[PATCH v2 1/3] iio: magnetometer: Add support for MEMSIC MMC35240 sensor

From: Daniel Baluta
Date: Fri Apr 24 2015 - 12:12:38 EST

Minimal implementation for MMC35240 3-axis magnetometer
sensor. It provides processed readings and possiblity to change
the sampling frequency.

Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx>
---
drivers/iio/magnetometer/Kconfig | 11 +
drivers/iio/magnetometer/Makefile | 1 +
drivers/iio/magnetometer/mmc35240.c | 468 ++++++++++++++++++++++++++++++++++++
3 files changed, 480 insertions(+)
create mode 100644 drivers/iio/magnetometer/mmc35240.c

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index a5d6de7..7aba685 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -47,6 +47,17 @@ config HID_SENSOR_MAGNETOMETER_3D
Say yes here to build support for the HID SENSOR
Magnetometer 3D.

+config MMC35240
+ tristate "MEMSIC MMC35240 3-axis magnetic sensor"
+ select REGMAP_I2C
+ depends on I2C
+ help
+ Say yes here to build support for the MEMSIC MMC35240 3-axis
+ magnetic sensor.
+
+ To compile this driver as a module, choose M here: the module
+ will be called mmc35240.
+
config IIO_ST_MAGN_3AXIS
tristate "STMicroelectronics magnetometers 3-Axis Driver"
depends on (I2C || SPI_MASTER) && SYSFS
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index 0f5d3c9..696a429 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -6,6 +6,7 @@
obj-$(CONFIG_AK8975) += ak8975.o
obj-$(CONFIG_MAG3110) += mag3110.o
obj-$(CONFIG_HID_SENSOR_MAGNETOMETER_3D) += hid-sensor-magn-3d.o
+obj-$(CONFIG_MMC35240) += mmc35240.o

