iio: Added Capella cm3232 ambient light sensor driver.

CM3232 is an advanced ambient light sensor with I2C protocol interface.
The I2C slave address is internally hardwired as 0x10 (7-bit).  Writing
to configure register is byte mode, but reading ALS register requests to
use word mode for 16-bit resolution.

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

5 files changed, 422 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index 9f4e3824e71e..572a7c483aa7 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -34,6 +34,7 @@ atmel,24c512		i2c serial eeprom  (24cxx)
 atmel,24c1024		i2c serial eeprom  (24cxx)
 atmel,at97sc3204t	i2c trusted platform module (TPM)
 capella,cm32181		CM32181: Ambient Light Sensor
+capella,cm3232		CM3232: Ambient Light Sensor
 catalyst,24c32		i2c serial eeprom
 cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
 dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
diff --git a/MAINTAINERS b/MAINTAINERS
index 2fa385321245..8d2d9a22449a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2379,6 +2379,12 @@ F:	security/capability.c
 F:	security/commoncap.c
 F:	kernel/capability.c
 
+CAPELLA MICROSYSTEMS LIGHT SENSOR DRIVER
+M:	Kevin Tsai <ktsai@capellamicro.com>
+S:	Maintained
+F:	drivers/iio/light/cm*
+F:	Documentation/devicetree/bindings/i2c/trivial-devices.txt
+
 CC2520 IEEE-802.15.4 RADIO DRIVER
 M:	Varka Bhadram <varkabhadram@gmail.com>
 L:	linux-wpan@vger.kernel.org
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 5a3237b2aaa5..ae68c64bdad3 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -48,6 +48,17 @@ config CM32181
 	 To compile this driver as a module, choose M here:
 	 the module will be called cm32181.
 
