iio: light: Add support for Sensortek STK3310

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.
- power management

Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 483 insertions, 0 deletions

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index a437bad..3d7bafa 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -175,6 +175,17 @@ 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..0f8c450
--- /dev/null
+++ b/drivers/iio/light/stk3310.c
@@ -0,0 +1,471 @@
+/**
+ * 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/regmap.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_PS_DATA_LSB			0x12
+#define STK3310_REG_ALS_DATA_MSB		0x13
+#define STK3310_REG_ALS_DATA_LSB		0x14
+#define STK3310_REG_ID				0x3E
+#define STK3310_MAX_REG				0x80
+
+#define STK3310_STATE_EN_PS			0x01
+#define STK3310_STATE_EN_ALS			0x02
+#define STK3310_STATE_STANDBY			0x00
+
+#define STK3310_CHIP_ID_VAL			0x13
+#define STK3311_CHIP_ID_VAL			0x1D
+#define STK3310_PS_MAX_VAL			0xFFFF
+
+#define STK3310_DRIVER_NAME			"stk3310"
+#define STK3310_REGMAP_NAME			"stk3310_regmap"
+
+#define STK3310_SCALE_AVAILABLE			"6.4 1.6 0.4 0.1"
+
+#define STK3310_IT_AVAILABLE \
+	"0.000185 0.000370 0.000741 0.001480 0.002960 0.005920 0.011840 " \
+	"0.023680 0.047360 0.094720 0.189440 0.378880 0.757760 1.515520 " \
+	"3.031040 6.062080"
+
+#define STK3310_REGFIELD(name)						    \
+	do {								    \
+		data->reg_##name =					    \
+			devm_regmap_field_alloc(&client->dev, regmap,	    \
+				stk3310_reg_field_##name);		    \
+		if (IS_ERR(data->reg_##name)) {				    \
+			dev_err(&client->dev, "reg field alloc failed.\n"); \
+			return PTR_ERR(data->reg_##name);		    \
+		}							    \
+	} while (0)
+
+static const struct reg_field stk3310_reg_field_state =
+				REG_FIELD(STK3310_REG_STATE, 0, 2);
+static const struct reg_field stk3310_reg_field_als_gain =
+				REG_FIELD(STK3310_REG_ALSCTRL, 4, 5);
+static const struct reg_field stk3310_reg_field_ps_gain =
+				REG_FIELD(STK3310_REG_PSCTRL, 4, 5);
+static const struct reg_field stk3310_reg_field_als_it =
+				REG_FIELD(STK3310_REG_ALSCTRL, 0, 3);
+static const struct reg_field stk3310_reg_field_ps_it =
+				REG_FIELD(STK3310_REG_PSCTRL, 0, 3);
+
+/*
+ * 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, 185},	{0, 370},	{0, 741},	{0, 1480},
+	{0, 2960},	{0, 5920},	{0, 11840},	{0, 23680},
+	{0, 47360},	{0, 94720},	{0, 189440},	{0, 378880},
+	{0, 757760},	{1, 515520},	{3, 31040},	{6, 62080},
+};
+
+struct stk3310_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	bool als_enabled;
+	bool ps_enabled;
+	struct regmap *regmap;
+	struct regmap_field *reg_state;
+	struct regmap_field *reg_als_gain;
+	struct regmap_field *reg_ps_gain;
+	struct regmap_field *reg_als_it;
+	struct regmap_field *reg_ps_it;
+};
+
+static const struct iio_chan_spec stk3310_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME),
+	},
+	{
+		.type = IIO_PROXIMITY,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME),
+	}
+};
+
+static IIO_CONST_ATTR(in_illuminance_scale_available, STK3310_SCALE_AVAILABLE);
+
+static IIO_CONST_ATTR(in_proximity_scale_available, STK3310_SCALE_AVAILABLE);
+
+static IIO_CONST_ATTR(in_illuminance_integration_time_available,
+		      STK3310_IT_AVAILABLE);
+
+static IIO_CONST_ATTR(in_proximity_integration_time_available,
+		      STK3310_IT_AVAILABLE);
+
+static struct attribute *stk3310_attributes[] = {
+	&iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
+	&iio_const_attr_in_proximity_scale_available.dev_attr.attr,
+	&iio_const_attr_in_illuminance_integration_time_available.dev_attr.attr,
+	&iio_const_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_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	u8 reg;
+	u16 buf;
+	int ret;
+	unsigned int index;
+	struct stk3310_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type == IIO_LIGHT)
+			reg = STK3310_REG_ALS_DATA_MSB;
+		else if (chan->type == IIO_PROXIMITY)
+			reg = STK3310_REG_PS_DATA_MSB;
+		else
+			return -EINVAL;
+		mutex_lock(&data->lock);
+		ret = regmap_bulk_read(data->regmap, reg, &buf, 2);
+		if (ret < 0) {
+			dev_err(&client->dev, "register read failed\n");
+			mutex_unlock(&data->lock);
+			return ret;
+		}
+		*val = swab16(buf);
+		if (chan->type == IIO_PROXIMITY) {
+			/*
+			 * Invert the proximity data so we return low values
+			 * for close objects and high values for far ones.
+			 */
+			regmap_field_read(data->reg_ps_gain, &index);
+			*val = stk3310_ps_max[index] - *val;
+		}