obj-$(CONFIG_IIO_ST_MAGN_3AXIS) += st_magn.o
st_magn-y := st_magn_core.o
diff --git a/drivers/iio/magnetometer/mmc35240.c b/drivers/iio/magnetometer/mmc35240.c
new file mode 100644
index 0000000..beefebc
--- /dev/null
+++ b/drivers/iio/magnetometer/mmc35240.c
@@ -0,0 +1,468 @@
+/*
+ * MMC35240 - MEMSIC 3-axis Magnetic Sensor
+ *
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License. See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
+ *
+ * TODO: offset, ACPI, continuous measurement mode, PM
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MMC35240_DRV_NAME "mmc35240"
+#define MMC35240_REGMAP_NAME "mmc35240_regmap"
+
+#define MMC35240_REG_XOUT_L 0x00
+#define MMC35240_REG_XOUT_H 0x01
+#define MMC35240_REG_YOUT_L 0x02
+#define MMC35240_REG_YOUT_H 0x03
+#define MMC35240_REG_ZOUT_L 0x04
+#define MMC35240_REG_ZOUT_H 0x05
+
+#define MMC35240_REG_STATUS 0x06
+#define MMC35240_REG_CTRL0 0x07
+#define MMC35240_REG_CTRL1 0x08
+
+#define MMC35240_REG_ID 0x20
+
+#define MMC35240_STATUS_MEAS_DONE_BIT BIT(0)
+
+#define MMC35240_CTRL0_REFILL_BIT BIT(7)
+#define MMC35240_CTRL0_RESET_BIT BIT(6)
+#define MMC35240_CTRL0_SET_BIT BIT(5)
+#define MMC35240_CTRL0_CMM_BIT BIT(1)
+#define MMC35240_CTRL0_TM_BIT BIT(0)
+
+/* output resolution bits */
+#define MMC35240_CTRL1_BW0_BIT BIT(0)
+#define MMC35240_CTRL1_BW1_BIT BIT(1)
+
+#define MMC35240_CTRL1_BW_MASK (MMC35240_CTRL1_BW0_BIT | \
+ MMC35240_CTRL1_BW1_BIT)
+#define MMC35240_CTRL1_BW_SHIFT 0
+
+#define MMC35240_WAIT_CHARGE_PUMP 50000 /* us */
+#define MMC53240_WAIT_SET_RESET 1000 /* us */
+
+enum mmc35240_resolution {
+ MMC35240_16_BITS_SLOW = 0, /* 100 Hz */
+ MMC35240_16_BITS_FAST, /* 200 Hz */
+ MMC35240_14_BITS, /* 333 Hz */
+ MMC35240_12_BITS, /* 666 Hz */
+};
+
+enum mmc35240_axis {
+ AXIS_X = 0,
+ AXIS_Y,
+ AXIS_Z,
+};
+
+static const struct {
+ int sens[3]; /* sensitivity per X, Y, Z axis */
+ int nfo; /* null field output */
+} mmc35240_props_table[] = {
+ /* 16 bits, 100Hz ODR */
+ {
+ {1024, 1024, 770},
+ 32768,
+ },
+ /* 16 bits, 200Hz ODR */
+ {
+ {1024, 1024, 770},
+ 32768,
+ },
+ /* 14 bits, 333Hz ODR */
+ {
+ {256, 256, 193},
+ 8192,
+ },
+ /* 12 bits, 666Hz ODR */
+ {
+ {64, 64, 48},
+ 2048,
+ },
+};
+
+struct mmc35240_data {
+ struct i2c_client *client;
+ struct mutex mutex;
+ struct regmap *regmap;
+ enum mmc35240_resolution res;
+};
+
+int mmc35240_samp_freq[] = {100, 200, 333, 666};
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("100 200 333 666");
+
+#define MMC35240_CHANNEL(_axis) { \
+ .type = IIO_MAGN, \
+ .modified = 1, \
+ .channel2 = IIO_MOD_ ## _axis, \
+ .address = AXIS_ ## _axis, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+}
+
+static const struct iio_chan_spec mmc35240_channels[] = {
+ MMC35240_CHANNEL(X),
+ MMC35240_CHANNEL(Y),
+ MMC35240_CHANNEL(Z),
+};
+
+static struct attribute *mmc35240_attributes[] = {
+ &iio_const_attr_sampling_frequency_available.dev_attr.attr,
+};
+
+static const struct attribute_group mmc35240_attribute_group = {
+ .attrs = mmc35240_attributes,
+};
+
+static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
+ int val, int val2)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
+ if (mmc35240_samp_freq[i] == val)
+ return i;
+ return -EINVAL;
+}
+
+static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
+{
+ int ret;
+ u8 coil_bit;
+
+ /*
+ * Recharge the capacitor at VCAP pin, requested to be issued
+ * before a SET/RESET command.
+ */
+ ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
+ MMC35240_CTRL0_REFILL_BIT,
+ MMC35240_CTRL0_REFILL_BIT);
+ if (ret < 0)
+ return ret;
+ usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
+
+ if (set)
+ coil_bit = MMC35240_CTRL0_SET_BIT;
+ else
+ coil_bit = MMC35240_CTRL0_RESET_BIT;
+
+ return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
+ MMC35240_CTRL0_REFILL_BIT,
+ coil_bit);
+}
+
+static int mmc35240_init(struct mmc35240_data *data)
+{
+ int ret;
+ unsigned int reg_id;
+
+ ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading product id\n");
+ return ret;
+ }
+
+ dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
+
+ /*
+ * make sure we restore sensor characteristics, by doing
+ * a RESET/SET sequence
+ */
+ ret = mmc35240_hw_set(data, false);
+ if (ret < 0)
+ return ret;
+ usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);
+
+ ret = mmc35240_hw_set(data, true);
+ if (ret < 0)
+ return ret;
+
+ /* set default sampling frequency */
+ return regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
+ MMC35240_CTRL1_BW_MASK,
+ data->res << MMC35240_CTRL1_BW_SHIFT);
+}
+
+static int mmc35240_take_measurement(struct mmc35240_data *data)
+{
+ int ret, tries = 100;
+ unsigned int reg_status;
+
+ ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
+ MMC35240_CTRL0_TM_BIT);
+ if (ret < 0)
+ return ret;
+
+ while (tries-- > 0) {
+ ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
+ &reg_status);
+ if (ret < 0)
+ return ret;
+ if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
+ break;
+ msleep(20);
+ }
+
+ if (tries < 0) {
+ dev_err(&data->client->dev, "data not ready\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
+{
+ int ret;
+
+ ret = mmc35240_take_measurement(data);
