iio: add bmp280 pressure and temperature driver

Minimal implementation, can read temperature and data using direct mode.

Datasheet available at
<http://ae-bst.resource.bosch.com/media/products/dokumente/bmp280/BST-BMP280-DS001-09.pdf>

Signed-off-by: Vlad Dogaru <vlad.dogaru@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 467 insertions, 0 deletions

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index 15afbc919521..a3be53792072 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -5,6 +5,17 @@
 
 menu "Pressure sensors"
 
+config BMP280
+        tristate "Bosch Sensortec BMP280 pressure sensor driver"
+        depends on I2C
+        select REGMAP_I2C
+        help
+         Say yes here to build support for Bosch Sensortec BMP280
+         pressure and temperature sensor.
+
+         To compile this driver as a module, choose M here: the module
+         will be called bmp280.
+
 config HID_SENSOR_PRESS
         depends on HID_SENSOR_HUB
         select IIO_BUFFER
diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
index 90a37e85cf21..88011f2ae00e 100644
--- a/drivers/iio/pressure/Makefile
+++ b/drivers/iio/pressure/Makefile
@@ -3,6 +3,7 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_BMP280) += bmp280.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_MPL115) += mpl115.o
 obj-$(CONFIG_MPL3115) += mpl3115.o
diff --git a/drivers/iio/pressure/bmp280.c b/drivers/iio/pressure/bmp280.c
new file mode 100644
index 000000000000..fb91cb35b331
--- /dev/null
+++ b/drivers/iio/pressure/bmp280.c
@@ -0,0 +1,455 @@
+/*
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Driver for Bosch Sensortec BMP280 digital pressure sensor.
+ *
+ * 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.
+ *
+ */
+
+#define pr_fmt(fmt) "bmp280: " fmt
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/acpi.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define BMP280_REG_TEMP_XLSB            0xFC
+#define BMP280_REG_TEMP_LSB             0xFB
+#define BMP280_REG_TEMP_MSB             0xFA
+#define BMP280_REG_PRESS_XLSB           0xF9
+#define BMP280_REG_PRESS_LSB            0xF8
+#define BMP280_REG_PRESS_MSB            0xF7
+
+#define BMP280_REG_CONFIG               0xF5
+#define BMP280_REG_CTRL_MEAS            0xF4
+#define BMP280_REG_STATUS               0xF3
+#define BMP280_REG_RESET                0xE0
+#define BMP280_REG_ID                   0xD0
+
+#define BMP280_REG_COMP_TEMP_START      0x88
+#define BMP280_COMP_TEMP_REG_COUNT      6
+
+#define BMP280_REG_COMP_PRESS_START     0x8E
+#define BMP280_COMP_PRESS_REG_COUNT     18
+
+#define BMP280_FILTER_MASK              (BIT(4) | BIT(3) | BIT(2))
+#define BMP280_FILTER_OFF               0
+#define BMP280_FILTER_2X                BIT(2)
+#define BMP280_FILTER_4X                BIT(3)
+#define BMP280_FILTER_8X                (BIT(3) | BIT(2))
+#define BMP280_FILTER_16X               BIT(4)
+
+#define BMP280_OSRS_TEMP_MASK           (BIT(7) | BIT(6) | BIT(5))
+#define BMP280_OSRS_TEMP_SKIP           0
+#define BMP280_OSRS_TEMP_1X             BIT(5)
+#define BMP280_OSRS_TEMP_2X             BIT(6)
+#define BMP280_OSRS_TEMP_4X             (BIT(6) | BIT(5))
+#define BMP280_OSRS_TEMP_8X             BIT(7)
+#define BMP280_OSRS_TEMP_16X            (BIT(7) | BIT(5))
+
+#define BMP280_OSRS_PRESS_MASK          (BIT(4) | BIT(3) | BIT(2))
+#define BMP280_OSRS_PRESS_SKIP          0
+#define BMP280_OSRS_PRESS_1X            BIT(2)
+#define BMP280_OSRS_PRESS_2X            BIT(3)
+#define BMP280_OSRS_PRESS_4X            (BIT(3) | BIT(2))
+#define BMP280_OSRS_PRESS_8X            BIT(4)
+#define BMP280_OSRS_PRESS_16X           (BIT(4) | BIT(2))
+
+#define BMP280_MODE_MASK                (BIT(1) | BIT(0))
+#define BMP280_MODE_SLEEP               0
+#define BMP280_MODE_FORCED              BIT(0)
+#define BMP280_MODE_NORMAL              (BIT(1) | BIT(0))
+
+#define BMP280_CHIP_ID                  0x58
+#define BMP280_SOFT_RESET_VAL           0xB6
+
+struct bmp280_data {
+        struct i2c_client *client;
+        struct mutex lock;
+        struct regmap *regmap;
+
+        /*
+         * Carryover value from temperature conversion, used in pressure
+         * calculation.
