iio:light: Add support for STMicro VL6180 sensor

This patch adds support for STMicro VL6180 - ALS, range and proximity sensor. Sensor is capable of measuring the light
intensity as well as object distance using TOF (Time of Flight) technology.
Signed-off-by: Manivannan Sadhasivam <manivannanece23@gmail.com>
Signed-off-by: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/light/vl6180.txt

+STMicro VL6180 -  ALS, range and proximity sensor
+
+Link to datasheet: http://www.st.com/resource/en/datasheet/vl6180x.pdf
+
+Required properties:
+
+	-compatible: should be "st,vl6180"
+	-reg: the I2C address of the sensor
+
+Example:
+
+vl6180@29 {
+	compatible = "st,vl6180";
+	reg = <0x29>;
+};

drivers/iio/light/Kconfig

@@ -405,4 +405,14 @@ config VEML6070
 	 To compile this driver as a module, choose M here: the
 	 module will be called veml6070.
 
+config VL6180
+	tristate "VL6180 ALS, range and proximity sensor"
+	depends on I2C
+	help
+	 Say Y here if you want to build a driver for the STMicroelectronics
+	 VL6180 combined ambient light, range and proximity sensor.
+
+	 To compile this driver as a module, choose M here: the
+	 module will be called vl6180.
+
 endmenu

drivers/iio/light/Makefile

@@ -38,3 +38,4 @@ obj-$(CONFIG_TSL4531)		+= tsl4531.o
 obj-$(CONFIG_US5182D)		+= us5182d.o
 obj-$(CONFIG_VCNL4000)		+= vcnl4000.o
 obj-$(CONFIG_VEML6070)		+= veml6070.o
+obj-$(CONFIG_VL6180)		+= vl6180.o