+config CM3232
+	depends on I2C
+	tristate "CM3232 ambient light sensor"
+	help
+	 Say Y here if you use cm3232.
+	 This option enables ambient light sensor using
+	 Capella Microsystems cm3232 device driver.
+
+	 To compile this driver as a module, choose M here:
+	 the module will be called cm3232.
+
 config CM36651
 	depends on I2C
 	tristate "CM36651 driver"
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index 74656c19a899..b12a5160d9e0 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
 obj-$(CONFIG_AL3320A)		+= al3320a.o
 obj-$(CONFIG_APDS9300)		+= apds9300.o
 obj-$(CONFIG_CM32181)		+= cm32181.o
+obj-$(CONFIG_CM3232)		+= cm3232.o
 obj-$(CONFIG_CM36651)		+= cm36651.o
 obj-$(CONFIG_GP2AP020A00F)	+= gp2ap020a00f.o
 obj-$(CONFIG_HID_SENSOR_ALS)	+= hid-sensor-als.o
diff --git a/drivers/iio/light/cm3232.c b/drivers/iio/light/cm3232.c
new file mode 100644
index 000000000000..90e3519a91de
--- /dev/null
+++ b/drivers/iio/light/cm3232.c
@@ -0,0 +1,403 @@
+/*
+ * CM3232 Ambient Light Sensor
+ *
+ * Copyright (C) 2014-2015 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.
+ *
+ * IIO driver for CM3232 (7-bit I2C slave address 0x10).
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/init.h>
+
+/* Registers Address */
+#define CM3232_REG_ADDR_CMD		0x00
+#define CM3232_REG_ADDR_ALS		0x50
+#define CM3232_REG_ADDR_ID		0x53
+
+#define CM3232_CMD_ALS_DISABLE		BIT(0)
+
+#define CM3232_CMD_ALS_IT_SHIFT		2
+#define CM3232_CMD_ALS_IT_MASK		(BIT(2) | BIT(3) | BIT(4))
+#define CM3232_CMD_ALS_IT_DEFAULT	(0x01 << CM3232_CMD_ALS_IT_SHIFT)
+
+#define CM3232_CMD_ALS_RESET		BIT(6)
+
+#define CM3232_CMD_DEFAULT		CM3232_CMD_ALS_IT_DEFAULT
+
+#define CM3232_HW_ID			0x32
+#define CM3232_CALIBSCALE_DEFAULT	100000
+#define CM3232_CALIBSCALE_RESOLUTION	100000
+#define CM3232_MLUX_PER_LUX		1000
+
+#define CM3232_MLUX_PER_BIT_DEFAULT	64
+#define CM3232_MLUX_PER_BIT_BASE_IT	100000
+
+static const struct {
+	int val;
+	int val2;
+	u8 it;
+} cm3232_als_it_scales[] = {
+	{0, 100000, 0},	/* 0.100000 */
+	{0, 200000, 1},	/* 0.200000 */
+	{0, 400000, 2},	/* 0.400000 */
+	{0, 800000, 3},	/* 0.800000 */
+	{1, 600000, 4},	/* 1.600000 */
+	{3, 200000, 5},	/* 3.200000 */
+};
+
+struct cm3232_als_info {
+	u8 regs_cmd_default;
+	u8 hw_id;
+	int calibscale;
+	int mlux_per_bit;
+	int mlux_per_bit_base_it;
+};
+
+static struct cm3232_als_info cm3232_als_info_default = {
+	.regs_cmd_default = CM3232_CMD_DEFAULT,
+	.hw_id = CM3232_HW_ID,
+	.calibscale = CM3232_CALIBSCALE_DEFAULT,
+	.mlux_per_bit = CM3232_MLUX_PER_BIT_DEFAULT,
+	.mlux_per_bit_base_it = CM3232_MLUX_PER_BIT_BASE_IT,
+};
+
+struct cm3232_chip {
+	struct i2c_client *client;
+	struct cm3232_als_info *als_info;
+	u8 regs_cmd;
+	u16 regs_als;
+};
+
+/**
+ * cm3232_reg_init() - Initialize CM3232
+ * @chip:	pointer of struct cm3232_chip.
+ *
+ * Check and initialize CM3232 ambient light sensor.
+ *
+ * Return: 0 for success; otherwise for error code.
+ */
+static int cm3232_reg_init(struct cm3232_chip *chip)
+{
+	struct i2c_client *client = chip->client;
+	s32 ret;
+
+	chip->als_info = &cm3232_als_info_default;
+
+	/* Identify device */
+	ret = i2c_smbus_read_word_data(client, CM3232_REG_ADDR_ID);
+	if (ret < 0) {
+		dev_err(&chip->client->dev, "Error reading addr_id\n");
+		return ret;
+	}
+
+	if ((ret & 0xFF) != chip->als_info->hw_id)
+		return -ENODEV;
+
+	/* Disable and reset device */
+	chip->regs_cmd = CM3232_CMD_ALS_DISABLE | CM3232_CMD_ALS_RESET;
+	ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
+					chip->regs_cmd);
+	if (ret < 0) {
+		dev_err(&chip->client->dev, "Error writing reg_cmd\n");
+		return ret;
+	}
+
+	/* Register default value */
+	chip->regs_cmd = chip->als_info->regs_cmd_default;
+
+	/* Configure register */
+	ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
+					chip->regs_cmd);
+	if (ret < 0)
+		dev_err(&chip->client->dev, "Error writing reg_cmd\n");
+
+	return 0;
+}
+
+/**
+ *  cm3232_read_als_it() - Get sensor integration time
+ *  @chip:	pointer of struct cm3232_chip
+ *  @val:	pointer of int to load the integration (sec).
+ *  @val2:	pointer of int to load the integration time (microsecond).
+ *
+ *  Report the current integration time.
+ *
+ *  Return: IIO_VAL_INT_PLUS_MICRO for success, otherwise -EINVAL.
+ */
+static int cm3232_read_als_it(struct cm3232_chip *chip, int *val, int *val2)
+{
+	u16 als_it;
+	int i;
+
+	als_it = chip->regs_cmd;
+	als_it &= CM3232_CMD_ALS_IT_MASK;
+	als_it >>= CM3232_CMD_ALS_IT_SHIFT;
+	for (i = 0; i < ARRAY_SIZE(cm3232_als_it_scales); i++) {
+		if (als_it == cm3232_als_it_scales[i].it) {
+			*val = cm3232_als_it_scales[i].val;
+			*val2 = cm3232_als_it_scales[i].val2;
+			return IIO_VAL_INT_PLUS_MICRO;
+		}
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * cm3232_write_als_it() - Write sensor integration time
+ * @chip:	pointer of struct cm3232_chip.
+ * @val:	integration time in second.
+ * @val2:	integration time in microsecond.
+ *
+ * Convert integration time to sensor value.
+ *
+ * Return: i2c_smbus_write_byte_data command return value.
+ */
+static int cm3232_write_als_it(struct cm3232_chip *chip, int val, int val2)
+{
