Re: [PATCH] iio: magnetometer: Add support for PNI RM3100 9-axis magnetometer

[Peter Meerwald-Stadler <pmeerw@pmeerw.net>]

On Thu, 20 Sep 2018, Song Qiang wrote:

> PNI RM3100 magnetometer is a high resolution, large signal immunity
> magnetometer, composed of 3 single sensors and a processing chip.
> PNI is currently not in the vendors list, so this is also adding it.

comments below

> 
> Following functions are available:
>  - Single-shot measurement from
>    /sys/bus/iio/devices/iio:deviceX/in_magn_{axis}_raw
>  - Triggerd buffer measurement.
>  - Both i2c and spi interface are supported.
>  - Both interrupt and polling measurement is supported, depands on if
>    the 'interrupts' in DT is declared.
> 
> Signed-off-by: Song Qiang <songqiang1304521@gmail.com>
> ---
>  .../bindings/iio/magnetometer/pni,rm3100.txt  |  57 +++
>  .../devicetree/bindings/vendor-prefixes.txt   |   1 +
>  MAINTAINERS                                   |  10 +
>  drivers/iio/magnetometer/Kconfig              |  29 ++
>  drivers/iio/magnetometer/Makefile             |   4 +
>  drivers/iio/magnetometer/rm3100-core.c        | 399 ++++++++++++++++++
>  drivers/iio/magnetometer/rm3100-i2c.c         |  66 +++
>  drivers/iio/magnetometer/rm3100-spi.c         |  72 ++++
>  drivers/iio/magnetometer/rm3100.h             |  90 ++++
>  9 files changed, 728 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/pni,rm3100.txt
>  create mode 100644 drivers/iio/magnetometer/rm3100-core.c
>  create mode 100644 drivers/iio/magnetometer/rm3100-i2c.c
>  create mode 100644 drivers/iio/magnetometer/rm3100-spi.c
>  create mode 100644 drivers/iio/magnetometer/rm3100.h
> 
> diff --git a/Documentation/devicetree/bindings/iio/magnetometer/pni,rm3100.txt b/Documentation/devicetree/bindings/iio/magnetometer/pni,rm3100.txt
> new file mode 100644
> index 000000000000..d0d2063e943f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/magnetometer/pni,rm3100.txt
> @@ -0,0 +1,57 @@
> +* PNI RM3100 9-axis magnetometer sensor
> +
> +I2C Bus:
> +
> +Required properties:
> +
> +- compatible : should be "pni,rm3100-i2c"
> +- reg : the I2C address of the magnetometer
> +
> +Optional properties:
> +
> +- interrupts: data ready (DRDY) from the chip.
> +  The interrupts can be triggered on rising edges.
> +
> +	Refer to interrupt-controller/interrupts.txt for generic
> +	interrupt client node bindings.
> +
> +- pinctrl-*: pinctrl setup for DRDY line.
> +
> +Example:
> +
> +rm3100: rm3100@20 {
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&rm3100_pins>;
> +
> +	compatible = "pni,rm3100-i2c";
> +	reg = <0x20>;
> +	interrupt-parent = <&gpio0>;
> +	interrupts = <4 IRQ_TYPE_EDGE_RISING>;
> +};
> +
> +SPI Bus:
> +
> +Required properties:
> +
> +- compatible : should be "pni,rm3100-spi"
> +- reg : address of sensor, usually 0 or 1.
> +
> +Optional properties:
> +
> +- interrupts: data ready (DRDY) from the chip.
> +  The interrupts can be triggered on rising edges.
> +
> +	Refer to interrupt-controller/interrupts.txt for generic
> +	interrupt client node bindings.
> +
> +- pinctrl-*: pinctrl setup for DRDY line, depands on archtechture.

