iio: accel: add Freescale MMA7455L/MMA7456L 3-axis accelerometer driver

Add support for Freescale MMA7455L/MMA7456L 3-axis in 10-bit mode for
I2C and SPI bus. This rather simple driver that currently doesn't
support all the hardware features of MMA7455L/MMA7456L.

Tested on Embedded Artist's LPC4357 Dev Kit with MMA7455L on I2C bus.

Data sheets for the two devices can be found here:
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA7455L.pdf
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA7456L.pdf

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/Kconfig

@@ -107,6 +107,35 @@ config KXCJK1013
 	  To compile this driver as a module, choose M here: the module will
 	  be called kxcjk-1013.
 
+config MMA7455
+	tristate
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+
+config MMA7455_I2C
+	tristate "Freescale MMA7455L/MMA7456L Accelerometer I2C Driver"
+	depends on I2C
+	select MMA7455
+	select REGMAP_I2C
+	help
+	  Say yes here to build support for the Freescale MMA7455L and
+	  MMA7456L 3-axis accelerometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mma7455_i2c.
+
+config MMA7455_SPI
+	tristate "Freescale MMA7455L/MMA7456L Accelerometer SPI Driver"
+	depends on SPI_MASTER
+	select MMA7455
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for the Freescale MMA7455L and
+	  MMA7456L 3-axis accelerometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mma7455_spi.
+
 config MMA8452
 	tristate "Freescale MMA8452Q and similar Accelerometers Driver"
 	depends on I2C

drivers/iio/accel/Makefile

@@ -10,6 +10,11 @@ obj-$(CONFIG_BMC150_ACCEL_SPI) += bmc150-accel-spi.o
 obj-$(CONFIG_HID_SENSOR_ACCEL_3D) += hid-sensor-accel-3d.o
 obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
 obj-$(CONFIG_KXSD9)	+= kxsd9.o
+
+obj-$(CONFIG_MMA7455)		+= mma7455_core.o
+obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o
+obj-$(CONFIG_MMA7455_SPI)	+= mma7455_spi.o
+
 obj-$(CONFIG_MMA8452)	+= mma8452.o
 
 obj-$(CONFIG_MMA9551_CORE)	+= mma9551_core.o

drivers/iio/accel/mma7455.h

@@ -0,0 +1,19 @@
+/*
+ * IIO accel driver for Freescale MMA7455L 3-axis 10-bit accelerometer
+ * Copyright 2015 Joachim Eastwood <manabian@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MMA7455_H
+#define __MMA7455_H
+
+extern const struct regmap_config mma7455_core_regmap;
+
+int mma7455_core_probe(struct device *dev, struct regmap *regmap,
+		       const char *name);
+int mma7455_core_remove(struct device *dev);
+
+#endif

