iio: pressure: add support for MS5611 pressure and temperature sensor

Add support for Measurement Specialities MS5611 pressure
and temperature sensor.

Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

6 files changed, 544 insertions, 0 deletions

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index a3be53792072..fa6295041947 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -52,6 +52,33 @@ config MPL3115
           To compile this driver as a module, choose M here: the module
           will be called mpl3115.
 
+config MS5611
+        tristate "Measurement Specialities MS5611 pressure sensor driver"
+        help
+          Say Y here to build support for the Measurement Specialities
+          MS5611 pressure and temperature sensor.
+
+          To compile this driver as a module, choose M here: the module will
+          be called ms5611_core.
+
+config MS5611_I2C
+        tristate "support I2C bus connection"
+        depends on I2C && MS5611
+        help
+          Say Y here to build I2C bus support for MS5611.
+
+          To compile this driver as a module, choose M here: the module will
+          be called ms5611_i2c.
+
+config MS5611_SPI
+        tristate "support SPI bus connection"
+        depends on SPI_MASTER && MS5611
+        help
+          Say Y here to build SPI bus support for MS5611.
+
+          To compile this driver as a module, choose M here: the module will
+          be called ms5611_spi.
+
 config IIO_ST_PRESS
         tristate "STMicroelectronics pressure sensor Driver"
         depends on (I2C || SPI_MASTER) && SYSFS
diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
index 88011f2ae00e..a4f98f8d90ed 100644
--- a/drivers/iio/pressure/Makefile
+++ b/drivers/iio/pressure/Makefile
@@ -7,6 +7,9 @@ obj-$(CONFIG_BMP280) += bmp280.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_MPL115) += mpl115.o
 obj-$(CONFIG_MPL3115) += mpl3115.o
+obj-$(CONFIG_MS5611) += ms5611_core.o
+obj-$(CONFIG_MS5611_I2C) += ms5611_i2c.o
+obj-$(CONFIG_MS5611_SPI) += ms5611_spi.o
 obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o
 st_pressure-y := st_pressure_core.o
 st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o
diff --git a/drivers/iio/pressure/ms5611.h b/drivers/iio/pressure/ms5611.h
new file mode 100644
index 000000000000..099c6cdea43f
--- /dev/null
+++ b/drivers/iio/pressure/ms5611.h
@@ -0,0 +1,44 @@
+/*
+ * MS5611 pressure and temperature sensor driver
+ *
+ * Copyright (c) Tomasz Duszynski <tduszyns@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 _MS5611_H
+#define _MS5611_H
+
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/mutex.h>
+
+#define MS5611_RESET                    0x1e
+#define MS5611_READ_ADC                 0x00
+#define MS5611_READ_PROM_WORD           0xA0
+#define MS5611_START_TEMP_CONV          0x58
+#define MS5611_START_PRESSURE_CONV      0x48
+
+#define MS5611_CONV_TIME_MIN            9040
+#define MS5611_CONV_TIME_MAX            10000
+
+#define MS5611_PROM_WORDS_NB            8
+
+struct ms5611_state {
+        void *client;
+        struct mutex lock;
+
+        int (*reset)(struct device *dev);
+        int (*read_prom_word)(struct device *dev, int index, u16 *word);
+        int (*read_adc_temp_and_pressure)(struct device *dev,
+                                          s32 *temp, s32 *pressure);
+
+        u16 prom[MS5611_PROM_WORDS_NB];
+};
+
+int ms5611_probe(struct iio_dev *indio_dev, struct device *dev);
+
+#endif /* _MS5611_H */
diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c
new file mode 100644
index 000000000000..e42c8531d9b3
--- /dev/null
+++ b/drivers/iio/pressure/ms5611_core.c
@@ -0,0 +1,215 @@
+/*
+ * MS5611 pressure and temperature sensor driver
+ *
+ * Copyright (c) Tomasz Duszynski <tduszyns@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.
+ *
+ * Data sheet:
+ *  http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/delay.h>
+
+#include "ms5611.h"
+
+static bool ms5611_prom_is_valid(u16 *prom, size_t len)
+{
+        int i, j;
+        uint16_t crc = 0, crc_orig = prom[7] & 0x000F;
+
+        prom[7] &= 0xFF00;
+
+        for (i = 0; i < len * 2; i++) {
+                if (i % 2 == 1)
+                        crc ^= prom[i >> 1] & 0x00FF;
+                else
+                        crc ^= prom[i >> 1] >> 8;
+
+                for (j = 0; j < 8; j++) {
+                        if (crc & 0x8000)
+                                crc = (crc << 1) ^ 0x3000;
+                        else
+                                crc <<= 1;
+                }
+        }
+
+        crc = (crc >> 12) & 0x000F;
+
+        return crc_orig != 0x0000 && crc == crc_orig;
+}
+
+static int ms5611_read_prom(struct iio_dev *indio_dev)
+{
+        int ret, i;
+        struct ms5611_state *st = iio_priv(indio_dev);
+
+        for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
+                ret = st->read_prom_word(&indio_dev->dev, i, &st->prom[i]);
+                if (ret < 0) {
+                        dev_err(&indio_dev->dev,
+                                "failed to read prom at %d\n", i);
+                        return ret;
+                }
+        }
+
+        if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) {
+                dev_err(&indio_dev->dev, "PROM integrity check failed\n");
+                return -ENODEV;
+        }
+
+        return 0;
+}
+
+static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
+                                         s32 *temp, s32 *pressure)
+{
+        int ret;
+        s32 t, p;
+        s64 off, sens, dt;
+        struct ms5611_state *st = iio_priv(indio_dev);
+
+        ret = st->read_adc_temp_and_pressure(&indio_dev->dev, &t, &p);
+        if (ret < 0) {
+                dev_err(&indio_dev->dev,
+                        "failed to read temperature and pressure\n");
+                return ret;
+        }
+
+        dt = t - (st->prom[5] << 8);
+        off = ((s64)st->prom[2] << 16) + ((st->prom[4] * dt) >> 7);
+        sens = ((s64)st->prom[1] << 15) + ((st->prom[3] * dt) >> 8);
+
+        t = 2000 + ((st->prom[6] * dt) >> 23);
+        if (t < 2000) {
+                s64 off2, sens2, t2;
+
+                t2 = (dt * dt) >> 31;
+                off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
+                sens2 = off2 >> 1;
+
+                if (t < -1500) {
+                        s64 tmp = (t + 1500) * (t + 1500);
+
+                        off2 += 7 * tmp;
+                        sens2 += (11 * tmp) >> 1;
+                }
+
+                t -= t2;
+                off -= off2;