iio: accel: Add support for Sensortek STK8312
authorTiberiu Breana <tiberiu.a.breana@intel.com>
Tue, 12 May 2015 15:48:42 +0000 (18:48 +0300)
committerJonathan Cameron <jic23@kernel.org>
Sun, 17 May 2015 10:03:31 +0000 (11:03 +0100)
Minimal implementation of an IIO driver for the Sensortek
STK8312 3-axis accelerometer. Datasheet:
http://www.syi-group.com/uploadpic/data/201361817562681623.pdf

Includes:
- ACPI support;
- read_raw for x,y,z axes;
- reading and setting the scale (range) parameter.
- power management

Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
drivers/iio/accel/Kconfig
drivers/iio/accel/Makefile
drivers/iio/accel/stk8312.c [new file with mode: 0644]

index 7c9a9a94a8ce9b627fe522c36ea2369563d05a39..8bd8ccbe818794e1f748f756c5142ad572ff4f10 100644 (file)
@@ -136,4 +136,15 @@ config MMA9553
 
          To compile this driver as a module, choose M here: the module
          will be called mma9553.
+
+config STK8312
+       tristate "Sensortek STK8312 3-Axis Accelerometer Driver"
+       depends on I2C
+       help
+         Say yes here to get support for the Sensortek STK8312 3-axis
+         accelerometer.
+
+         Choosing M will build the driver as a module. If so, the module
+         will be called stk8312.
+
 endmenu
index 99d89e46cad132d220898c5007003ae0cc8efd8b..8b327c19edefb11b08b13a13d8901b44e336a186 100644 (file)
@@ -14,6 +14,8 @@ obj-$(CONFIG_MMA9551_CORE)    += mma9551_core.o
 obj-$(CONFIG_MMA9551)          += mma9551.o
 obj-$(CONFIG_MMA9553)          += mma9553.o
 
+obj-$(CONFIG_STK8312)          += stk8312.o
+
 obj-$(CONFIG_IIO_SSP_SENSORS_COMMONS) += ssp_accel_sensor.o
 
