Message-ID: <20210131121645.305bf768@archlinux>
Date:   Sun, 31 Jan 2021 12:16:45 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Mike Looijmans <mike.looijmans@...ic.nl>
Cc:     linux-iio@...r.kernel.org, Dan Robertson <dan@...obertson.com>,
        Gaëtan André <rvlander@...tanandre.eu>,
        Jonathan Bakker <xc-racer2@...e.ca>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 2/2] iio: accel: Add support for the Bosch-Sensortec
 BMI088

On Mon, 25 Jan 2021 16:07:32 +0100
Mike Looijmans <mike.looijmans@...ic.nl> wrote:

> The BMI088 is a combined module with both accelerometer and gyroscope.
> This adds the accelerometer driver support for the SPI interface.
> The gyroscope part is already supported by the BMG160 driver.
> 
> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
Hi Mike,

I'll drop the include <linux/acpi.h> as no acpi stuff in
here that I can see.

Otherwise, looks good to me.  Will give a bit of time for Rob or
anyone else to take another look at this and the binding patch.

Thanks,

Jonathan

> 
> ---
> 
> Changes in v8:
> include order asm/ after linux/
> Suspend/resume redesigned, use runtime PM for both cases. Removed the
> pm wrappers and let runtime PM handle power up/down. This also removed
> the need for an internal mutex, thus reducing code further.
> 
> Changes in v7:
> Change bmi088_accel to bmi088-accel
> Order includes alphabetically
> Suspend and disable on remove
> Make bmi088_regmap_spi_{read|write} static
> 
> Changes in v6:
> Hope you have good memory - v5 was almost a year ago now
> Remove superfluous *val=0
> Make sample_frequency selection into read_avail list
> 
> Changes in v5:
> Add includes and forward defines in header
> BIT(7) instead of 0x80
> Reset already sets defaults, do not set them again
> Remove now unused bmi088_accel_set_bw
> Remove unused AXIS_MAX
> Use MASK define for ODR setting
> Explain buffer use and alignment
> Split bmi088_accel_set_power_state into "on" and "off" parts
> Cosmetic changes to improve readability
> 
> Changes in v4:
> Remove unused #include directives
> Remove unused #defines for event and irq
> Replace (ret < 0) with (ret) for all regmap calls
> Consistent checking of IO errors in probe and init
> Removed #ifdef CONFIG_PM guard
> Use bitops for set_frequency instead of loop with shift
> s/__s16/s16/g
> Remove excess blank lines
> Don't return -EAGAIN in pm_runtime
> 
> Changes in v3:
> Processed comments from Jonathan Cameron and Lars-Peter Clausen
> implement runtime PM (tested by code tracing) and sleep
> fix scale and offset factors for accel and temperature and
> return raw values instead of pre-scaled ones
> Use iio_device_{claim,release}_direct_mode
> Remove unused code and structs
> Use a cache-aligned buffer for bulk read
> Configure and enable caching register values
> 
> Changes in v2:
> Remove unused typedefs and variables
> Fix error return when iio_device_register fails
> 
>  drivers/iio/accel/Kconfig             |  18 +
>  drivers/iio/accel/Makefile            |   2 +
>  drivers/iio/accel/bmi088-accel-core.c | 570 ++++++++++++++++++++++++++
>  drivers/iio/accel/bmi088-accel-spi.c  |  83 ++++
>  drivers/iio/accel/bmi088-accel.h      |  18 +
>  5 files changed, 691 insertions(+)
>  create mode 100644 drivers/iio/accel/bmi088-accel-core.c
>  create mode 100644 drivers/iio/accel/bmi088-accel-spi.c
>  create mode 100644 drivers/iio/accel/bmi088-accel.h
> 
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 2e0c62c39155..cceda3cecbcf 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -157,6 +157,24 @@ config BMC150_ACCEL_SPI
>  	tristate
>  	select REGMAP_SPI
>  
> +config BMI088_ACCEL
> +	tristate "Bosch BMI088 Accelerometer Driver"
> +	depends on SPI
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	select REGMAP
> +	select BMI088_ACCEL_SPI
> +	help
> +	  Say yes here to build support for the Bosch BMI088 accelerometer.
