PNI RM3100 is a high resolution, large signal immunity magnetometer,
composed of 3 single sensors and a processing chip with a MagI2C
interface.
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, depends on if
the 'interrupts' in DT is declared.
Signed-off-by: Song Qiang <songqiang1304...@gmail.com>
---
MAINTAINERS | 7 +
drivers/iio/magnetometer/Kconfig | 29 ++
drivers/iio/magnetometer/Makefile | 4 +
drivers/iio/magnetometer/rm3100-core.c | 539 +++++++++++++++++++++++++
drivers/iio/magnetometer/rm3100-i2c.c | 58 +++
drivers/iio/magnetometer/rm3100-spi.c | 64 +++
drivers/iio/magnetometer/rm3100.h | 17 +
7 files changed, 718 insertions(+)
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/MAINTAINERS b/MAINTAINERS
index 967ce8cdd1cc..14eeeb072403 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11393,6 +11393,13 @@ M: "Rafael J. Wysocki" <rafael.j.wyso...@intel.com>
S: Maintained
F: drivers/pnp/
+PNI RM3100 IIO DRIVER
+M: Song Qiang <songqiang1304...@gmail.com>
+L: linux-...@vger.kernel.org
+S: Maintained
+F: drivers/iio/magnetometer/rm3100*
+F: Documentation/devicetree/bindings/iio/magnetometer/pni,rm3100.txt
+
POSIX CLOCKS and TIMERS
M: Thomas Gleixner <t...@linutronix.de>
L: linux-kernel@vger.kernel.org
diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index ed9d776d01af..8a63cbbca4b7 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 3-Axis Magnetometer (I2C)"
+ depends on I2C
+ select SENSORS_RM3100
+ select REGMAP_I2C
+ help
+ Say Y here to add support for the PNI RM3100 3-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 3-Axis Magnetometer (SPI)"
+ depends on SPI_MASTER
+ select SENSORS_RM3100
+ select REGMAP_SPI
+ help
+ Say Y here to add support for the PNI RM3100 3-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..cacdaee28ae3
--- /dev/null
+++ b/drivers/iio/magnetometer/rm3100-core.c
@@ -0,0 +1,539 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PNI RM3100 3-axis geomagnetic sensor driver core.
+ *
+ * Copyright (C) 2018 Song Qiang <songqiang1304...@gmail.com>
+ *
+ * User Manual available at
+ * <https://www.pnicorp.com/download/rm3100-user-manual/>
+ *
+ * TODO: event generation, pm.
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
+#include "rm3100.h"
+
+/* Cycle Count Registers. */
+#define RM3100_REG_CC_X 0x05
+#define RM3100_REG_CC_Y 0x07
+#define RM3100_REG_CC_Z 0x09
+
+/* Continuous Measurement Mode register. */
+#define RM3100_REG_CMM 0x01
+#define RM3100_CMM_START BIT(0)
+#define RM3100_CMM_X BIT(4)
+#define RM3100_CMM_Y BIT(5)
+#define RM3100_CMM_Z BIT(6)
+
+/* TiMe Rate Configuration register. */
+#define RM3100_REG_TMRC 0x0B
+#define RM3100_TMRC_OFFSET 0x92
+
+/* Result Status register. */
+#define RM3100_REG_STATUS 0x34
+#define RM3100_STATUS_DRDY BIT(7)
+
+/* Measurement result registers. */
+#define RM3100_REG_MX2 0x24
+#define RM3100_REG_MY2 0x27
+#define RM3100_REG_MZ2 0x2a
+
+#define RM3100_W_REG_START RM3100_REG_CMM
+#define RM3100_W_REG_END RM3100_REG_STATUS
+#define RM3100_R_REG_START RM3100_REG_CMM
+#define RM3100_R_REG_END RM3100_REG_STATUS
+#define RM3100_V_REG_START RM3100_REG_MX2
+#define RM3100_V_REG_END RM3100_REG_STATUS
+
+/*
+ * This is computed by hand, is the sum of channel storage bits and padding
+ * bits, which is 4+4+4+12=24 in here.
+ */
+#define RM3100_SCAN_BYTES 24
+
+struct rm3100_data {
+ struct regmap *regmap;
+ struct completion measuring_done;
+ bool use_interrupt;
+
+ int conversion_time;
+ int cycle_count_index;
+
+ u8 buffer[RM3100_SCAN_BYTES];
+
+ /*
+ * This lock is for protecting the consistency of series of i2c
+ * operations, that is, to make sure a measurement process will
+ * not be interrupted by a set frequency operation, which should
+ * be taken where a series of i2c operation starts, released where
+ * the operation ends.