depends
architecture

> +
> +Example:
> +
> +rm3100: rm3100@0{
> +	compatible = "pni,rm3100-spi";
> +	reg = <0>;
> +
> +	interrupt-parent = <&gpio0>;
> +	interrupts = <4 IRQ_TYPE_EDGE_RISING>;
> +};
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index 41f0b97eb933..5bf3395fe9ae 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -288,6 +288,7 @@ pine64	Pine64
>  pixcir  PIXCIR MICROELECTRONICS Co., Ltd
>  plathome	Plat'Home Co., Ltd.
>  plda	PLDA
> +pni     PNI
>  portwell	Portwell Inc.
>  poslab	Poslab Technology Co., Ltd.
>  powervr	PowerVR (deprecated, use img)
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 967ce8cdd1cc..30ee8cf98312 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11393,6 +11393,16 @@ M:	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
>  S:	Maintained
>  F:	drivers/pnp/
>  
> +PNI RM3100 IIO DRIVER
> +M:	Song Qiang <songqiang1304521@gmail.com>
> +L:	linux-iio@vger.kernel.org
> +S:	Maintained
> +F:	drivers/iio/magnetometer/rm3100-core.c
> +F:	drivers/iio/magnetometer/rm3100-i2c.c
> +F:	drivers/iio/magnetometer/rm3100-spi.c
> +F:	drivers/iio/magnetometer/rm3100.h
> +F:	Documentation/devicetree/bindings/iio/magnetometer/rm3100.txt
> +
>  POSIX CLOCKS and TIMERS
>  M:	Thomas Gleixner <tglx@linutronix.de>
>  L:	linux-kernel@vger.kernel.org
> diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
> index ed9d776d01af..f130b866a4fc 100644
> --- a/drivers/iio/magnetometer/Kconfig
> +++ b/drivers/iio/magnetometer/Kconfig
> @@ -175,4 +175,33 @@ config SENSORS_HMC5843_SPI
>  	  - hmc5843_core (core functions)
>  	  - hmc5843_spi (support for HMC5983)
>  
> +config SENSORS_RM3100
> +	tristate
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +
> +config SENSORS_RM3100_I2C
> +	tristate "PNI RM3100 9-Axis Magnetometer (I2C)"
> +	depends on I2C
> +	select SENSORS_RM3100
> +	select REGMAP_I2C
> +	help
> +	  Say Y here to add support for the PNI RM3100 9-Axis Magnetometer.
> +
> +	  This driver can also be compiled as a module.
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called rm3100-i2c.
> +
> +config SENSORS_RM3100_SPI
> +	tristate "PNI RM3100 9-Axis Magnetometer (SPI)"
> +	depends on SPI_MASTER
> +	select SENSORS_RM3100
> +	select REGMAP_SPI
> +	help
> +	  Say Y here to add support for the PNI RM3100 9-Axis Magnetometer.
> +
> +	  This driver can also be compiled as a module.
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called rm3100-spi.
> +
>  endmenu
> diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
> index 664b2f866472..ba1bc34b82fa 100644
> --- a/drivers/iio/magnetometer/Makefile
> +++ b/drivers/iio/magnetometer/Makefile
> @@ -24,3 +24,7 @@ obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
>  obj-$(CONFIG_SENSORS_HMC5843)		+= hmc5843_core.o
>  obj-$(CONFIG_SENSORS_HMC5843_I2C)	+= hmc5843_i2c.o
>  obj-$(CONFIG_SENSORS_HMC5843_SPI)	+= hmc5843_spi.o
> +
> +obj-$(CONFIG_SENSORS_RM3100)		+= rm3100-core.o
> +obj-$(CONFIG_SENSORS_RM3100_I2C)	+= rm3100-i2c.o
> +obj-$(CONFIG_SENSORS_RM3100_SPI)	+= rm3100-spi.o
> diff --git a/drivers/iio/magnetometer/rm3100-core.c b/drivers/iio/magnetometer/rm3100-core.c
> new file mode 100644
> index 000000000000..55d515e0fe67
> --- /dev/null
> +++ b/drivers/iio/magnetometer/rm3100-core.c
> @@ -0,0 +1,399 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * PNI RM3100 9-axis geomagnetic sensor driver core.
> + *
> + * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
> + *
> + * User Manual available at
> + * <https://www.pnicorp.com/download/rm3100-user-manual/>
> + *
> + * TODO: Scale channel, event generaton, pm.