+ if (ret < 0)
+ return ret;
+
+ return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
+ 3 * sizeof(__le16));
+}
+
+int mmc35240_raw_to_gauss(struct mmc35240_data *data, int index, __le16 buf[],
+ int *val, int *val2)
+{
+ int raw_x, raw_y, raw_z;
+ int sens_x, sens_y, sens_z;
+ int nfo;
+
+ raw_x = le16_to_cpu(buf[AXIS_X]);
+ raw_y = le16_to_cpu(buf[AXIS_Y]);
+ raw_z = le16_to_cpu(buf[AXIS_Z]);
+
+ sens_x = mmc35240_props_table[data->res].sens[AXIS_X];
+ sens_y = mmc35240_props_table[data->res].sens[AXIS_Y];
+ sens_z = mmc35240_props_table[data->res].sens[AXIS_Z];
+
+ nfo = mmc35240_props_table[data->res].nfo;
+
+ switch (index) {
+ case AXIS_X:
+ *val = (raw_x - nfo) / sens_x;
+ *val2 = ((raw_x - nfo) % sens_x) * 1000000;
+ break;
+ case AXIS_Y:
+ *val = (raw_y - nfo) / sens_y - (raw_z - nfo) / sens_z;
+ *val2 = (((raw_y - nfo) % sens_y - (raw_z - nfo) % sens_z))
+ * 1000000;
+ break;
+ case AXIS_Z:
+ *val = (raw_y - nfo) / sens_y + (raw_z - nfo) / sens_z;
+ *val2 = (((raw_y - nfo) % sens_y + (raw_z - nfo) % sens_z))
+ * 1000000;
+ break;
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int mmc35240_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long mask)
+{
+ struct mmc35240_data *data = iio_priv(indio_dev);
+ int ret, i;
+ unsigned int reg;
+ __le16 buf[3];
+
+ switch (mask) {
+ case IIO_CHAN_INFO_PROCESSED:
+ mutex_lock(&data->mutex);
+ ret = mmc35240_read_measurement(data, buf);
+ mutex_unlock(&data->mutex);
+ if (ret < 0)
+ return ret;
+ ret = mmc35240_raw_to_gauss(data, chan->address,
+ buf, val, val2);
+ if (ret < 0)
+ return ret;
+ return IIO_VAL_INT_PLUS_MICRO;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ mutex_lock(&data->mutex);
+ ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
+ mutex_unlock(&data->mutex);
+ if (ret < 0)
+ return ret;
+
+ i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
+ if (i < 0 || i > ARRAY_SIZE(mmc35240_samp_freq))
+ return -EINVAL;
+
+ *val = mmc35240_samp_freq[i];
+ *val2 = 0;
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int mmc35240_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ struct mmc35240_data *data = iio_priv(indio_dev);
+ int i, ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ i = mmc35240_get_samp_freq_index(data, val, val2);
+ if (i < 0)
+ return -EINVAL;
+ mutex_lock(&data->mutex);
+ ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
+ MMC35240_CTRL1_BW_MASK,
+ i << MMC35240_CTRL1_BW_SHIFT);
+ mutex_unlock(&data->mutex);
+ return ret;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info mmc35240_info = {
+ .driver_module = THIS_MODULE,
+ .read_raw = mmc35240_read_raw,
+ .write_raw = mmc35240_write_raw,
+ .attrs = &mmc35240_attribute_group,
+};
+
+static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MMC35240_REG_CTRL0:
+ case MMC35240_REG_CTRL1:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MMC35240_REG_XOUT_L:
+ case MMC35240_REG_XOUT_H:
+ case MMC35240_REG_YOUT_L:
+ case MMC35240_REG_YOUT_H:
+ case MMC35240_REG_ZOUT_L:
+ case MMC35240_REG_ZOUT_H:
+ case MMC35240_REG_STATUS:
+ case MMC35240_REG_ID:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MMC35240_REG_CTRL0:
+ case MMC35240_REG_CTRL1:
+ return false;
+ default:
+ return true;
+ }
+}
+
+static struct reg_default mmc35240_reg_defaults[] = {
+ { MMC35240_REG_CTRL0, 0x00 },
+ { MMC35240_REG_CTRL1, 0x00 },
+};
+
+static const struct regmap_config mmc35240_regmap_config = {
+ .name = MMC35240_REGMAP_NAME,
+
+ .reg_bits = 8,
+ .val_bits = 8,
+
+ .max_register = MMC35240_REG_ID,
+ .cache_type = REGCACHE_FLAT,
+
+ .writeable_reg = mmc35240_is_writeable_reg,
+ .readable_reg = mmc35240_is_readable_reg,
+ .volatile_reg = mmc35240_is_volatile_reg,
+
+ .reg_defaults = mmc35240_reg_defaults,
+ .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
+};
+
+static int mmc35240_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct mmc35240_data *data;
+ struct iio_dev *indio_dev;
+ struct regmap *regmap;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
+ if (IS_ERR(regmap)) {
+ dev_err(&client->dev, "regmap initialization failed\n");
+ return PTR_ERR(regmap);
+ }
+
+ data = iio_priv(indio_dev);
+ data->client = client;
+ data->regmap = regmap;
+ data->res = MMC35240_16_BITS_SLOW;
+
+ mutex_init(&data->mutex);
+
+ indio_dev->dev.parent = &client->dev;
+ indio_dev->info = &mmc35240_info;
+ indio_dev->name = MMC35240_DRV_NAME;
+ indio_dev->channels = mmc35240_channels;
+ indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ ret = mmc35240_init(data);
+ if (ret < 0) {
+ dev_err(&client->dev, "mmc35240 chip init failed\n");
+ return ret;
+ }
+ return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id mmc35240_id[] = {
+ {"MMC35240", 0},
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, mmc35240_id);
+
+static struct i2c_driver mmc35240_driver = {
+ .driver = {
+ .name = MMC35240_DRV_NAME,
+ },
+ .probe = mmc35240_probe,
+ .id_table = mmc35240_id,
+};
+
+module_i2c_driver(mmc35240_driver);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta@xxxxxxxxx>");
+MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1

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