PM
>>> +	int ret;
>>> +
>>> +	if (on) {
>>> +		ret = pm_runtime_get_sync(&data->client->dev);
>>> +	} else {
>>> +		pm_runtime_mark_last_busy(&data->client->dev);
>>> +		ret = pm_runtime_put_autosuspend(&data->client->dev);
>>> +	}
>>> +
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev,
>>> +			"failed to change power state to %d\n", on);
>>> +		if (on)
>>> +			pm_runtime_put_noidle(&data->client->dev);
>>> +
>>> +		return ret;
>>> +	}
>>> +#endif
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_get_odr(struct bmc150_magn_data *data, int *val)
>>> +{
>>> +	int ret, reg_val;
>>> +	u8 i, odr_val;
>>> +
>>> +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_OPMODE_ODR, &reg_val);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +	odr_val = (reg_val & BMC150_MAGN_MASK_ODR) >> BMC150_MAGN_SHIFT_ODR;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++)
>>> +		if (bmc150_magn_samp_freq_table[i].reg_val == odr_val) {
>>> +			*val = bmc150_magn_samp_freq_table[i].freq;
>>> +			return 0;
>>> +		}
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static int bmc150_magn_set_odr(struct bmc150_magn_data *data, int val)
>>> +{
>>> +	int ret;
>>> +	u8 i;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++) {
>>> +		if (bmc150_magn_samp_freq_table[i].freq == val) {
>>> +			ret = regmap_update_bits(data->regmap,
>>> +						 BMC150_MAGN_REG_OPMODE_ODR,
>>> +						 BMC150_MAGN_MASK_ODR,
>>> +						 bmc150_magn_samp_freq_table[i].
>>> +						 reg_val <<
>>> +						 BMC150_MAGN_SHIFT_ODR);
>>> +			if (ret < 0)
>>> +				return ret;
>>> +			return 0;
>>> +		}
>>> +	}
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static s32 bmc150_magn_compensate_x(struct bmc150_magn_trim_regs *tregs, s16 x,
>>> +				    u16 rhall)
>>> +{
>>> +	s16 val;
>>> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
>>> +
>>> +	if (x == BMC150_MAGN_XY_OVERFLOW_VAL)
>>> +		return S32_MIN;
>>> +
>>> +	if (!rhall)
>>> +		rhall = xyz1;
>>> +
>>> +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
>>> +	val = ((s16)((((s32)x) * ((((((((s32)tregs->xy2) * ((((s32)val) *
>>> +	      ((s32)val)) >> 7)) + (((s32)val) *
>>> +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
>>> +	      ((s32)(((s16)tregs->x2) + ((s16)0xA0)))) >> 12)) >> 13)) +
>>> +	      (((s16)tregs->x1) << 3);
>>> +
>>> +	return (s32)val;
>>> +}
>>> +
>>> +static s32 bmc150_magn_compensate_y(struct bmc150_magn_trim_regs *tregs, s16 y,
>>> +				    u16 rhall)
>>> +{
>>> +	s16 val;
>>> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
>>> +
>>> +	if (y == BMC150_MAGN_XY_OVERFLOW_VAL)
>>> +		return S32_MIN;
>>> +
>>> +	if (!rhall)
>>> +		rhall = xyz1;
>>> +
>>> +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
>>> +	val = ((s16)((((s32)y) * ((((((((s32)tregs->xy2) * ((((s32)val) *
>>> +	      ((s32)val)) >> 7)) + (((s32)val) *
>>> +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
>>> +	      ((s32)(((s16)tregs->y2) + ((s16)0xA0)))) >> 12)) >> 13)) +
>>> +	      (((s16)tregs->y1) << 3);
>>> +