 obj-$(CONFIG_IIO_ST_ACCEL_3AXIS) += st_accel.o
diff --git a/drivers/iio/accel/stk8312.c b/drivers/iio/accel/stk8312.c
new file mode 100644 (file)
index 0000000..d211d9f
--- /dev/null
@@ -0,0 +1,390 @@
+/**
+ * Sensortek STK8312 3-Axis Accelerometer
+ *
+ * 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 STK8312; 7-bit I2C address: 0x3D.
+ */
+
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define STK8312_REG_XOUT               0x00
+#define STK8312_REG_YOUT               0x01
+#define STK8312_REG_ZOUT               0x02
+#define STK8312_REG_MODE               0x07
+#define STK8312_REG_STH                        0x13
+#define STK8312_REG_RESET              0x20
+#define STK8312_REG_AFECTRL            0x24
+#define STK8312_REG_OTPADDR            0x3D
+#define STK8312_REG_OTPDATA            0x3E
+#define STK8312_REG_OTPCTRL            0x3F
+
+#define STK8312_MODE_ACTIVE            1
+#define STK8312_MODE_STANDBY           0
+#define STK8312_MODE_MASK              0x01
+#define STK8312_RNG_MASK               0xC0
+#define STK8312_RNG_SHIFT              6
+#define STK8312_READ_RETRIES           16
+
+#define STK8312_DRIVER_NAME            "stk8312"
+
+/*
+ * The accelerometer has two measurement ranges:
+ *
+ * -6g - +6g (8-bit, signed)
+ * -16g - +16g (8-bit, signed)
+ *
+ * scale1 = (6 + 6) * 9.81 / (2^8 - 1)     = 0.4616
+ * scale2 = (16 + 16) * 9.81 / (2^8 - 1)   = 1.2311
+ */
+#define STK8312_SCALE_AVAIL            "0.4616 1.2311"
+
+static const int stk8312_scale_table[][2] = {
+       {0, 461600}, {1, 231100}
+};
+
+#define STK8312_ACCEL_CHANNEL(reg, axis) {                     \
+       .type = IIO_ACCEL,                                      \
+       .address = reg,                                         \
+       .modified = 1,                                          \
+       .channel2 = IIO_MOD_##axis,                             \
+       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
+       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
+}
+
+static const struct iio_chan_spec stk8312_channels[] = {
+       STK8312_ACCEL_CHANNEL(STK8312_REG_XOUT, X),
+       STK8312_ACCEL_CHANNEL(STK8312_REG_YOUT, Y),
+       STK8312_ACCEL_CHANNEL(STK8312_REG_ZOUT, Z),
+};
+
+struct stk8312_data {
+       struct i2c_client *client;
+       struct mutex lock;
+       int range;
+       u8 mode;
+};
+
+static IIO_CONST_ATTR(in_accel_scale_available, STK8312_SCALE_AVAIL);
+
+static struct attribute *stk8312_attributes[] = {
+       &iio_const_attr_in_accel_scale_available.dev_attr.attr,
+       NULL,
+};
+
+static const struct attribute_group stk8312_attribute_group = {
+       .attrs = stk8312_attributes
+};
+
+static int stk8312_otp_init(struct stk8312_data *data)
+{
+       int ret;
+       int count = 10;
+       struct i2c_client *client = data->client;
+
+       ret = i2c_smbus_write_byte_data(client, STK8312_REG_OTPADDR, 0x70);
+       if (ret < 0)
+               goto exit_err;
+       ret = i2c_smbus_write_byte_data(client, STK8312_REG_OTPCTRL, 0x02);
+       if (ret < 0)
+               goto exit_err;
+
+       do {
+               usleep_range(1000, 5000);
+               ret = i2c_smbus_read_byte_data(client, STK8312_REG_OTPCTRL);
+               if (ret < 0)
+                       goto exit_err;
+               count--;
+       } while (!(ret & 0x80) && count > 0);
+
+       if (count == 0)
+               goto exit_err;
+
+       ret = i2c_smbus_read_byte_data(client, STK8312_REG_OTPDATA);
+       if (ret < 0)
+               goto exit_err;
+
+       ret = i2c_smbus_write_byte_data(data->client,
+                       STK8312_REG_AFECTRL, ret);
+       if (ret < 0)
+               goto exit_err;
+       msleep(150);
+
+       return ret;
+
+exit_err:
+       dev_err(&client->dev, "failed to initialize sensor\n");
+       return ret;
+}
+
+static int stk8312_set_mode(struct stk8312_data *data, u8 mode)
+{
+       int ret;
+       u8 masked_reg;
+       struct i2c_client *client = data->client;
+
+       if (mode > 1)
+               return -EINVAL;
+       else if (mode == data->mode)
+               return 0;
+
+       ret = i2c_smbus_read_byte_data(client, STK8312_REG_MODE);
+       if (ret < 0) {
+               dev_err(&client->dev, "failed to change sensor mode\n");
+               return ret;
+       }
+       masked_reg = ret & (~STK8312_MODE_MASK);
+       masked_reg |= mode;
+
+       ret = i2c_smbus_write_byte_data(client,
+                       STK8312_REG_MODE, masked_reg);
+       if (ret < 0) {
+               dev_err(&client->dev, "failed to change sensor mode\n");
+               return ret;
+       }
+
+       data->mode = mode;
+       if (mode == STK8312_MODE_ACTIVE) {
+               /* Need to run OTP sequence before entering active mode */
+               usleep_range(1000, 5000);
+               ret = stk8312_otp_init(data);
+       }
+
+       return ret;
+}
+
+static int stk8312_set_range(struct stk8312_data *data, u8 range)
+{
+       int ret;
+       u8 masked_reg;
+       u8 mode;
+       struct i2c_client *client = data->client;
+
+       if (range != 1 && range != 2)
+               return -EINVAL;
+       else if (range == data->range)
+               return 0;
+
+       mode = data->mode;
+       /* We need to go in standby mode to modify registers */
+       ret = stk8312_set_mode(data, STK8312_MODE_STANDBY);
+       if (ret < 0)
+               return ret;
+
+       ret = i2c_smbus_read_byte_data(client, STK8312_REG_STH);
+       if (ret < 0) {
+               dev_err(&client->dev, "failed to change sensor range\n");
+               return ret;
+       }
+
+       masked_reg = ret & (~STK8312_RNG_MASK);
+       masked_reg |= range << STK8312_RNG_SHIFT;
+
+       ret = i2c_smbus_write_byte_data(client, STK8312_REG_STH, masked_reg);