at least read support for _SCALE is mandatory, IMHO

> + */
> +
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/slab.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/kfifo_buf.h>
> +
> +#include "rm3100.h"
> +
> +static const struct regmap_range rm3100_readable_ranges[] = {
> +		regmap_reg_range(RM_W_REG_START, RM_W_REG_END),
> +};
> +
> +const struct regmap_access_table rm3100_readable_table = {

static

> +		.yes_ranges = rm3100_readable_ranges,
> +		.n_yes_ranges = ARRAY_SIZE(rm3100_readable_ranges),
> +};
> +
> +static const struct regmap_range rm3100_writable_ranges[] = {
> +		regmap_reg_range(RM_R_REG_START, RM_R_REG_END),
> +};
> +
> +const struct regmap_access_table rm3100_writable_table = {

static

> +		.yes_ranges = rm3100_writable_ranges,
> +		.n_yes_ranges = ARRAY_SIZE(rm3100_writable_ranges),
> +};
> +
> +static const struct regmap_range rm3100_volatile_ranges[] = {
> +		regmap_reg_range(RM_V_REG_START, RM_V_REG_END),
> +};
> +
> +const struct regmap_access_table rm3100_volatile_table = {

static

> +		.yes_ranges = rm3100_volatile_ranges,
> +		.n_yes_ranges = ARRAY_SIZE(rm3100_volatile_ranges),
> +};
> +
> +static irqreturn_t rm3100_measurement_irq_handler(int irq, void *d)
> +{
> +	struct rm3100_data *data = d;
> +
> +	complete(&data->measuring_done);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int rm3100_wait_measurement(struct rm3100_data *data)
> +{
> +	struct regmap *regmap = data->regmap;
> +	unsigned int val;
> +	u16 tries = 20;

why not use int for tries?

> +	int ret;
> +
> +	/* A read cycle of 400kbits i2c bus is about 20us, plus the time
> +	 * used for schduling, a read cycle of fast mode of this device

scheduling

> +	 * can reach 1.7ms, it may be possible for data arrives just

to arrive

> +	 * after we check the RM_REG_STATUS. In this case, irq_handler is
> +	 * called before measuring_done is reinitialized, it will wait
> +	 * forever for a data that has already been ready.

for data

> +	 * Reinitialize measuring_done before looking up makes sure we
> +	 * will always capture interrupt no matter when it happened.
> +	 */
> +	if (data->use_interrupt)
> +		reinit_completion(&data->measuring_done);
> +
> +	ret = regmap_read(regmap, RM_REG_STATUS, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	if ((val & RM_STATUS_DRDY) != RM_STATUS_DRDY) {
> +		if (data->use_interrupt) {
> +			ret = wait_for_completion_timeout(&data->measuring_done,
> +				msecs_to_jiffies(data->conversion_time));
> +			if (!ret)
> +				return -ETIMEDOUT;
> +		} else {
> +			do {
> +				ret = regmap_read(regmap, RM_REG_STATUS, &val);
> +				if (ret < 0)
> +					return ret;
> +
> +				if (val & RM_STATUS_DRDY)
> +					break;
> +
> +				usleep_range(1000, 5000);
> +			} while (--tries);
> +			if (!tries)
> +				return -ETIMEDOUT;
> +		}
> +	}
> +	return 0;
> +}
> +
> +static int rm3100_read_mag(struct rm3100_data *data, int idx, int *val)
> +{
> +	struct regmap *regmap = data->regmap;
> +	u8 buffer[3];
> +	int ret;
> +
> +	mutex_lock(&data->lock);
> +	ret = rm3100_wait_measurement(data);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	}
> +
> +	ret = regmap_bulk_read(regmap, RM_REG_MX2 + 3 * idx, buffer, 3);

sizeof(buf)

> +	mutex_unlock(&data->lock);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = le32_to_cpu((buffer[0] << 16) + (buffer[1] << 8) + buffer[2]);

no need for le32_to_cpu() 