>>> +	return (s32)val;
>>> +}
>>> +
>>> +static s32 bmc150_magn_compensate_z(struct bmc150_magn_trim_regs *tregs, s16 z,
>>> +				    u16 rhall)
>>> +{
>>> +	s32 val;
>>> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
>>> +	u16 z1 = le16_to_cpu(tregs->z1);
>>> +	s16 z2 = le16_to_cpu(tregs->z2);
>>> +	s16 z3 = le16_to_cpu(tregs->z3);
>>> +	s16 z4 = le16_to_cpu(tregs->z4);
>>> +
>>> +	if (z == BMC150_MAGN_Z_OVERFLOW_VAL)
>>> +		return S32_MIN;
>>> +
>>> +	val = (((((s32)(z - z4)) << 15) - ((((s32)z3) * ((s32)(((s16)rhall) -
>>> +	      ((s16)xyz1)))) >> 2)) / (z2 + ((s16)(((((s32)z1) *
>>> +	      ((((s16)rhall) << 1))) + (1 << 15)) >> 16))));
>>> +
>>> +	return val;
>>> +}
>>> +
>>> +static int bmc150_magn_read_xyz(struct bmc150_magn_data *data, s32 *buffer)
>>> +{
>>> +	int ret;
>>> +	__le16 values[AXIS_XYZR_MAX];
>>> +	s16 raw_x, raw_y, raw_z;
>>> +	u16 rhall;
>>> +	struct bmc150_magn_trim_regs tregs;
>>> +
>>> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_X_L,
>>> +			       values, sizeof(values));
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	raw_x = (s16)le16_to_cpu(values[AXIS_X]) >> BMC150_MAGN_SHIFT_XY_L;
>>> +	raw_y = (s16)le16_to_cpu(values[AXIS_Y]) >> BMC150_MAGN_SHIFT_XY_L;
>>> +	raw_z = (s16)le16_to_cpu(values[AXIS_Z]) >> BMC150_MAGN_SHIFT_Z_L;
>>> +	rhall = le16_to_cpu(values[RHALL]) >> BMC150_MAGN_SHIFT_RHALL_L;
>>> +
>>> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
>>> +			       &tregs, sizeof(tregs));
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	buffer[AXIS_X] = bmc150_magn_compensate_x(&tregs, raw_x, rhall);
>>> +	buffer[AXIS_Y] = bmc150_magn_compensate_y(&tregs, raw_y, rhall);
>>> +	buffer[AXIS_Z] = bmc150_magn_compensate_z(&tregs, raw_z, rhall);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
>>> +				struct iio_chan_spec const *chan,
>>> +				int *val, int *val2, long mask)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret, tmp;
>>> +	s32 values[AXIS_XYZ_MAX];
>>> +
>>> +	switch (mask) {
>>> +	case IIO_CHAN_INFO_RAW:
>>> +		if (iio_buffer_enabled(indio_dev))
>>> +			return -EBUSY;
>>> +		mutex_lock(&data->mutex);
>>> +
>>> +		ret = bmc150_magn_set_power_state(data, true);
>>> +		if (ret < 0)
>> You just returned with the mutex held...  Check the other places this might happen please.
> Oops... Seems I missed the unlock twice in this function. Thanks for catching this!
> 
>>> +			return ret;
>>> +
>>> +		ret = bmc150_magn_read_xyz(data, values);
>>> +		if (ret < 0) {
>>> +			bmc150_magn_set_power_state(data, false);
>>> +			mutex_unlock(&data->mutex);
>>> +			return ret;
>>> +		}
>>> +		*val = values[chan->scan_index];
>>> +
>>> +		ret = bmc150_magn_set_power_state(data, false);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +
>>> +		mutex_unlock(&data->mutex);
>>> +		return IIO_VAL_INT;
>>> +	case IIO_CHAN_INFO_SCALE:
>>> +		/*
>>> +		 * The API/driver performs an off-chip temperature
>>> +		 * compensation and outputs x/y/z magnetic field data in
>>> +		 * 16 LSB/uT to the upper application layer.