+         */
+        s32 t_fine;
+};
+
+/* Compensation parameters. */
+struct bmp280_comp_temp {
+        u16 dig_t1;
+        s16 dig_t2, dig_t3;
+};
+
+struct bmp280_comp_press {
+        u16 dig_p1;
+        s16 dig_p2, dig_p3, dig_p4, dig_p5, dig_p6, dig_p7, dig_p8, dig_p9;
+};
+
+static const struct iio_chan_spec bmp280_channels[] = {
+        {
+                .type = IIO_PRESSURE,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+        },
+        {
+                .type = IIO_TEMP,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+        },
+};
+
+static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+        switch (reg) {
+        case BMP280_REG_CONFIG:
+        case BMP280_REG_CTRL_MEAS:
+        case BMP280_REG_RESET:
+                return true;
+        default:
+                return false;
+        };
+}
+
+static bool bmp280_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+        switch (reg) {
+        case BMP280_REG_TEMP_XLSB:
+        case BMP280_REG_TEMP_LSB:
+        case BMP280_REG_TEMP_MSB:
+        case BMP280_REG_PRESS_XLSB:
+        case BMP280_REG_PRESS_LSB:
+        case BMP280_REG_PRESS_MSB:
+        case BMP280_REG_STATUS:
+                return true;
+        default:
+                return false;
+        }
+}
+
+static const struct regmap_config bmp280_regmap_config = {
+        .reg_bits = 8,
+        .val_bits = 8,
+
+        .max_register = BMP280_REG_TEMP_XLSB,
+        .cache_type = REGCACHE_RBTREE,
+
+        .writeable_reg = bmp280_is_writeable_reg,
+        .volatile_reg = bmp280_is_volatile_reg,
+};
+
+static int bmp280_read_compensation_temp(struct bmp280_data *data,
+                                         struct bmp280_comp_temp *comp)
+{
+        int ret;
+        __le16 buf[BMP280_COMP_TEMP_REG_COUNT / 2];
+
+        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_TEMP_START,
+                               buf, BMP280_COMP_TEMP_REG_COUNT);
+        if (ret < 0) {
+                dev_err(&data->client->dev,
+                        "failed to read temperature calibration parameters\n");
+                return ret;
+        }
+
+        comp->dig_t1 = (u16) le16_to_cpu(buf[0]);
+        comp->dig_t2 = (s16) le16_to_cpu(buf[1]);
+        comp->dig_t3 = (s16) le16_to_cpu(buf[2]);
+
+        return 0;
+}
+
+static int bmp280_read_compensation_press(struct bmp280_data *data,
+                                          struct bmp280_comp_press *comp)
+{
+        int ret;
+        __le16 buf[BMP280_COMP_PRESS_REG_COUNT / 2];
+
+        ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_PRESS_START,
+                               buf, BMP280_COMP_PRESS_REG_COUNT);
+        if (ret < 0) {
+                dev_err(&data->client->dev,
+                        "failed to read pressure calibration parameters\n");
+                return ret;
+        }
+
+        comp->dig_p1 = (s16) le16_to_cpu(buf[0]);
+        comp->dig_p2 = (u16) le16_to_cpu(buf[1]);
+        comp->dig_p3 = (u16) le16_to_cpu(buf[2]);
+        comp->dig_p4 = (u16) le16_to_cpu(buf[3]);
+        comp->dig_p5 = (u16) le16_to_cpu(buf[4]);
+        comp->dig_p6 = (u16) le16_to_cpu(buf[5]);
+        comp->dig_p7 = (u16) le16_to_cpu(buf[6]);
+        comp->dig_p8 = (u16) le16_to_cpu(buf[7]);
+        comp->dig_p9 = (u16) le16_to_cpu(buf[8]);
+
+        return 0;
+}
+
+/*
+ * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
+ * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
+ * value.
