iio: gyro: Add driver for the MPU-3050 gyroscope

This adds a new driver for the Invensense MPU-3050 gyroscope.
This driver is based on information from the rough input driver
in drivers/input/misc/mpu3050.c and the scratch misc driver
posted by Nathan Royer in 2011. Some years have passed but this
is finally a fully-fledged driver for this gyroscope. It was
developed and tested on the Qualcomm APQ8060 Dragonboard.

The driver supports both raw and buffered input. It also
supports the internal trigger mechanism by registering a trigger
that can fire in response to the internal sample engine of the
component. In addition to reading out the gyroscope sensor
values, the driver also supports reading the temperature from
the sensor.

The driver currently only supports I2C but the MPU-3050 can
also be used from SPI, so the I2C portions are split in their
own file and we just use regmap to access all registers, so
it will be trivial to plug in SPI support if/when someone has
a system requiring this.

To conserve power, the driver utilizes the runtime PM
framework and will put the sensor in off mode and disable the
regulators when unused, after a timeout of 10 seconds.

The fullscale can be set for the sensor to 250, 500, 1000 or
2000 deg/s. This corresponds to scale values of rougly 0.000122,
0.000275, 0.000512 or 0.001068. By writing such values (or close
to these) into "in_anglevel_scale", the corresponding fullscale
can be chosen. It will default to 2000 deg/s (~35 rad/s).

The gyro component can have DC offsets on all axes. These can be
compensated using the standard sysfs ABI property
"in_anglevel_[xyz]_calibbias". This is in positive/negative
values of the raw values, so a suitable calibration bias can be
determined by userspace by reading the "in_anglevel_[xyz]_raw"
for a few iterations while holding the sensor still, create an
average integer, and writing the negative inverse of that into
"in_anglevel_[xyz]_calibbias". After this the hardware will
automatically subtract the bias, also when using buffered
readings.

Since the MPU-3050 has an outgoing I2C port it needs to act as
an I2C mux. This means that the device is switching I2C traffic
to devices beyond it. On my system this is the only way to reach
the accelerometer. The "sensor fusion" ability of the MPU-3050
to directly talk to the device on the outgoing I2C port is
currently not used by the driver, but it has code to allow I2C
traffic to pass through so that the Linux kernel can reach the
device on the other side with a kernel driver.

Example usage with the native trigger:

$ generic_buffer -a -c10 -n mpu3050
iio device number being used is 0
iio trigger number being used is 0
No channels are enabled, enabling all channels
Enabling: in_anglvel_z_en
Enabling: in_timestamp_en
Enabling: in_anglvel_y_en
Enabling: in_temp_en
Enabling: in_anglvel_x_en
/sys/bus/iio/devices/iio:device0 mpu3050-dev0
29607.142578 -0.117493 0.074768 0.012817 180788797150
29639.285156 -0.117493 0.076904 0.013885 180888982335
29696.427734 -0.116425 0.076904 0.012817 180989178039
29742.857422 -0.117493 0.076904 0.012817 181089377742
29764.285156 -0.116425 0.077972 0.012817 181189574187
29860.714844 -0.115356 0.076904 0.012817 181289772705
29864.285156 -0.117493 0.076904 0.012817 181389971520
29910.714844 -0.115356 0.076904 0.013885 181490170483
29917.857422 -0.116425 0.076904 0.011749 181590369742
29975.000000 -0.116425 0.076904 0.012817 181690567075
Disabling: in_anglvel_z_en
Disabling: in_timestamp_en
Disabling: in_anglvel_y_en
Disabling: in_temp_en
Disabling: in_anglvel_x_en

The first column is the temperature in millidegrees, then the x,y,z
axes in succession followed by the timestamp. Also tested successfully
using the HRTimer trigger.

Cc: Nick Vaccaro <nvaccaro@google.com>
Cc: Ge Gao <ggao@invensense.com>
Cc: Anna Si <asi@invensense.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Crestez Dan Leonard <leonard.crestez@intel.com>
Cc: Daniel Baluta <daniel.baluta@intel.com>
Cc: Gregor Boirie <gregor.boirie@parrot.com>
Cc: Peter Rosin <peda@axentia.se>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

MAINTAINERS

@@ -6496,6 +6496,13 @@ S:	Maintained
 F:	arch/x86/include/asm/pmc_core.h
 F:	drivers/platform/x86/intel_pmc_core*
 
+INVENSENSE MPU-3050 GYROSCOPE DRIVER
+M:	Linus Walleij <linus.walleij@linaro.org>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/gyro/mpu3050*
+F:	Documentation/devicetree/bindings/iio/gyroscope/inv,mpu3050.txt
+
 IOC3 ETHERNET DRIVER
 M:	Ralf Baechle <ralf@linux-mips.org>
 L:	linux-mips@linux-mips.org

drivers/iio/gyro/Kconfig

@@ -84,6 +84,23 @@ config HID_SENSOR_GYRO_3D
 	  Say yes here to build support for the HID SENSOR
 	  Gyroscope 3D.
 
+config MPU3050
+	tristate
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP
+
+config MPU3050_I2C
+	tristate "Invensense MPU3050 devices on I2C"
+	depends on !(INPUT_MPU3050=y || INPUT_MPU3050=m)
+	select MPU3050
+	select REGMAP_I2C
+	select I2C_MUX
+	help
+	  This driver supports the Invensense MPU3050 gyroscope over I2C.
+	  This driver can be built as a module. The module will be called
+	  inv-mpu3050-i2c.
+
 config IIO_ST_GYRO_3AXIS
 	tristate "STMicroelectronics gyroscopes 3-Axis Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS

drivers/iio/gyro/Makefile

@@ -14,6 +14,11 @@ obj-$(CONFIG_BMG160_SPI) += bmg160_spi.o
 
 obj-$(CONFIG_HID_SENSOR_GYRO_3D) += hid-sensor-gyro-3d.o
 
+# Currently this is rolled into one module, split it if
+# we ever create a separate SPI interface for MPU-3050
+obj-$(CONFIG_MPU3050) += mpu3050.o
+mpu3050-objs := mpu3050-core.o mpu3050-i2c.o
+
 itg3200-y               := itg3200_core.o
 itg3200-$(CONFIG_IIO_BUFFER) += itg3200_buffer.o
 obj-$(CONFIG_ITG3200)   += itg3200.o

