iio: Add tcs3472 color light sensor driver

chip has four 16-bit channels for red, green, blue, clear color
intensity; driver supports the TCS3x7x family of devices and was
tested with a TCS34725 chip; further information here:
http://www.ams.com/eng/Products/Light-Sensors/Color-Sensor/TCS34725

v2 (thanks to Jonathan Cameron):
* drop dynamic buffer allocation, buffer is in tcs3472_data
* limit sysfs output to PAGE_SIZE
* check val2 == 0 when writing CALIBSCALE

Signed-off-by: Peter Meerwald <[e-mail]>
Cc: Jon Brenner <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/light/Kconfig

···
 	  changes. The ALS-control output values can be set per zone for the
 	  three current output channels.
 
+config TCS3472
+	tristate "TAOS TCS3472 color light-to-digital converter"
+	depends on I2C
+	help
+	 If you say yes here you get support for the TAOS TCS3472
+	 family of color light-to-digital converters with IR filter.
+
+	 This driver can also be built as a module.  If so, the module
+	 will be called tcs3472.
+
 config SENSORS_TSL2563
 	tristate "TAOS TSL2560, TSL2561, TSL2562 and TSL2563 ambient light sensors"
 	depends on I2C

drivers/iio/light/Makefile

···
 obj-$(CONFIG_HID_SENSOR_ALS)	+= hid-sensor-als.o
 obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
 obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
+obj-$(CONFIG_TCS3472)		+= tcs3472.o
 obj-$(CONFIG_TSL4531)		+= tsl4531.o
 obj-$(CONFIG_VCNL4000)		+= vcnl4000.o

