Minimal implementation of an IIO driver for the Sensortek
STK8312 3-axis accelerometer.
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@xxxxxxxxx>
---
drivers/iio/accel/Kconfig | 11 ++
drivers/iio/accel/Makefile | 2 +
drivers/iio/accel/stk8312.c | 413 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 426 insertions(+)
create mode 100644 drivers/iio/accel/stk8312.c
diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 7c9a9a9..8bd8ccb 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -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
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 99d89e4..8b327c1 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -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
index 0000000..6c7da79
--- /dev/null
+++ b/drivers/iio/accel/stk8312.c
@@ -0,0 +1,413 @@
+/**
+ * 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_ALERT_MASK 0x40
+#define STK8312_DATA6_MASK 0x3F
+#define STK8312_RNG_SHIFT 6
+#define STK8312_READ_RETRIES 16
+
+#define STK8312_DRIVER_NAME "stk8312"
+
+/*
+ * The accelerometer has 3 measurement ranges:
+ *
+ * -1.5g - +1.5g (6 bit, signed)
+ * -6g - +6g (8 bit, signed)
+ * -16g - +16g (8 bit, signed)
+ *
+ * scale0 = (1.5 + 1.5) * 9.81 / (2^6 - 1) = 0.4671
+ * scale1 = (6 + 6) * 9.81 / (2^8 - 1) = 0.4616
+ * scale2 = (16 + 16) * 9.81 / (2^8 - 1) = 1.2311
+ */
+#define STK8312_SCALE_AVAIL "0.4671 0.4616 1.2311"
+
+static const int stk8312_scale_table[][2] = {
+ {0, 467100}, {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 > 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;
+ int retries = STK8312_READ_RETRIES;
+ 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;
+ }
+ if (data->range == 0) {
+ /* 6bit mode */
+ while (retries--) {
+ if (ret & STK8312_ALERT_MASK) {
+ /* The register is being updated. Try again. */
+ msleep(20);
+ ret = i2c_smbus_read_byte_data(client, address);
+ if (ret < 0) {
+ dev_err(&data->client->dev,
+ "register read failed\n");
+ return ret;
+ }
+ } else {
+ ret &= STK8312_DATA6_MASK;
+ return sign_extend32(ret, 5);
+ }
+ }
+ dev_err(&data->client->dev,
+ "register read failed, data not ready\n");
+ return -EIO;
+ }
+ /* 8bit mode */
+ 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][0];
+ *val2 = stk8312_scale_table[data->range][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;
+ 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_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@xxxxxxxxx>");
+MODULE_DESCRIPTION("STK8312 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1
--
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