drivers/iio/light/vl6180.c

+/*
+ * vl6180.c - Support for STMicroelectronics VL6180 ALS, range and proximity
+ * sensor
+ *
+ * Copyright 2017 Peter Meerwald-Stadler <pmeerw@pmeerw.net>
+ * Copyright 2017 Manivannan Sadhasivam <manivannanece23@gmail.com>
+ *
+ * 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 VL6180 (7-bit I2C slave address 0x29)
+ *
+ * Range: 0 to 100mm
+ * ALS: < 1 Lux up to 100 kLux
+ * IR: 850nm
+ *
+ * TODO: irq, threshold events, continuous mode, hardware buffer
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define VL6180_DRV_NAME "vl6180"
+
+/* Device identification register and value */
+#define VL6180_MODEL_ID	0x000
+#define VL6180_MODEL_ID_VAL 0xb4
+
+/* Configuration registers */
+#define VL6180_INTR_CONFIG 0x014
+#define VL6180_INTR_CLEAR 0x015
+#define VL6180_OUT_OF_RESET 0x016
+#define VL6180_HOLD 0x017
+#define VL6180_RANGE_START 0x018
+#define VL6180_ALS_START 0x038
+#define VL6180_ALS_GAIN 0x03f
+#define VL6180_ALS_IT 0x040
+
+/* Status registers */
+#define VL6180_RANGE_STATUS 0x04d
+#define VL6180_ALS_STATUS 0x04e
+#define VL6180_INTR_STATUS 0x04f
+
+/* Result value registers */
+#define VL6180_ALS_VALUE 0x050
+#define VL6180_RANGE_VALUE 0x062
+#define VL6180_RANGE_RATE 0x066
+
+/* bits of the RANGE_START and ALS_START register */
+#define VL6180_MODE_CONT BIT(1) /* continuous mode */
+#define VL6180_STARTSTOP BIT(0) /* start measurement, auto-reset */
+
+/* bits of the INTR_STATUS and INTR_CONFIG register */
+#define VL6180_ALS_READY BIT(5)
+#define VL6180_RANGE_READY BIT(2)
+
+/* bits of the INTR_CLEAR register */
+#define VL6180_CLEAR_ERROR BIT(2)
+#define VL6180_CLEAR_ALS BIT(1)
+#define VL6180_CLEAR_RANGE BIT(0)
+
+/* bits of the HOLD register */
+#define VL6180_HOLD_ON BIT(0)
+
+/* default value for the ALS_IT register */
+#define VL6180_ALS_IT_100 0x63 /* 100 ms */
+
+/* values for the ALS_GAIN register */
+#define VL6180_ALS_GAIN_1 0x46
+#define VL6180_ALS_GAIN_1_25 0x45
+#define VL6180_ALS_GAIN_1_67 0x44
+#define VL6180_ALS_GAIN_2_5 0x43
+#define VL6180_ALS_GAIN_5 0x42
+#define VL6180_ALS_GAIN_10 0x41
+#define VL6180_ALS_GAIN_20 0x40
+#define VL6180_ALS_GAIN_40 0x47
+
+struct vl6180_data {
+	struct i2c_client *client;
+	struct mutex lock;
+};
+
+enum { VL6180_ALS, VL6180_RANGE, VL6180_PROX };
+
+/**
+ * struct vl6180_chan_regs - Registers for accessing channels
+ * @drdy_mask:			Data ready bit in status register
+ * @start_reg:			Conversion start register
+ * @value_reg:			Result value register
+ * @word:			Register word length
+ */
+struct vl6180_chan_regs {
+	u8 drdy_mask;
+	u16 start_reg, value_reg;
+	bool word;
+};
+
+static const struct vl6180_chan_regs vl6180_chan_regs_table[] = {
+	[VL6180_ALS] = {
+		.drdy_mask = VL6180_ALS_READY,
+		.start_reg = VL6180_ALS_START,
+		.value_reg = VL6180_ALS_VALUE,
+		.word = true,
+	},
+	[VL6180_RANGE] = {
+		.drdy_mask = VL6180_RANGE_READY,
+		.start_reg = VL6180_RANGE_START,
+		.value_reg = VL6180_RANGE_VALUE,
+		.word = false,
+	},
+	[VL6180_PROX] = {
+		.drdy_mask = VL6180_RANGE_READY,
+		.start_reg = VL6180_RANGE_START,
+		.value_reg = VL6180_RANGE_RATE,
+		.word = true,
+	},
+};
+
+static int vl6180_read(struct i2c_client *client, u16 cmd, void *databuf,
+		       u8 len)
+{
+	__be16 cmdbuf = cpu_to_be16(cmd);
+	struct i2c_msg msgs[2] = {
+		{ .addr = client->addr, .len = sizeof(cmdbuf), .buf = (u8 *) &cmdbuf },
+		{ .addr = client->addr, .len = len, .buf = databuf,
+		  .flags = I2C_M_RD } };
+	int ret;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		dev_err(&client->dev, "failed reading register 0x%04x\n", cmd);
+
+	return ret;
+}
+
+static int vl6180_read_byte(struct i2c_client *client, u16 cmd)
+{
+	u8 data;
+	int ret;
+
+	ret = vl6180_read(client, cmd, &data, sizeof(data));
+	if (ret < 0)
+		return ret;
+
+	return data;
+}
+
+static int vl6180_read_word(struct i2c_client *client, u16 cmd)
+{
+	__be16 data;
+	int ret;
+
+	ret = vl6180_read(client, cmd, &data, sizeof(data));
+	if (ret < 0)
+		return ret;
+
+	return be16_to_cpu(data);
+}
+
+static int vl6180_write_byte(struct i2c_client *client, u16 cmd, u8 val)
+{
+	u8 buf[3];
+	struct i2c_msg msgs[1] = {
+		{ .addr = client->addr, .len = sizeof(buf), .buf = (u8 *) &buf } };
