[PATCH 1/3] iio: light: Add support for Sensortek STK3310

[Tiberiu Breana <tiberiu.a.breana@intel.com>]

Minimal implementation of an IIO driver for the Sensortek
STK3310 ambient light and proximity sensor. The STK3311
model is also supported.

Includes:
- ACPI support;
- read_raw and write_raw;
- reading and setting configuration parameters for gain/scale
  and integration time for both ALS and PS.

Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
---
 drivers/iio/light/Kconfig   |  11 +
 drivers/iio/light/Makefile  |   1 +
 drivers/iio/light/stk3310.c | 492 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 504 insertions(+)
 create mode 100644 drivers/iio/light/stk3310.c

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 01a1a16..096129d 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -174,6 +174,17 @@ config LTR501
 	 This driver can also be built as a module.  If so, the module
          will be called ltr501.
 
+config STK3310
+	tristate "STK3310 ALS and proximity sensor"
+	depends on I2C
+	help
+	 Say yes here to get support for the Sensortek STK3310 ambient light
+	 and proximity sensor. The STK3311 model is also supported by this
+	 driver.
+
+	 Choosing M will build the driver as a module. If so, the module
+	 will be called stk3310.
+
 config TCS3414
 	tristate "TAOS TCS3414 digital color sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index ad7c30f..90e7fd2 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_JSA1212)		+= jsa1212.o
 obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
 obj-$(CONFIG_LTR501)		+= ltr501.o
 obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
+obj-$(CONFIG_STK3310)          += stk3310.o
 obj-$(CONFIG_TCS3414)		+= tcs3414.o
 obj-$(CONFIG_TCS3472)		+= tcs3472.o
 obj-$(CONFIG_TSL4531)		+= tsl4531.o
diff --git a/drivers/iio/light/stk3310.c b/drivers/iio/light/stk3310.c
new file mode 100644
index 0000000..5bcf5a0
--- /dev/null
+++ b/drivers/iio/light/stk3310.c
@@ -0,0 +1,492 @@
+/**
+ * Sensortek STK3310/STK3311 Ambient Light and Proximity Sensor
+ *
+ * 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 STK3310/STK3311. 7-bit I2C address: 0x48.
+ */
+
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define STK3310_REG_STATE			0x00
+#define STK3310_REG_PSCTRL			0x01
+#define STK3310_REG_ALSCTRL			0x02
+#define STK3310_REG_PS_DATA_MSB			0x11
+#define STK3310_REG_ALS_DATA_MSB		0x13
+#define STK3310_REG_PDT_ID			0x3E
+
+#define STK3310_STATE_EN_PS			0x01
+#define STK3310_STATE_EN_ALS			0x02
+#define STK3310_STATE_STANDBY			0x00
+#define STK3310_STATE_MASK			0x07
+
+#define STK3310_GAIN_MASK			0x30
+#define STK3310_IT_MASK				0x0F
+#define STK3310_GAIN_SHIFT			4
+#define STK3310_IT_SHIFT			0
+
+#define STK3310_CHIP_ID_VAL			0x13
+#define STK3311_CHIP_ID_VAL			0x1D
+
+#define STK3310_GAIN_MAX			3
+#define STK3310_IT_MAX				15
+#define STK3310_PS_MAX_VAL			0xffff
+
+#define STK3310_SCALE_AVAILABLE			"6.4 1.6 0.4 0.1"
+
+#define STK3310_DRIVER_NAME			"stk3310"
+
+/*
+ * Maximum PS values with regard to scale. Used to export the 'inverse'
+ * PS value (high values for far objects, low values for near objects).
+ */
+static const int stk3310_ps_max[4] = {
+	STK3310_PS_MAX_VAL / 64,
+	STK3310_PS_MAX_VAL / 16,
+	STK3310_PS_MAX_VAL /  4,
+	STK3310_PS_MAX_VAL,
+};
+
+static const int stk3310_scale_table[][2] = {
+	{6, 400000}, {1, 600000}, {0, 400000}, {0, 100000}
+};
+
+/* Integration time in seconds, microseconds */
+static const int stk3310_it_table[][2] = {
+	{0, 185000}, {0, 370000}, {0, 741000}, {0, 148000},
+	{0, 296000}, {0, 592000}, {0, 118400}, {0, 236800},
+	{0, 473600}, {0, 947200}, {0, 189440}, {0, 378880},
+	{0, 757760}, {1, 515520}, {3, 31040},  {6, 62080},
+};
+
+enum stk3310_data_type {
+	STK3310_ALS,
+	STK3310_PS
+};
+
+enum stk3310_config_type {
+	STK3310_GAIN,
+	STK3310_IT,
+	STK3310_TYPE_COUNT
+};
+
+struct stk3310_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	/* Cache table for storing config values */
+	int cache[2][STK3310_TYPE_COUNT];
+};
+
+static const struct iio_chan_spec stk3310_channels[] = {
+	{
+		.channel = 0,
+		.type = IIO_LIGHT,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME),
+	},
+	{
+		.channel = 1,
+		.type = IIO_PROXIMITY,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME),
+	}
+};
+
+static ssize_t stk3310_get_it_vals(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	int i;