>>> +		 */
>>> +		*val = 0;
>>> +		*val2 = 625;
>>> +		return IIO_VAL_INT_PLUS_MICRO;
>>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>>> +		ret = bmc150_magn_get_odr(data, val);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +		return IIO_VAL_INT;
>>> +	case IIO_CHAN_INFO_CALIBREPETITIONS:
>>> +		switch (chan->channel2) {
>>> +		case IIO_MOD_X:
>>> +		case IIO_MOD_Y:
>>> +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
>>> +					  &tmp);
>>> +			if (ret < 0)
>>> +				return ret;
>>> +			*val = BMC150_MAGN_REGVAL_TO_REPXY(tmp);
>>> +			return IIO_VAL_INT;
>>> +		case IIO_MOD_Z:
>>> +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
>>> +					  &tmp);
>>> +			if (ret < 0)
>>> +				return ret;
>>> +			*val = BMC150_MAGN_REGVAL_TO_REPZ(tmp);
>>> +			return IIO_VAL_INT;
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +}
>>> +
>>> +static int bmc150_magn_write_raw(struct iio_dev *indio_dev,
>>> +				 struct iio_chan_spec const *chan,
>>> +				 int val, int val2, long mask)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	switch (mask) {
>>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>>> +		mutex_lock(&data->mutex);
>>> +		ret = bmc150_magn_set_odr(data, val);
>>> +		mutex_unlock(&data->mutex);
>>> +		return ret;
>>> +	case IIO_CHAN_INFO_CALIBREPETITIONS:
>>> +		switch (chan->channel2) {
>>> +		case IIO_MOD_X:
>>> +		case IIO_MOD_Y:
>>> +			if (val < 1 || val > 511)
>>> +				return -EINVAL;
>>> +			return regmap_update_bits(data->regmap,
>>> +						  BMC150_MAGN_REG_REP_XY,
>>> +						  0xFF,
>>> +						  BMC150_MAGN_REPXY_TO_REGVAL
>>> +						  (val));
>>> +		case IIO_MOD_Z:
>>> +			if (val < 1 || val > 256)
>>> +				return -EINVAL;
>>> +			return regmap_update_bits(data->regmap,
>>> +						  BMC150_MAGN_REG_REP_Z,
>>> +						  0xFF,
>>> +						  BMC150_MAGN_REPZ_TO_REGVAL
>>> +						  (val));
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +}
>>> +
>>> +static int bmc150_magn_validate_trigger(struct iio_dev *indio_dev,
>>> +					struct iio_trigger *trig)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	if (data->dready_trig != trig)
>>> +		return -EINVAL;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_update_scan_mode(struct iio_dev *indio_dev,
>>> +					const unsigned long *scan_mask)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	kfree(data->buffer);
>>> +	data->buffer = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
>> Call be cynical, but how large can this buffer get?
>>
>> I'd just allocate it as part of data in the first place then you
>> can drop this function entirely and don't have to clean it up
>> separately.
> With all channels enabled it is 24 bytes. I'll allocate it with data.