drivers/iio/gyro/mpu3050-core.c

+/*
+ * MPU3050 gyroscope driver
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * Based on the input subsystem driver, Copyright (C) 2011 Wistron Co.Ltd
+ * Joseph Lai <joseph_lai@wistron.com> and trimmed down by
+ * Alan Cox <alan@linux.intel.com> in turn based on bma023.c.
+ * Device behaviour based on a misc driver posted by Nathan Royer in 2011.
+ *
+ * TODO: add support for setting up the low pass 3dB frequency.
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+
+#include "mpu3050.h"
+
+#define MPU3050_CHIP_ID		0x69
+
+/*
+ * Register map: anything suffixed *_H is a big-endian high byte and always
+ * followed by the corresponding low byte (*_L) even though these are not
+ * explicitly included in the register definitions.
+ */
+#define MPU3050_CHIP_ID_REG	0x00
+#define MPU3050_PRODUCT_ID_REG	0x01
+#define MPU3050_XG_OFFS_TC	0x05
+#define MPU3050_YG_OFFS_TC	0x08
+#define MPU3050_ZG_OFFS_TC	0x0B
+#define MPU3050_X_OFFS_USR_H	0x0C
+#define MPU3050_Y_OFFS_USR_H	0x0E
+#define MPU3050_Z_OFFS_USR_H	0x10
+#define MPU3050_FIFO_EN		0x12
+#define MPU3050_AUX_VDDIO	0x13
+#define MPU3050_SLV_ADDR	0x14
+#define MPU3050_SMPLRT_DIV	0x15
+#define MPU3050_DLPF_FS_SYNC	0x16
+#define MPU3050_INT_CFG		0x17
+#define MPU3050_AUX_ADDR	0x18
+#define MPU3050_INT_STATUS	0x1A
+#define MPU3050_TEMP_H		0x1B
+#define MPU3050_XOUT_H		0x1D
+#define MPU3050_YOUT_H		0x1F
+#define MPU3050_ZOUT_H		0x21
+#define MPU3050_DMP_CFG1	0x35
+#define MPU3050_DMP_CFG2	0x36
+#define MPU3050_BANK_SEL	0x37
+#define MPU3050_MEM_START_ADDR	0x38
+#define MPU3050_MEM_R_W		0x39
+#define MPU3050_FIFO_COUNT_H	0x3A
+#define MPU3050_FIFO_R		0x3C
+#define MPU3050_USR_CTRL	0x3D
+#define MPU3050_PWR_MGM		0x3E
+
+/* MPU memory bank read options */
+#define MPU3050_MEM_PRFTCH	BIT(5)
+#define MPU3050_MEM_USER_BANK	BIT(4)
+/* Bits 8-11 select memory bank */
+#define MPU3050_MEM_RAM_BANK_0	0
+#define MPU3050_MEM_RAM_BANK_1	1
+#define MPU3050_MEM_RAM_BANK_2	2
+#define MPU3050_MEM_RAM_BANK_3	3
+#define MPU3050_MEM_OTP_BANK_0	4
+
+#define MPU3050_AXIS_REGS(axis) (MPU3050_XOUT_H + (axis * 2))
+
+/* Register bits */
+
+/* FIFO Enable */
+#define MPU3050_FIFO_EN_FOOTER		BIT(0)
+#define MPU3050_FIFO_EN_AUX_ZOUT	BIT(1)
+#define MPU3050_FIFO_EN_AUX_YOUT	BIT(2)
+#define MPU3050_FIFO_EN_AUX_XOUT	BIT(3)
+#define MPU3050_FIFO_EN_GYRO_ZOUT	BIT(4)
+#define MPU3050_FIFO_EN_GYRO_YOUT	BIT(5)
+#define MPU3050_FIFO_EN_GYRO_XOUT	BIT(6)
+#define MPU3050_FIFO_EN_TEMP_OUT	BIT(7)
+
+/*
+ * Digital Low Pass filter (DLPF)
+ * Full Scale (FS)
+ * and Synchronization
+ */
+#define MPU3050_EXT_SYNC_NONE		0x00
+#define MPU3050_EXT_SYNC_TEMP		0x20
+#define MPU3050_EXT_SYNC_GYROX		0x40
+#define MPU3050_EXT_SYNC_GYROY		0x60
+#define MPU3050_EXT_SYNC_GYROZ		0x80
+#define MPU3050_EXT_SYNC_ACCELX	0xA0
+#define MPU3050_EXT_SYNC_ACCELY	0xC0
+#define MPU3050_EXT_SYNC_ACCELZ	0xE0
+#define MPU3050_EXT_SYNC_MASK		0xE0
+#define MPU3050_EXT_SYNC_SHIFT		5
+
+#define MPU3050_FS_250DPS		0x00
+#define MPU3050_FS_500DPS		0x08
+#define MPU3050_FS_1000DPS		0x10
+#define MPU3050_FS_2000DPS		0x18
+#define MPU3050_FS_MASK			0x18
+#define MPU3050_FS_SHIFT		3
+
+#define MPU3050_DLPF_CFG_256HZ_NOLPF2	0x00
+#define MPU3050_DLPF_CFG_188HZ		0x01
+#define MPU3050_DLPF_CFG_98HZ		0x02
+#define MPU3050_DLPF_CFG_42HZ		0x03
+#define MPU3050_DLPF_CFG_20HZ		0x04
+#define MPU3050_DLPF_CFG_10HZ		0x05
+#define MPU3050_DLPF_CFG_5HZ		0x06
+#define MPU3050_DLPF_CFG_2100HZ_NOLPF	0x07
+#define MPU3050_DLPF_CFG_MASK		0x07
+#define MPU3050_DLPF_CFG_SHIFT		0
+
+/* Interrupt config */
+#define MPU3050_INT_RAW_RDY_EN		BIT(0)
+#define MPU3050_INT_DMP_DONE_EN		BIT(1)
+#define MPU3050_INT_MPU_RDY_EN		BIT(2)
+#define MPU3050_INT_ANYRD_2CLEAR	BIT(4)
+#define MPU3050_INT_LATCH_EN		BIT(5)
+#define MPU3050_INT_OPEN		BIT(6)
+#define MPU3050_INT_ACTL		BIT(7)
+/* Interrupt status */
+#define MPU3050_INT_STATUS_RAW_RDY	BIT(0)
+#define MPU3050_INT_STATUS_DMP_DONE	BIT(1)
+#define MPU3050_INT_STATUS_MPU_RDY	BIT(2)
+#define MPU3050_INT_STATUS_FIFO_OVFLW	BIT(7)
+/* USR_CTRL */
+#define MPU3050_USR_CTRL_FIFO_EN	BIT(6)
+#define MPU3050_USR_CTRL_AUX_IF_EN	BIT(5)
+#define MPU3050_USR_CTRL_AUX_IF_RST	BIT(3)
+#define MPU3050_USR_CTRL_FIFO_RST	BIT(1)
+#define MPU3050_USR_CTRL_GYRO_RST	BIT(0)
+/* PWR_MGM */
+#define MPU3050_PWR_MGM_PLL_X		0x01
+#define MPU3050_PWR_MGM_PLL_Y		0x02
+#define MPU3050_PWR_MGM_PLL_Z		0x03
+#define MPU3050_PWR_MGM_CLKSEL_MASK	0x07
+#define MPU3050_PWR_MGM_STBY_ZG		BIT(3)
+#define MPU3050_PWR_MGM_STBY_YG		BIT(4)
+#define MPU3050_PWR_MGM_STBY_XG		BIT(5)
+#define MPU3050_PWR_MGM_SLEEP		BIT(6)
+#define MPU3050_PWR_MGM_RESET		BIT(7)
+#define MPU3050_PWR_MGM_MASK		0xff
+
+/*
+ * Fullscale precision is (for finest precision) +/- 250 deg/s, so the full
+ * scale is actually 500 deg/s. All 16 bits are then used to cover this scale,
+ * in two's complement.
+ */
+static unsigned int mpu3050_fs_precision[] = {
+	IIO_DEGREE_TO_RAD(250),
+	IIO_DEGREE_TO_RAD(500),
+	IIO_DEGREE_TO_RAD(1000),
+	IIO_DEGREE_TO_RAD(2000)
+};
+
+/*
+ * Regulator names
+ */
+static const char mpu3050_reg_vdd[] = "vdd";
+static const char mpu3050_reg_vlogic[] = "vlogic";
+
+static unsigned int mpu3050_get_freq(struct mpu3050 *mpu3050)
+{
+	unsigned int freq;
+
+	if (mpu3050->lpf == MPU3050_DLPF_CFG_256HZ_NOLPF2)
+		freq = 8000;
+	else
+		freq = 1000;
+	freq /= (mpu3050->divisor + 1);
+
+	return freq;
+}
+
+static int mpu3050_start_sampling(struct mpu3050 *mpu3050)
+{
+	__be16 raw_val[3];
+	int ret;
+	int i;
+
+	/* Reset */
+	ret = regmap_update_bits(mpu3050->map, MPU3050_PWR_MGM,
+				 MPU3050_PWR_MGM_RESET, MPU3050_PWR_MGM_RESET);
+	if (ret)
+		return ret;
+
+	/* Turn on the Z-axis PLL */
