iio: light: Add support for Capella CM3323 color sensor

Minimal implementation providing raw light intensity and integration time attribute.

Userspace applications can use GREEN channel for raw illuminance readings following this table:

Integration Time | G Sensitivity
================================

40 ms            | 0.18
80 ms            | 0.09
160 ms           | 0.045
320 ms           | 0.0225
640 ms           | 0.01125
1280 ms          | 0.005625

Signed-off-by Daniel Baluta <[email protected]>

---
Changes since v2:
* use iio_device_register instead of devm_* variant, in order to better control call order at remove
* introduce cm3323_disable and call it in error path for cm3323_probe

Changes since v1:
* fixed nits after Peter's review - https://lkml.org/lkml/2015/1/22/196
* removed IIO_LIGHT channel since illuminance can be computed in userspace based on GREEN channel

 drivers/iio/light/Kconfig  |   10 ++
 drivers/iio/light/Makefile |    1 +
 drivers/iio/light/cm3323.c |  286 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 297 insertions(+)
 create mode 100644 drivers/iio/light/cm3323.c

drivers/iio/light/Kconfig +10 -0

index ae68c64..cd937d9 100644
@@ -59,6 +59,16 @@ config CM3232
 	 To compile this driver as a module, choose M here:
 	 the module will be called cm3232.
 
+config CM3323
+	depends on I2C
+	tristate "Capella CM3323 color light sensor"
+	help
+	 Say Y here if you want to build a driver for Capela CM3323
+	 color sensor.
+
+	 To compile this driver as a module, choose M here: the module will
+	 be called cm3323.
+
 config CM36651
 	depends on I2C
 	tristate "CM36651 driver"

drivers/iio/light/Makefile +1 -0

index b12a516..ad7c30f 100644
@@ -8,6 +8,7 @@ obj-$(CONFIG_AL3320A)		+= al3320a.o
 obj-$(CONFIG_APDS9300)		+= apds9300.o
 obj-$(CONFIG_CM32181)		+= cm32181.o
 obj-$(CONFIG_CM3232)		+= cm3232.o
+obj-$(CONFIG_CM3323)		+= cm3323.o
 obj-$(CONFIG_CM36651)		+= cm36651.o
 obj-$(CONFIG_GP2AP020A00F)	+= gp2ap020a00f.o
 obj-$(CONFIG_HID_SENSOR_ALS)	+= hid-sensor-als.o