+ */
+ struct mutex lock;
+};
+
+static const struct regmap_range rm3100_readable_ranges[] = {
+ regmap_reg_range(RM3100_W_REG_START, RM3100_W_REG_END),
+};
+
+const struct regmap_access_table rm3100_readable_table = {
+ .yes_ranges = rm3100_readable_ranges,
+ .n_yes_ranges = ARRAY_SIZE(rm3100_readable_ranges),
+};
+EXPORT_SYMBOL_GPL(rm3100_readable_table);
+
+static const struct regmap_range rm3100_writable_ranges[] = {
+ regmap_reg_range(RM3100_R_REG_START, RM3100_R_REG_END),
+};
+
+const struct regmap_access_table rm3100_writable_table = {
+ .yes_ranges = rm3100_writable_ranges,
+ .n_yes_ranges = ARRAY_SIZE(rm3100_writable_ranges),
+};
+EXPORT_SYMBOL_GPL(rm3100_writable_table);
+
+static const struct regmap_range rm3100_volatile_ranges[] = {
+ regmap_reg_range(RM3100_V_REG_START, RM3100_V_REG_END),
+};
+
+const struct regmap_access_table rm3100_volatile_table = {
+ .yes_ranges = rm3100_volatile_ranges,
+ .n_yes_ranges = ARRAY_SIZE(rm3100_volatile_ranges),
+};
+EXPORT_SYMBOL_GPL(rm3100_volatile_table);
+
+static irqreturn_t rm3100_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;
+ int tries = 20;
+ int ret;
+
+ /*
+ * A read cycle of 400kbits i2c bus is about 20us, plus the time
+ * used for scheduling, a read cycle of fast mode of this device
+ * can reach 1.7ms, it may be possible for data to arrive just
+ * after we check the RM3100_REG_STATUS. In this case, irq_handler is
+ * called before measuring_done is reinitialized, it will wait
+ * forever for data that has already been ready.
+ * Reinitialize measuring_done before looking up makes sure we
+ * will always capture interrupt no matter when it happens.
+ */
+ if (data->use_interrupt)
+ reinit_completion(&data->measuring_done);
+
+ ret = regmap_read(regmap, RM3100_REG_STATUS, &val);
+ if (ret < 0)
+ return ret;
+
+ if ((val & RM3100_STATUS_DRDY) != RM3100_STATUS_DRDY) {
+ if (data->use_interrupt) {
+ ret = wait_for_completion_timeout(&data->measuring_done,
+ msecs_to_jiffies(data->conversion_time));
+ if (ret < 0)
+ return -ETIMEDOUT;
+ } else {
+ do {
+ usleep_range(1000, 5000);
+
+ ret = regmap_read(regmap, RM3100_REG_STATUS,
+ &val);
+ if (ret < 0)
+ return ret;
+
+ if (val & RM3100_STATUS_DRDY)
+ break;
+ } 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, RM3100_REG_MX2 + 3 * idx, buffer, 3);
+ mutex_unlock(&data->lock);
+ if (ret < 0)
+ return ret;
+
+ *val = sign_extend32((buffer[0] << 16) | (buffer[1] << 8) | buffer[2],
+ 23);
+
+ return IIO_VAL_INT;
+}
+
+#define RM3100_CHANNEL(axis, idx) \
+ { \
+ .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_SCALE) | \
+ BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+ .scan_index = idx, \
+ .scan_type = { \
+ .sign = 's', \
+ .realbits = 24, \
+ .storagebits = 32, \
+ .shift = 8, \
+ .endianness = IIO_BE, \
+ }, \
+ }
+
+static const struct iio_chan_spec rm3100_channels[] = {
+ RM3100_CHANNEL(X, 0),
+ RM3100_CHANNEL(Y, 1),
+ RM3100_CHANNEL(Z, 2),
+ IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+static const unsigned long rm3100_scan_masks[] = {BIT(0) | BIT(1) | BIT(2), 0};
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
+ "600 300 150 75 37 18 9 4.5 2.3 1.2 0.6 0.3 0.015 0.075"
+);
+
+static struct attribute *rm3100_attributes[] = {
+ &iio_const_attr_sampling_frequency_available.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group rm3100_attribute_group = {
+ .attrs = rm3100_attributes,
+};
+
+#define RM3100_SAMP_NUM 14
+
+/*
+ * Frequency : rm3100_samp_rates[][0].rm3100_samp_rates[][1]Hz.