+		mutex_unlock(&data->lock);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_INT_TIME:
+		if (chan->type == IIO_LIGHT)
+			regmap_field_read(data->reg_als_it, &index);
+		else
+			regmap_field_read(data->reg_ps_it, &index);
+		*val = stk3310_it_table[index][0];
+		*val2 = stk3310_it_table[index][1];
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_LIGHT)
+			regmap_field_read(data->reg_als_gain, &index);
+		else
+			regmap_field_read(data->reg_ps_gain, &index);
+		*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;
+	unsigned int index;
+	struct stk3310_data *data = iio_priv(indio_dev);
+
+	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);
+		if (chan->type == IIO_LIGHT)
+			ret = regmap_field_write(data->reg_als_it, index);
+		else
+			ret = regmap_field_write(data->reg_ps_it, index);
+		if (ret < 0)
+			dev_err(&data->client->dev,
+					"sensor configuration failed\n");
+		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);
+		if (chan->type == IIO_LIGHT)
+			ret = regmap_field_write(data->reg_als_gain, index);
+		else
+			ret = regmap_field_write(data->reg_ps_gain, index);
+		if (ret < 0)
+			dev_err(&data->client->dev,
+					"sensor configuration failed\n");
+		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_set_state(struct stk3310_data *data, u8 state)
+{
+	int ret;
+	struct i2c_client *client = data->client;
+
+	/* 3-bit state; 0b100 is not supported. */
+	if (state > 7 || state == 4)
+		return -EINVAL;
+
+	mutex_lock(&data->lock);
+	ret = regmap_field_write(data->reg_state, state);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to change sensor state\n");
+	} else if (state != STK3310_STATE_STANDBY) {
+		/* Don't reset the 'enabled' flags if we're going in standby */
+		data->ps_enabled  = !!(state & 0x01);
+		data->als_enabled = !!(state & 0x02);
+	}
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int stk3310_init(struct iio_dev *indio_dev)
+{
+	int ret;
+	int chipid;
+	u8 state;
+	struct stk3310_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+
+	regmap_read(data->regmap, STK3310_REG_ID, &chipid);
+	if (chipid != STK3310_CHIP_ID_VAL &&
+	    chipid != STK3311_CHIP_ID_VAL) {
+		dev_err(&client->dev, "invalid chip id: 0x%x\n", chipid);
+		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;
+}
+
+static bool stk3310_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case STK3310_REG_ALS_DATA_MSB:
+	case STK3310_REG_ALS_DATA_LSB:
+	case STK3310_REG_PS_DATA_LSB:
+	case STK3310_REG_PS_DATA_MSB:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static struct regmap_config stk3310_regmap_config = {
+	.name = STK3310_REGMAP_NAME,
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = STK3310_MAX_REG,
+	.cache_type = REGCACHE_RBTREE,
+	.volatile_reg = stk3310_is_volatile_reg,
+};
+
+static int stk3310_regmap_init(struct stk3310_data *data)
+{
+	struct regmap *regmap;
+	struct i2c_client *client;
+
+	client = data->client;
+	regmap = devm_regmap_init_i2c(client, &stk3310_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "regmap initialization failed.\n");
+		return PTR_ERR(regmap);
+	}
+	data->regmap = regmap;
+
+	STK3310_REGFIELD(state);
+	STK3310_REGFIELD(als_gain);
+	STK3310_REGFIELD(ps_gain);
+	STK3310_REGFIELD(als_it);
+	STK3310_REGFIELD(ps_it);
+
+	return 0;
+}
+
+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);
+
+	ret = stk3310_regmap_init(data);
+	if (ret < 0)
+		return ret;
+
+	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)
+		return ret;
+
+	ret = iio_device_register(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);
+
+	iio_device_unregister(indio_dev);
+	return stk3310_set_state(iio_priv(indio_dev), STK3310_STATE_STANDBY);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int stk3310_suspend(struct device *dev)
+{
+	struct stk3310_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return stk3310_set_state(data, STK3310_STATE_STANDBY);
+}
+
+static int stk3310_resume(struct device *dev)
+{
+	int state = 0;
+	struct stk3310_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+	if (data->ps_enabled)
+		state |= STK3310_STATE_EN_PS;
+	if (data->als_enabled)
+		state |= STK3310_STATE_EN_ALS;
+
+	return stk3310_set_state(data, state);
+}
+
+static SIMPLE_DEV_PM_OPS(stk3310_pm_ops, stk3310_suspend, stk3310_resume);
+
+#define STK3310_PM_OPS (&stk3310_pm_ops)
+#else
+#define STK3310_PM_OPS NULL
+#endif
+
+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",
+		.pm = STK3310_PM_OPS,
+		.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");