iio: add Capella CM32181 ambient light sensor driver.

Add Capella Microsystem CM32181 Ambient Light Sensor IIO driver.
This driver will convert raw data to lux value under open-air
condition. Change the calibscale based on the cover material.

Signed-off-by: Kevin Tsai <ktsai@capellamicro.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

4 files changed, 392 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index b1cb3415e6f1..c65f71cfaa5c 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -16,6 +16,7 @@ adt7461			+/-1C TDM Extended Temp Range I.C
 at,24c08                i2c serial eeprom  (24cxx)
 atmel,24c02             i2c serial eeprom  (24cxx)
 atmel,at97sc3204t       i2c trusted platform module (TPM)
+capella,cm32181         CM32181: Ambient Light Sensor
 catalyst,24c32          i2c serial eeprom
 dallas,ds1307           64 x 8, Serial, I2C Real-Time Clock
 dallas,ds1338           I2C RTC with 56-Byte NV RAM
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index a022f27c6690..d12b2a0dbfbc 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -27,6 +27,17 @@ config APDS9300
          To compile this driver as a module, choose M here: the
          module will be called apds9300.
 
+config CM32181
+        depends on I2C
+        tristate "CM32181 driver"
+        help
+         Say Y here if you use cm32181.
+         This option enables ambient light sensor using
+         Capella cm32181 device driver.
+
+         To compile this driver as a module, choose M here:
+         the module will be called cm32181.
+
 config CM36651
         depends on I2C
         tristate "CM36651 driver"
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index daa327f39e04..60e35ac07ff0 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -5,6 +5,7 @@
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ADJD_S311)         += adjd_s311.o
 obj-$(CONFIG_APDS9300)          += apds9300.o
+obj-$(CONFIG_CM32181)           += cm32181.o
 obj-$(CONFIG_CM36651)           += cm36651.o
 obj-$(CONFIG_GP2AP020A00F)      += gp2ap020a00f.o
 obj-$(CONFIG_HID_SENSOR_ALS)    += hid-sensor-als.o
diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
new file mode 100644
index 000000000000..f17b4e6183c6
--- /dev/null
+++ b/drivers/iio/light/cm32181.c
@@ -0,0 +1,379 @@
+/*
+ * Copyright (C) 2013 Capella Microsystems Inc.
+ * Author: Kevin Tsai <ktsai@capellamicro.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2, as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/regulator/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/init.h>
+
+/* Registers Address */
+#define CM32181_REG_ADDR_CMD            0x00
+#define CM32181_REG_ADDR_ALS            0x04
+#define CM32181_REG_ADDR_STATUS         0x06
+#define CM32181_REG_ADDR_ID             0x07
+
+/* Number of Configurable Registers */
+#define CM32181_CONF_REG_NUM            0x01
+
+/* CMD register */
+#define CM32181_CMD_ALS_ENABLE          0x00
+#define CM32181_CMD_ALS_DISABLE         0x01
+#define CM32181_CMD_ALS_INT_EN          0x02
+
+#define CM32181_CMD_ALS_IT_SHIFT        6
+#define CM32181_CMD_ALS_IT_MASK         (0x0F << CM32181_CMD_ALS_IT_SHIFT)
+#define CM32181_CMD_ALS_IT_DEFAULT      (0x00 << CM32181_CMD_ALS_IT_SHIFT)
+
+#define CM32181_CMD_ALS_SM_SHIFT        11
+#define CM32181_CMD_ALS_SM_MASK         (0x03 << CM32181_CMD_ALS_SM_SHIFT)
+#define CM32181_CMD_ALS_SM_DEFAULT      (0x01 << CM32181_CMD_ALS_SM_SHIFT)
+
+#define CM32181_MLUX_PER_BIT            5       /* ALS_SM=01 IT=800ms */
+#define CM32181_MLUX_PER_BIT_BASE_IT    800000  /* Based on IT=800ms */
+#define CM32181_CALIBSCALE_DEFAULT      1000
+#define CM32181_CALIBSCALE_RESOLUTION   1000
+#define MLUX_PER_LUX                    1000
+
+static const u8 cm32181_reg[CM32181_CONF_REG_NUM] = {
+        CM32181_REG_ADDR_CMD,
+};
+
+static const int als_it_bits[] = {12, 8, 0, 1, 2, 3};
+static const int als_it_value[] = {25000, 50000, 100000, 200000, 400000,
+        800000};
+
+struct cm32181_chip {
+        struct i2c_client *client;
+        struct mutex lock;
+        u16 conf_regs[CM32181_CONF_REG_NUM];
+        int calibscale;
+};
+
+/**
+ * cm32181_reg_init() - Initialize CM32181 registers
+ * @cm32181:    pointer of struct cm32181.
+ *
+ * Initialize CM32181 ambient light sensor register to default values.
+ *
+ * Return: 0 for success; otherwise for error code.