+	int ret;
+
+	buf[0] = cmd >> 8;
+	buf[1] = cmd & 0xff;
+	buf[2] = val;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0) {
+		dev_err(&client->dev, "failed writing register 0x%04x\n", cmd);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int vl6180_write_word(struct i2c_client *client, u16 cmd, u16 val)
+{
+	__be16 buf[2];
+	struct i2c_msg msgs[1] = {
+		{ .addr = client->addr, .len = sizeof(buf), .buf = (u8 *) &buf } };
+	int ret;
+
+	buf[0] = cpu_to_be16(cmd);
+	buf[1] = cpu_to_be16(val);
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0) {
+		dev_err(&client->dev, "failed writing register 0x%04x\n", cmd);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int vl6180_measure(struct vl6180_data *data, int addr)
+{
+	struct i2c_client *client = data->client;
+	int tries = 20, ret;
+	u16 value;
+
+	mutex_lock(&data->lock);
+	/* Start single shot measurement */
+	ret = vl6180_write_byte(client,
+		vl6180_chan_regs_table[addr].start_reg, VL6180_STARTSTOP);
+	if (ret < 0)
+		goto fail;
+
+	while (tries--) {
+		ret = vl6180_read_byte(client, VL6180_INTR_STATUS);
+		if (ret < 0)
+			goto fail;
+
+		if (ret & vl6180_chan_regs_table[addr].drdy_mask)
+			break;
+		msleep(20);
+	}
+
+	if (tries < 0) {
+		ret = -EIO;
+		goto fail;
+	}
+
+	/* Read result value from appropriate registers */
+	ret = vl6180_chan_regs_table[addr].word ?
+		vl6180_read_word(client, vl6180_chan_regs_table[addr].value_reg) :
+		vl6180_read_byte(client, vl6180_chan_regs_table[addr].value_reg);
+	if (ret < 0)
+		goto fail;
+	value = ret;
+
+	/* Clear the interrupt flag after data read */
+	ret = vl6180_write_byte(client, VL6180_INTR_CLEAR,
+		VL6180_CLEAR_ERROR | VL6180_CLEAR_ALS | VL6180_CLEAR_RANGE);
+	if (ret < 0)
+		goto fail;
+
+	ret = value;
+
+fail:
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static const struct iio_chan_spec vl6180_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.address = VL6180_ALS,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_INT_TIME) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+	}, {
+		.type = IIO_DISTANCE,
+		.address = VL6180_RANGE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
+	}, {
+		.type = IIO_PROXIMITY,
+		.address = VL6180_PROX,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	}
+};
+
+/*
+ * Columns 3 & 4 represent the same value in decimal and hex notations.
+ * Kept in order to avoid the datatype conversion while reading the
+ * hardware_gain.
+ */
+static const int vl6180_als_gain[8][4] = {
+	{ 1,	0,	70,	VL6180_ALS_GAIN_1 },
+	{ 1,    250000, 69,	VL6180_ALS_GAIN_1_25 },
+	{ 1,    670000, 68,	VL6180_ALS_GAIN_1_67 },
+	{ 2,    500000, 67,	VL6180_ALS_GAIN_2_5 },
+	{ 5,    0,      66,	VL6180_ALS_GAIN_5 },
+	{ 10,   0,      65,	VL6180_ALS_GAIN_10 },
+	{ 20,   0,      64,	VL6180_ALS_GAIN_20 },
+	{ 40,   0,      71,	VL6180_ALS_GAIN_40 }
+};
+
+static int vl6180_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct vl6180_data *data = iio_priv(indio_dev);
+	int ret, i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = vl6180_measure(data, chan->address);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_INT_TIME:
+		ret = vl6180_read_word(data->client, VL6180_ALS_IT);
+		if (ret < 0)
+			return ret;
+		*val = 0; /* 1 count = 1ms (0 = 1ms) */
+		*val2 = (ret + 1) * 1000; /* convert to seconds */
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_LIGHT:
+			*val = 0; /* one ALS count is 0.32 Lux */
+			*val2 = 320000;
+			break;
+		case IIO_DISTANCE:
+			*val = 0; /* sensor reports mm, scale to meter */
+			*val2 = 1000;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		ret = vl6180_read_byte(data->client, VL6180_ALS_GAIN);
+		if (ret < 0)
+			return -EINVAL;
+		for (i = 0; i < ARRAY_SIZE(vl6180_als_gain); i++) {
+			if (ret == vl6180_als_gain[i][2]) {
+				*val = vl6180_als_gain[i][0];
+				*val2 = vl6180_als_gain[i][1];
+			}
+		}
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static IIO_CONST_ATTR(als_gain_available, "1 1.25 1.67 2.5 5 10 20 40");
+
+static struct attribute *vl6180_attributes[] = {
+	&iio_const_attr_als_gain_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group vl6180_attribute_group = {
+	.attrs = vl6180_attributes,
+};
+
