iio: Add Dyna-Image AL3320A ambient light sensor driver

Minimal implementation. This driver provides raw illuminance readings.

This is based on drivers/hwmon/al3320.c (*) driver from msm tree written
by Tsechih Lin <[e-mail]>

* https://android.googlesource.com/kernel/msm.git

Signed-off-by: Daniel Baluta <[e-mail]>
Reviewed-by: Hartmut Knaack <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/light/Kconfig

···
 	 This driver can also be built as a module.  If so, the module
 	 will be called adjd_s311.
 
+config AL3320A
+	tristate "AL3320A ambient light sensor"
+	depends on I2C
+	help
+	 Say Y here if you want to build a driver for the Dyna Image AL3320A
+	 ambient light sensor.
+
+	 To compile this driver as a module, choose M here: the
+	 module will be called al3320a.
+
 config APDS9300
 	tristate "APDS9300 ambient light sensor"
 	depends on I2C

drivers/iio/light/Makefile

···
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
+obj-$(CONFIG_AL3320A)		+= al3320a.o
 obj-$(CONFIG_APDS9300)		+= apds9300.o
 obj-$(CONFIG_CM32181)		+= cm32181.o
 obj-$(CONFIG_CM36651)		+= cm36651.o

drivers/iio/light/al3320a.c

···
+/*
+ * AL3320A - Dyna Image Ambient Light Sensor
+ *
+ * Copyright (c) 2014, 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 AL3320A (7-bit I2C slave address 0x1C).
+ *
+ * TODO: interrupt support, thresholds
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define AL3320A_DRV_NAME "al3320a"
+
+#define AL3320A_REG_CONFIG		0x00
+#define AL3320A_REG_STATUS		0x01
+#define AL3320A_REG_INT			0x02
+#define AL3320A_REG_WAIT		0x06
+#define AL3320A_REG_CONFIG_RANGE	0x07
+#define AL3320A_REG_PERSIST		0x08
+#define AL3320A_REG_MEAN_TIME		0x09
+#define AL3320A_REG_ADUMMY		0x0A
+#define AL3320A_REG_DATA_LOW		0x22
+
+#define AL3320A_REG_LOW_THRESH_LOW	0x30
+#define AL3320A_REG_LOW_THRESH_HIGH	0x31
+#define AL3320A_REG_HIGH_THRESH_LOW	0x32
+#define AL3320A_REG_HIGH_THRESH_HIGH	0x33
+
+#define AL3320A_CONFIG_DISABLE		0x00
+#define AL3320A_CONFIG_ENABLE		0x01
+
+#define AL3320A_GAIN_SHIFT		1
+#define AL3320A_GAIN_MASK		(BIT(2) | BIT(1))
+
+/* chip params default values */
+#define AL3320A_DEFAULT_MEAN_TIME	4
+#define AL3320A_DEFAULT_WAIT_TIME	0 /* no waiting */
+
+#define AL3320A_SCALE_AVAILABLE "0.512 0.128 0.032 0.01"
+
+enum al3320a_range {
+	AL3320A_RANGE_1, /* 33.28 Klx */
+	AL3320A_RANGE_2, /* 8.32 Klx  */
+	AL3320A_RANGE_3, /* 2.08 Klx  */
+	AL3320A_RANGE_4  /* 0.65 Klx  */
+};
+
+static const int al3320a_scales[][2] = {
+	{0, 512000}, {0, 128000}, {0, 32000}, {0, 10000}
+};
+
+struct al3320a_data {
+	struct i2c_client *client;
+};
+
+static const struct iio_chan_spec al3320a_channels[] = {
+	{
+		.type	= IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+	}
+};
+
+static IIO_CONST_ATTR(in_illuminance_scale_available, AL3320A_SCALE_AVAILABLE);
+
+static struct attribute *al3320a_attributes[] = {
+	&iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group al3320a_attribute_group = {
+	.attrs = al3320a_attributes,
+};
+
+static int al3320a_init(struct al3320a_data *data)
+{
+	int ret;
+
+	/* power on */
+	ret = i2c_smbus_write_byte_data(data->client, AL3320A_REG_CONFIG,
+					AL3320A_CONFIG_ENABLE);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte_data(data->client, AL3320A_REG_CONFIG_RANGE,
+					AL3320A_RANGE_3 << AL3320A_GAIN_SHIFT);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte_data(data->client, AL3320A_REG_MEAN_TIME,
+					AL3320A_DEFAULT_MEAN_TIME);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_write_byte_data(data->client, AL3320A_REG_WAIT,
+					AL3320A_DEFAULT_WAIT_TIME);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int al3320a_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct al3320a_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * ALS ADC value is stored in two adjacent registers:
+		 * - low byte of output is stored at AL3320A_REG_DATA_LOW
+		 * - high byte of output is stored at AL3320A_REG_DATA_LOW + 1
+		 */
+		ret = i2c_smbus_read_word_data(data->client,
+					       AL3320A_REG_DATA_LOW);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		ret = i2c_smbus_read_byte_data(data->client,
+					       AL3320A_REG_CONFIG_RANGE);
+		if (ret < 0)
+			return ret;
+
+		ret = (ret & AL3320A_GAIN_MASK) >> AL3320A_GAIN_SHIFT;
+		*val = al3320a_scales[ret][0];
+		*val2 = al3320a_scales[ret][1];
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+	return -EINVAL;
+}
+
+static int al3320a_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct al3320a_data *data = iio_priv(indio_dev);
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		for (i = 0; i < ARRAY_SIZE(al3320a_scales); i++) {
+			if (val == al3320a_scales[i][0] &&
+			    val2 == al3320a_scales[i][1])
+				return i2c_smbus_write_byte_data(data->client,
+					AL3320A_REG_CONFIG_RANGE,
+					i << AL3320A_GAIN_SHIFT);
+		}
+		break;
+	}
+	return -EINVAL;
+}
+
+static const struct iio_info al3320a_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= al3320a_read_raw,
+	.write_raw	= al3320a_write_raw,
+	.attrs		= &al3320a_attribute_group,
+};
+
+static int al3320a_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct al3320a_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;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &al3320a_info;
+	indio_dev->name = AL3320A_DRV_NAME;
+	indio_dev->channels = al3320a_channels;
+	indio_dev->num_channels = ARRAY_SIZE(al3320a_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = al3320a_init(data);
+	if (ret < 0) {
+		dev_err(&client->dev, "al3320a chip init failed\n");
+		return ret;
+	}
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static int al3320a_remove(struct i2c_client *client)
+{
+	return i2c_smbus_write_byte_data(client, AL3320A_REG_CONFIG,
+					 AL3320A_CONFIG_DISABLE);
+}
+
+static const struct i2c_device_id al3320a_id[] = {
+	{"al3320a", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, al3320a_id);
+
+static struct i2c_driver al3320a_driver = {
+	.driver = {
+		.name = AL3320A_DRV_NAME,
+	},
+	.probe		= al3320a_probe,
+	.remove		= al3320a_remove,
+	.id_table	= al3320a_id,
+};
+
+module_i2c_driver(al3320a_driver);
+
+MODULE_AUTHOR("Daniel Baluta <[e-mail]>");
+MODULE_DESCRIPTION("AL3320A Ambient Light Sensor driver");
+MODULE_LICENSE("GPL v2");