drivers/iio/light/tcs3472.c

···
+/*
+ * tcs3472.c - Support for TAOS TCS3472 color light-to-digital converter
+ *
+ * Copyright (c) 2013 Peter Meerwald <[e-mail]>
+ *
+ * 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.
+ *
+ * Color light sensor with 16-bit channels for red, green, blue, clear);
+ * 7-bit I2C slave address 0x39 (TCS34721, TCS34723) or 0x29 (TCS34725,
+ * TCS34727)
+ *
+ * TODO: interrupt support, thresholds, wait time
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/pm.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define TCS3472_DRV_NAME "tcs3472"
+
+#define TCS3472_COMMAND BIT(7)
+#define TCS3472_AUTO_INCR BIT(5)
+
+#define TCS3472_ENABLE (TCS3472_COMMAND | 0x00)
+#define TCS3472_ATIME (TCS3472_COMMAND | 0x01)
+#define TCS3472_WTIME (TCS3472_COMMAND | 0x03)
+#define TCS3472_AILT (TCS3472_COMMAND | 0x04)
+#define TCS3472_AIHT (TCS3472_COMMAND | 0x06)
+#define TCS3472_PERS (TCS3472_COMMAND | 0x0c)
+#define TCS3472_CONFIG (TCS3472_COMMAND | 0x0d)
+#define TCS3472_CONTROL (TCS3472_COMMAND | 0x0f)
+#define TCS3472_ID (TCS3472_COMMAND | 0x12)
+#define TCS3472_STATUS (TCS3472_COMMAND | 0x13)
+#define TCS3472_CDATA (TCS3472_COMMAND | TCS3472_AUTO_INCR | 0x14)
+#define TCS3472_RDATA (TCS3472_COMMAND | TCS3472_AUTO_INCR | 0x16)
+#define TCS3472_GDATA (TCS3472_COMMAND | TCS3472_AUTO_INCR | 0x18)
+#define TCS3472_BDATA (TCS3472_COMMAND | TCS3472_AUTO_INCR | 0x1a)
+
+#define TCS3472_STATUS_AVALID BIT(0)
+#define TCS3472_ENABLE_AEN BIT(1)
+#define TCS3472_ENABLE_PON BIT(0)
+#define TCS3472_CONTROL_AGAIN_MASK (BIT(0) | BIT(1))
+
+struct tcs3472_data {
+	struct i2c_client *client;
+	u8 enable;
+	u8 control;
+	u8 atime;
+	u16 buffer[4];
+};
+
+/* 4 16-bit channels + timestamp = 16 bytes */
+#define TSL3472_BUFFER_SIZE 16
+
+#define TCS3472_CHANNEL(_color, _si, _addr) { \
+	.type = IIO_INTENSITY, \
+	.modified = 1, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBSCALE) | \
+		BIT(IIO_CHAN_INFO_INT_TIME), \
+	.channel2 = IIO_MOD_LIGHT_##_color, \
+	.address = _addr, \
+	.scan_index = _si, \
+	.scan_type = IIO_ST('u', 16, 16, 0), \
+}
+
+static const int tcs3472_agains[] = { 1, 4, 16, 60 };
+
+static const struct iio_chan_spec tcs3472_channels[] = {
+	TCS3472_CHANNEL(CLEAR, 0, TCS3472_CDATA),
+	TCS3472_CHANNEL(RED, 1, TCS3472_RDATA),
+	TCS3472_CHANNEL(GREEN, 2, TCS3472_GDATA),
+	TCS3472_CHANNEL(BLUE, 3, TCS3472_BDATA),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static int tcs3472_req_data(struct tcs3472_data *data)
+{
+	int tries = 50;
+	int ret;
+
+	while (tries--) {
+		ret = i2c_smbus_read_byte_data(data->client, TCS3472_STATUS);
+		if (ret < 0)
+			return ret;
+		if (ret & TCS3472_STATUS_AVALID)
+			break;
+		msleep(20);
+	}
+
+	if (tries < 0) {
+		dev_err(&data->client->dev, "data not ready\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int tcs3472_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct tcs3472_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = tcs3472_req_data(data);
+		if (ret < 0)
+			return ret;
+		ret = i2c_smbus_read_word_data(data->client, chan->address);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		*val = tcs3472_agains[data->control &
+			TCS3472_CONTROL_AGAIN_MASK];
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = (256 - data->atime) * 2400;
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+	return -EINVAL;
+}
+
+static int tcs3472_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int val, int val2, long mask)
+{
+	struct tcs3472_data *data = iio_priv(indio_dev);
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBSCALE:
+		if (val2 != 0)
+			return -EINVAL;
+		for (i = 0; i < ARRAY_SIZE(tcs3472_agains); i++) {
+			if (val == tcs3472_agains[i]) {
+				data->control &= ~TCS3472_CONTROL_AGAIN_MASK;
+				data->control |= i;
+				return i2c_smbus_write_byte_data(
+					data->client, TCS3472_CONTROL,
+					data->control);
+			}
+		}
+		return -EINVAL;
+	case IIO_CHAN_INFO_INT_TIME:
+		if (val != 0)
+			return -EINVAL;
+		for (i = 0; i < 256; i++) {
+			if (val2 == (256 - i) * 2400) {
+				data->atime = i;
+				return i2c_smbus_write_word_data(
+					data->client, TCS3472_ATIME,
+					data->atime);
+			}
+
+		}
+		return -EINVAL;
+	}
+	return -EINVAL;
+}
+
+static irqreturn_t tcs3472_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct tcs3472_data *data = iio_priv(indio_dev);