> +	*val = sign_extend32(*val, 23);
> +
> +	return IIO_VAL_INT;
> +}
> +
> +#define RM_CHANNEL(axis, idx)					\

use RM3100_ prefix please

> +	{								\
> +		.type = IIO_MAGN,					\
> +		.modified = 1,						\
> +		.channel2 = IIO_MOD_##axis,				\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
> +		.scan_index = idx,					\
> +		.scan_type = {						\
> +			.sign = 's',					\
> +			.realbits = 24,					\
> +			.storagebits = 32,				\
> +			.shift = 8,					\
> +			.endianness = IIO_LE,				\
> +		},							\
> +	}
> +
> +static const struct iio_chan_spec rm3100_channels[] = {
> +	RM_CHANNEL(X, 0),
> +	RM_CHANNEL(Y, 1),
> +	RM_CHANNEL(Z, 2),
> +	IIO_CHAN_SOFT_TIMESTAMP(3),
> +};
> +
> +static const unsigned long rm3100_scan_masks[] = {GENMASK(2, 0), 0};
> +
> +#define RM_SAMP_NUM	14

prefix

> +
> +/* Frequency : rm3100_samp_rates[][0].rm3100_samp_rates[][1]Hz.
> + * Time between reading: rm3100_sam_rates[][2]ms (The first on is actially 1.7).

one
actually
1.7 what unit?


> + */
> +static const int rm3100_samp_rates[RM_SAMP_NUM][3] = {
> +	{600, 0, 2}, {300, 0, 3}, {150, 0, 7}, {75, 0, 13}, {37, 0, 27},
> +	{18, 0, 55}, {9, 0, 110}, {4, 500000, 220}, {2, 300000, 440},
> +	{1, 200000, 800}, {0, 600000, 1600}, {0, 300000, 3300},
> +	{0, 15000, 6700},  {0, 75000, 13000}
> +};
> +
> +static int rm3100_get_samp_freq(struct rm3100_data *data, int *val, int *val2)
> +{
> +	int ret;
> +	int tmp;
> +
> +	ret = regmap_read(data->regmap, RM_REG_TMRC, &tmp);
> +	if (ret < 0)
> +		return ret;
> +	*val = rm3100_samp_rates[tmp-RM_TMRC_OFFSET][0];

space around - operator

> +	*val2 = rm3100_samp_rates[tmp-RM_TMRC_OFFSET][1];
> +
> +	return IIO_VAL_INT_PLUS_MICRO;
> +}
> +
> +static int rm3100_set_samp_freq(struct rm3100_data *data, int val, int val2)
> +{
> +	struct regmap *regmap = data->regmap;
> +	int cycle_count;
> +	int ret;
> +	int i;
> +
> +	/* All cycle count registers use the same value. */
> +	ret = regmap_read(regmap, RM_REG_CCXL, &cycle_count);

check ret?

> +	if (cycle_count < 0)
> +		return cycle_count;
> +
> +	for (i = 0; i < RM_SAMP_NUM; i++) {
> +		if (val == rm3100_samp_rates[i][0] &&
> +			val2 == rm3100_samp_rates[i][1])
> +			break;
> +	}
> +
> +	if (i != RM_SAMP_NUM) {
> +		mutex_lock(&data->lock);
> +		ret = regmap_write(regmap, RM_REG_TMRC, i + RM_TMRC_OFFSET);
> +		if (ret < 0)

unlock?

> +			return ret;
> +
> +		/* Checking if cycle count registers need changing. */
> +		if (val == 600 && cycle_count == 200) {
> +			for (i = 0; i < 3; i++) {
> +				regmap_write(regmap, RM_REG_CCXL + 2 * i, 100);
> +				if (ret < 0)

unlock?

> +					return ret;
> +			}
> +		} else if (val != 600 && cycle_count == 100) {
> +			for (i = 0; i < 3; i++) {
> +				regmap_write(regmap, RM_REG_CCXL + 2 * i, 200);
> +				if (ret < 0)

unlock?

> +					return ret;
> +			}
> +		}
> +		/* Writing TMRC registers requires CMM reset. */
> +		ret = regmap_write(regmap, RM_REG_CMM, 0);
> +		if (ret < 0)

unlock?

> +			return ret;
> +		ret = regmap_write(regmap, RM_REG_CMM, RM_CMM_PMX |
> +			RM_CMM_PMY | RM_CMM_PMZ | RM_CMM_START);
> +		if (ret < 0)

unlock?