+	ret = regmap_update_bits(mpu3050->map, MPU3050_PWR_MGM,
+				 MPU3050_PWR_MGM_CLKSEL_MASK,
+				 MPU3050_PWR_MGM_PLL_Z);
+	if (ret)
+		return ret;
+
+	/* Write calibration offset registers */
+	for (i = 0; i < 3; i++)
+		raw_val[i] = cpu_to_be16(mpu3050->calibration[i]);
+
+	ret = regmap_bulk_write(mpu3050->map, MPU3050_X_OFFS_USR_H, raw_val,
+				sizeof(raw_val));
+	if (ret)
+		return ret;
+
+	/* Set low pass filter (sample rate), sync and full scale */
+	ret = regmap_write(mpu3050->map, MPU3050_DLPF_FS_SYNC,
+			   MPU3050_EXT_SYNC_NONE << MPU3050_EXT_SYNC_SHIFT |
+			   mpu3050->fullscale << MPU3050_FS_SHIFT |
+			   mpu3050->lpf << MPU3050_DLPF_CFG_SHIFT);
+	if (ret)
+		return ret;
+
+	/* Set up sampling frequency */
+	ret = regmap_write(mpu3050->map, MPU3050_SMPLRT_DIV, mpu3050->divisor);
+	if (ret)
+		return ret;
+
+	/*
+	 * Max 50 ms start-up time after setting DLPF_FS_SYNC
+	 * according to the data sheet, then wait for the next sample
+	 * at this frequency T = 1000/f ms.
+	 */
+	msleep(50 + 1000 / mpu3050_get_freq(mpu3050));
+
+	return 0;
+}
+
+static int mpu3050_set_8khz_samplerate(struct mpu3050 *mpu3050)
+{
+	int ret;
+	u8 divisor;
+	enum mpu3050_lpf lpf;
+
+	lpf = mpu3050->lpf;
+	divisor = mpu3050->divisor;
+
+	mpu3050->lpf = LPF_256_HZ_NOLPF; /* 8 kHz base frequency */
+	mpu3050->divisor = 0; /* Divide by 1 */
+	ret = mpu3050_start_sampling(mpu3050);
+
+	mpu3050->lpf = lpf;
+	mpu3050->divisor = divisor;
+
+	return ret;
+}
+
+static int mpu3050_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2,
+			    long mask)
+{
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	int ret;
+	__be16 raw_val;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_OFFSET:
+		switch (chan->type) {
+		case IIO_TEMP:
+			/* The temperature scaling is (x+23000)/280 Celsius */
+			*val = 23000;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_CALIBBIAS:
+		switch (chan->type) {
+		case IIO_ANGL_VEL:
+			*val = mpu3050->calibration[chan->scan_index-1];
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = mpu3050_get_freq(mpu3050);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_TEMP:
+			/* Millidegrees, see about temperature scaling above */
+			*val = 1000;
+			*val2 = 280;
+			return IIO_VAL_FRACTIONAL;
+		case IIO_ANGL_VEL:
+			/*
+			 * Convert to the corresponding full scale in
+			 * radians. All 16 bits are used with sign to
+			 * span the available scale: to account for the one
+			 * missing value if we multiply by 1/S16_MAX, instead
+			 * multiply with 2/U16_MAX.
+			 */
+			*val = mpu3050_fs_precision[mpu3050->fullscale] * 2;
+			*val2 = U16_MAX;
+			return IIO_VAL_FRACTIONAL;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_RAW:
+		/* Resume device */
+		pm_runtime_get_sync(mpu3050->dev);
+		mutex_lock(&mpu3050->lock);
+
+		ret = mpu3050_set_8khz_samplerate(mpu3050);
+		if (ret)
+			goto out_read_raw_unlock;
+
+		switch (chan->type) {
+		case IIO_TEMP:
+			ret = regmap_bulk_read(mpu3050->map, MPU3050_TEMP_H,
+					       &raw_val, sizeof(raw_val));
+			if (ret) {
+				dev_err(mpu3050->dev,
+					"error reading temperature\n");
+				goto out_read_raw_unlock;
+			}
+
+			*val = be16_to_cpu(raw_val);
+			ret = IIO_VAL_INT;
+
+			goto out_read_raw_unlock;
+		case IIO_ANGL_VEL:
+			ret = regmap_bulk_read(mpu3050->map,
+				       MPU3050_AXIS_REGS(chan->scan_index-1),
+				       &raw_val,
+				       sizeof(raw_val));
+			if (ret) {
+				dev_err(mpu3050->dev,
+					"error reading axis data\n");
+				goto out_read_raw_unlock;
+			}
+
+			*val = be16_to_cpu(raw_val);
+			ret = IIO_VAL_INT;
+
+			goto out_read_raw_unlock;
+		default:
+			ret = -EINVAL;
+			goto out_read_raw_unlock;
+		}
+	default:
+		break;
+	}
+
+	return -EINVAL;
+
+out_read_raw_unlock:
+	mutex_unlock(&mpu3050->lock);
+	pm_runtime_mark_last_busy(mpu3050->dev);
+	pm_runtime_put_autosuspend(mpu3050->dev);
+
+	return ret;
+}
+
+static int mpu3050_write_raw(struct iio_dev *indio_dev,
+			     const struct iio_chan_spec *chan,
+			     int val, int val2, long mask)
+{
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	/*
+	 * Couldn't figure out a way to precalculate these at compile time.
+	 */
+	unsigned int fs250 =
+		DIV_ROUND_CLOSEST(mpu3050_fs_precision[0] * 1000000 * 2,
+				  U16_MAX);
+	unsigned int fs500 =
+		DIV_ROUND_CLOSEST(mpu3050_fs_precision[1] * 1000000 * 2,
+				  U16_MAX);
+	unsigned int fs1000 =
+		DIV_ROUND_CLOSEST(mpu3050_fs_precision[2] * 1000000 * 2,
+				  U16_MAX);
+	unsigned int fs2000 =
+		DIV_ROUND_CLOSEST(mpu3050_fs_precision[3] * 1000000 * 2,
+				  U16_MAX);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (chan->type != IIO_ANGL_VEL)
+			return -EINVAL;
+		mpu3050->calibration[chan->scan_index-1] = val;
+		return 0;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		/*
+		 * The max samplerate is 8000 Hz, the minimum
+		 * 1000 / 256 ~= 4 Hz
+		 */
+		if (val < 4 || val > 8000)
+			return -EINVAL;
+
+		/*
+		 * Above 1000 Hz we must turn off the digital low pass filter
+		 * so we get a base frequency of 8kHz to the divider
+		 */
+		if (val > 1000) {
+			mpu3050->lpf = LPF_256_HZ_NOLPF;
+			mpu3050->divisor = DIV_ROUND_CLOSEST(8000, val) - 1;
+			return 0;
+		}
+
+		mpu3050->lpf = LPF_188_HZ;
+		mpu3050->divisor = DIV_ROUND_CLOSEST(1000, val) - 1;
+		return 0;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type != IIO_ANGL_VEL)
+			return -EINVAL;
+		/*
+		 * We support +/-250, +/-500, +/-1000 and +/2000 deg/s
+		 * which means we need to round to the closest radians
+		 * which will be roughly +/-4.3, +/-8.7, +/-17.5, +/-35
+		 * rad/s. The scale is then for the 16 bits used to cover
+		 * it 2/(2^16) of that.
+		 */
+
+		/* Just too large, set the max range */
+		if (val != 0) {