> +
> +	  This is a combo module with both accelerometer and gyroscope. This
> +	  driver only implements the accelerometer part, which has its own
> +	  address and register map. BMG160 provides the gyroscope driver.
> +
> +config BMI088_ACCEL_SPI
> +	tristate
> +	select REGMAP_SPI
> +
>  config DA280
>  	tristate "MiraMEMS DA280 3-axis 14-bit digital accelerometer driver"
>  	depends on I2C
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index 4f6c1ebe13b0..32cd1342a31a 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -20,6 +20,8 @@ obj-$(CONFIG_BMA400_SPI) += bma400_spi.o
>  obj-$(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-$(CONFIG_BMI088_ACCEL) += bmi088-accel-core.o
> +obj-$(CONFIG_BMI088_ACCEL_SPI) += bmi088-accel-spi.o
>  obj-$(CONFIG_DA280)	+= da280.o
>  obj-$(CONFIG_DA311)	+= da311.o
>  obj-$(CONFIG_DMARD06)	+= dmard06.o
> diff --git a/drivers/iio/accel/bmi088-accel-core.c b/drivers/iio/accel/bmi088-accel-core.c
> new file mode 100644
> index 000000000000..f86010a3cda3
> --- /dev/null
> +++ b/drivers/iio/accel/bmi088-accel-core.c
> @@ -0,0 +1,570 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * 3-axis accelerometer driver supporting following Bosch-Sensortec chips:
> + *  - BMI088
> + *
> + * Copyright (c) 2018-2021, Topic Embedded Products
> + */
> +
> +#include <linux/acpi.h>

Why?  I'll tidy this up whilst applying if there isn't a v9.

> +#include <linux/delay.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/pm.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <asm/unaligned.h>
> +
> +#include "bmi088-accel.h"
> +
> +#define BMI088_ACCEL_REG_CHIP_ID			0x00
> +#define BMI088_ACCEL_REG_ERROR				0x02
> +
> +#define BMI088_ACCEL_REG_INT_STATUS			0x1D
> +#define BMI088_ACCEL_INT_STATUS_BIT_DRDY		BIT(7)
> +
> +#define BMI088_ACCEL_REG_RESET				0x7E
> +#define BMI088_ACCEL_RESET_VAL				0xB6
> +
> +#define BMI088_ACCEL_REG_PWR_CTRL			0x7D
> +#define BMI088_ACCEL_REG_PWR_CONF			0x7C
> +
> +#define BMI088_ACCEL_REG_INT_MAP_DATA			0x58
> +#define BMI088_ACCEL_INT_MAP_DATA_BIT_INT1_DRDY		BIT(2)
> +#define BMI088_ACCEL_INT_MAP_DATA_BIT_INT2_FWM		BIT(5)
> +
> +#define BMI088_ACCEL_REG_INT1_IO_CONF			0x53
> +#define BMI088_ACCEL_INT1_IO_CONF_BIT_ENABLE_OUT	BIT(3)
> +#define BMI088_ACCEL_INT1_IO_CONF_BIT_LVL		BIT(1)
> +
> +#define BMI088_ACCEL_REG_INT2_IO_CONF			0x54
> +#define BMI088_ACCEL_INT2_IO_CONF_BIT_ENABLE_OUT	BIT(3)
> +#define BMI088_ACCEL_INT2_IO_CONF_BIT_LVL		BIT(1)
> +
> +#define BMI088_ACCEL_REG_ACC_CONF			0x40
> +#define BMI088_ACCEL_MODE_ODR_MASK			0x0f
> +
> +#define BMI088_ACCEL_REG_ACC_RANGE			0x41
> +#define BMI088_ACCEL_RANGE_3G				0x00
> +#define BMI088_ACCEL_RANGE_6G				0x01
> +#define BMI088_ACCEL_RANGE_12G				0x02
> +#define BMI088_ACCEL_RANGE_24G				0x03
> +
> +#define BMI088_ACCEL_REG_TEMP				0x22
> +#define BMI088_ACCEL_REG_TEMP_SHIFT			5
> +#define BMI088_ACCEL_TEMP_UNIT				125
> +#define BMI088_ACCEL_TEMP_OFFSET			23000
> +
> +#define BMI088_ACCEL_REG_XOUT_L				0x12
> +#define BMI088_ACCEL_AXIS_TO_REG(axis) \
> +	(BMI088_ACCEL_REG_XOUT_L + (axis * 2))
> +
> +#define BMI088_ACCEL_MAX_STARTUP_TIME_US		1000
> +#define BMI088_AUTO_SUSPEND_DELAY_MS			2000
> +
> +#define BMI088_ACCEL_REG_FIFO_STATUS			0x0E
> +#define BMI088_ACCEL_REG_FIFO_CONFIG0			0x48
