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 <Tsechih_Lin@asus.com>

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

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 243 insertions, 0 deletions

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index bf05ca5b0a57..5bea821adcae 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -17,6 +17,16 @@ config ADJD_S311
          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
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index 8b8c09f9c1f8..47877a36cc12 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -4,6 +4,7 @@
 
 # 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
diff --git a/drivers/iio/light/al3320a.c b/drivers/iio/light/al3320a.c
new file mode 100644
index 000000000000..6aac6513fd41
--- /dev/null
+++ b/drivers/iio/light/al3320a.c
@@ -0,0 +1,232 @@
+/*
+ * 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 <daniel.baluta@intel.com>");
+MODULE_DESCRIPTION("AL3320A Ambient Light Sensor driver");
+MODULE_LICENSE("GPL v2");