+			mpu3050->fullscale = FS_2000_DPS;
+			return 0;
+		}
+
+		/*
+		 * Now we're dealing with fractions below zero in millirad/s
+		 * do some integer interpolation and match with the closest
+		 * fullscale in the table.
+		 */
+		if (val2 <= fs250 ||
+		    val2 < ((fs500 + fs250) / 2))
+			mpu3050->fullscale = FS_250_DPS;
+		else if (val2 <= fs500 ||
+			 val2 < ((fs1000 + fs500) / 2))
+			mpu3050->fullscale = FS_500_DPS;
+		else if (val2 <= fs1000 ||
+			 val2 < ((fs2000 + fs1000) / 2))
+			mpu3050->fullscale = FS_1000_DPS;
+		else
+			/* Catch-all */
+			mpu3050->fullscale = FS_2000_DPS;
+		return 0;
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static irqreturn_t mpu3050_trigger_handler(int irq, void *p)
+{
+	const struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	int ret;
+	/*
+	 * Temperature 1*16 bits
+	 * Three axes 3*16 bits
+	 * Timestamp 64 bits (4*16 bits)
+	 * Sum total 8*16 bits
+	 */
+	__be16 hw_values[8];
+	s64 timestamp;
+	unsigned int datums_from_fifo = 0;
+
+	/*
+	 * If we're using the hardware trigger, get the precise timestamp from
+	 * the top half of the threaded IRQ handler. Otherwise get the
+	 * timestamp here so it will be close in time to the actual values
+	 * read from the registers.
+	 */
+	if (iio_trigger_using_own(indio_dev))
+		timestamp = mpu3050->hw_timestamp;
+	else
+		timestamp = iio_get_time_ns(indio_dev);
+
+	mutex_lock(&mpu3050->lock);
+
+	/* Using the hardware IRQ trigger? Check the buffer then. */
+	if (mpu3050->hw_irq_trigger) {
+		__be16 raw_fifocnt;
+		u16 fifocnt;
+		/* X, Y, Z + temperature */
+		unsigned int bytes_per_datum = 8;
+		bool fifo_overflow = false;
+
+		ret = regmap_bulk_read(mpu3050->map,
+				       MPU3050_FIFO_COUNT_H,
+				       &raw_fifocnt,
+				       sizeof(raw_fifocnt));
+		if (ret)
+			goto out_trigger_unlock;
+		fifocnt = be16_to_cpu(raw_fifocnt);
+
+		if (fifocnt == 512) {
+			dev_info(mpu3050->dev,
+				 "FIFO overflow! Emptying and resetting FIFO\n");
+			fifo_overflow = true;
+			/* Reset and enable the FIFO */
+			ret = regmap_update_bits(mpu3050->map,
+						 MPU3050_USR_CTRL,
+						 MPU3050_USR_CTRL_FIFO_EN |
+						 MPU3050_USR_CTRL_FIFO_RST,
+						 MPU3050_USR_CTRL_FIFO_EN |
+						 MPU3050_USR_CTRL_FIFO_RST);
+			if (ret) {
+				dev_info(mpu3050->dev, "error resetting FIFO\n");
+				goto out_trigger_unlock;
+			}
+			mpu3050->pending_fifo_footer = false;
+		}
+
+		if (fifocnt)
+			dev_dbg(mpu3050->dev,
+				"%d bytes in the FIFO\n",
+				fifocnt);
+
+		while (!fifo_overflow && fifocnt > bytes_per_datum) {
+			unsigned int toread;
+			unsigned int offset;
+			__be16 fifo_values[5];
+
+			/*
+			 * If there is a FIFO footer in the pipe, first clear
+			 * that out. This follows the complex algorithm in the
+			 * datasheet that states that you may never leave the
+			 * FIFO empty after the first reading: you have to
+			 * always leave two footer bytes in it. The footer is
+			 * in practice just two zero bytes.
+			 */
+			if (mpu3050->pending_fifo_footer) {
+				toread = bytes_per_datum + 2;
+				offset = 0;
+			} else {
+				toread = bytes_per_datum;
+				offset = 1;
+				/* Put in some dummy value */
+				fifo_values[0] = 0xAAAA;
+			}
+
+			ret = regmap_bulk_read(mpu3050->map,
+					       MPU3050_FIFO_R,
+					       &fifo_values[offset],
+					       toread);
+
+			dev_dbg(mpu3050->dev,
+				"%04x %04x %04x %04x %04x\n",
+				fifo_values[0],
+				fifo_values[1],
+				fifo_values[2],
+				fifo_values[3],
+				fifo_values[4]);
+
+			/* Index past the footer (fifo_values[0]) and push */
+			iio_push_to_buffers_with_timestamp(indio_dev,
+							   &fifo_values[1],
+							   timestamp);
+
+			fifocnt -= toread;
+			datums_from_fifo++;
+			mpu3050->pending_fifo_footer = true;
+
+			/*
+			 * If we're emptying the FIFO, just make sure to
+			 * check if something new appeared.
+			 */
+			if (fifocnt < bytes_per_datum) {
+				ret = regmap_bulk_read(mpu3050->map,
+						       MPU3050_FIFO_COUNT_H,
+						       &raw_fifocnt,
+						       sizeof(raw_fifocnt));
+				if (ret)
+					goto out_trigger_unlock;
+				fifocnt = be16_to_cpu(raw_fifocnt);
+			}
+
+			if (fifocnt < bytes_per_datum)
+				dev_dbg(mpu3050->dev,
+					"%d bytes left in the FIFO\n",
+					fifocnt);
+
+			/*
+			 * At this point, the timestamp that triggered the
+			 * hardware interrupt is no longer valid for what
+			 * we are reading (the interrupt likely fired for
+			 * the value on the top of the FIFO), so set the
+			 * timestamp to zero and let userspace deal with it.
+			 */
+			timestamp = 0;
+		}
+	}
+
+	/*
+	 * If we picked some datums from the FIFO that's enough, else
+	 * fall through and just read from the current value registers.
+	 * This happens in two cases:
+	 *
+	 * - We are using some other trigger (external, like an HRTimer)
+	 *   than the sensor's own sample generator. In this case the
+	 *   sensor is just set to the max sampling frequency and we give
+	 *   the trigger a copy of the latest value every time we get here.
+	 *
+	 * - The hardware trigger is active but unused and we actually use
+	 *   another trigger which calls here with a frequency higher
+	 *   than what the device provides data. We will then just read
+	 *   duplicate values directly from the hardware registers.
+	 */
+	if (datums_from_fifo) {
+		dev_dbg(mpu3050->dev,
+			"read %d datums from the FIFO\n",
+			datums_from_fifo);
+		goto out_trigger_unlock;
+	}
+
+	ret = regmap_bulk_read(mpu3050->map, MPU3050_TEMP_H, &hw_values,
+			       sizeof(hw_values));
+	if (ret) {
+		dev_err(mpu3050->dev,
+			"error reading axis data\n");
+		goto out_trigger_unlock;
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, hw_values, timestamp);
