iio: Add Freescale MPL3115A2 pressure / temperature sensor driver

I2C-controlled MEMS sensor with 20-bit pressure measurement (pascal) and
12-bit temperature measurement

driver only exposes basic functionality, see TODO remarks
datasheet: http://cache.freescale.com/files/sensors/doc/data_sheet/MPL3115A2.pdf

v2:
* store 20-bit value in 32-bit buffer element (instead of 24-bit)
* zero buffer to prevent kernel data leak to userspace
* fix mutex unlock in trigger handler (thanks Andi Shyti)

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Reviewed-by: Andi Shyti <andi@etezian.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 342 insertions, 0 deletions

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index 4f2e0f9bad8c..a8b9cae5c173 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -5,6 +5,18 @@
 
 menu "Pressure sensors"
 
+config MPL3115
+        tristate "Freescale MPL3115A2 pressure sensor driver"
+        depends on I2C
+        select IIO_BUFFER
+        select IIO_TRIGGERED_BUFFER
+        help
+          Say yes here to build support for the Freescale MPL3115A2
+          pressure sensor / altimeter.
+
+          To compile this driver as a module, choose M here: the module
+          will be called mpl3115.
+
 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 be71464c2752..42bb9fcf5436 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-$(CONFIG_MPL3115) += mpl3115.o
 obj-$(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/mpl3115.c b/drivers/iio/pressure/mpl3115.c
new file mode 100644
index 000000000000..ac8c8ab723e5
--- /dev/null
+++ b/drivers/iio/pressure/mpl3115.c
@@ -0,0 +1,329 @@
+/*
+ * mpl3115.c - Support for Freescale MPL3115A2 pressure/temperature sensor
+ *
+ * Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>
+ *
+ * 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.
+ *
+ * (7-bit I2C slave address 0x60)
+ *
+ * TODO: FIFO buffer, altimeter mode, oversampling, continuous mode,
+ * interrupts, user offset correction, raw mode
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/delay.h>
+
+#define MPL3115_STATUS 0x00
+#define MPL3115_OUT_PRESS 0x01 /* MSB first, 20 bit */
+#define MPL3115_OUT_TEMP 0x04 /* MSB first, 12 bit */
+#define MPL3115_WHO_AM_I 0x0c
+#define MPL3115_CTRL_REG1 0x26
+
+#define MPL3115_DEVICE_ID 0xc4
+
+#define MPL3115_STATUS_PRESS_RDY BIT(2)
+#define MPL3115_STATUS_TEMP_RDY BIT(1)
+
+#define MPL3115_CTRL_RESET BIT(2) /* software reset */
+#define MPL3115_CTRL_OST BIT(1) /* initiate measurement */
+#define MPL3115_CTRL_ACTIVE BIT(0) /* continuous measurement */
+#define MPL3115_CTRL_OS_258MS (BIT(5) | BIT(4)) /* 64x oversampling */
+
+struct mpl3115_data {
+        struct i2c_client *client;
+        struct mutex lock;
+        u8 ctrl_reg1;
+};
+
+static int mpl3115_request(struct mpl3115_data *data)
+{
+        int ret, tries = 15;
+
+        /* trigger measurement */
+        ret = i2c_smbus_write_byte_data(data->client, MPL3115_CTRL_REG1,
+                data->ctrl_reg1 | MPL3115_CTRL_OST);
+        if (ret < 0)
+                return ret;
+
+        while (tries-- > 0) {
+                ret = i2c_smbus_read_byte_data(data->client, MPL3115_CTRL_REG1);
+                if (ret < 0)
+                        return ret;
+                /* wait for data ready, i.e. OST cleared */
+                if (!(ret & MPL3115_CTRL_OST))
+                        break;
+                msleep(20);
+        }
+
+        if (tries < 0) {
+                dev_err(&data->client->dev, "data not ready\n");
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static int mpl3115_read_raw(struct iio_dev *indio_dev,
+                            struct iio_chan_spec const *chan,
+                            int *val, int *val2, long mask)
+{
+        struct mpl3115_data *data = iio_priv(indio_dev);
+        s32 tmp = 0;
+        int ret;
+
+        switch (mask) {
+        case IIO_CHAN_INFO_RAW:
+                if (iio_buffer_enabled(indio_dev))
+                        return -EBUSY;
+
+                switch (chan->type) {