> +#define BMI088_ACCEL_REG_FIFO_CONFIG1			0x49
> +#define BMI088_ACCEL_REG_FIFO_DATA			0x3F
> +#define BMI088_ACCEL_FIFO_LENGTH			100
> +
> +#define BMI088_ACCEL_FIFO_MODE_FIFO			0x40
> +#define BMI088_ACCEL_FIFO_MODE_STREAM			0x80
> +
> +enum bmi088_accel_axis {
> +	AXIS_X,
> +	AXIS_Y,
> +	AXIS_Z,
> +};
> +
> +static const int bmi088_sample_freqs[] = {
> +	12, 500000,
> +	25, 0,
> +	50, 0,
> +	100, 0,
> +	200, 0,
> +	400, 0,
> +	800, 0,
> +	1600, 0,
> +};
> +
> +/* Available OSR (over sampling rate) sets the 3dB cut-off frequency */
> +enum bmi088_osr_modes {
> +	BMI088_ACCEL_MODE_OSR_NORMAL = 0xA,
> +	BMI088_ACCEL_MODE_OSR_2 = 0x9,
> +	BMI088_ACCEL_MODE_OSR_4 = 0x8,
> +};
> +
> +/* Available ODR (output data rates) in Hz */
> +enum bmi088_odr_modes {
> +	BMI088_ACCEL_MODE_ODR_12_5 = 0x5,
> +	BMI088_ACCEL_MODE_ODR_25 = 0x6,
> +	BMI088_ACCEL_MODE_ODR_50 = 0x7,
> +	BMI088_ACCEL_MODE_ODR_100 = 0x8,
> +	BMI088_ACCEL_MODE_ODR_200 = 0x9,
> +	BMI088_ACCEL_MODE_ODR_400 = 0xa,
> +	BMI088_ACCEL_MODE_ODR_800 = 0xb,
> +	BMI088_ACCEL_MODE_ODR_1600 = 0xc,
> +};
> +
> +struct bmi088_scale_info {
> +	int scale;
> +	u8 reg_range;
> +};
> +
> +struct bmi088_accel_chip_info {
> +	const char *name;
> +	u8 chip_id;
> +	const struct iio_chan_spec *channels;
> +	int num_channels;
> +};
> +
> +struct bmi088_accel_data {
> +	struct regmap *regmap;
> +	const struct bmi088_accel_chip_info *chip_info;
> +	u8 buffer[2] ____cacheline_aligned; /* shared DMA safe buffer */
> +};
> +
> +static const struct regmap_range bmi088_volatile_ranges[] = {
> +	/* All registers below 0x40 are volatile, except the CHIP ID. */
> +	regmap_reg_range(BMI088_ACCEL_REG_ERROR, 0x3f),
> +	/* Mark the RESET as volatile too, it is self-clearing */
> +	regmap_reg_range(BMI088_ACCEL_REG_RESET, BMI088_ACCEL_REG_RESET),
> +};
> +
> +static const struct regmap_access_table bmi088_volatile_table = {
> +	.yes_ranges	= bmi088_volatile_ranges,
> +	.n_yes_ranges	= ARRAY_SIZE(bmi088_volatile_ranges),
> +};
> +
> +const struct regmap_config bmi088_regmap_conf = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = 0x7E,
> +	.volatile_table = &bmi088_volatile_table,
> +	.cache_type = REGCACHE_RBTREE,
> +};
> +EXPORT_SYMBOL_GPL(bmi088_regmap_conf);
> +
> +static int bmi088_accel_power_up(struct bmi088_accel_data *data)
> +{
> +	struct device *dev = regmap_get_device(data->regmap);
> +	int ret;
> +
> +	/* Enable accelerometer and temperature sensor */
> +	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CTRL, 0x4);
> +	if (ret)
> +		return ret;
> +
> +	/* Datasheet recommends to wait at least 5ms before communication */
> +	usleep_range(5000, 6000);
> +
> +	/* Disable suspend mode */
> +	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CONF, 0x0);
> +	if (ret)
> +		return ret;
> +
> +	/* Recommended at least 1ms before further communication */
> +	usleep_range(1000, 1200);
> +
> +	return 0;
> +}
> +
> +static int bmi088_accel_power_down(struct bmi088_accel_data *data)
> +{
> +	struct device *dev = regmap_get_device(data->regmap);
> +	int ret;
> +
> +	/* Enable suspend mode */
> +	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CONF, 0x3);
> +	if (ret)
> +		return ret;
> +
> +	/* Recommended at least 1ms before further communication */
> +	usleep_range(1000, 1200);