+
+out_trigger_unlock:
+	mutex_unlock(&mpu3050->lock);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int mpu3050_buffer_preenable(struct iio_dev *indio_dev)
+{
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+
+	pm_runtime_get_sync(mpu3050->dev);
+
+	/* Unless we have OUR trigger active, run at full speed */
+	if (!mpu3050->hw_irq_trigger)
+		return mpu3050_set_8khz_samplerate(mpu3050);
+
+	return 0;
+}
+
+static int mpu3050_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+
+	pm_runtime_mark_last_busy(mpu3050->dev);
+	pm_runtime_put_autosuspend(mpu3050->dev);
+
+	return 0;
+}
+
+static const struct iio_buffer_setup_ops mpu3050_buffer_setup_ops = {
+	.preenable = mpu3050_buffer_preenable,
+	.postenable = iio_triggered_buffer_postenable,
+	.predisable = iio_triggered_buffer_predisable,
+	.postdisable = mpu3050_buffer_postdisable,
+};
+
+static const struct iio_mount_matrix *
+mpu3050_get_mount_matrix(const struct iio_dev *indio_dev,
+			 const struct iio_chan_spec *chan)
+{
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+
+	return &mpu3050->orientation;
+}
+
+static const struct iio_chan_spec_ext_info mpu3050_ext_info[] = {
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_TYPE, mpu3050_get_mount_matrix),
+	{ },
+};
+
+#define MPU3050_AXIS_CHANNEL(axis, index)				\
+	{								\
+		.type = IIO_ANGL_VEL,					\
+		.modified = 1,						\
+		.channel2 = IIO_MOD_##axis,				\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+			BIT(IIO_CHAN_INFO_CALIBBIAS),			\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.ext_info = mpu3050_ext_info,				\
+		.scan_index = index,					\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 16,					\
+			.storagebits = 16,				\
+			.endianness = IIO_BE,				\
+		},							\
+	}
+
+static const struct iio_chan_spec mpu3050_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_BE,
+		},
+	},
+	MPU3050_AXIS_CHANNEL(X, 1),
+	MPU3050_AXIS_CHANNEL(Y, 2),
+	MPU3050_AXIS_CHANNEL(Z, 3),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+/* Four channels apart from timestamp, scan mask = 0x0f */
+static const unsigned long mpu3050_scan_masks[] = { 0xf, 0 };
+
+/*
+ * These are just the hardcoded factors resulting from the more elaborate
+ * calculations done with fractions in the scale raw get/set functions.
+ */
+static IIO_CONST_ATTR(anglevel_scale_available,
+		      "0.000122070 "
+		      "0.000274658 "
+		      "0.000518798 "
+		      "0.001068115");
+
+static struct attribute *mpu3050_attributes[] = {
+	&iio_const_attr_anglevel_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group mpu3050_attribute_group = {
+	.attrs = mpu3050_attributes,
+};
+
+static const struct iio_info mpu3050_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = mpu3050_read_raw,
+	.write_raw = mpu3050_write_raw,
+	.attrs = &mpu3050_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+/**
+ * mpu3050_read_mem() - read MPU-3050 internal memory
+ * @mpu3050: device to read from
+ * @bank: target bank
+ * @addr: target address
+ * @len: number of bytes
+ * @buf: the buffer to store the read bytes in
+ */
+static int mpu3050_read_mem(struct mpu3050 *mpu3050,
+			    u8 bank,
+			    u8 addr,
+			    u8 len,
+			    u8 *buf)
+{
+	int ret;
+
+	ret = regmap_write(mpu3050->map,
+			   MPU3050_BANK_SEL,
+			   bank);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(mpu3050->map,
+			   MPU3050_MEM_START_ADDR,
+			   addr);
+	if (ret)
+		return ret;
+
+	return regmap_bulk_read(mpu3050->map,
+				MPU3050_MEM_R_W,
+				buf,
+				len);
+}
+
+static int mpu3050_hw_init(struct mpu3050 *mpu3050)
+{
+	int ret;
+	u8 otp[8];
+
+	/* Reset */
+	ret = regmap_update_bits(mpu3050->map,
+				 MPU3050_PWR_MGM,
+				 MPU3050_PWR_MGM_RESET,
+				 MPU3050_PWR_MGM_RESET);
+	if (ret)
+		return ret;
+
+	/* Turn on the PLL */
+	ret = regmap_update_bits(mpu3050->map,
+				 MPU3050_PWR_MGM,
+				 MPU3050_PWR_MGM_CLKSEL_MASK,
+				 MPU3050_PWR_MGM_PLL_Z);
+	if (ret)
+		return ret;
+
+	/* Disable IRQs */
+	ret = regmap_write(mpu3050->map,
+			   MPU3050_INT_CFG,
+			   0);
+	if (ret)
+		return ret;
+
+	/* Read out the 8 bytes of OTP (one-time-programmable) memory */
+	ret = mpu3050_read_mem(mpu3050,
+			       (MPU3050_MEM_PRFTCH |
+				MPU3050_MEM_USER_BANK |
+				MPU3050_MEM_OTP_BANK_0),
+			       0,
+			       sizeof(otp),
+			       otp);
+	if (ret)
+		return ret;
+
+	/* This is device-unique data so it goes into the entropy pool */
+	add_device_randomness(otp, sizeof(otp));
+
+	dev_info(mpu3050->dev,
+		 "die ID: %04X, wafer ID: %02X, A lot ID: %04X, "
+		 "W lot ID: %03X, WP ID: %01X, rev ID: %02X\n",
+		 /* Die ID, bits 0-12 */
+		 (otp[1] << 8 | otp[0]) & 0x1fff,
+		 /* Wafer ID, bits 13-17 */
+		 ((otp[2] << 8 | otp[1]) & 0x03e0) >> 5,
+		 /* A lot ID, bits 18-33 */
+		 ((otp[4] << 16 | otp[3] << 8 | otp[2]) & 0x3fffc) >> 2,
+		 /* W lot ID, bits 34-45 */
+		 ((otp[5] << 8 | otp[4]) & 0x3ffc) >> 2,
+		 /* WP ID, bits 47-49 */
+		 ((otp[6] << 8 | otp[5]) & 0x0380) >> 7,
+		 /* rev ID, bits 50-55 */
+		 otp[6] >> 2);
+
+	return 0;
+}
+
+static int mpu3050_power_up(struct mpu3050 *mpu3050)
+{
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(mpu3050->regs), mpu3050->regs);
+	if (ret) {
+		dev_err(mpu3050->dev, "cannot enable regulators\n");
+		return ret;
+	}
+	/*
+	 * 20-100 ms start-up time for register read/write according to
+	 * the datasheet, be on the safe side and wait 200 ms.
+	 */
+	msleep(200);
+
+	/* Take device out of sleep mode */
+	ret = regmap_update_bits(mpu3050->map, MPU3050_PWR_MGM,
+				 MPU3050_PWR_MGM_SLEEP, 0);
+	if (ret) {
+		dev_err(mpu3050->dev, "error setting power mode\n");
+		return ret;
+	}
+	msleep(10);
+
+	return 0;
+}
+