+ *
+ * Taken from datasheet, Section 3.11.3, "Compensation formula".
+ */
+static s32 bmp280_compensate_temp(struct bmp280_data *data,
+                                  struct bmp280_comp_temp *comp,
+                                  s32 adc_temp)
+{
+        s32 var1, var2, t;
+
+        var1 = (((adc_temp >> 3) - ((s32) comp->dig_t1 << 1)) *
+                ((s32) comp->dig_t2)) >> 11;
+        var2 = (((((adc_temp >> 4) - ((s32) comp->dig_t1)) *
+                  ((adc_temp >> 4) - ((s32) comp->dig_t1))) >> 12) *
+                ((s32) comp->dig_t3)) >> 14;
+
+        data->t_fine = var1 + var2;
+        t = (data->t_fine * 5 + 128) >> 8;
+
+        return t;
+}
+
+/*
+ * Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24
+ * integer bits and 8 fractional bits).  Output value of "24674867"
+ * represents 24674867/256 = 96386.2 Pa = 963.862 hPa
+ *
+ * Taken from datasheet, Section 3.11.3, "Compensation formula".
+ */
+static u32 bmp280_compensate_press(struct bmp280_data *data,
+                                   struct bmp280_comp_press *comp,
+                                   s32 adc_press)
+{
+        s64 var1, var2, p;
+
+        var1 = ((s64) data->t_fine) - 128000;
+        var2 = var1 * var1 * (s64) comp->dig_p6;
+        var2 = var2 + ((var1 * (s64) comp->dig_p5) << 17);
+        var2 = var2 + (((s64) comp->dig_p4) << 35);
+        var1 = ((var1 * var1 * (s64) comp->dig_p3) >> 8) +
+                ((var1 * (s64) comp->dig_p2) << 12);
+        var1 = (((((s64) 1) << 47) + var1)) * ((s64) comp->dig_p1) >> 33;
+
+        if (var1 == 0)
+                return 0;
+
+        p = ((((s64) 1048576 - adc_press) << 31) - var2) * 3125;
+        do_div(p, var1);
+        var1 = (((s64) comp->dig_p9) * (p >> 13) * (p >> 13)) >> 25;
+        var2 = (((s64) comp->dig_p8) * p) >> 19;
+        p = ((p + var1 + var2) >> 8) + (((s64) comp->dig_p7) << 4);
+
+        return (u32) p;
+}
+
+static int bmp280_read_temp(struct bmp280_data *data,
+                            int *val)
+{
+        int ret;
+        __be32 tmp = 0;
+        s32 adc_temp, comp_temp;
+        struct bmp280_comp_temp comp;
+
+        ret = bmp280_read_compensation_temp(data, &comp);
+        if (ret < 0)
+                return ret;
+
+        ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
+                               (u8 *) &tmp, 3);
+        if (ret < 0) {
+                dev_err(&data->client->dev, "failed to read temperature\n");
+                return ret;
+        }
+
+        adc_temp = be32_to_cpu(tmp) >> 12;
+        comp_temp = bmp280_compensate_temp(data, &comp, adc_temp);
+
+        /*
+         * val might be NULL if we're called by the read_press routine,
+         * who only cares about the carry over t_fine value.