> +
> +	/* Disable accelerometer and temperature sensor */
> +	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CTRL, 0x0);
> +	if (ret)
> +		return ret;
> +
> +	/* Datasheet recommends to wait at least 5ms before communication */
> +	usleep_range(5000, 6000);
> +
> +	return 0;
> +}
> +
> +static int bmi088_accel_get_sample_freq(struct bmi088_accel_data *data,
> +					int *val, int *val2)
> +{
> +	unsigned int value;
> +	int ret;
> +
> +	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_ACC_CONF,
> +			  &value);
> +	if (ret)
> +		return ret;
> +
> +	value &= BMI088_ACCEL_MODE_ODR_MASK;
> +	value -= BMI088_ACCEL_MODE_ODR_12_5;
> +	value <<= 1;
> +
> +	if (value >= ARRAY_SIZE(bmi088_sample_freqs) - 1)
> +		return -EINVAL;
> +
> +	*val = bmi088_sample_freqs[value];
> +	*val2 = bmi088_sample_freqs[value + 1];
> +
> +	return IIO_VAL_INT_PLUS_MICRO;
> +}
> +
> +static int bmi088_accel_set_sample_freq(struct bmi088_accel_data *data, int val)
> +{
> +	unsigned int regval;
> +	int index = 0;
> +
> +	while (index < ARRAY_SIZE(bmi088_sample_freqs) &&
> +	       bmi088_sample_freqs[index] != val)
> +		index += 2;
> +
> +	if (index >= ARRAY_SIZE(bmi088_sample_freqs))
> +		return -EINVAL;
> +
> +	regval = (index >> 1) + BMI088_ACCEL_MODE_ODR_12_5;
> +
> +	return regmap_update_bits(data->regmap, BMI088_ACCEL_REG_ACC_CONF,
> +				  BMI088_ACCEL_MODE_ODR_MASK, regval);
> +}
> +
> +static int bmi088_accel_get_temp(struct bmi088_accel_data *data, int *val)
> +{
> +	int ret;
> +	s16 temp;
> +
> +	ret = regmap_bulk_read(data->regmap, BMI088_ACCEL_REG_TEMP,
> +			       &data->buffer, sizeof(__be16));
> +	if (ret)
> +		return ret;
> +
> +	/* data->buffer is cacheline aligned */
> +	temp = be16_to_cpu(*(__be16 *)data->buffer);
> +
> +	*val = temp >> BMI088_ACCEL_REG_TEMP_SHIFT;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int bmi088_accel_get_axis(struct bmi088_accel_data *data,
> +				 struct iio_chan_spec const *chan,
> +				 int *val)
> +{
> +	int ret;
> +	s16 raw_val;
> +
> +	ret = regmap_bulk_read(data->regmap,
> +			       BMI088_ACCEL_AXIS_TO_REG(chan->scan_index),
> +			       data->buffer, sizeof(__le16));
> +	if (ret)
> +		return ret;
> +
> +	raw_val = le16_to_cpu(*(__le16 *)data->buffer);
> +	*val = raw_val;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int bmi088_accel_read_raw(struct iio_dev *indio_dev,
> +				 struct iio_chan_spec const *chan,
> +				 int *val, int *val2, long mask)
> +{
> +	struct bmi088_accel_data *data = iio_priv(indio_dev);
> +	struct device *dev = regmap_get_device(data->regmap);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_TEMP:
> +			pm_runtime_get_sync(dev);
> +			ret = bmi088_accel_get_temp(data, val);
> +			goto out_read_raw_pm_put;
> +		case IIO_ACCEL:
> +			pm_runtime_get_sync(dev);
> +			ret = iio_device_claim_direct_mode(indio_dev);
> +			if (ret)
> +				goto out_read_raw_pm_put;
> +
> +			ret = bmi088_accel_get_axis(data, chan, val);
> +			iio_device_release_direct_mode(indio_dev);
> +			if (!ret)
> +				ret = IIO_VAL_INT;
> +
> +			goto out_read_raw_pm_put;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_OFFSET:
> +		switch (chan->type) {
> +		case IIO_TEMP:
> +			/* Offset applies before scale */
> +			*val = BMI088_ACCEL_TEMP_OFFSET/BMI088_ACCEL_TEMP_UNIT;