drivers/iio/light/cm3323.c new file +286 -0

new file mode 100644
index 0000000..869033e
@@ -0,0 +1,286 @@
+/*
+ * CM3323 - Capella Color Light 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 CM3323 (7-bit I2C slave address 0x10)
+ *
+ * TODO: calibscale to correct the lens factor
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define CM3323_DRV_NAME "cm3323"
+
+#define CM3323_CMD_CONF		0x00
+#define CM3323_CMD_RED_DATA	0x08
+#define CM3323_CMD_GREEN_DATA	0x09
+#define CM3323_CMD_BLUE_DATA	0x0A
+#define CM3323_CMD_CLEAR_DATA	0x0B
+
+#define CM3323_CONF_SD_BIT	BIT(0) /* sensor disable */
+#define CM3323_CONF_AF_BIT	BIT(1) /* auto/manual force mode */
+#define CM3323_CONF_IT_MASK	(BIT(4) | BIT(5) | BIT(6))
+#define CM3323_CONF_IT_SHIFT	4
+
+#define CM3323_INT_TIME_AVAILABLE "0.04 0.08 0.16 0.32 0.64 1.28"
+
+static const struct {
+	int val;
+	int val2;
+} cm3323_int_time[] = {
+	{0, 40000},  /* 40 ms */
+	{0, 80000},  /* 80 ms */
+	{0, 160000}, /* 160 ms */
+	{0, 320000}, /* 320 ms */
+	{0, 640000}, /* 640 ms */
+	{1, 280000}, /* 1280 ms */
+};
+
+struct cm3323_data {
+	struct i2c_client *client;
+	u16 reg_conf;
+	struct mutex mutex;
+};
+
+#define CM3323_COLOR_CHANNEL(_color, _addr) { \
+	.type = IIO_INTENSITY, \
+	.modified = 1, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME), \
+	.channel2 = IIO_MOD_LIGHT_##_color, \
+	.address = _addr, \
+}
+
+static const struct iio_chan_spec cm3323_channels[] = {
+	CM3323_COLOR_CHANNEL(RED, CM3323_CMD_RED_DATA),
+	CM3323_COLOR_CHANNEL(GREEN, CM3323_CMD_GREEN_DATA),
+	CM3323_COLOR_CHANNEL(BLUE, CM3323_CMD_BLUE_DATA),
+	CM3323_COLOR_CHANNEL(CLEAR, CM3323_CMD_CLEAR_DATA),
+};
+
+static IIO_CONST_ATTR_INT_TIME_AVAIL(CM3323_INT_TIME_AVAILABLE);
+
+static struct attribute *cm3323_attributes[] = {
+	&iio_const_attr_integration_time_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group cm3323_attribute_group = {
+	.attrs = cm3323_attributes,
+};
+
+static int cm3323_init(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct cm3323_data *data = iio_priv(indio_dev);
+
+	ret = i2c_smbus_read_word_data(data->client, CM3323_CMD_CONF);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Error reading reg_conf\n");
+		return ret;
+	}
+
+	/* enable sensor and set auto force mode */
+	ret &= ~(CM3323_CONF_SD_BIT | CM3323_CONF_AF_BIT);
+
+	ret = i2c_smbus_write_word_data(data->client, CM3323_CMD_CONF, ret);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Error writing reg_conf\n");
+		return ret;
+	}
+
+	data->reg_conf = ret;
+
+	return 0;
+}
+
+static void cm3323_disable(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct cm3323_data *data = iio_priv(indio_dev);
+
+	ret = i2c_smbus_write_word_data(data->client, CM3323_CMD_CONF,
+					CM3323_CONF_SD_BIT);
+	if (ret < 0)
+		dev_err(&data->client->dev, "Error writing reg_conf\n");
+}
+
+static int cm3323_set_it_bits(struct cm3323_data *data, int val, int val2)
+{
+	int i, ret;
+	u16 reg_conf;
+
+	for (i = 0; i < ARRAY_SIZE(cm3323_int_time); i++) {
+		if (val == cm3323_int_time[i].val &&
+		    val2 == cm3323_int_time[i].val2) {
+			reg_conf = data->reg_conf;
+			reg_conf |= i << CM3323_CONF_IT_SHIFT;
+
+			ret = i2c_smbus_write_word_data(data->client,
+							CM3323_CMD_CONF,
+							reg_conf);
+			if (ret < 0)
+				return ret;
+
+			data->reg_conf = reg_conf;
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+
+static int cm3323_get_it_bits(struct cm3323_data *data)
+{
+	int bits;
+
+	bits = (data->reg_conf & CM3323_CONF_IT_MASK) >>
+		CM3323_CONF_IT_SHIFT;
+
+	if (bits >= ARRAY_SIZE(cm3323_int_time))
+		return -EINVAL;
+	return bits;
+}
+
+static int cm3323_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan, int *val,
+			   int *val2, long mask)
+{
+	int i, ret;
+	struct cm3323_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->mutex);
+		ret = i2c_smbus_read_word_data(data->client, chan->address);
+		if (ret < 0) {
+			mutex_unlock(&data->mutex);
+			return ret;
+		}
+		*val = ret;
+		mutex_unlock(&data->mutex);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_INT_TIME:
+		mutex_lock(&data->mutex);
+		i = cm3323_get_it_bits(data);
+		if (i < 0) {
+			mutex_unlock(&data->mutex);
+			return -EINVAL;
+		}
+
+		*val = cm3323_int_time[i].val;
+		*val2 = cm3323_int_time[i].val2;
+		mutex_unlock(&data->mutex);
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int cm3323_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int val,
+			    int val2, long mask)
+{
+	struct cm3323_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		mutex_lock(&data->mutex);
+		ret = cm3323_set_it_bits(data, val, val2);
+		mutex_unlock(&data->mutex);
+
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info cm3323_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= cm3323_read_raw,
+	.write_raw	= cm3323_write_raw,
+	.attrs		= &cm3323_attribute_group,
+};
+
+static int cm3323_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct cm3323_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	mutex_init(&data->mutex);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &cm3323_info;
+	indio_dev->name = CM3323_DRV_NAME;
+	indio_dev->channels = cm3323_channels;
+	indio_dev->num_channels = ARRAY_SIZE(cm3323_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = cm3323_init(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "cm3323 chip init failed\n");
+		return ret;
+	}
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to register iio dev\n");
+		goto err_init;
+	}
+	return 0;
+err_init:
+	cm3323_disable(indio_dev);
+	return ret;
+}
+
+static int cm3323_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+	cm3323_disable(indio_dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id cm3323_id[] = {
+	{"cm3323", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, cm3323_id);
+
+static struct i2c_driver cm3323_driver = {
+	.driver = {
+		.name = CM3323_DRV_NAME,
+	},
+	.probe		= cm3323_probe,
+	.remove		= cm3323_remove,
+	.id_table	= cm3323_id,
+};
+
+module_i2c_driver(cm3323_driver);
+
+MODULE_AUTHOR("Daniel Baluta <[email protected]>");
+MODULE_DESCRIPTION("Capella CM3323 Color Light Sensor driver");
+MODULE_LICENSE("GPL v2");