> +			return ret;
> +		mutex_unlock(&data->lock);
> +
> +		data->conversion_time = rm3100_samp_rates[i][2] + 3000;
> +		return 0;
> +	}
> +	return -EINVAL;
> +}
> +
> +static int rm3100_read_raw(struct iio_dev *indio_dev,
> +			   const struct iio_chan_spec *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct rm3100_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret < 0)

release_direct_mode() here?

> +			return ret;
> +		ret = rm3100_read_mag(data, chan->scan_index, val);
> +		iio_device_release_direct_mode(indio_dev);
> +
> +		return ret;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		return ret = rm3100_get_samp_freq(data, val, val2);

return ret = ???, just
return rm3100_...

> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int rm3100_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct rm3100_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = rm3100_set_samp_freq(data, val, val2);
> +		if (ret < 0)
> +			return ret;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +}
> +
> +static const struct iio_info rm3100_info = {
> +	.read_raw = rm3100_read_raw,
> +	.write_raw = rm3100_write_raw,
> +};
> +
> +static irqreturn_t rm3100_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct rm3100_data *data = iio_priv(indio_dev);
> +	struct regmap *regmap = data->regmap;
> +	u8 *buffer;
> +	int ret;
> +	int i;
> +
> +	buffer = devm_kzalloc(data->dev, indio_dev->scan_bytes, GFP_KERNEL);

try to allocate the maximum needed amount of memory beforehand, in 
_probe() perhaps 

> +	if (!buffer)
> +		goto done;
> +
> +	mutex_lock(&data->lock);
> +	ret = rm3100_wait_measurement(data);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		goto done;
> +	}
> +
> +	for (i = 0; i < 3; i++) {
> +		ret = regmap_bulk_read(regmap, RM_REG_MX2 + 3 * i,
> +				buffer + 4 * i, 3);
> +		if (ret < 0)
> +			return ret;
> +	}
> +	mutex_unlock(&data->lock);
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
> +			iio_get_time_ns(indio_dev));
> +done:
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +int rm3100_common_probe(struct device *dev, struct regmap *regmap, int irq)
> +{
> +	struct iio_dev *indio_dev;
> +	struct rm3100_data *data;
> +	int tmp;
> +	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->dev = dev;
> +	data->regmap = regmap;
> +
> +	mutex_init(&data->lock);
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->name = "rm3100";
> +	indio_dev->info = &rm3100_info;
> +	indio_dev->channels = rm3100_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(rm3100_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->available_scan_masks = rm3100_scan_masks;
> +
> +	if (!irq)
> +		data->use_interrupt = false;
> +	else {
> +		data->use_interrupt = true;
> +		ret = devm_request_irq(dev,
> +			irq,
> +			rm3100_measurement_irq_handler,
> +			IRQF_TRIGGER_RISING,
> +			indio_dev->name,
> +			data);
> +		if (ret < 0) {
> +			dev_err(dev,
> +			"request irq line failed.");

\n

> +			return -ret;
> +		}
> +		init_completion(&data->measuring_done);
> +	}
> +
> +	ret = iio_triggered_buffer_setup(indio_dev, NULL,
> +					rm3100_trigger_handler, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* 3sec more wait time. */
> +	ret = regmap_read(data->regmap, RM_REG_TMRC, &tmp);