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_TEMP:
> +			/* 0.125 degrees per LSB */
> +			*val = BMI088_ACCEL_TEMP_UNIT;
> +			return IIO_VAL_INT;
> +		case IIO_ACCEL:
> +			pm_runtime_get_sync(dev);
> +			ret = regmap_read(data->regmap,
> +					  BMI088_ACCEL_REG_ACC_RANGE, val);
> +			if (ret)
> +				goto out_read_raw_pm_put;
> +
> +			*val2 = 15 - (*val & 0x3);
> +			*val = 3 * 980;
> +			ret = IIO_VAL_FRACTIONAL_LOG2;
> +
> +			goto out_read_raw_pm_put;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		pm_runtime_get_sync(dev);
> +		ret = bmi088_accel_get_sample_freq(data, val, val2);
> +		goto out_read_raw_pm_put;
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +
> +out_read_raw_pm_put:
> +	pm_runtime_mark_last_busy(dev);
> +	pm_runtime_put_autosuspend(dev);
> +
> +	return ret;
> +}
> +
> +static int bmi088_accel_read_avail(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     const int **vals, int *type, int *length,
> +			     long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		*vals = bmi088_sample_freqs;
> +		*length = ARRAY_SIZE(bmi088_sample_freqs);
> +		return IIO_AVAIL_LIST;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int bmi088_accel_write_raw(struct iio_dev *indio_dev,
> +				  struct iio_chan_spec const *chan,
> +				  int val, int val2, long mask)
> +{
> +	struct bmi088_accel_data *data = iio_priv(indio_dev);
> +	struct device *dev = regmap_get_device(data->regmap);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		pm_runtime_get_sync(dev);
> +		ret = bmi088_accel_set_sample_freq(data, val);
> +		pm_runtime_mark_last_busy(dev);
> +		pm_runtime_put_autosuspend(dev);
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +#define BMI088_ACCEL_CHANNEL(_axis) { \
> +	.type = IIO_ACCEL, \
> +	.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), \
> +	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> +	.scan_index = AXIS_##_axis, \
> +}
> +
> +static const struct iio_chan_spec bmi088_accel_channels[] = {
> +	{
> +		.type = IIO_TEMP,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
> +				      BIT(IIO_CHAN_INFO_OFFSET),
> +		.scan_index = -1,
> +	},
> +	BMI088_ACCEL_CHANNEL(X),
> +	BMI088_ACCEL_CHANNEL(Y),
> +	BMI088_ACCEL_CHANNEL(Z),
> +	IIO_CHAN_SOFT_TIMESTAMP(3),
> +};
> +
> +static const struct bmi088_accel_chip_info bmi088_accel_chip_info_tbl[] = {
> +	[0] = {
> +		.name = "bmi088a",
> +		.chip_id = 0x1E,
> +		.channels = bmi088_accel_channels,
> +		.num_channels = ARRAY_SIZE(bmi088_accel_channels),
> +	},
> +};
> +
> +static const struct iio_info bmi088_accel_info = {
> +	.read_raw	= bmi088_accel_read_raw,
> +	.write_raw	= bmi088_accel_write_raw,
> +	.read_avail	= bmi088_accel_read_avail,
> +};
> +
> +static const unsigned long bmi088_accel_scan_masks[] = {
> +	BIT(AXIS_X) | BIT(AXIS_Y) | BIT(AXIS_Z),
> +	0
> +};
> +
> +static int bmi088_accel_chip_init(struct bmi088_accel_data *data)
> +{
> +	struct device *dev = regmap_get_device(data->regmap);
> +	int ret, i;
> +	unsigned int val;
> +
> +	/* Do a dummy read to enable SPI interface, won't harm I2C */
> +	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);
> +
> +	/*
> +	 * Reset chip to get it in a known good state. A delay of 1ms after
> +	 * reset is required according to the data sheet