+                case IIO_PRESSURE: /* in 0.25 pascal / LSB */
+                        mutex_lock(&data->lock);
+                        ret = mpl3115_request(data);
+                        if (ret < 0) {
+                                mutex_unlock(&data->lock);
+                                return ret;
+                        }
+                        ret = i2c_smbus_read_i2c_block_data(data->client,
+                                MPL3115_OUT_PRESS, 3, (u8 *) &tmp);
+                        mutex_unlock(&data->lock);
+                        if (ret < 0)
+                                return ret;
+                        *val = sign_extend32(be32_to_cpu(tmp) >> 12, 23);
+                        return IIO_VAL_INT;
+                case IIO_TEMP: /* in 0.0625 celsius / LSB */
+                        mutex_lock(&data->lock);
+                        ret = mpl3115_request(data);
+                        if (ret < 0) {
+                                mutex_unlock(&data->lock);
+                                return ret;
+                        }
+                        ret = i2c_smbus_read_i2c_block_data(data->client,
+                                MPL3115_OUT_TEMP, 2, (u8 *) &tmp);
+                        mutex_unlock(&data->lock);
+                        if (ret < 0)
+                                return ret;
+                        *val = sign_extend32(be32_to_cpu(tmp) >> 20, 15);
+                        return IIO_VAL_INT;
+                default:
+                        return -EINVAL;
+                }
+        case IIO_CHAN_INFO_SCALE:
+                switch (chan->type) {
+                case IIO_PRESSURE:
+                        *val = 0;
+                        *val2 = 250; /* want kilopascal */
+                        return IIO_VAL_INT_PLUS_MICRO;
+                case IIO_TEMP:
+                        *val = 0;
+                        *val2 = 62500;
+                        return IIO_VAL_INT_PLUS_MICRO;
+                default:
+                        return -EINVAL;
+                }
+        }
+        return -EINVAL;
+}
+
+static irqreturn_t mpl3115_trigger_handler(int irq, void *p)
+{
+        struct iio_poll_func *pf = p;
+        struct iio_dev *indio_dev = pf->indio_dev;
+        struct mpl3115_data *data = iio_priv(indio_dev);
+        u8 buffer[16]; /* 32-bit channel + 16-bit channel + padding + ts */
+        int ret, pos = 0;
+
+        mutex_lock(&data->lock);
+        ret = mpl3115_request(data);
+        if (ret < 0) {
+                mutex_unlock(&data->lock);
+                goto done;
+        }
+
+        memset(buffer, 0, sizeof(buffer));
+        if (test_bit(0, indio_dev->active_scan_mask)) {
+                ret = i2c_smbus_read_i2c_block_data(data->client,
+                        MPL3115_OUT_PRESS, 3, &buffer[pos]);
+                if (ret < 0) {
+                        mutex_unlock(&data->lock);
+                        goto done;
+                }
+                pos += 4;
+        }
+
+        if (test_bit(1, indio_dev->active_scan_mask)) {
+                ret = i2c_smbus_read_i2c_block_data(data->client,
+                        MPL3115_OUT_TEMP, 2, &buffer[pos]);
+                if (ret < 0) {
+                        mutex_unlock(&data->lock);
+                        goto done;
+                }
+        }
+        mutex_unlock(&data->lock);
+
+        iio_push_to_buffers_with_timestamp(indio_dev, buffer,
+                iio_get_time_ns());
+
+done:
+        iio_trigger_notify_done(indio_dev->trig);
+        return IRQ_HANDLED;
+}
+
+static const struct iio_chan_spec mpl3115_channels[] = {
+        {
+                .type = IIO_PRESSURE,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+                        BIT(IIO_CHAN_INFO_SCALE),
+                .scan_index = 0,
+                .scan_type = {
+                        .sign = 's',
+                        .realbits = 20,
+                        .storagebits = 32,
+                        .shift = 12,
+                        .endianness = IIO_BE,