+	int len;
+
+	for (i = 0, len = 0; i < ARRAY_SIZE(stk3310_it_table); i++) {
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d.%06d ",
+				stk3310_it_table[i][0],
+				stk3310_it_table[i][1]);
+	}
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static IIO_CONST_ATTR(in_illuminance_scale_available, STK3310_SCALE_AVAILABLE);
+
+static IIO_DEVICE_ATTR(in_illuminance_integration_time_available,
+		       S_IRUGO, stk3310_get_it_vals, NULL, 0);
+
+static IIO_DEVICE_ATTR(in_proximity_integration_time_available,
+		       S_IRUGO, stk3310_get_it_vals, NULL, 0);
+
+static struct attribute *stk3310_attributes[] = {
+	&iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
+	&iio_dev_attr_in_proximity_integration_time_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group stk3310_attribute_group = {
+	.attrs = stk3310_attributes
+};
+
+static int stk3310_get_index(const int table[][2], int table_size,
+			     int val, int val2)
+{
+	int i;
+
+	for (i = 0; i < table_size; i++) {
+		if (val == table[i][0] && val2 == table[i][1])
+			return i;
+	}
+
+	return -EINVAL;
+}
+
+static int stk3310_set_cfg(struct stk3310_data *data,
+			   enum stk3310_data_type type,
+			   enum stk3310_config_type cfg,
+			   u8 val)
+{
+	u8 reg;
+	u8 shift;
+	u8 masked_reg;
+	u8 mask;
+	int ret;
+
+	if (val < 0)
+		return -EINVAL;
+	switch (type) {
+	case STK3310_ALS:
+		reg = STK3310_REG_ALSCTRL;
+		break;
+	case STK3310_PS:
+		reg = STK3310_REG_PSCTRL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	switch (cfg) {
+	case STK3310_GAIN:
+		if (val > STK3310_GAIN_MAX)
+			return -EINVAL;
+		shift = STK3310_GAIN_SHIFT;
+		mask = STK3310_GAIN_MASK;
+		break;
+	case STK3310_IT:
+		if (val > STK3310_IT_MAX)
+			return -EINVAL;
+		shift = STK3310_IT_SHIFT;
+		mask = STK3310_IT_MASK;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = i2c_smbus_read_byte_data(data->client, reg);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "register read failed\n");
+		return ret;
+	}
+	masked_reg = ret & (~mask);
+	masked_reg |= (val << shift);
+
+	ret = i2c_smbus_write_byte_data(data->client, reg, masked_reg);
+	if (ret < 0)
+		dev_err(&data->client->dev, "sensor configuration failed\n");
+	else
+		data->cache[type][cfg] = val;
+
+	return ret;
+}
+
+static int stk3310_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	int ret;
+	int index;
+	u8 reg;
+	enum stk3310_data_type type;
+	struct stk3310_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+
+	switch (chan->type) {
+	case IIO_LIGHT:
+		type = STK3310_ALS;
+		reg = STK3310_REG_ALS_DATA_MSB;
+		break;
+	case IIO_PROXIMITY:
+		type = STK3310_PS;
+		reg = STK3310_REG_PS_DATA_MSB;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->lock);
+		ret = i2c_smbus_read_word_swapped(client, reg);
+		if (ret < 0) {
+			dev_err(&client->dev, "register read failed\n");
+			mutex_unlock(&data->lock);
+			return ret;
+		}
+		*val = ret;
+		index = data->cache[STK3310_ALS][STK3310_GAIN];
+		if (type == STK3310_PS) {
+			/*
+			 * Invert the proximity data so we return low values
+			 * for close objects and high values for far ones.
+			 */
+			index = data->cache[STK3310_PS][STK3310_GAIN];
+			*val = stk3310_ps_max[index] - *val;
+		}
+		mutex_unlock(&data->lock);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_INT_TIME:
+		index = data->cache[type][STK3310_IT];
+		*val = stk3310_it_table[index][0];
+		*val2 = stk3310_it_table[index][1];
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SCALE:
+		index = data->cache[type][STK3310_GAIN];
+		*val = stk3310_scale_table[index][0];
+		*val2 = stk3310_scale_table[index][1];
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+
+	return -EINVAL;
+}
+
+static int stk3310_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	int ret;
+	int index;
+	enum stk3310_data_type type;
+	struct stk3310_data *data = iio_priv(indio_dev);
+
+	switch (chan->type) {
+	case IIO_LIGHT:
+		type = STK3310_ALS;
+		break;
+	case IIO_PROXIMITY:
+		type = STK3310_PS;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		index = stk3310_get_index(stk3310_it_table,
+					  ARRAY_SIZE(stk3310_it_table),
+					  val, val2);
+		if (index < 0)
+			return -EINVAL;
+		mutex_lock(&data->lock);
+		ret = stk3310_set_cfg(data, type, STK3310_IT, index);
+		mutex_unlock(&data->lock);
