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Release 4.7 drivers/iio/magnetometer/mmc35240.c

/*
 * 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/acpi.h>
#include <linux/pm.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 */

/*
 * Memsic OTP process code piece is put here for reference:
 *
 * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
 * 1) For X axis, the COEFFICIENT is always 1.
 * 2) For Y axis, the COEFFICIENT is as below:
 *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
 *                                   (reg_data[2] >> 4)) + 1.0;
 * 3) For Z axis, the COEFFICIENT is as below:
 *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
 * We implemented the OTP logic into driver.
 */

/* scale = 1000 here for Y otp */

#define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)

/* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */

#define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)


#define MMC35240_X_COEFF(x)	(x)

#define MMC35240_Y_COEFF(y)	(y + 1000)

#define MMC35240_Z_COEFF(z)	(z + 13500)


#define MMC35240_OTP_START_ADDR		0x1B


enum mmc35240_resolution {
	
MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
	
MMC35240_16_BITS_FAST,     /* 4.08 ms */
	
MMC35240_14_BITS,          /* 2.16 ms */
	
MMC35240_12_BITS,          /* 1.20 ms */
};


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, 125Hz ODR */
	{
		{1024, 1024, 1024},
		32768,
        },
	/* 16 bits, 250Hz ODR */
	{
		{1024, 1024, 770},
		32768,
        },
	/* 14 bits, 450Hz ODR */
	{
		{256, 256, 193},
		8192,
        },
	/* 12 bits, 800Hz ODR */
	{
		{64, 64, 48},
		2048,
        },
};


struct mmc35240_data {
	
struct i2c_client *client;
	
struct mutex mutex;
	
struct regmap *regmap;
	
enum mmc35240_resolution res;

	/* OTP compensation */
	
int axis_coef[3];
	
int axis_scale[3];
};

static const struct {
	
int val;
	
int val2;
} 
mmc35240_samp_freq[] = { {1, 500000},
			   {13, 0},
			   {25, 0},
			   {50, 0} };

static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");


#define MMC35240_CHANNEL(_axis) { \
        .type = IIO_MAGN, \
        .modified = 1, \
        .channel2 = IIO_MOD_ ## _axis, \
        .address = AXIS_ ## _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), \
}


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,
	NULL
};


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 == val && mmc35240_samp_freq[i].val2 == val2) return i; return -EINVAL; }

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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, coil_bit, coil_bit); }

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static int mmc35240_init(struct mmc35240_data *data) { int ret, y_convert, z_convert; unsigned int reg_id; u8 otp_data[6]; 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 SET/RESET sequence, the axis polarity being naturally * aligned after RESET */ ret = mmc35240_hw_set(data, true); if (ret < 0) return ret; usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1); ret = mmc35240_hw_set(data, false); if (ret < 0) return ret; /* set default sampling frequency */ ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1, MMC35240_CTRL1_BW_MASK, data->res << MMC35240_CTRL1_BW_SHIFT); if (ret < 0) return ret; ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR, (u8 *)otp_data, sizeof(otp_data)); if (ret < 0) return ret; y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) | (otp_data[2] >> 4)); z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f); data->axis_coef[0] = MMC35240_X_COEFF(1); data->axis_coef[1] = MMC35240_Y_COEFF(y_convert); data->axis_coef[2] = MMC35240_Z_COEFF(z_convert); data->axis_scale[0] = 1; data->axis_scale[1] = 1000; data->axis_scale[2] = 10000; return 0; }

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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; /* minimum wait time to complete measurement is 10 ms */ usleep_range(10000, 11000); } if (tries < 0) { dev_err(&data->client->dev, "data not ready\n"); return -EIO; } return 0; }

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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)); }

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/** * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply compensation for output value. * * @data: device private data * @index: axis index for which we want the conversion * @buf: raw data to be converted, 2 bytes in little endian format * @val: compensated output reading (unit is milli gauss) * * Returns: 0 in case of success, -EINVAL when @index is not valid */
static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index, __le16 buf[], int *val) { int raw[3]; int sens[3]; int nfo; raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]); raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]); raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]); sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X]; sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y]; sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z]; nfo = mmc35240_props_table[data->res].nfo; switch (index) { case AXIS_X: *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X]; break; case AXIS_Y: *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] - (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z]; break; case AXIS_Z: *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] + (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z]; break; default: return -EINVAL; } /* apply OTP compensation */ *val = (*val) * data->axis_coef[index] / data->axis_scale[index]; return 0; }

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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_RAW: mutex_lock(&data->mutex); ret = mmc35240_read_measurement(data, buf); mutex_unlock(&data->mutex); if (ret < 0) return ret; ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val); if (ret < 0) return ret; return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: *val = 0; *val2 = 1000; 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].val; *val2 = mmc35240_samp_freq[i].val2; return IIO_VAL_INT_PLUS_MICRO; default: return -EINVAL; } }

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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; } }

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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; } }

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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; } }

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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; } }

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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); 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); }

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#ifdef CONFIG_PM_SLEEP
static int mmc35240_suspend(struct device *dev) { struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); struct mmc35240_data *data = iio_priv(indio_dev); regcache_cache_only(data->regmap, true); return 0; }

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static int mmc35240_resume(struct device *dev) { struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); struct mmc35240_data *data = iio_priv(indio_dev); int ret; regcache_mark_dirty(data->regmap); ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0, MMC35240_REG_CTRL1); if (ret < 0) dev_err(dev, "Failed to restore control registers\n"); regcache_cache_only(data->regmap, false); return 0; }

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#endif static const struct dev_pm_ops mmc35240_pm_ops = { SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume) }; static const struct of_device_id mmc35240_of_match[] = { { .compatible = "memsic,mmc35240", }, { } }; MODULE_DEVICE_TABLE(of, mmc35240_of_match); static const struct acpi_device_id mmc35240_acpi_match[] = { {"MMC35240", 0}, { }, }; MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match); 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, .of_match_table = mmc35240_of_match, .pm = &mmc35240_pm_ops, .acpi_match_table = ACPI_PTR(mmc35240_acpi_match), }, .probe = mmc35240_probe, .id_table = mmc35240_id, }; module_i2c_driver(mmc35240_driver); MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>"); MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver"); MODULE_LICENSE("GPL v2");

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