+ * Time between reading: rm3100_sam_rates[][2]ms.
+ * The first one is actually 1.7ms.
+ */
+static const int rm3100_samp_rates[RM3100_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;
+ unsigned int tmp;
+
+ mutex_lock(&data->lock);
+ ret = regmap_read(data->regmap, RM3100_REG_TMRC, &tmp);
+ mutex_unlock(&data->lock);
+ if (ret < 0)
+ return ret;
+ *val = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][0];
+ *val2 = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][1];
+
+ return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int rm3100_set_cycle_count(struct rm3100_data *data, int val)
+{
+ int ret;
+ u8 i;
+
+ for (i = 0; i < 3; i++) {
+ ret = regmap_write(data->regmap, RM3100_REG_CC_X + 2 * i, val);
+ if (ret < 0)
+ return ret;
+ }
+
+ switch (val) {
+ case 50:
+ data->cycle_count_index = 0;
+ break;
+ case 100:
+ data->cycle_count_index = 1;
+ break;
+ /*
+ * This function will never be called by users' code, so here we
+ * assume that it will never get a wrong parameter.
+ */
+ default:
+ data->cycle_count_index = 2;
+ }
+
+ return 0;
+}
+
+static int rm3100_set_samp_freq(struct rm3100_data *data, int val, int val2)
+{
+ struct regmap *regmap = data->regmap;
+ unsigned int cycle_count;
+ int ret;
+ int i;
+
+ mutex_lock(&data->lock);
+ /* All cycle count registers use the same value. */
+ ret = regmap_read(regmap, RM3100_REG_CC_X, &cycle_count);
+ if (ret < 0)
+ goto unlock_return;
+
+ for (i = 0; i < RM3100_SAMP_NUM; i++) {
+ if (val == rm3100_samp_rates[i][0] &&
+ val2 == rm3100_samp_rates[i][1])
+ break;
+ }
+ if (i == RM3100_SAMP_NUM) {
+ ret = -EINVAL;
+ goto unlock_return;
+ }
+
+ ret = regmap_write(regmap, RM3100_REG_TMRC, i + RM3100_TMRC_OFFSET);
+ if (ret < 0)
+ goto unlock_return;
+
+ /* Checking if cycle count registers need changing. */
+ if (val == 600 && cycle_count == 200) {
+ ret = rm3100_set_cycle_count(data, 100);
+ if (ret < 0)
+ goto unlock_return;
+ } else if (val != 600 && cycle_count == 100) {
+ ret = rm3100_set_cycle_count(data, 200);
+ if (ret < 0)
+ goto unlock_return;
+ }
+
+ /* Writing TMRC registers requires CMM reset. */
+ ret = regmap_write(regmap, RM3100_REG_CMM, 0);
+ if (ret < 0)
+ goto unlock_return;
+ ret = regmap_write(regmap, RM3100_REG_CMM,
+ RM3100_CMM_X | RM3100_CMM_Y | RM3100_CMM_Z | RM3100_CMM_START);
+ if (ret < 0)
+ goto unlock_return;
+ mutex_unlock(&data->lock);
+
+ data->conversion_time = rm3100_samp_rates[i][2] + 3000;
+ return 0;
+
+unlock_return:
+ mutex_unlock(&data->lock);
+ return ret;
+}
+
+/*
+ * The scale of this sensor depends on the cycle count value, these three
+ * values are corresponding to the cycle count value 50, 100, 200.
+ * scale = output / gain * 10^4.
+ */
+const static int rm3100_scale[] = {500, 263, 133};
+
+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)
+ return ret;
+
+ ret = rm3100_read_mag(data, chan->scan_index, val);
+ iio_device_release_direct_mode(indio_dev);
+
+ return ret;
+ case IIO_CHAN_INFO_SCALE:
+ *val = 0;
+ *val2 = rm3100_scale[data->cycle_count_index];
+
+ return IIO_VAL_INT_PLUS_MICRO;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ return rm3100_get_samp_freq(data, val, val2);
+ 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);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ return rm3100_set_samp_freq(data, val, val2);
+ default:
+ return -EINVAL;
+ }
+
+}
+
+static const struct iio_info rm3100_info = {
+ .attrs = &rm3100_attribute_group,
+ .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;
+ int ret;
+ int i;
+
+ mutex_lock(&data->lock);
+ ret = rm3100_wait_measurement(data);
+ if (ret < 0) {
+ mutex_unlock(&data->lock);
+ goto done;
+ }
+
+ ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
+ mutex_unlock(&data->lock);
+ if (ret < 0)
+ goto done;
+
+ /* Convert XXXYYYZZZxxx to XXXxYYYxZZZx. x for paddings. */
+ for (i = 0; i < 2; i++)
+ memcpy(data->buffer + (2 - i) * 4, data->buffer + (2 - i) * 3,
+ 3);
+
+ /*
+ * Always using the same buffer so that we wouldn't need to set the
+ * paddings to 0 in case of leaking any data.
