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

From: Daniel Baluta
Date: Fri Apr 24 2015 - 12:15:08 EST

On Fri, Apr 24, 2015 at 7:00 PM, Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote:
> On Sun, Apr 19, 2015 at 4:28 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>> On 15/04/15 12:02, Daniel Baluta wrote:
>>> 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>
>> a couple of really minor points inline.
>>
>> Looks good to me.
>
> Thanks. Fixed most of the issues and sent v2. See below.
>
>>
>> Jonathan
>>> ---
>>> drivers/iio/magnetometer/Kconfig | 11 +
>>> drivers/iio/magnetometer/Makefile | 1 +
>>> drivers/iio/magnetometer/mmc35240.c | 476 ++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 488 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..c46c1f7
>>> --- /dev/null
>>> +++ b/drivers/iio/magnetometer/mmc35240.c
>>> @@ -0,0 +1,476 @@
>>> +/*
>>> + * 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 */
>>> + MMC35240_MAX_BITS /* this must be last */
>>> +};
>>> +
>>> +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_info(&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;
>>> +
>> Why this seperation into read_measurement and take_measurement?
>
> We need this for future implementation of Continuous Mode, where there
> is no need
> to call take_measurement.

Also the same pattern is in LTR501 driver and I think it looks nicer.
>
>>> + ret = mmc35240_take_measurement(data);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
>>> + 3 * sizeof(__be16));
>>> +}
>>> +
>>> +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_PLUS_MICRO;
>>> + 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);
>>> + i2c_set_clientdata(client, indio_dev);
>> If you are dropping the remove, you don't actually need the above either.
>
> All right. Fixed.
>
>>
>>> + 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 int mmc35240_remove(struct i2c_client *client)
>>> +{
>>> + return 0;
>>> +}
>>> +
>>> +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,
>>> + .remove = mmc35240_remove,
>>> + .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");
>>>
>>
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