+static int mpu3050_power_down(struct mpu3050 *mpu3050)
+{
+	int ret;
+
+	/*
+	 * Put MPU-3050 into sleep mode before cutting regulators.
+	 * This is important, because we may not be the sole user
+	 * of the regulator so the power may stay on after this, and
+	 * then we would be wasting power unless we go to sleep mode
+	 * first.
+	 */
+	ret = regmap_update_bits(mpu3050->map, MPU3050_PWR_MGM,
+				 MPU3050_PWR_MGM_SLEEP, MPU3050_PWR_MGM_SLEEP);
+	if (ret)
+		dev_err(mpu3050->dev, "error putting to sleep\n");
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(mpu3050->regs), mpu3050->regs);
+	if (ret)
+		dev_err(mpu3050->dev, "error disabling regulators\n");
+
+	return 0;
+}
+
+static irqreturn_t mpu3050_irq_handler(int irq, void *p)
+{
+	struct iio_trigger *trig = p;
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+
+	if (!mpu3050->hw_irq_trigger)
+		return IRQ_NONE;
+
+	/* Get the time stamp as close in time as possible */
+	mpu3050->hw_timestamp = iio_get_time_ns(indio_dev);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t mpu3050_irq_thread(int irq, void *p)
+{
+	struct iio_trigger *trig = p;
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	unsigned int val;
+	int ret;
+
+	/* ACK IRQ and check if it was from us */
+	ret = regmap_read(mpu3050->map, MPU3050_INT_STATUS, &val);
+	if (ret) {
+		dev_err(mpu3050->dev, "error reading IRQ status\n");
+		return IRQ_HANDLED;
+	}
+	if (!(val & MPU3050_INT_STATUS_RAW_RDY))
+		return IRQ_NONE;
+
+	iio_trigger_poll_chained(p);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * mpu3050_drdy_trigger_set_state() - set data ready interrupt state
+ * @trig: trigger instance
+ * @enable: true if trigger should be enabled, false to disable
+ */
+static int mpu3050_drdy_trigger_set_state(struct iio_trigger *trig,
+					  bool enable)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	unsigned int val;
+	int ret;
+
+	/* Disabling trigger: disable interrupt and return */
+	if (!enable) {
+		/* Disable all interrupts */
+		ret = regmap_write(mpu3050->map,
+				   MPU3050_INT_CFG,
+				   0);
+		if (ret)
+			dev_err(mpu3050->dev, "error disabling IRQ\n");
+
+		/* Clear IRQ flag */
+		ret = regmap_read(mpu3050->map, MPU3050_INT_STATUS, &val);
+		if (ret)
+			dev_err(mpu3050->dev, "error clearing IRQ status\n");
+
+		/* Disable all things in the FIFO and reset it */
+		ret = regmap_write(mpu3050->map, MPU3050_FIFO_EN, 0);
+		if (ret)
+			dev_err(mpu3050->dev, "error disabling FIFO\n");
+
+		ret = regmap_write(mpu3050->map, MPU3050_USR_CTRL,
+				   MPU3050_USR_CTRL_FIFO_RST);
+		if (ret)
+			dev_err(mpu3050->dev, "error resetting FIFO\n");
+
+		pm_runtime_mark_last_busy(mpu3050->dev);
+		pm_runtime_put_autosuspend(mpu3050->dev);
+		mpu3050->hw_irq_trigger = false;
+
+		return 0;
+	} else {
+		/* Else we're enabling the trigger from this point */
+		pm_runtime_get_sync(mpu3050->dev);
+		mpu3050->hw_irq_trigger = true;
+
+		/* Disable all things in the FIFO */
+		ret = regmap_write(mpu3050->map, MPU3050_FIFO_EN, 0);
+		if (ret)
+			return ret;
+
+		/* Reset and enable the FIFO */
+		ret = regmap_update_bits(mpu3050->map, MPU3050_USR_CTRL,
+					 MPU3050_USR_CTRL_FIFO_EN |
+					 MPU3050_USR_CTRL_FIFO_RST,
+					 MPU3050_USR_CTRL_FIFO_EN |
+					 MPU3050_USR_CTRL_FIFO_RST);
+		if (ret)
+			return ret;
+
+		mpu3050->pending_fifo_footer = false;
+
+		/* Turn on the FIFO for temp+X+Y+Z */
+		ret = regmap_write(mpu3050->map, MPU3050_FIFO_EN,
+				   MPU3050_FIFO_EN_TEMP_OUT |
+				   MPU3050_FIFO_EN_GYRO_XOUT |
+				   MPU3050_FIFO_EN_GYRO_YOUT |
+				   MPU3050_FIFO_EN_GYRO_ZOUT |
+				   MPU3050_FIFO_EN_FOOTER);
+		if (ret)
+			return ret;
+
+		/* Configure the sample engine */
+		ret = mpu3050_start_sampling(mpu3050);
+		if (ret)
+			return ret;
+
+		/* Clear IRQ flag */
+		ret = regmap_read(mpu3050->map, MPU3050_INT_STATUS, &val);
+		if (ret)
+			dev_err(mpu3050->dev, "error clearing IRQ status\n");
+
+		/* Give us interrupts whenever there is new data ready */
+		val = MPU3050_INT_RAW_RDY_EN;
+
+		if (mpu3050->irq_actl)
+			val |= MPU3050_INT_ACTL;
+		if (mpu3050->irq_latch)
+			val |= MPU3050_INT_LATCH_EN;
+		if (mpu3050->irq_opendrain)
+			val |= MPU3050_INT_OPEN;
+
+		ret = regmap_write(mpu3050->map, MPU3050_INT_CFG, val);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct iio_trigger_ops mpu3050_trigger_ops = {
+	.owner = THIS_MODULE,
+	.set_trigger_state = mpu3050_drdy_trigger_set_state,
+};
+
+static int mpu3050_trigger_probe(struct iio_dev *indio_dev, int irq)
+{
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+	unsigned long irq_trig;
+	int ret;
+
+	mpu3050->trig = devm_iio_trigger_alloc(&indio_dev->dev,
+					       "%s-dev%d",
+					       indio_dev->name,
+					       indio_dev->id);
+	if (!mpu3050->trig)
+		return -ENOMEM;
+
+	/* Check if IRQ is open drain */
+	if (of_property_read_bool(mpu3050->dev->of_node, "drive-open-drain"))
+		mpu3050->irq_opendrain = true;
+
+	irq_trig = irqd_get_trigger_type(irq_get_irq_data(irq));
+	/*
+	 * Configure the interrupt generator hardware to supply whatever
+	 * the interrupt is configured for, edges low/high level low/high,
+	 * we can provide it all.
+	 */
+	switch (irq_trig) {
+	case IRQF_TRIGGER_RISING:
+		dev_info(&indio_dev->dev,
+			 "pulse interrupts on the rising edge\n");
+		if (mpu3050->irq_opendrain) {
+			dev_info(&indio_dev->dev,
+				 "rising edge incompatible with open drain\n");
+			mpu3050->irq_opendrain = false;
+		}
+		break;
+	case IRQF_TRIGGER_FALLING:
+		mpu3050->irq_actl = true;
+		dev_info(&indio_dev->dev,
+			 "pulse interrupts on the falling edge\n");
+		break;
+	case IRQF_TRIGGER_HIGH:
+		mpu3050->irq_latch = true;
+		dev_info(&indio_dev->dev,