drivers/iio/accel/mma7455_core.c

@@ -0,0 +1,311 @@
+/*
+ * IIO accel core driver for Freescale MMA7455L 3-axis 10-bit accelerometer
+ * Copyright 2015 Joachim Eastwood <manabian@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * UNSUPPORTED hardware features:
+ *  - 8-bit mode with different scales
+ *  - INT1/INT2 interrupts
+ *  - Offset calibration
+ *  - Events
+ */
+
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "mma7455.h"
+
+#define MMA7455_REG_XOUTL		0x00
+#define MMA7455_REG_XOUTH		0x01
+#define MMA7455_REG_YOUTL		0x02
+#define MMA7455_REG_YOUTH		0x03
+#define MMA7455_REG_ZOUTL		0x04
+#define MMA7455_REG_ZOUTH		0x05
+#define MMA7455_REG_STATUS		0x09
+#define  MMA7455_STATUS_DRDY		BIT(0)
+#define MMA7455_REG_WHOAMI		0x0f
+#define  MMA7455_WHOAMI_ID		0x55
+#define MMA7455_REG_MCTL		0x16
+#define  MMA7455_MCTL_MODE_STANDBY	0x00
+#define  MMA7455_MCTL_MODE_MEASURE	0x01
+#define MMA7455_REG_CTL1		0x18
+#define  MMA7455_CTL1_DFBW_MASK		BIT(7)
+#define  MMA7455_CTL1_DFBW_125HZ	BIT(7)
+#define  MMA7455_CTL1_DFBW_62_5HZ	0
+#define MMA7455_REG_TW			0x1e
+
+/*
+ * When MMA7455 is used in 10-bit it has a fullscale of -8g
+ * corresponding to raw value -512. The userspace interface
+ * uses m/s^2 and we declare micro units.
+ * So scale factor is given by:
+ *       g * 8 * 1e6 / 512 = 153228.90625, with g = 9.80665
+ */
+#define MMA7455_10BIT_SCALE	153229
+
+struct mma7455_data {
+	struct regmap *regmap;
+	struct device *dev;
+};
+
+static int mma7455_drdy(struct mma7455_data *mma7455)
+{
+	unsigned int reg;
+	int tries = 3;
+	int ret;
+
+	while (tries-- > 0) {
+		ret = regmap_read(mma7455->regmap, MMA7455_REG_STATUS, &reg);
+		if (ret)
+			return ret;
+
+		if (reg & MMA7455_STATUS_DRDY)
+			return 0;
+
+		msleep(20);
+	}
+
+	dev_warn(mma7455->dev, "data not ready\n");
+
+	return -EIO;
+}
+
+static irqreturn_t mma7455_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct mma7455_data *mma7455 = iio_priv(indio_dev);
+	u8 buf[16]; /* 3 x 16-bit channels + padding + ts */
+	int ret;
+
+	ret = mma7455_drdy(mma7455);
+	if (ret)
+		goto done;
+
+	ret = regmap_bulk_read(mma7455->regmap, MMA7455_REG_XOUTL, buf,
+			       sizeof(__le16) * 3);
+	if (ret)
+		goto done;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, buf, iio_get_time_ns());
+
+done:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int mma7455_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct mma7455_data *mma7455 = iio_priv(indio_dev);
+	unsigned int reg;
+	__le16 data;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev))
+			return -EBUSY;
+
+		ret = mma7455_drdy(mma7455);
+		if (ret)
+			return ret;
+
+		ret = regmap_bulk_read(mma7455->regmap, chan->address, &data,
+				       sizeof(data));
+		if (ret)
+			return ret;
+
+		*val = sign_extend32(le16_to_cpu(data), 9);
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = MMA7455_10BIT_SCALE;
+
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = regmap_read(mma7455->regmap, MMA7455_REG_CTL1, &reg);
+		if (ret)
+			return ret;
+
+		if (reg & MMA7455_CTL1_DFBW_MASK)
+			*val = 250;
+		else
+			*val = 125;
+
+		return IIO_VAL_INT;
+	}
+
+	return -EINVAL;
+}
+
+static int mma7455_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct mma7455_data *mma7455 = iio_priv(indio_dev);
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		if (val == 250 && val2 == 0)
+			i = MMA7455_CTL1_DFBW_125HZ;
+		else if (val == 125 && val2 == 0)
+			i = MMA7455_CTL1_DFBW_62_5HZ;
+		else
+			return -EINVAL;
+
+		return regmap_update_bits(mma7455->regmap, MMA7455_REG_CTL1,
+					  MMA7455_CTL1_DFBW_MASK, i);
+
+	case IIO_CHAN_INFO_SCALE:
+		/* In 10-bit mode there is only one scale available */
+		if (val == 0 && val2 == MMA7455_10BIT_SCALE)
+			return 0;
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static IIO_CONST_ATTR(sampling_frequency_available, "125 250");
+
+static struct attribute *mma7455_attributes[] = {
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group mma7455_group = {
+	.attrs = mma7455_attributes,
+};
+
+static const struct iio_info mma7455_info = {
+	.attrs = &mma7455_group,
+	.read_raw = mma7455_read_raw,
+	.write_raw = mma7455_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+#define MMA7455_CHANNEL(axis, idx) { \
+	.type = IIO_ACCEL, \
+	.modified = 1, \
+	.address = MMA7455_REG_##axis##OUTL,\
+	.channel2 = IIO_MOD_##axis, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+				    BIT(IIO_CHAN_INFO_SCALE), \
+	.scan_index = idx, \
+	.scan_type = { \
+		.sign = 's', \
+		.realbits = 10, \
+		.storagebits = 16, \
+		.endianness = IIO_LE, \
+	}, \
+}
+
+static const struct iio_chan_spec mma7455_channels[] = {
+	MMA7455_CHANNEL(X, 0),
+	MMA7455_CHANNEL(Y, 1),
+	MMA7455_CHANNEL(Z, 2),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+static const unsigned long mma7455_scan_masks[] = {0x7, 0};
+
+const struct regmap_config mma7455_core_regmap = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MMA7455_REG_TW,
+};
+EXPORT_SYMBOL_GPL(mma7455_core_regmap);
+
+int mma7455_core_probe(struct device *dev, struct regmap *regmap,
+		       const char *name)
+{
+	struct mma7455_data *mma7455;
+	struct iio_dev *indio_dev;
+	unsigned int reg;
+	int ret;
+
+	ret = regmap_read(regmap, MMA7455_REG_WHOAMI, &reg);
+	if (ret) {
+		dev_err(dev, "unable to read reg\n");
+		return ret;
+	}
+
+	if (reg != MMA7455_WHOAMI_ID) {
+		dev_err(dev, "device id mismatch\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*mma7455));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, indio_dev);
+	mma7455 = iio_priv(indio_dev);
+	mma7455->regmap = regmap;
+	mma7455->dev = dev;
+
+	indio_dev->info = &mma7455_info;
+	indio_dev->name = name;
+	indio_dev->dev.parent = dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mma7455_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mma7455_channels);
+	indio_dev->available_scan_masks = mma7455_scan_masks;
+
+	regmap_write(mma7455->regmap, MMA7455_REG_MCTL,
+		     MMA7455_MCTL_MODE_MEASURE);
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 mma7455_trigger_handler, NULL);
+	if (ret) {
+		dev_err(dev, "unable to setup triggered buffer\n");
+		return ret;
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "unable to register device\n");
+		iio_triggered_buffer_cleanup(indio_dev);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mma7455_core_probe);
+
+int mma7455_core_remove(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct mma7455_data *mma7455 = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	regmap_write(mma7455->regmap, MMA7455_REG_MCTL,
+		     MMA7455_MCTL_MODE_STANDBY);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mma7455_core_remove);
+
+MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
+MODULE_DESCRIPTION("Freescale MMA7455L core accelerometer driver");
+MODULE_LICENSE("GPL v2");