> 
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	if (!data->buffer)
>>> +		return -ENOMEM;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("2 6 8 10 15 20 25 30");
>>> +
>>> +static struct attribute *bmc150_magn_attributes[] = {
>>> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
>>> +	NULL,
>>> +};
>>> +
>>> +static const struct attribute_group bmc150_magn_attrs_group = {
>>> +	.attrs = bmc150_magn_attributes,
>>> +};
>>> +
>>> +#define BMC150_MAGN_CHANNEL(_axis) {					\
>>> +	.type = IIO_MAGN,						\
>>> +	.modified = 1,							\
>>> +	.channel2 = IIO_MOD_##_axis,					\
>>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
>>> +			      BIT(IIO_CHAN_INFO_CALIBREPETITIONS),	\
>>> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) |	\
>>> +				    BIT(IIO_CHAN_INFO_SCALE),		\
>>> +	.scan_index = AXIS_##_axis,					\
>>> +	.scan_type = {							\
>>> +		.sign = 's',						\
>>> +		.realbits = 32,						\
>>> +		.storagebits = 32,					\
>>> +		.shift = 0,						\
>>> +		.endianness = IIO_LE					\
>>> +	},								\
>>> +}
>>> +
>>> +static const struct iio_chan_spec bmc150_magn_channels[] = {
>>> +	BMC150_MAGN_CHANNEL(X),
>>> +	BMC150_MAGN_CHANNEL(Y),
>>> +	BMC150_MAGN_CHANNEL(Z),
>>> +	IIO_CHAN_SOFT_TIMESTAMP(3),
>>> +};
>>> +
>>> +static const struct iio_info bmc150_magn_info = {
>>> +	.attrs = &bmc150_magn_attrs_group,
>>> +	.read_raw = bmc150_magn_read_raw,
>>> +	.write_raw = bmc150_magn_write_raw,
>>> +	.validate_trigger = bmc150_magn_validate_trigger,
>>> +	.update_scan_mode = bmc150_magn_update_scan_mode,
>>> +	.driver_module = THIS_MODULE,
>>> +};
>>> +
>>> +static const unsigned long bmc150_magn_scan_masks[] = {0x07, 0};
>>> +
>>> +static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
>>> +{
>>> +	struct iio_poll_func *pf = p;
>>> +	struct iio_dev *indio_dev = pf->indio_dev;
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_read_xyz(data, data->buffer);
>>> +	mutex_unlock(&data->mutex);
>>> +	if (ret < 0)
>>> +		goto err;
>>> +
>>> +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
>>> +					   pf->timestamp);
>>> +
>>> +err:
>>> +	iio_trigger_notify_done(data->dready_trig);
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +static int bmc150_magn_init(struct bmc150_magn_data *data)
>>> +{
>>> +	int ret, chip_id;
>>> +	struct bmc150_magn_preset preset;
>>> +	struct bmc150_magn_trim_regs tregs;
>>> +
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND,
>>> +					 false);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev,
>>> +			"Failed to bring up device from suspend mode\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_CHIP_ID, &chip_id);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed reading chip id\n");
>>> +		goto err_poweroff;
>>> +	}
>>> +	if (chip_id != BMC150_MAGN_CHIP_ID_VAL) {
>>> +		dev_err(&data->client->dev, "Invalid chip id 0x%x\n", ret);
>>> +		ret = -ENODEV;
>>> +		goto err_poweroff;
>>> +	}
>>> +	dev_dbg(&data->client->dev, "Chip id %x\n", ret);
>>> +
>>> +	preset = bmc150_magn_presets_table[BMC150_MAGN_DEFAULT_PRESET];
>>> +	ret = bmc150_magn_set_odr(data, preset.odr);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to set ODR to %d\n",
>>> +			preset.odr);
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	ret = regmap_update_bits(data->regmap,
>>> +				 BMC150_MAGN_REG_REP_XY,
>>> +				 0xFF,
>>> +				 BMC150_MAGN_REPXY_TO_REGVAL(preset.rep_xy));
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to set REP XY to %d\n",
>>> +			preset.rep_xy);
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	ret = regmap_update_bits(data->regmap,
>>> +				 BMC150_MAGN_REG_REP_Z,
>>> +				 0xFF,
>> Umm. With a mask of 0xFF are we not just setting the whole register?  In which
>> case why use update_bits?   regmap_write instead...
> 
> I am using regmap_update_bits because it also checks if the value actually changed.
> I could use regmap_write here instead, since we are initializing the driver, but
> I would keep regmap_update_bits where the value is updated by the user (so we don't
> do the i2c transfer if the value did not change).
> 
>>> +				 BMC150_MAGN_REPZ_TO_REGVAL(preset.rep_z));
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to set REP Z to %d\n",
>>> +			preset.rep_z);
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	/* Cache trim registers in regmap. */
>> A little ugly. Is there no way of asking regmap to fill it's cache for certain registers?
>> Actually as I read it having taken a quick look, regcache_hw_init will read all your registers
>> given you haven't provided defaults.  Hence this will be cached already..
> Unfortunately it does not work in this case.
> In the current implementation the registers are not cached because num_reg_defaults_raw is not set.