+		return ret;
+
+	case IIO_CHAN_INFO_SCALE:
+		index = stk3310_get_index(stk3310_scale_table,
+					  ARRAY_SIZE(stk3310_scale_table),
+					  val, val2);
+		if (index < 0)
+			return -EINVAL;
+		mutex_lock(&data->lock);
+		ret = stk3310_set_cfg(data, type, STK3310_GAIN, index);
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info stk3310_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= stk3310_read_raw,
+	.write_raw		= stk3310_write_raw,
+	.attrs			= &stk3310_attribute_group,
+};
+
+static int stk3310_cache_store(struct stk3310_data *data)
+{
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_read_byte_data(data->client, STK3310_REG_ALSCTRL);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "register read failed\n");
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	data->cache[STK3310_ALS][STK3310_GAIN] =
+			(ret & STK3310_GAIN_MASK) >> STK3310_GAIN_SHIFT;
+	data->cache[STK3310_ALS][STK3310_IT] =
+			(ret & STK3310_IT_MASK) >> STK3310_IT_SHIFT;
+
+	ret = i2c_smbus_read_byte_data(data->client, STK3310_REG_PSCTRL);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "register read failed\n");
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	data->cache[STK3310_PS][STK3310_GAIN] =
+			(ret & STK3310_GAIN_MASK) >> STK3310_GAIN_SHIFT;
+	data->cache[STK3310_PS][STK3310_IT] =
+			(ret & STK3310_IT_MASK) >> STK3310_IT_SHIFT;
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int stk3310_set_state(struct stk3310_data *data, u8 state)
+{
+	int ret;
+	int masked_reg;
+	struct i2c_client *client = data->client;
+
+	/* 3-bit state; 0b100 is not supported. */
+	if (state < 0 || state > 7 || state == 4)
+		return -EINVAL;
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_read_byte_data(data->client, STK3310_REG_STATE);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		dev_err(&client->dev, "register read failed\n");
+		return ret;
+	}
+	masked_reg = ret & (~STK3310_STATE_MASK);
+	masked_reg |= state;
+
+	ret = i2c_smbus_write_byte_data(data->client, STK3310_REG_STATE,
+					masked_reg);
+	if (ret < 0)
+		dev_err(&client->dev, "failed to change sensor state\n");
+
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int stk3310_init(struct iio_dev *indio_dev)
+{
+	int ret;
+	u8 state;
+	struct stk3310_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+
+	ret = i2c_smbus_read_byte_data(client, STK3310_REG_PDT_ID);
+	if (ret != STK3310_CHIP_ID_VAL &&
+	    ret != STK3311_CHIP_ID_VAL) {
+		dev_err(&client->dev, "invalid chip id: 0x%x\n", ret);
+		return -ENODEV;
+	}
+
+	state = STK3310_STATE_EN_ALS | STK3310_STATE_EN_PS;
+	ret = stk3310_set_state(data, state);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to enable sensor");
+		return ret;
+	}
+
+	/* Cache the initial configuration values */
+	return stk3310_cache_store(data);
+}
+
+static int stk3310_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct stk3310_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 = &stk3310_info;
+	indio_dev->name = STK3310_DRIVER_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = stk3310_channels;
+	indio_dev->num_channels = ARRAY_SIZE(stk3310_channels);
+
+	ret = stk3310_init(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "sensor initialization failed\n");
+		return ret;
+	}
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "device_register failed\n");
+		stk3310_set_state(data, STK3310_STATE_STANDBY);
+	}
+
+	return ret;
+}
+
+static int stk3310_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct stk3310_data *data = iio_priv(indio_dev);
+
+	return stk3310_set_state(data, STK3310_STATE_STANDBY);
+}
+
+static const struct i2c_device_id stk3310_i2c_id[] = {
+	{"STK3310", 0},
+	{"STK3311", 0},
+	{}
+};
+
+static const struct acpi_device_id stk3310_acpi_id[] = {
+	{"STK3310", 0},
+	{"STK3311", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(acpi, stk3310_acpi_id);
+
+static struct i2c_driver stk3310_driver = {
+	.driver = {
+		.name = "stk3310",
+		.acpi_match_table = ACPI_PTR(stk3310_acpi_id),
+	},
+	.probe =            stk3310_probe,
+	.remove =           stk3310_remove,
+	.id_table =         stk3310_i2c_id,
+};
+
+module_i2c_driver(stk3310_driver);
+
+MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
+MODULE_DESCRIPTION("STK3310 Ambient Light and Proximity Sensor driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1