+         */
+        if (val) {
+                *val = comp_temp * 10;
+                return IIO_VAL_INT;
+        }
+
+        return 0;
+}
+
+static int bmp280_read_press(struct bmp280_data *data,
+                             int *val, int *val2)
+{
+        int ret;
+        __be32 tmp = 0;
+        s32 adc_press;
+        u32 comp_press;
+        struct bmp280_comp_press comp;
+
+        ret = bmp280_read_compensation_press(data, &comp);
+        if (ret < 0)
+                return ret;
+
+        /* Read and compensate temperature so we get a reading of t_fine. */
+        ret = bmp280_read_temp(data, NULL);
+        if (ret < 0)
+                return ret;
+
+        ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
+                               (u8 *) &tmp, 3);
+        if (ret < 0) {
+                dev_err(&data->client->dev, "failed to read pressure\n");
+                return ret;
+        }
+
+        adc_press = be32_to_cpu(tmp) >> 12;
+        comp_press = bmp280_compensate_press(data, &comp, adc_press);
+
+        *val = comp_press / 256000;
+        *val2 = comp_press * 1000000 / 256000;
+
+        return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int bmp280_read_raw(struct iio_dev *indio_dev,
+                           struct iio_chan_spec const *chan,
+                           int *val, int *val2, long mask)
+{
+        int ret;
+        struct bmp280_data *data = iio_priv(indio_dev);
+
+        mutex_lock(&data->lock);
+
+        switch (mask) {
+        case IIO_CHAN_INFO_PROCESSED:
+                switch (chan->type) {
+                case IIO_PRESSURE:
+                        ret = bmp280_read_press(data, val, val2);
+                        break;
+                case IIO_TEMP:
+                        ret = bmp280_read_temp(data, val);
+                        break;
+                default:
+                        ret = -EINVAL;
+                        break;
+                }
+                break;
+        default:
+                ret = -EINVAL;
+                break;
+        }
+
+        mutex_unlock(&data->lock);
+
+        return ret;
+}
+
+static const struct iio_info bmp280_info = {
+        .driver_module = THIS_MODULE,
+        .read_raw = &bmp280_read_raw,
+};
+
+static int bmp280_chip_init(struct bmp280_data *data)
+{
+        int ret;
+
+        ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS,
+                                 BMP280_OSRS_TEMP_MASK |
+                                 BMP280_OSRS_PRESS_MASK |
+                                 BMP280_MODE_MASK,
+                                 BMP280_OSRS_TEMP_2X |
+                                 BMP280_OSRS_PRESS_16X |
+                                 BMP280_MODE_NORMAL);
+        if (ret < 0) {
+                dev_err(&data->client->dev,
+                        "failed to write config register\n");
+                return ret;
+        }
+
+        ret = regmap_update_bits(data->regmap, BMP280_REG_CONFIG,
+                                 BMP280_FILTER_MASK,
+                                 BMP280_FILTER_4X);
+        if (ret < 0) {
+                dev_err(&data->client->dev,
+                        "failed to write config register\n");
+                return ret;
+        }
+
+        return ret;
+}
+
+static int bmp280_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        int ret;
+        struct iio_dev *indio_dev;
+        struct bmp280_data *data;
+        unsigned int chip_id;
+
+        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+        if (!indio_dev)
+                return -ENOMEM;
+
+        i2c_set_clientdata(client, indio_dev);
+        data = iio_priv(indio_dev);
+        mutex_init(&data->lock);
+        data->client = client;
+
+        indio_dev->dev.parent = &client->dev;
+        indio_dev->name = id->name;
+        indio_dev->channels = bmp280_channels;
+        indio_dev->num_channels = ARRAY_SIZE(bmp280_channels);
+        indio_dev->info = &bmp280_info;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+
+        data->regmap = devm_regmap_init_i2c(client, &bmp280_regmap_config);
+        if (IS_ERR(data->regmap)) {
+                dev_err(&client->dev, "failed to allocate register map\n");
+                return PTR_ERR(data->regmap);
+        }
+
+        ret = regmap_read(data->regmap, BMP280_REG_ID, &chip_id);
+        if (ret < 0)
+                return ret;
+        if (chip_id != BMP280_CHIP_ID) {
+                dev_err(&client->dev, "bad chip id.  expected %x got %x\n",
+                        BMP280_CHIP_ID, chip_id);
+                return -EINVAL;
+        }
+
+        ret = bmp280_chip_init(data);
+        if (ret < 0)
+                return ret;
+
+        return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct acpi_device_id bmp280_acpi_match[] = {
+        {"BMP0280", 0},
+        { },
+};
+MODULE_DEVICE_TABLE(acpi, bmp280_acpi_match);
+
+static const struct i2c_device_id bmp280_id[] = {
+        {"bmp280", 0},
+        { },
+};
+MODULE_DEVICE_TABLE(i2c, bmp280_id);
+
+static struct i2c_driver bmp280_driver = {
+        .driver = {
+                .name   = "bmp280",
+                .acpi_match_table = ACPI_PTR(bmp280_acpi_match),
+        },
+        .probe          = bmp280_probe,
+        .id_table       = bmp280_id,
+};
+module_i2c_driver(bmp280_driver);
+
+MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
+MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP280 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");