> After setting num_reg_defaults_raw, regcache_hw_init will read all registers starting from register
> 0, but bmc150 magn starts its register map at register 0x40. I am not sure yet how to force a different
> stat register value or how to cache the registers in another way.
> 
> I will remove the regmap_bulk_read for now, so the actual transfer will be done when the first interrupt
> is handled. I will look further into this and come with a follow-up patch when I find a better solution.
Mark - any suggestions?
> 
>>> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
>>> +			       &tregs, sizeof(tregs));
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to read trim registers\n");
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
>>> +					 true);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to power on device\n");
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +err_poweroff:
>>> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_reset_intr(struct bmc150_magn_data *data)
>>> +{
>>> +	int tmp;
>>> +
>>> +	/*
>>> +	 * Data Ready (DRDY) is always cleared after
>>> +	 * readout of data registers ends.
>>> +	 */
>>> +	return regmap_read(data->regmap, BMC150_MAGN_REG_X_L, &tmp);
>> Good to see this here.  Often people don't bother on the basis
>> of course the driver has already read the data register!
>> (which it might not have done if the trigger is being used by another
>> device).
>>> +}
>>> +
>>> +static int bmc150_magn_trig_try_reen(struct iio_trigger *trig)
>>> +{
>>> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	if (!data->dready_trigger_on)
>>> +		return 0;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_reset_intr(data);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_data_rdy_trigger_set_state(struct iio_trigger *trig,
>>> +						  bool state)
>>> +{
>>> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret = 0;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	if (state == data->dready_trigger_on)
>>> +		goto err_unlock;
>>> +
>>> +	ret = bmc150_magn_set_power_state(data, state);
>>> +	if (ret < 0)
>>> +		goto err_unlock;
>>> +
>>> +	ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_INT_DRDY,
>>> +				 BMC150_MAGN_MASK_DRDY_EN,
>>> +				 state << BMC150_MAGN_SHIFT_DRDY_EN);
>>> +	if (ret < 0)
>>> +		goto err_poweroff;
>>> +
>>> +	data->dready_trigger_on = state;
>>> +
>>> +	if (state) {
>>> +		ret = bmc150_magn_reset_intr(data);
>>> +		if (ret < 0)
>>> +			goto err_poweroff;
>>> +	}
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return 0;
>>> +
>>> +err_poweroff:
>>> +	bmc150_magn_set_power_state(data, false);
>>> +err_unlock:
>>> +	mutex_unlock(&data->mutex);
>>> +	return ret;
>>> +}
>>> +
>>> +static const struct iio_trigger_ops bmc150_magn_trigger_ops = {
>>> +	.set_trigger_state = bmc150_magn_data_rdy_trigger_set_state,
>>> +	.try_reenable = bmc150_magn_trig_try_reen,
>>> +	.owner = THIS_MODULE,
>>> +};
>>> +
>>> +static int bmc150_magn_gpio_probe(struct i2c_client *client)
>>> +{
>>> +	struct device *dev;
>>> +	struct gpio_desc *gpio;
>>> +	int ret;
>>> +
>>> +	if (!client)
>>> +		return -EINVAL;
>>> +
>>> +	dev = &client->dev;
>>> +
>>> +	/* data ready GPIO interrupt pin */
>>> +	gpio = devm_gpiod_get_index(dev, BMC150_MAGN_GPIO_INT, 0);
>>> +	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;
>>> +
>>> +	ret = gpiod_to_irq(gpio);
>>> +
>>> +	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static const char *bmc150_magn_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 bmc150_magn_probe(struct i2c_client *client,