+	int len = 0;
+	int i, j = 0;
+
+	int ret = tcs3472_req_data(data);
+	if (ret < 0)
+		goto done;
+
+	for_each_set_bit(i, indio_dev->active_scan_mask,
+		indio_dev->masklength) {
+		ret = i2c_smbus_read_word_data(data->client,
+			TCS3472_CDATA + 2*i);
+		if (ret < 0)
+			goto done;
+
+		data->buffer[j++] = ret;
+		len += 2;
+	}
+
+	if (indio_dev->scan_timestamp)
+		*(s64 *)((u8 *)data->buffer + ALIGN(len, sizeof(s64)))
+			= iio_get_time_ns();
+	iio_push_to_buffers(indio_dev, (u8 *)data->buffer);
+
+done:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static ssize_t tcs3472_show_int_time_available(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	size_t len = 0;
+	int i;
+
+	for (i = 1; i <= 256; i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06d ",
+			2400 * i);
+
+	/* replace trailing space by newline */
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static IIO_CONST_ATTR(calibscale_available, "1 4 16 60");
+static IIO_DEV_ATTR_INT_TIME_AVAIL(tcs3472_show_int_time_available);
+
+static struct attribute *tcs3472_attributes[] = {
+	&iio_const_attr_calibscale_available.dev_attr.attr,
+	&iio_dev_attr_integration_time_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group tcs3472_attribute_group = {
+	.attrs = tcs3472_attributes,
+};
+
+static const struct iio_info tcs3472_info = {
+	.read_raw = tcs3472_read_raw,
+	.write_raw = tcs3472_write_raw,
+	.attrs = &tcs3472_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+static int tcs3472_probe(struct i2c_client *client,
+			   const struct i2c_device_id *id)
+{
+	struct tcs3472_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (indio_dev == NULL)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &tcs3472_info;
+	indio_dev->name = TCS3472_DRV_NAME;
+	indio_dev->channels = tcs3472_channels;
+	indio_dev->num_channels = ARRAY_SIZE(tcs3472_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = i2c_smbus_read_byte_data(data->client, TCS3472_ID);
+	if (ret < 0)
+		return ret;
+
+	if (ret == 0x44)
+		dev_info(&client->dev, "TCS34721/34725 found\n");
+	else if (ret == 0x4d)
+		dev_info(&client->dev, "TCS34723/34727 found\n");
+	else
+		return -ENODEV;
+
+	ret = i2c_smbus_read_byte_data(data->client, TCS3472_CONTROL);
+	if (ret < 0)
+		return ret;
+	data->control = ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, TCS3472_ATIME);
+	if (ret < 0)
+		return ret;
+	data->atime = ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, TCS3472_ENABLE);
+	if (ret < 0)
+		return ret;
+
+	/* enable device */
+	data->enable = ret | TCS3472_ENABLE_PON | TCS3472_ENABLE_AEN;
+	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
+		data->enable);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+		tcs3472_trigger_handler, NULL);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto buffer_cleanup;
+
+	return 0;
+
+buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+	return ret;
+}
+
+static int tcs3472_powerdown(struct tcs3472_data *data)
+{
+	return i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
+		data->enable & ~(TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON));
+}
+
+static int tcs3472_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	tcs3472_powerdown(iio_priv(indio_dev));
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int tcs3472_suspend(struct device *dev)
+{
+	return tcs3472_powerdown(iio_priv(dev_to_iio_dev(dev)));
+}
+
+static int tcs3472_resume(struct device *dev)
+{
+	struct tcs3472_data *data = iio_priv(dev_to_iio_dev(dev));
+	return i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
+		data->enable | (TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON));
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(tcs3472_pm_ops, tcs3472_suspend, tcs3472_resume);
+
+static const struct i2c_device_id tcs3472_id[] = {
+	{ "tcs3472", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tcs3472_id);
+
+static struct i2c_driver tcs3472_driver = {
+	.driver = {
+		.name	= TCS3472_DRV_NAME,
+		.pm	= &tcs3472_pm_ops,
+		.owner	= THIS_MODULE,
+	},
+	.probe		= tcs3472_probe,
+	.remove		= tcs3472_remove,
+	.id_table	= tcs3472_id,
+};
+module_i2c_driver(tcs3472_driver);
+
+MODULE_AUTHOR("Peter Meerwald <[e-mail]>");
+MODULE_DESCRIPTION("TCS3472 color light sensors driver");
+MODULE_LICENSE("GPL");