+                }
+        },
+        {
+                .type = IIO_TEMP,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+                        BIT(IIO_CHAN_INFO_SCALE),
+                .scan_index = 1,
+                .scan_type = {
+                        .sign = 's',
+                        .realbits = 12,
+                        .storagebits = 16,
+                        .shift = 4,
+                        .endianness = IIO_BE,
+                }
+        },
+        IIO_CHAN_SOFT_TIMESTAMP(2),
+};
+
+static const struct iio_info mpl3115_info = {
+        .read_raw = &mpl3115_read_raw,
+        .driver_module = THIS_MODULE,
+};
+
+static int mpl3115_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{
+        struct mpl3115_data *data;
+        struct iio_dev *indio_dev;
+        int ret;
+
+        ret = i2c_smbus_read_byte_data(client, MPL3115_WHO_AM_I);
+        if (ret < 0)
+                return ret;
+        if (ret != MPL3115_DEVICE_ID)
+                return -ENODEV;
+
+        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+        if (!indio_dev)
+                return -ENOMEM;
+
+        data = iio_priv(indio_dev);
+        data->client = client;
+        mutex_init(&data->lock);
+
+        i2c_set_clientdata(client, indio_dev);
+        indio_dev->info = &mpl3115_info;
+        indio_dev->name = id->name;
+        indio_dev->dev.parent = &client->dev;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+        indio_dev->channels = mpl3115_channels;
+        indio_dev->num_channels = ARRAY_SIZE(mpl3115_channels);
+
+        /* software reset, I2C transfer is aborted (fails) */
+        i2c_smbus_write_byte_data(client, MPL3115_CTRL_REG1,
+                MPL3115_CTRL_RESET);
+        msleep(50);
+
+        data->ctrl_reg1 = MPL3115_CTRL_OS_258MS;
+        ret = i2c_smbus_write_byte_data(client, MPL3115_CTRL_REG1,
+                data->ctrl_reg1);
+        if (ret < 0)
+                return ret;
+
+        ret = iio_triggered_buffer_setup(indio_dev, NULL,
+                mpl3115_trigger_handler, NULL);
+        if (ret < 0)
+                return ret;
+
+        ret = iio_device_register(indio_dev);
+        if (ret < 0)
+                goto buffer_cleanup;
+        return 0;
+
+buffer_cleanup:
+        iio_triggered_buffer_cleanup(indio_dev);
+        return ret;
+}
+
+static int mpl3115_standby(struct mpl3115_data *data)
+{
+        return i2c_smbus_write_byte_data(data->client, MPL3115_CTRL_REG1,
+                data->ctrl_reg1 & ~MPL3115_CTRL_ACTIVE);
+}
+
+static int mpl3115_remove(struct i2c_client *client)
+{
+        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+        iio_device_unregister(indio_dev);
+        iio_triggered_buffer_cleanup(indio_dev);
+        mpl3115_standby(iio_priv(indio_dev));
+
+        return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mpl3115_suspend(struct device *dev)
+{
+        return mpl3115_standby(iio_priv(i2c_get_clientdata(
+                to_i2c_client(dev))));
+}
+
+static int mpl3115_resume(struct device *dev)
+{
+        struct mpl3115_data *data = iio_priv(i2c_get_clientdata(
+                to_i2c_client(dev)));
+
+        return i2c_smbus_write_byte_data(data->client, MPL3115_CTRL_REG1,
+                data->ctrl_reg1);
+}
+
+static SIMPLE_DEV_PM_OPS(mpl3115_pm_ops, mpl3115_suspend, mpl3115_resume);
+#define MPL3115_PM_OPS (&mpl3115_pm_ops)
+#else
+#define MPL3115_PM_OPS NULL
+#endif
+
+static const struct i2c_device_id mpl3115_id[] = {
+        { "mpl3115", 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, mpl3115_id);
+
+static struct i2c_driver mpl3115_driver = {
+        .driver = {
+                .name   = "mpl3115",
+                .pm     = MPL3115_PM_OPS,
+        },
+        .probe = mpl3115_probe,
+        .remove = mpl3115_remove,
+        .id_table = mpl3115_id,
+};
+module_i2c_driver(mpl3115_driver);
+
+MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
+MODULE_DESCRIPTION("Freescale MPL3115 pressure/temperature driver");
+MODULE_LICENSE("GPL");