> +	 */
> +	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_RESET,
> +			   BMI088_ACCEL_RESET_VAL);
> +	if (ret)
> +		return ret;
> +
> +	usleep_range(1000, 2000);
> +
> +	/* Do a dummy read again after a reset to enable the SPI interface */
> +	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);
> +
> +	/* Read chip ID */
> +	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_CHIP_ID, &val);
> +	if (ret) {
> +		dev_err(dev, "Error: Reading chip id\n");
> +		return ret;
> +	}
> +
> +	/* Validate chip ID */
> +	for (i = 0; i < ARRAY_SIZE(bmi088_accel_chip_info_tbl); i++) {
> +		if (bmi088_accel_chip_info_tbl[i].chip_id == val) {
> +			data->chip_info = &bmi088_accel_chip_info_tbl[i];
> +			break;
> +		}
> +	}
> +	if (i == ARRAY_SIZE(bmi088_accel_chip_info_tbl)) {
> +		dev_err(dev, "Invalid chip %x\n", val);
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +int bmi088_accel_core_probe(struct device *dev, struct regmap *regmap,
> +	int irq, const char *name, bool block_supported)
> +{
> +	struct bmi088_accel_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	dev_set_drvdata(dev, indio_dev);
> +
> +	data->regmap = regmap;
> +
> +	ret = bmi088_accel_chip_init(data);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->channels = data->chip_info->channels;
> +	indio_dev->num_channels = data->chip_info->num_channels;
> +	indio_dev->name = name ? name : data->chip_info->name;
> +	indio_dev->available_scan_masks = bmi088_accel_scan_masks;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &bmi088_accel_info;
> +
> +	/* Enable runtime PM */
> +	pm_runtime_get_noresume(dev);
> +	pm_runtime_set_suspended(dev);
> +	pm_runtime_enable(dev);
> +	/* We need ~6ms to startup, so set the delay to 6 seconds */
> +	pm_runtime_set_autosuspend_delay(dev, 6000);
> +	pm_runtime_use_autosuspend(dev);
> +	pm_runtime_put(dev);
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		dev_err(dev, "Unable to register iio device\n");
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(bmi088_accel_core_probe);
> +
> +
> +int bmi088_accel_core_remove(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct bmi088_accel_data *data = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	pm_runtime_disable(dev);
> +	pm_runtime_set_suspended(dev);
> +	pm_runtime_put_noidle(dev);
> +	bmi088_accel_power_down(data);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(bmi088_accel_core_remove);
> +
> +static int __maybe_unused bmi088_accel_runtime_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct bmi088_accel_data *data = iio_priv(indio_dev);
> +
> +	return bmi088_accel_power_down(data);
> +}
> +
> +static int __maybe_unused bmi088_accel_runtime_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct bmi088_accel_data *data = iio_priv(indio_dev);
> +
> +	return bmi088_accel_power_up(data);
> +}
> +
> +const struct dev_pm_ops bmi088_accel_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +				pm_runtime_force_resume)
> +	SET_RUNTIME_PM_OPS(bmi088_accel_runtime_suspend,
> +			   bmi088_accel_runtime_resume, NULL)
> +};
> +EXPORT_SYMBOL_GPL(bmi088_accel_pm_ops);
> +
> +MODULE_AUTHOR("Niek van Agt <niek.van.agt@...icproducts.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("BMI088 accelerometer driver (core)");