>>> +			     const struct i2c_device_id *id)
>>> +{
>>> +	struct bmc150_magn_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 = bmc150_magn_match_acpi_device(&client->dev);
>>> +	else
>>> +		return -ENOSYS;
>>> +
>>> +	mutex_init(&data->mutex);
>>> +	data->regmap = devm_regmap_init_i2c(client, &bmc150_magn_regmap_config);
>>> +	if (IS_ERR(data->regmap)) {
>>> +		dev_err(&client->dev, "Failed to allocate register map\n");
>>> +		return PTR_ERR(data->regmap);
>>> +	}
>>> +
>>> +	ret = bmc150_magn_init(data);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	indio_dev->dev.parent = &client->dev;
>>> +	indio_dev->channels = bmc150_magn_channels;
>>> +	indio_dev->num_channels = ARRAY_SIZE(bmc150_magn_channels);
>>> +	indio_dev->available_scan_masks = bmc150_magn_scan_masks;
>>> +	indio_dev->name = name;
>>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>>> +	indio_dev->info = &bmc150_magn_info;
>>> +
>>> +	if (client->irq <= 0)
>>> +		client->irq = bmc150_magn_gpio_probe(client);
>>> +
>>> +	if (client->irq > 0) {
>>> +		data->dready_trig = devm_iio_trigger_alloc(&client->dev,
>>> +							   "%s-dev%d",
>>> +							   indio_dev->name,
>>> +							   indio_dev->id);
>>> +		if (!data->dready_trig) {
>>> +			ret = -ENOMEM;
>>> +			dev_err(&client->dev, "iio trigger alloc failed\n");
>>> +			goto err_poweroff;
>>> +		}
>>> +
>>> +		data->dready_trig->dev.parent = &client->dev;
>>> +		data->dready_trig->ops = &bmc150_magn_trigger_ops;
>>> +		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
>>> +		ret = iio_trigger_register(data->dready_trig);
>>> +		if (ret) {
>>> +			dev_err(&client->dev, "iio trigger register failed\n");
>>> +			goto err_poweroff;
>>> +		}
>>> +
>>> +		ret = iio_triggered_buffer_setup(indio_dev,
>>> +						 &iio_pollfunc_store_time,
>>> +						 bmc150_magn_trigger_handler,
>>> +						 NULL);
>>> +		if (ret < 0) {
>>> +			dev_err(&client->dev,
>>> +				"iio triggered buffer setup failed\n");
>>> +			goto err_trigger_unregister;
>>> +		}
>>> +
>>> +		ret = devm_request_threaded_irq(&client->dev, client->irq,
>>> +					     iio_trigger_generic_data_rdy_poll,
>>> +					     NULL,
>>> +					     IRQF_TRIGGER_RISING | IRQF_ONESHOT,
>>> +					     BMC150_MAGN_IRQ_NAME,
>>> +					     data->dready_trig);
>>> +		if (ret < 0) {
>>> +			dev_err(&client->dev, "request irq %d failed\n",
>>> +				client->irq);
>>> +			goto err_buffer_cleanup;
>>> +		}
>>> +	}
>>> +
>>> +	ret = iio_device_register(indio_dev);
>>> +	if (ret < 0) {
>>> +		dev_err(&client->dev, "unable to register iio device\n");
>>> +		goto err_buffer_cleanup;
>>> +	}
>>> +
>>> +	ret = pm_runtime_set_active(&client->dev);
>>> +	if (ret)
>>> +		goto err_iio_unregister;
>>> +
>>> +	pm_runtime_enable(&client->dev);
>>> +	pm_runtime_set_autosuspend_delay(&client->dev,
>>> +					 BMC150_MAGN_AUTO_SUSPEND_DELAY_MS);
>>> +	pm_runtime_use_autosuspend(&client->dev);
>>> +
>>> +	dev_dbg(&indio_dev->dev, "Registered device %s\n", name);
>>> +
>>> +	return 0;
>>> +
>>> +err_iio_unregister:
>>> +	iio_device_unregister(indio_dev);
>>> +err_buffer_cleanup:
>>
>> Hmm. There is an issue with this being obviously correct.
>> The unwind ordering different from setup.
>> Because you have devm_request_threaded_irq calls they will unwind only after these
>> calls, but should occur before.
>> Now it probaby makes no difference, but it does fail the obviously correct test.