+			 "interrupts active high level\n");
+		if (mpu3050->irq_opendrain) {
+			dev_info(&indio_dev->dev,
+				 "active high incompatible with open drain\n");
+			mpu3050->irq_opendrain = false;
+		}
+		/*
+		 * With level IRQs, we mask the IRQ until it is processed,
+		 * but with edge IRQs (pulses) we can queue several interrupts
+		 * in the top half.
+		 */
+		irq_trig |= IRQF_ONESHOT;
+		break;
+	case IRQF_TRIGGER_LOW:
+		mpu3050->irq_latch = true;
+		mpu3050->irq_actl = true;
+		irq_trig |= IRQF_ONESHOT;
+		dev_info(&indio_dev->dev,
+			 "interrupts active low level\n");
+		break;
+	default:
+		/* This is the most preferred mode, if possible */
+		dev_err(&indio_dev->dev,
+			"unsupported IRQ trigger specified (%lx), enforce "
+			"rising edge\n", irq_trig);
+		irq_trig = IRQF_TRIGGER_RISING;
+		break;
+	}
+
+	/* An open drain line can be shared with several devices */
+	if (mpu3050->irq_opendrain)
+		irq_trig |= IRQF_SHARED;
+
+	ret = request_threaded_irq(irq,
+				   mpu3050_irq_handler,
+				   mpu3050_irq_thread,
+				   irq_trig,
+				   mpu3050->trig->name,
+				   mpu3050->trig);
+	if (ret) {
+		dev_err(mpu3050->dev,
+			"can't get IRQ %d, error %d\n", irq, ret);
+		return ret;
+	}
+
+	mpu3050->irq = irq;
+	mpu3050->trig->dev.parent = mpu3050->dev;
+	mpu3050->trig->ops = &mpu3050_trigger_ops;
+	iio_trigger_set_drvdata(mpu3050->trig, indio_dev);
+
+	ret = iio_trigger_register(mpu3050->trig);
+	if (ret)
+		return ret;
+
+	indio_dev->trig = iio_trigger_get(mpu3050->trig);
+
+	return 0;
+}
+
+int mpu3050_common_probe(struct device *dev,
+			 struct regmap *map,
+			 int irq,
+			 const char *name)
+{
+	struct iio_dev *indio_dev;
+	struct mpu3050 *mpu3050;
+	unsigned int val;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*mpu3050));
+	if (!indio_dev)
+		return -ENOMEM;
+	mpu3050 = iio_priv(indio_dev);
+
+	mpu3050->dev = dev;
+	mpu3050->map = map;
+	mutex_init(&mpu3050->lock);
+	/* Default fullscale: 2000 degrees per second */
+	mpu3050->fullscale = FS_2000_DPS;
+	/* 1 kHz, divide by 100, default frequency = 10 Hz */
+	mpu3050->lpf = MPU3050_DLPF_CFG_188HZ;
+	mpu3050->divisor = 99;
+
+	/* Read the mounting matrix, if present */
+	ret = of_iio_read_mount_matrix(dev, "mount-matrix",
+				       &mpu3050->orientation);
+	if (ret)
+		return ret;
+
+	/* Fetch and turn on regulators */
+	mpu3050->regs[0].supply = mpu3050_reg_vdd;
+	mpu3050->regs[1].supply = mpu3050_reg_vlogic;
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(mpu3050->regs),
+				      mpu3050->regs);
+	if (ret) {
+		dev_err(dev, "Cannot get regulators\n");
+		return ret;
+	}
+
+	ret = mpu3050_power_up(mpu3050);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(map, MPU3050_CHIP_ID_REG, &val);
+	if (ret) {
+		dev_err(dev, "could not read device ID\n");
+		ret = -ENODEV;
+
+		goto err_power_down;
+	}
+
+	if (val != MPU3050_CHIP_ID) {
+		dev_err(dev, "unsupported chip id %02x\n", (u8)val);
+		ret = -ENODEV;
+		goto err_power_down;
+	}
+
+	ret = regmap_read(map, MPU3050_PRODUCT_ID_REG, &val);
+	if (ret) {
+		dev_err(dev, "could not read device ID\n");
+		ret = -ENODEV;
+
+		goto err_power_down;
+	}
+	dev_info(dev, "found MPU-3050 part no: %d, version: %d\n",
+		 ((val >> 4) & 0xf), (val & 0xf));
+
+	ret = mpu3050_hw_init(mpu3050);
+	if (ret)
+		goto err_power_down;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->channels = mpu3050_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mpu3050_channels);
+	indio_dev->info = &mpu3050_info;
+	indio_dev->available_scan_masks = mpu3050_scan_masks;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->name = name;
+
+	ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
+					 mpu3050_trigger_handler,
+					 &mpu3050_buffer_setup_ops);
+	if (ret) {
+		dev_err(dev, "triggered buffer setup failed\n");
+		goto err_power_down;
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "device register failed\n");
+		goto err_cleanup_buffer;
+	}
+
+	dev_set_drvdata(dev, indio_dev);
+
+	/* Check if we have an assigned IRQ to use as trigger */
+	if (irq) {
+		ret = mpu3050_trigger_probe(indio_dev, irq);
+		if (ret)
+			dev_err(dev, "failed to register trigger\n");
+	}
+
+	/* Enable runtime PM */
+	pm_runtime_get_noresume(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	/*
+	 * Set autosuspend to two orders of magnitude larger than the
+	 * start-up time. 100ms start-up time means 10000ms autosuspend,
+	 * i.e. 10 seconds.
+	 */
+	pm_runtime_set_autosuspend_delay(dev, 10000);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_put(dev);
+
+	return 0;
+
+err_cleanup_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+err_power_down:
+	mpu3050_power_down(mpu3050);
+
+	return ret;
+}
+EXPORT_SYMBOL(mpu3050_common_probe);
+
+int mpu3050_common_remove(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+
+	pm_runtime_get_sync(dev);
+	pm_runtime_put_noidle(dev);
+	pm_runtime_disable(dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	if (mpu3050->irq)
+		free_irq(mpu3050->irq, mpu3050);
+	iio_device_unregister(indio_dev);
+	mpu3050_power_down(mpu3050);
+
+	return 0;
+}
+EXPORT_SYMBOL(mpu3050_common_remove);
+
+#ifdef CONFIG_PM
+static int mpu3050_runtime_suspend(struct device *dev)
+{
+	return mpu3050_power_down(iio_priv(dev_get_drvdata(dev)));
+}
+
+static int mpu3050_runtime_resume(struct device *dev)
+{
+	return mpu3050_power_up(iio_priv(dev_get_drvdata(dev)));
+}
+#endif /* CONFIG_PM */
+
+const struct dev_pm_ops mpu3050_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(mpu3050_runtime_suspend,
+			   mpu3050_runtime_resume, NULL)
+};
+EXPORT_SYMBOL(mpu3050_dev_pm_ops);
+
+MODULE_AUTHOR("Linus Walleij");
+MODULE_DESCRIPTION("MPU3050 gyroscope driver");
+MODULE_LICENSE("GPL");