+ */
+static int cm32181_reg_init(struct cm32181_chip *cm32181)
+{
+        struct i2c_client *client = cm32181->client;
+        int i;
+        s32 ret;
+
+        ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ID);
+        if (ret < 0)
+                return ret;
+
+        /* check device ID */
+        if ((ret & 0xFF) != 0x81)
+                return -ENODEV;
+
+        /* Default Values */
+        cm32181->conf_regs[CM32181_REG_ADDR_CMD] = CM32181_CMD_ALS_ENABLE |
+                        CM32181_CMD_ALS_IT_DEFAULT | CM32181_CMD_ALS_SM_DEFAULT;
+        cm32181->calibscale = CM32181_CALIBSCALE_DEFAULT;
+
+        /* Initialize registers*/
+        for (i = 0; i < CM32181_CONF_REG_NUM; i++) {
+                ret = i2c_smbus_write_word_data(client, cm32181_reg[i],
+                        cm32181->conf_regs[i]);
+                if (ret < 0)
+                        return ret;
+        }
+
+        return 0;
+}
+
+/**
+ *  cm32181_read_als_it() - Get sensor integration time (ms)
+ *  @cm32181:   pointer of struct cm32181
+ *  @val:       pointer of int to load the als_it value.
+ *
+ *  Report the current integartion time by millisecond.
+ *
+ *  Return: IIO_VAL_INT for success, otherwise -EINVAL.
+ */
+static int cm32181_read_als_it(struct cm32181_chip *cm32181, int *val)
+{
+        u16 als_it;
+        int i;
+
+        als_it = cm32181->conf_regs[CM32181_REG_ADDR_CMD];
+        als_it &= CM32181_CMD_ALS_IT_MASK;
+        als_it >>= CM32181_CMD_ALS_IT_SHIFT;
+        for (i = 0; i < ARRAY_SIZE(als_it_bits); i++) {
+                if (als_it == als_it_bits[i]) {
+                        *val = als_it_value[i];
+                        return IIO_VAL_INT;
+                }
+        }
+
+        return -EINVAL;
+}
+
+/**
+ * cm32181_write_als_it() - Write sensor integration time
+ * @cm32181:    pointer of struct cm32181.
+ * @val:        integration time by millisecond.
+ *
+ * Convert integration time (ms) to sensor value.
+ *
+ * Return: i2c_smbus_write_word_data command return value.
+ */
+static int cm32181_write_als_it(struct cm32181_chip *cm32181, int val)
+{
+        struct i2c_client *client = cm32181->client;
+        u16 als_it;
+        int ret, i, n;
+
+        n = ARRAY_SIZE(als_it_value);
+        for (i = 0; i < n; i++)
+                if (val <= als_it_value[i])
+                        break;
+        if (i >= n)
+                i = n - 1;
+
+        als_it = als_it_bits[i];
+        als_it <<= CM32181_CMD_ALS_IT_SHIFT;
+
+        mutex_lock(&cm32181->lock);
+        cm32181->conf_regs[CM32181_REG_ADDR_CMD] &=
+                ~CM32181_CMD_ALS_IT_MASK;
+        cm32181->conf_regs[CM32181_REG_ADDR_CMD] |=
+                als_it;
+        ret = i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
+                        cm32181->conf_regs[CM32181_REG_ADDR_CMD]);
+        mutex_unlock(&cm32181->lock);
+
+        return ret;
+}
+
+/**
+ * cm32181_get_lux() - report current lux value
+ * @cm32181:    pointer of struct cm32181.
+ *
+ * Convert sensor raw data to lux.  It depends on integration
+ * time and claibscale variable.
+ *
+ * Return: Positive value is lux, otherwise is error code.
+ */
+static int cm32181_get_lux(struct cm32181_chip *cm32181)
+{
+        struct i2c_client *client = cm32181->client;
+        int ret;
+        int als_it;
+        unsigned long lux;
+
+        ret = cm32181_read_als_it(cm32181, &als_it);
+        if (ret < 0)
+                return -EINVAL;
+
+        lux = CM32181_MLUX_PER_BIT;
+        lux *= CM32181_MLUX_PER_BIT_BASE_IT;
+        lux /= als_it;
+
+        ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ALS);
+        if (ret < 0)
+                return ret;
+
+        lux *= ret;
+        lux *= cm32181->calibscale;
+        lux /= CM32181_CALIBSCALE_RESOLUTION;
+        lux /= MLUX_PER_LUX;
+
+        if (lux > 0xFFFF)
+                lux = 0xFFFF;
+
+        return lux;
+}
+
+static int cm32181_read_raw(struct iio_dev *indio_dev,
+                            struct iio_chan_spec const *chan,
+                            int *val, int *val2, long mask)
+{
+        struct cm32181_chip *cm32181 = iio_priv(indio_dev);
+        int ret;
+
+        switch (mask) {
+        case IIO_CHAN_INFO_PROCESSED:
+                ret = cm32181_get_lux(cm32181);
+                if (ret < 0)
+                        return ret;
+                *val = ret;
+                return IIO_VAL_INT;
+        case IIO_CHAN_INFO_CALIBSCALE:
+                *val = cm32181->calibscale;
+                return IIO_VAL_INT;
+        case IIO_CHAN_INFO_INT_TIME:
+                ret = cm32181_read_als_it(cm32181, val);
+                return ret;
+        }
+
+        return -EINVAL;
+}
+
+static int cm32181_write_raw(struct iio_dev *indio_dev,
+                             struct iio_chan_spec const *chan,
+                             int val, int val2, long mask)
+{
+        struct cm32181_chip *cm32181 = iio_priv(indio_dev);
+        int ret;
+
+        switch (mask) {
+        case IIO_CHAN_INFO_CALIBSCALE:
+                cm32181->calibscale = val;
+                return val;
+        case IIO_CHAN_INFO_INT_TIME:
+                ret = cm32181_write_als_it(cm32181, val);
+                return ret;
+        }
+
+        return -EINVAL;
+}
+
+/**
+ * cm32181_get_it_available() - Get available ALS IT value
+ * @dev:        pointer of struct device.