check ret

> +	data->conversion_time = rm3100_samp_rates[tmp-RM_TMRC_OFFSET][2] + 3000;
> +
> +	/* Starting all channels' conversion. */
> +	ret = regmap_write(regmap, RM_REG_CMM,
> +		RM_CMM_PMX | RM_CMM_PMY | RM_CMM_PMZ | RM_CMM_START);
> +	if (ret < 0)
> +		return ret;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +EXPORT_SYMBOL(rm3100_common_probe);
> +
> +int rm3100_common_remove(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct rm3100_data *data = iio_priv(indio_dev);
> +	struct regmap *regmap = data->regmap;
> +
> +	regmap_write(regmap, RM_REG_CMM, 0x00);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(rm3100_common_remove);
> +
> +MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
> +MODULE_DESCRIPTION("PNI RM3100 9-axis magnetometer i2c driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/magnetometer/rm3100-i2c.c b/drivers/iio/magnetometer/rm3100-i2c.c
> new file mode 100644
> index 000000000000..b50dc5b1b30b
> --- /dev/null
> +++ b/drivers/iio/magnetometer/rm3100-i2c.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Support for PNI RM3100 9-axis geomagnetic sensor a i2c bus.
> + *
> + * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
> + *
> + * User Manual available at
> + * <https://www.pnicorp.com/download/rm3100-user-manual/>
> + *
> + * i2c slave address 0x20 + SA1 << 1 + SA0.
> + */
> +
> +#include <linux/i2c.h>
> +
> +#include "rm3100.h"
> +
> +static const struct regmap_config rm3100_regmap_config = {
> +		.reg_bits = 8,
> +		.val_bits = 8,
> +
> +		.rd_table = &rm3100_readable_table,
> +		.wr_table = &rm3100_writable_table,
> +		.volatile_table = &rm3100_volatile_table,
> +
> +		.cache_type = REGCACHE_RBTREE,
> +};
> +
> +static int rm3100_probe(struct i2c_client *client)
> +{
> +	struct regmap *regmap;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +		I2C_FUNC_SMBUS_READ_I2C_BLOCK | I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EOPNOTSUPP;
> +
> +	regmap =  devm_regmap_init_i2c(client, &rm3100_regmap_config);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	return rm3100_common_probe(&client->dev, regmap, client->irq);
> +}
> +
> +static int rm3100_remove(struct i2c_client *client)
> +{
> +	return rm3100_common_remove(&client->dev);
> +}
> +
> +static const struct of_device_id rm3100_dt_match[] = {
> +	{ .compatible = "pni,rm3100-i2c", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, rm3100_dt_match);
> +
> +static struct i2c_driver rm3100_driver = {
> +	.driver = {
> +		.name = "rm3100-i2c",
> +		.of_match_table = rm3100_dt_match,
> +	},
> +	.probe_new = rm3100_probe,
> +	.remove = rm3100_remove,
> +};
> +module_i2c_driver(rm3100_driver);
> +
> +MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
> +MODULE_DESCRIPTION("PNI RM3100 9-axis magnetometer i2c driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/magnetometer/rm3100-spi.c b/drivers/iio/magnetometer/rm3100-spi.c
> new file mode 100644
> index 000000000000..2c7dd9e3a1a2
> --- /dev/null
> +++ b/drivers/iio/magnetometer/rm3100-spi.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Support for PNI RM3100 9-axis geomagnetic sensor a spi bus.
> + *
> + * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
> + *
> + * User Manual available at
> + * <https://www.pnicorp.com/download/rm3100-user-manual/>
> + */
> +
> +#include <linux/spi/spi.h>
> +
> +#include "rm3100.h"
> +
> +static const struct regmap_config rm3100_regmap_config = {
> +		.reg_bits = 8,
> +		.val_bits = 8,
> +
> +		.rd_table = &rm3100_readable_table,
> +		.wr_table = &rm3100_writable_table,
> +		.volatile_table = &rm3100_volatile_table,
> +
> +		.read_flag_mask = 0x80,
> +
> +		.cache_type = REGCACHE_RBTREE,
> +};
> +
> +static int rm3100_probe(struct spi_device *spi)
> +{
> +	struct regmap *regmap;
> +	int ret;
> +
> +	/* Actually this device supports both mode 0 and mode 3. */
> +	spi->mode = SPI_MODE_0;
> +	/* data rates cannot exceeds 1Mbits. */