> diff --git a/drivers/iio/accel/bmi088-accel-spi.c b/drivers/iio/accel/bmi088-accel-spi.c
> new file mode 100644
> index 000000000000..dd1e3f6cf211
> --- /dev/null
> +++ b/drivers/iio/accel/bmi088-accel-spi.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * 3-axis accelerometer driver supporting following Bosch-Sensortec chips:
> + *  - BMI088
> + *
> + * Copyright (c) 2018-2020, Topic Embedded Products
> + */
> +
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +
> +#include "bmi088-accel.h"
> +
> +static int bmi088_regmap_spi_write(void *context, const void *data, size_t count)
> +{
> +	struct spi_device *spi = context;
> +
> +	/* Write register is same as generic SPI */
> +	return spi_write(spi, data, count);
> +}
> +
> +static int bmi088_regmap_spi_read(void *context, const void *reg,
> +				size_t reg_size, void *val, size_t val_size)
> +{
> +	struct spi_device *spi = context;
> +	u8 addr[2];
> +
> +	addr[0] = *(u8 *)reg;
> +	addr[0] |= BIT(7); /* Set RW = '1' */
> +	addr[1] = 0; /* Read requires a dummy byte transfer */
> +
> +	return spi_write_then_read(spi, addr, sizeof(addr), val, val_size);
> +}
> +
> +static struct regmap_bus bmi088_regmap_bus = {
> +	.write = bmi088_regmap_spi_write,
> +	.read = bmi088_regmap_spi_read,
> +};
> +
> +static int bmi088_accel_probe(struct spi_device *spi)
> +{
> +	struct regmap *regmap;
> +	const struct spi_device_id *id = spi_get_device_id(spi);
> +
> +	regmap = devm_regmap_init(&spi->dev, &bmi088_regmap_bus,
> +			spi, &bmi088_regmap_conf);
> +
> +	if (IS_ERR(regmap)) {
> +		dev_err(&spi->dev, "Failed to initialize spi regmap\n");
> +		return PTR_ERR(regmap);
> +	}
> +
> +	return bmi088_accel_core_probe(&spi->dev, regmap, spi->irq, id->name,
> +				       true);
> +}
> +
> +static int bmi088_accel_remove(struct spi_device *spi)
> +{
> +	return bmi088_accel_core_remove(&spi->dev);
> +}
> +
> +static const struct spi_device_id bmi088_accel_id[] = {
> +	{"bmi088-accel", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, bmi088_accel_id);
> +
> +static struct spi_driver bmi088_accel_driver = {
> +	.driver = {
> +		.name	= "bmi088_accel_spi",
> +		.pm	= &bmi088_accel_pm_ops,
> +	},
> +	.probe		= bmi088_accel_probe,
> +	.remove		= bmi088_accel_remove,
> +	.id_table	= bmi088_accel_id,
> +};
> +module_spi_driver(bmi088_accel_driver);
> +
> +MODULE_AUTHOR("Niek van Agt <niek.van.agt@...icproducts.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("BMI088 accelerometer driver (SPI)");
> diff --git a/drivers/iio/accel/bmi088-accel.h b/drivers/iio/accel/bmi088-accel.h
> new file mode 100644
> index 000000000000..5c25f16b672c
> --- /dev/null
> +++ b/drivers/iio/accel/bmi088-accel.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef BMI088_ACCEL_H
> +#define BMI088_ACCEL_H
> +
> +#include <linux/pm.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
> +
> +struct device;
> +
> +extern const struct regmap_config bmi088_regmap_conf;
> +extern const struct dev_pm_ops bmi088_accel_pm_ops;
> +
> +int bmi088_accel_core_probe(struct device *dev, struct regmap *regmap, int irq,
> +			    const char *name, bool block_supported);
> +int bmi088_accel_core_remove(struct device *dev);
> +
> +#endif /* BMI088_ACCEL_H */

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