+	struct i2c_client *client = chip->client;
+	u16 als_it, cmd;
+	int i;
+	s32 ret;
+
+	for (i = 0; i < ARRAY_SIZE(cm3232_als_it_scales); i++) {
+		if (val == cm3232_als_it_scales[i].val &&
+			val2 == cm3232_als_it_scales[i].val2) {
+
+			als_it = cm3232_als_it_scales[i].it;
+			als_it <<= CM3232_CMD_ALS_IT_SHIFT;
+
+			cmd = chip->regs_cmd & ~CM3232_CMD_ALS_IT_MASK;
+			cmd |= als_it;
+			ret = i2c_smbus_write_byte_data(client,
+							CM3232_REG_ADDR_CMD,
+							cmd);
+			if (ret < 0)
+				return ret;
+			chip->regs_cmd = cmd;
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+
+/**
+ * cm3232_get_lux() - report current lux value
+ * @chip:	pointer of struct cm3232_chip.
+ *
+ * Convert sensor data to lux.  It depends on integration
+ * time and calibscale variable.
+ *
+ * Return: Zero or positive value is lux, otherwise error code.
+ */
+static int cm3232_get_lux(struct cm3232_chip *chip)
+{
+	struct i2c_client *client = chip->client;
+	struct cm3232_als_info *als_info = chip->als_info;
+	int ret;
+	int val, val2;
+	int als_it;
+	u64 lux;
+
+	/* Calculate mlux per bit based on als_it */
+	ret = cm3232_read_als_it(chip, &val, &val2);
+	if (ret < 0)
+		return -EINVAL;
+	als_it = val * 1000000 + val2;
+	lux = (__force u64)als_info->mlux_per_bit;
+	lux *= als_info->mlux_per_bit_base_it;
+	lux = div_u64(lux, als_it);
+
+	ret = i2c_smbus_read_word_data(client, CM3232_REG_ADDR_ALS);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error reading reg_addr_als\n");
+		return ret;
+	}
+
+	chip->regs_als = (u16)ret;
+	lux *= chip->regs_als;
+	lux *= als_info->calibscale;
+	lux = div_u64(lux, CM3232_CALIBSCALE_RESOLUTION);
+	lux = div_u64(lux, CM3232_MLUX_PER_LUX);
+
+	if (lux > 0xFFFF)
+		lux = 0xFFFF;
+
+	return (int)lux;
+}
+
+static int cm3232_read_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int *val, int *val2, long mask)
+{
+	struct cm3232_chip *chip = iio_priv(indio_dev);
+	struct cm3232_als_info *als_info = chip->als_info;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = cm3232_get_lux(chip);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		*val = als_info->calibscale;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_INT_TIME:
+		return cm3232_read_als_it(chip, val, val2);
+	}
+
+	return -EINVAL;
+}
+
+static int cm3232_write_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int val, int val2, long mask)
+{
+	struct cm3232_chip *chip = iio_priv(indio_dev);
+	struct cm3232_als_info *als_info = chip->als_info;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBSCALE:
+		als_info->calibscale = val;
+		return 0;
+	case IIO_CHAN_INFO_INT_TIME:
+		return cm3232_write_als_it(chip, val, val2);
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * cm3232_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 in second.
+ *
+ * Return: string length.
+ */
+static ssize_t cm3232_get_it_available(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	int i, len;
+
+	for (i = 0, len = 0; i < ARRAY_SIZE(cm3232_als_it_scales); i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%u.%06u ",
+			cm3232_als_it_scales[i].val,
+			cm3232_als_it_scales[i].val2);
+	return len + scnprintf(buf + len, PAGE_SIZE - len, "\n");
+}
+
+static const struct iio_chan_spec cm3232_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, cm3232_get_it_available, NULL, 0);
+
+static struct attribute *cm3232_attributes[] = {
+	&iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group cm3232_attribute_group = {
+	.attrs = cm3232_attributes
+};
+
+static const struct iio_info cm3232_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= &cm3232_read_raw,
+	.write_raw		= &cm3232_write_raw,
+	.attrs			= &cm3232_attribute_group,
+};
+
+static int cm3232_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct cm3232_chip *chip;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	chip = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	chip->client = client;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->channels = cm3232_channels;
+	indio_dev->num_channels = ARRAY_SIZE(cm3232_channels);
+	indio_dev->info = &cm3232_info;
+	indio_dev->name = id->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = cm3232_reg_init(chip);
+	if (ret) {
+		dev_err(&client->dev,
+			"%s: register init failed\n",
+			__func__);
+		return ret;
+	}
+
+	return iio_device_register(indio_dev);
+}
+
+static int cm3232_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
+		CM3232_CMD_ALS_DISABLE);
+
+	iio_device_unregister(indio_dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id cm3232_id[] = {
+	{"cm3232", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, cm3232_id);
+
+static const struct of_device_id cm3232_of_match[] = {
+	{.compatible = "capella,cm3232"},
+	{}
+};
+
+static struct i2c_driver cm3232_driver = {
+	.driver = {
+		.name	= "cm3232",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(cm3232_of_match),
+	},
+	.id_table	= cm3232_id,
+	.probe		= cm3232_probe,
+	.remove		= cm3232_remove,
+};
+
+module_i2c_driver(cm3232_driver);
+
+MODULE_AUTHOR("Kevin Tsai <ktsai@capellamicro.com>");
+MODULE_DESCRIPTION("CM3232 ambient light sensor driver");
+MODULE_LICENSE("GPL");