+ */
+ iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+ iio_get_time_ns(indio_dev));
+
+done:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static void rm3100_remove(void *pdata)
+{
+ struct rm3100_data *data = pdata;
+ struct device *dev = regmap_get_device(data->regmap);
+ int ret;
+
+ ret = regmap_write(data->regmap, RM3100_REG_CMM, 0x00);
+ if (ret < 0)
+ dev_err(dev, "failed to stop the device.\n");
+}
+
+int rm3100_common_probe(struct device *dev, struct regmap *regmap, int irq)
+{
+ struct iio_dev *indio_dev;
+ struct rm3100_data *data;
+ unsigned int tmp;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ data = iio_priv(indio_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_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 = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
+ rm3100_trigger_handler, NULL);
+ if (ret < 0)
+ return ret;
+
+ ret = regmap_read(regmap, RM3100_REG_TMRC, &tmp);
+ if (ret < 0)
+ return ret;
+ /* Initializing max wait time, 3sec more wait time for conversion. */
+ data->conversion_time =
+ rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][2] + 3000;
+
+ /* Cycle count values may not be what we want. */
+ ret = regmap_read(data->regmap, RM3100_REG_TMRC, &tmp);
+ if (ret < 0)
+ return ret;
+ if ((tmp - RM3100_TMRC_OFFSET) == 0)
+ rm3100_set_cycle_count(data, 100);
+ else
+ rm3100_set_cycle_count(data, 200);
+
+ /* Starting all channels' conversion. */
+ ret = regmap_write(regmap, RM3100_REG_CMM,
+ RM3100_CMM_X | RM3100_CMM_Y | RM3100_CMM_Z | RM3100_CMM_START);
+ if (ret < 0)
+ return ret;
+
+ ret = devm_add_action(dev, rm3100_remove, data);
+ if (ret < 0) {
+ rm3100_remove(data);
+ return ret;
+ }
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+EXPORT_SYMBOL_GPL(rm3100_common_probe);
+
+MODULE_AUTHOR("Song Qiang <songqiang1304...@gmail.com>");
+MODULE_DESCRIPTION("PNI RM3100 3-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..8f02e0366886
--- /dev/null
+++ b/drivers/iio/magnetometer/rm3100-i2c.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support for PNI RM3100 3-axis geomagnetic sensor on a i2c bus.
+ *
+ * Copyright (C) 2018 Song Qiang <songqiang1304...@gmail.com>
+ *
+ * i2c slave address: 0x20 + SA1 << 1 + SA0.
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.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 const struct of_device_id rm3100_dt_match[] = {
+ { .compatible = "pni,rm3100", },
+ { }
+};
+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,
+};
+module_i2c_driver(rm3100_driver);
+
+MODULE_AUTHOR("Song Qiang <songqiang1304...@gmail.com>");
+MODULE_DESCRIPTION("PNI RM3100 3-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..65d5eb9e4f5e
--- /dev/null
+++ b/drivers/iio/magnetometer/rm3100-spi.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support for PNI RM3100 3-axis geomagnetic sensor on a spi bus.
+ *
+ * Copyright (C) 2018 Song Qiang <songqiang1304...@gmail.com>
+ */
+
+#include <linux/module.h>
+#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 exceed 1Mbits. */
+ 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 const struct of_device_id rm3100_dt_match[] = {
+ { .compatible = "pni,rm3100", },
+ { }
+};
+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,
+};
+module_spi_driver(rm3100_driver);
+
+MODULE_AUTHOR("Song Qiang <songqiang1304...@gmail.com>");
+MODULE_DESCRIPTION("PNI RM3100 3-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..c3508218bc77
--- /dev/null
+++ b/drivers/iio/magnetometer/rm3100.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 Song Qiang <songqiang1304...@gmail.com>
+ */
+
+#ifndef RM3100_CORE_H
+#define RM3100_CORE_H
+
+#include <linux/regmap.h>
+
+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);
+
+#endif /* RM3100_CORE_H */
--
2.17.1