+       if (ret < 0)
+               dev_err(&client->dev, "failed to change sensor range\n");
+       else
+               data->range = range;
+
+       return stk8312_set_mode(data, mode);
+}
+
+static int stk8312_read_accel(struct stk8312_data *data, u8 address)
+{
+       int ret;
+       struct i2c_client *client = data->client;
+
+       if (address > 2)
+               return -EINVAL;
+
+       ret = i2c_smbus_read_byte_data(client, address);
+       if (ret < 0) {
+               dev_err(&client->dev, "register read failed\n");
+               return ret;
+       }
+
+       return sign_extend32(ret, 7);
+}
+
+static int stk8312_read_raw(struct iio_dev *indio_dev,
+                           struct iio_chan_spec const *chan,
+                           int *val, int *val2, long mask)
+{
+       struct stk8312_data *data = iio_priv(indio_dev);
+
+       if (chan->type != IIO_ACCEL)
+               return -EINVAL;
+
+       switch (mask) {
+       case IIO_CHAN_INFO_RAW:
+               mutex_lock(&data->lock);
+               *val = stk8312_read_accel(data, chan->address);
+               mutex_unlock(&data->lock);
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_SCALE:
+               *val = stk8312_scale_table[data->range - 1][0];
+               *val2 = stk8312_scale_table[data->range - 1][1];
+               return IIO_VAL_INT_PLUS_MICRO;
+       }
+
+       return -EINVAL;
+}
+
+static int stk8312_write_raw(struct iio_dev *indio_dev,
+                            struct iio_chan_spec const *chan,
+                            int val, int val2, long mask)
+{
+       int i;
+       int index = -1;
+       int ret;
+       struct stk8312_data *data = iio_priv(indio_dev);
+
+       switch (mask) {
+       case IIO_CHAN_INFO_SCALE:
+               for (i = 0; i < ARRAY_SIZE(stk8312_scale_table); i++)
+                       if (val == stk8312_scale_table[i][0] &&
+                           val2 == stk8312_scale_table[i][1]) {
+                               index = i + 1;
+                               break;
+                       }
+               if (index < 0)
+                       return -EINVAL;
+
+               mutex_lock(&data->lock);
+               ret = stk8312_set_range(data, index);
+               mutex_unlock(&data->lock);
+
+               return ret;
+       }
+
+       return -EINVAL;
+}
+
+static const struct iio_info stk8312_info = {
+       .driver_module          = THIS_MODULE,
+       .read_raw               = stk8312_read_raw,
+       .write_raw              = stk8312_write_raw,
+       .attrs                  = &stk8312_attribute_group,
+};
+
+static int stk8312_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+       int ret;
+       struct iio_dev *indio_dev;
+       struct stk8312_data *data;
+
+       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+       if (!indio_dev) {
+               dev_err(&client->dev, "iio allocation failed!\n");
+               return -ENOMEM;
+       }
+
+       data = iio_priv(indio_dev);
+       data->client = client;
+       i2c_set_clientdata(client, indio_dev);
+       mutex_init(&data->lock);
+
+       indio_dev->dev.parent = &client->dev;
+       indio_dev->info = &stk8312_info;
+       indio_dev->name = STK8312_DRIVER_NAME;
+       indio_dev->modes = INDIO_DIRECT_MODE;
+       indio_dev->channels = stk8312_channels;
+       indio_dev->num_channels = ARRAY_SIZE(stk8312_channels);
+
+       /* A software reset is recommended at power-on */
+       ret = i2c_smbus_write_byte_data(data->client, STK8312_REG_RESET, 0x00);
+       if (ret < 0) {
+               dev_err(&client->dev, "failed to reset sensor\n");
+               return ret;
+       }
+       ret = stk8312_set_range(data, 1);
+       if (ret < 0)
+               return ret;
+
+       ret = stk8312_set_mode(data, STK8312_MODE_ACTIVE);
+       if (ret < 0)
+               return ret;
+
+       ret = iio_device_register(indio_dev);
+       if (ret < 0) {
+               dev_err(&client->dev, "device_register failed\n");
+               stk8312_set_mode(data, STK8312_MODE_STANDBY);
+       }
+
+       return ret;
+}
+
+static int stk8312_remove(struct i2c_client *client)
+{
+       struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+       iio_device_unregister(indio_dev);
+
+       return stk8312_set_mode(iio_priv(indio_dev), STK8312_MODE_STANDBY);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int stk8312_suspend(struct device *dev)
+{
+       struct stk8312_data *data;
+
+       data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+       return stk8312_set_mode(data, STK8312_MODE_STANDBY);
+}
+
+static int stk8312_resume(struct device *dev)
+{
+       struct stk8312_data *data;
+
+       data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+       return stk8312_set_mode(data, STK8312_MODE_ACTIVE);
+}
+
+static SIMPLE_DEV_PM_OPS(stk8312_pm_ops, stk8312_suspend, stk8312_resume);
+
+#define STK8312_PM_OPS (&stk8312_pm_ops)
+#else
+#define STK8312_PM_OPS NULL
+#endif
+
+static const struct i2c_device_id stk8312_i2c_id[] = {
+       {"STK8312", 0},
+       {}
+};
+
+static const struct acpi_device_id stk8312_acpi_id[] = {
+       {"STK8312", 0},
+       {}
+};
+
+MODULE_DEVICE_TABLE(acpi, stk8312_acpi_id);
+
+static struct i2c_driver stk8312_driver = {
+       .driver = {
+               .name = "stk8312",
+               .pm = STK8312_PM_OPS,
+               .acpi_match_table = ACPI_PTR(stk8312_acpi_id),
+       },
+       .probe =            stk8312_probe,
+       .remove =           stk8312_remove,
+       .id_table =         stk8312_i2c_id,
+};
+
+module_i2c_driver(stk8312_driver);
+
+MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
+MODULE_DESCRIPTION("STK8312 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");