+/* HOLD is needed before updating any config registers */
+static int vl6180_hold(struct vl6180_data *data, bool hold)
+{
+	return vl6180_write_byte(data->client, VL6180_HOLD,
+		hold ? VL6180_HOLD_ON : 0);
+}
+
+static int vl6180_set_als_gain(struct vl6180_data *data, int val, int val2)
+{
+	int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(vl6180_als_gain); i++) {
+		if (val == vl6180_als_gain[i][0] &&
+			val2 == vl6180_als_gain[i][1]) {
+			mutex_lock(&data->lock);
+			ret = vl6180_hold(data, true);
+			if (ret < 0)
+				goto fail;
+			ret = vl6180_write_byte(data->client, VL6180_ALS_GAIN,
+				vl6180_als_gain[i][3]);
+fail:
+			vl6180_hold(data, false);
+			mutex_unlock(&data->lock);
+			return ret;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int vl6180_set_it(struct vl6180_data *data, int val2)
+{
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = vl6180_hold(data, true);
+	if (ret < 0)
+		goto fail;
+	ret = vl6180_write_word(data->client, VL6180_ALS_IT,
+		(val2 - 500) / 1000); /* write value in ms */
+fail:
+	vl6180_hold(data, false);
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int vl6180_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct vl6180_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		if (val != 0 || val2 < 500 || val2 >= 512500)
+			return -EINVAL;
+
+		return vl6180_set_it(data, val2);
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		if (chan->type != IIO_LIGHT)
+			return -EINVAL;
+
+		return vl6180_set_als_gain(data, val, val2);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info vl6180_info = {
+	.read_raw = vl6180_read_raw,
+	.write_raw = vl6180_write_raw,
+	.attrs = &vl6180_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+static int vl6180_init(struct vl6180_data *data)
+{
+	struct i2c_client *client = data->client;
+	int ret;
+
+	ret = vl6180_read_byte(client, VL6180_MODEL_ID);
+	if (ret < 0)
+		return ret;
+
+	if (ret != VL6180_MODEL_ID_VAL) {
+		dev_err(&client->dev, "invalid model ID %02x\n", ret);
+		return -ENODEV;
+	}
+
+	ret = vl6180_hold(data, true);
+	if (ret < 0)
+		return ret;
+
+	ret = vl6180_read_byte(client, VL6180_OUT_OF_RESET);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Detect false reset condition here. This bit is always set when the
+	 * system comes out of reset.
+	 */
+	if (ret != 0x01)
+		dev_info(&client->dev, "device is not fresh out of reset\n");
+
+	/* Enable ALS and Range ready interrupts */
+	ret = vl6180_write_byte(client, VL6180_INTR_CONFIG,
+				VL6180_ALS_READY | VL6180_RANGE_READY);
+	if (ret < 0)
+		return ret;
+
+	/* ALS integration time: 100ms */
+	ret = vl6180_write_word(client, VL6180_ALS_IT, VL6180_ALS_IT_100);
+	if (ret < 0)
+		return ret;
+
+	/* ALS gain: 1 */
+	ret = vl6180_write_byte(client, VL6180_ALS_GAIN, VL6180_ALS_GAIN_1);
+	if (ret < 0)
+		return ret;
+
+	ret = vl6180_write_byte(client, VL6180_OUT_OF_RESET, 0x00);
+	if (ret < 0)
+		return ret;
+
+	return vl6180_hold(data, false);
+}
+
+static int vl6180_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct vl6180_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;
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &vl6180_info;
+	indio_dev->channels = vl6180_channels;
+	indio_dev->num_channels = ARRAY_SIZE(vl6180_channels);
+	indio_dev->name = VL6180_DRV_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = vl6180_init(data);
+	if (ret < 0)
+		return ret;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct of_device_id vl6180_of_match[] = {
+	{ .compatible = "st,vl6180", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, vl6180_of_match);
+
+static const struct i2c_device_id vl6180_id[] = {
+	{ "vl6180", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, vl6180_id);
+
+static struct i2c_driver vl6180_driver = {
+	.driver = {
+		.name   = VL6180_DRV_NAME,
+		.of_match_table = of_match_ptr(vl6180_of_match),
+	},
+	.probe  = vl6180_probe,
+	.id_table = vl6180_id,
+};
+
+module_i2c_driver(vl6180_driver);
+
+MODULE_AUTHOR("Peter Meerwald-Stadler <pmeerw@pmeerw.net>");
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannanece23@gmail.com>");
+MODULE_DESCRIPTION("STMicro VL6180 ALS, range and proximity sensor driver");
+MODULE_LICENSE("GPL");