+ * @attr:       pointer of struct device_attribute.
+ * @buf:        pointer of return string buffer.
+ *
+ * Display the available integration time values by millisecond.
+ *
+ * Return: string length.
+ */
+static ssize_t cm32181_get_it_available(struct device *dev,
+                        struct device_attribute *attr, char *buf)
+{
+        int i, n, len;
+
+        n = ARRAY_SIZE(als_it_value);
+        for (i = 0, len = 0; i < n; i++)
+                len += sprintf(buf + len, "%d ", als_it_value[i]);
+        return len + sprintf(buf + len, "\n");
+}
+
+static const struct iio_chan_spec cm32181_channels[] = {
+        {
+                .type = IIO_LIGHT,
+                .info_mask_separate =
+                        BIT(IIO_CHAN_INFO_PROCESSED) |
+                        BIT(IIO_CHAN_INFO_CALIBSCALE) |
+                        BIT(IIO_CHAN_INFO_INT_TIME),
+        }
+};
+
+static IIO_DEVICE_ATTR(in_illuminance_integration_time_available,
+                        S_IRUGO, cm32181_get_it_available, NULL, 0);
+
+static struct attribute *cm32181_attributes[] = {
+        &iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
+        NULL,
+};
+
+static const struct attribute_group cm32181_attribute_group = {
+        .attrs = cm32181_attributes
+};
+
+static const struct iio_info cm32181_info = {
+        .driver_module          = THIS_MODULE,
+        .read_raw               = &cm32181_read_raw,
+        .write_raw              = &cm32181_write_raw,
+        .attrs                  = &cm32181_attribute_group,
+};
+
+static int cm32181_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        struct cm32181_chip *cm32181;
+        struct iio_dev *indio_dev;
+        int ret;
+
+        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*cm32181));
+        if (!indio_dev) {
+                dev_err(&client->dev, "devm_iio_device_alloc failed\n");
+                return -ENOMEM;
+        }
+
+        cm32181 = iio_priv(indio_dev);
+        i2c_set_clientdata(client, indio_dev);
+        cm32181->client = client;
+
+        mutex_init(&cm32181->lock);
+        indio_dev->dev.parent = &client->dev;
+        indio_dev->channels = cm32181_channels;
+        indio_dev->num_channels = ARRAY_SIZE(cm32181_channels);
+        indio_dev->info = &cm32181_info;
+        indio_dev->name = id->name;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+
+        ret = cm32181_reg_init(cm32181);
+        if (ret) {
+                dev_err(&client->dev,
+                        "%s: register init failed\n",
+                        __func__);
+                return ret;
+        }
+
+        ret = iio_device_register(indio_dev);
+        if (ret) {
+                dev_err(&client->dev,
+                        "%s: regist device failed\n",
+                        __func__);
+                return ret;
+        }
+
+        return 0;
+}
+
+static int cm32181_remove(struct i2c_client *client)
+{
+        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+        iio_device_unregister(indio_dev);
+        return 0;
+}
+
+static const struct i2c_device_id cm32181_id[] = {
+        { "cm32181", 0 },
+        { }
+};
+
+MODULE_DEVICE_TABLE(i2c, cm32181_id);
+
+static const struct of_device_id cm32181_of_match[] = {
+        { .compatible = "capella,cm32181" },
+        { }
+};
+
+static struct i2c_driver cm32181_driver = {
+        .driver = {
+                .name   = "cm32181",
+                .of_match_table = of_match_ptr(cm32181_of_match),
+                .owner  = THIS_MODULE,
+        },
+        .id_table       = cm32181_id,
+        .probe          = cm32181_probe,
+        .remove         = cm32181_remove,
+};
+
+module_i2c_driver(cm32181_driver);
+
+MODULE_AUTHOR("Kevin Tsai <ktsai@capellamicro.com>");
+MODULE_DESCRIPTION("CM32181 ambient light sensor driver");
+MODULE_LICENSE("GPL");