>>
>> It's also the case in the remove.  I'd be inclined not to use the devm versin
>> of the irq request, but do it explicitly. This one comes up a lot and much like
>> the devm_iio_register_device call it's only really a good idea if everything
>> is managed.  In mixed cases, I'd avoid it.
>>
> I agree. I will use request_threaded_irq instead.
> 
>> Maybe I'm just being overly fussy...
>>
>>> +	if (data->dready_trig)
>>> +		iio_triggered_buffer_cleanup(indio_dev);
>>> +err_trigger_unregister:
>>> +	if (data->dready_trig)
>>> +		iio_trigger_unregister(data->dready_trig);
>>> +err_poweroff:
>>> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_remove(struct i2c_client *client)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	pm_runtime_disable(&client->dev);
>>> +	pm_runtime_set_suspended(&client->dev);
>>> +	pm_runtime_put_noidle(&client->dev);
>>> +
>>> +	iio_device_unregister(indio_dev);
>>> +
>>> +	if (data->dready_trig) {
>>> +		iio_triggered_buffer_cleanup(indio_dev);
>>> +		iio_trigger_unregister(data->dready_trig);
>>> +	}
>> As mentioned above, this clean up isn't needed if you simply
>> always make data->buffer the largest size it can ever be.
> Yes, I will remove this after allocating the data->buffer with data.
>>> +	kfree(data->buffer);
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +#ifdef CONFIG_PM
>>> +static int bmc150_magn_runtime_suspend(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
>>> +					 true);
>>> +	mutex_unlock(&data->mutex);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "powering off device failed\n");
>>> +		return -EAGAIN;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_runtime_resume(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	return bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
>>> +					  true);
>>> +}
>>> +#endif
>>> +
>>> +#ifdef CONFIG_PM_SLEEP
>>> +static int bmc150_magn_suspend(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
>>> +					 true);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_resume(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
>>> +					 true);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +#endif
>>> +
>>> +static const struct dev_pm_ops bmc150_magn_pm_ops = {
>>> +	SET_SYSTEM_SLEEP_PM_OPS(bmc150_magn_suspend, bmc150_magn_resume)
>>> +	SET_RUNTIME_PM_OPS(bmc150_magn_runtime_suspend,
>>> +			   bmc150_magn_runtime_resume, NULL)
>>> +};
>>> +
>>> +static const struct acpi_device_id bmc150_magn_acpi_match[] = {
>>> +	{"BMC150B", 0},
>>> +	{},
>>> +};
>> nitpick, no blank line here. Tends to directly associate the structure
>> with the following macro which is visually nice..
> Sure, I will remove all blank lines you mentioned.
>>> +
>>> +MODULE_DEVICE_TABLE(acpi, bmc150_magn_acpi_match);
>>> +
>>> +static const struct i2c_device_id bmc150_magn_id[] = {
>>> +	{"bmc150_magn", 0},
>>> +	{},
>>> +};
>> Nitpick, no blank line.
>>> +
>>> +MODULE_DEVICE_TABLE(i2c, bmc150_magn_id);
>>> +
>>> +static struct i2c_driver bmc150_magn_driver = {
>>> +	.driver = {
>>> +		   .name = BMC150_MAGN_DRV_NAME,
>>> +		   .acpi_match_table = ACPI_PTR(bmc150_magn_acpi_match),
>>> +		   .pm = &bmc150_magn_pm_ops,
>>> +		   },
>>> +	.probe = bmc150_magn_probe,
>>> +	.remove = bmc150_magn_remove,
>>> +	.id_table = bmc150_magn_id,
>>> +};
>> Nitpick. I'd not bother with the blank line here.
>>> +
>>> +module_i2c_driver(bmc150_magn_driver);
>>> +
>>> +MODULE_AUTHOR("Irina Tirdea <irina.tirdea@xxxxxxxxx>");
>>> +MODULE_LICENSE("GPL v2");
>>> +MODULE_DESCRIPTION("BMC150 magnetometer driver");
>>>
> 
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