drivers/iio/gyro/mpu3050-i2c.c

+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/pm_runtime.h>
+
+#include "mpu3050.h"
+
+static const struct regmap_config mpu3050_i2c_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int mpu3050_i2c_bypass_select(struct i2c_mux_core *mux, u32 chan_id)
+{
+	struct mpu3050 *mpu3050 = i2c_mux_priv(mux);
+
+	/* Just power up the device, that is all that is needed */
+	pm_runtime_get_sync(mpu3050->dev);
+	return 0;
+}
+
+static int mpu3050_i2c_bypass_deselect(struct i2c_mux_core *mux, u32 chan_id)
+{
+	struct mpu3050 *mpu3050 = i2c_mux_priv(mux);
+
+	pm_runtime_mark_last_busy(mpu3050->dev);
+	pm_runtime_put_autosuspend(mpu3050->dev);
+	return 0;
+}
+
+static int mpu3050_i2c_probe(struct i2c_client *client,
+			     const struct i2c_device_id *id)
+{
+	struct regmap *regmap;
+	const char *name;
+	struct mpu3050 *mpu3050;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_I2C_BLOCK))
+		return -EOPNOTSUPP;
+
+	if (id)
+		name = id->name;
+	else
+		return -ENODEV;
+
+	regmap = devm_regmap_init_i2c(client, &mpu3050_i2c_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "Failed to register i2c regmap %d\n",
+			(int)PTR_ERR(regmap));
+		return PTR_ERR(regmap);
+	}
+
+	ret = mpu3050_common_probe(&client->dev, regmap, client->irq, name);
+	if (ret)
+		return ret;
+
+	/* The main driver is up, now register the I2C mux */
+	mpu3050 = iio_priv(dev_get_drvdata(&client->dev));
+	mpu3050->i2cmux = i2c_mux_alloc(client->adapter, &client->dev,
+					1, 0, I2C_MUX_LOCKED | I2C_MUX_GATE,
+					mpu3050_i2c_bypass_select,
+					mpu3050_i2c_bypass_deselect);
+	/* Just fail the mux, there is no point in killing the driver */
+	if (!mpu3050->i2cmux)
+		dev_err(&client->dev, "failed to allocate I2C mux\n");
+	else {
+		mpu3050->i2cmux->priv = mpu3050;
+		ret = i2c_mux_add_adapter(mpu3050->i2cmux, 0, 0, 0);
+		if (ret)
+			dev_err(&client->dev, "failed to add I2C mux\n");
+	}
+
+	return 0;
+}
+
+static int mpu3050_i2c_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(&client->dev);
+	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
+
+	if (mpu3050->i2cmux)
+		i2c_mux_del_adapters(mpu3050->i2cmux);
+
+	return mpu3050_common_remove(&client->dev);
+}
+
+/*
+ * device id table is used to identify what device can be
+ * supported by this driver
+ */
+static const struct i2c_device_id mpu3050_i2c_id[] = {
+	{ "mpu3050" },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, mpu3050_i2c_id);
+
+static const struct of_device_id mpu3050_i2c_of_match[] = {
+	{ .compatible = "invensense,mpu3050", .data = "mpu3050" },
+	/* Deprecated vendor ID from the Input driver */
+	{ .compatible = "invn,mpu3050", .data = "mpu3050" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mpu3050_i2c_of_match);
+
+static struct i2c_driver mpu3050_i2c_driver = {
+	.probe = mpu3050_i2c_probe,
+	.remove = mpu3050_i2c_remove,
+	.id_table = mpu3050_i2c_id,
+	.driver = {
+		.of_match_table = mpu3050_i2c_of_match,
+		.name = "mpu3050-i2c",
+		.pm = &mpu3050_dev_pm_ops,
+	},
+};
+module_i2c_driver(mpu3050_i2c_driver);
+
+MODULE_AUTHOR("Linus Walleij");
+MODULE_DESCRIPTION("Invensense MPU3050 gyroscope driver");
+MODULE_LICENSE("GPL");

drivers/iio/gyro/mpu3050.h

+#include <linux/iio/iio.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/i2c.h>
+
+/**
+ * enum mpu3050_fullscale - indicates the full range of the sensor in deg/sec
+ */
+enum mpu3050_fullscale {
+	FS_250_DPS = 0,
+	FS_500_DPS,
+	FS_1000_DPS,
+	FS_2000_DPS,
+};
+
+/**
+ * enum mpu3050_lpf - indicates the low pass filter width
+ */
+enum mpu3050_lpf {
+	/* This implicity sets sample frequency to 8 kHz */
+	LPF_256_HZ_NOLPF = 0,
+	/* All others sets the sample frequency to 1 kHz */
+	LPF_188_HZ,
+	LPF_98_HZ,
+	LPF_42_HZ,
+	LPF_20_HZ,
+	LPF_10_HZ,
+	LPF_5_HZ,
+	LPF_2100_HZ_NOLPF,
+};
+
+enum mpu3050_axis {
+	AXIS_X = 0,
+	AXIS_Y,
+	AXIS_Z,
+	AXIS_MAX,
+};
+
+/**
+ * struct mpu3050 - instance state container for the device
+ * @dev: parent device for this instance
+ * @orientation: mounting matrix, flipped axis etc
+ * @map: regmap to reach the registers
+ * @lock: serialization lock to marshal all requests
+ * @irq: the IRQ used for this device
+ * @regs: the regulators to power this device
+ * @fullscale: the current fullscale setting for the device
+ * @lpf: digital low pass filter setting for the device
+ * @divisor: base frequency divider: divides 8 or 1 kHz
+ * @calibration: the three signed 16-bit calibration settings that
+ * get written into the offset registers for each axis to compensate
+ * for DC offsets
+ * @trig: trigger for the MPU-3050 interrupt, if present
+ * @hw_irq_trigger: hardware interrupt trigger is in use
+ * @irq_actl: interrupt is active low
+ * @irq_latch: latched IRQ, this means that it is a level IRQ
+ * @irq_opendrain: the interrupt line shall be configured open drain
+ * @pending_fifo_footer: tells us if there is a pending footer in the FIFO
+ * that we have to read out first when handling the FIFO
+ * @hw_timestamp: latest hardware timestamp from the trigger IRQ, when in
+ * use
+ * @i2cmux: an I2C mux reflecting the fact that this sensor is a hub with
+ * a pass-through I2C interface coming out of it: this device needs to be
+ * powered up in order to reach devices on the other side of this mux
+ */
+struct mpu3050 {
+	struct device *dev;
+	struct iio_mount_matrix orientation;
+	struct regmap *map;
+	struct mutex lock;
+	int irq;
+	struct regulator_bulk_data regs[2];
+	enum mpu3050_fullscale fullscale;
+	enum mpu3050_lpf lpf;
+	u8 divisor;
+	s16 calibration[3];
+	struct iio_trigger *trig;
+	bool hw_irq_trigger;
+	bool irq_actl;
+	bool irq_latch;
+	bool irq_opendrain;
+	bool pending_fifo_footer;
+	s64 hw_timestamp;
+	struct i2c_mux_core *i2cmux;
+};
+
+/* Probe called from different transports */
+int mpu3050_common_probe(struct device *dev,
+			 struct regmap *map,
+			 int irq,
+			 const char *name);
+int mpu3050_common_remove(struct device *dev);
+
+/* PM ops */
+extern const struct dev_pm_ops mpu3050_dev_pm_ops;