exceed

> +	spi->max_speed_hz = 1000000;
> +	spi->bits_per_word = 8;
> +	ret = spi_setup(spi);
> +	if (ret)
> +		return ret;
> +
> +	regmap =  devm_regmap_init_spi(spi, &rm3100_regmap_config);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	return rm3100_common_probe(&spi->dev, regmap, spi->irq);
> +}
> +
> +static int rm3100_remove(struct spi_device *spi)
> +{
> +	return rm3100_common_remove(&spi->dev);
> +}
> +
> +static const struct of_device_id rm3100_dt_match[] = {
> +	{ .compatible = "pni,rm3100-spi", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, rm3100_dt_match);
> +
> +static struct spi_driver rm3100_driver = {
> +		.driver = {
> +				.name = "rm3100-spi",
> +				.of_match_table = rm3100_dt_match,
> +		},
> +		.probe = rm3100_probe,
> +		.remove = rm3100_remove,
> +};
> +module_spi_driver(rm3100_driver);
> +
> +MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
> +MODULE_DESCRIPTION("PNI RM3100 9-axis magnetometer spi driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/magnetometer/rm3100.h b/drivers/iio/magnetometer/rm3100.h
> new file mode 100644
> index 000000000000..5e30bc0f5149
> --- /dev/null
> +++ b/drivers/iio/magnetometer/rm3100.h
> @@ -0,0 +1,90 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Header file for PNI RM3100 driver
> + *
> + * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
> + */
> +
> +#ifndef RM3100_CORE_H
> +#define RM3100_CORE_H
> +
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#define RM_REG_REV_ID		0x36
> +
> +/* Cycle Count Registers MSBs and LSBs. */
> +#define RM_REG_CCXM		0x04
> +#define RM_REG_CCXL		0x05
> +#define RM_REG_CCYM		0x06
> +#define RM_REG_CCYL		0x07
> +#define RM_REG_CCZM		0x08
> +#define RM_REG_CCZL		0x09
> +
> +/* Single Measurement Mode register. */
> +#define RM_REG_POLL		0x00
> +#define RM_POLL_PMX		BIT(4)
> +#define RM_POLL_PMY		BIT(5)
> +#define RM_POLL_PMZ		BIT(6)
> +
> +/* Continues Measurement Mode register. */
> +#define RM_REG_CMM		0x01
> +#define RM_CMM_START		BIT(0)
> +#define RM_CMM_DRDM		BIT(2)
> +#define RM_CMM_PMX		BIT(4)
> +#define RM_CMM_PMY		BIT(5)
> +#define RM_CMM_PMZ		BIT(6)
> +
> +/* TiMe Rate Configuration register. */
> +#define RM_REG_TMRC		0x0B
> +#define RM_TMRC_OFFSET		0x92
> +
> +/* Result Status register. */
> +#define RM_REG_STATUS		0x34
> +#define RM_STATUS_DRDY		BIT(7)
> +
> +/* Measurement result registers. */
> +#define RM_REG_MX2		0x24
> +#define RM_REG_MX1		0x25
> +#define RM_REG_MX0		0x26
> +#define RM_REG_MY2		0x27
> +#define RM_REG_MY1		0x28
> +#define RM_REG_MY0		0x29
> +#define RM_REG_MZ2		0x2a
> +#define RM_REG_MZ1		0x2b
> +#define RM_REG_MZ0		0x2c
> +
> +#define RM_REG_HSHAKE		0x35
> +
> +#define RM_W_REG_START		RM_REG_POLL
> +#define RM_W_REG_END		RM_REG_REV_ID
> +#define RM_R_REG_START		RM_REG_POLL
> +#define RM_R_REG_END		RM_REG_HSHAKE
> +#define RM_V_REG_START		RM_REG_MX2
> +#define RM_V_REG_END		RM_REG_HSHAKE
> +
> +/* Built-In Self Test reigister. */
> +#define RM_REG_BIST		0x33
> +
> +struct rm3100_data {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct completion measuring_done;
> +	bool use_interrupt;
> +
> +	int conversion_time;
> +
> +	/* To protect consistency of every measurement and sampling
> +	 * frequency change operations.
> +	 */
> +	struct mutex lock;
> +};
> +
> +extern const struct regmap_access_table rm3100_readable_table;
> +extern const struct regmap_access_table rm3100_writable_table;
> +extern const struct regmap_access_table rm3100_volatile_table;
> +
> +int rm3100_common_probe(struct device *dev, struct regmap *regmap, int irq);
> +int rm3100_common_remove(struct device *dev);
> +
> +#endif /* RM3100_CORE_H */
> 

-- 

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418