iio: light: lv0104cs: Add support for LV0104CS light sensor

This patch adds support for the On Semiconductor LV0104CS ambient
light sensor.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

3 files changed, 542 insertions, 0 deletions

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 93fd421b10d7..074e50657366 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -275,6 +275,16 @@ config LTR501
 	 This driver can also be built as a module.  If so, the module
          will be called ltr501.
 
+config LV0104CS
+	tristate "LV0104CS Ambient Light Sensor"
+	depends on I2C
+	help
+	 Say Y here if you want to build support for the On Semiconductor
+	 LV0104CS ambient light sensor.
+
+	 To compile this driver as a module, choose M here:
+	 the module will be called lv0104cs.
+
 config MAX44000
 	tristate "MAX44000 Ambient and Infrared Proximity Sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index f714067a7816..f1777036d4f8 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_ISL29125)		+= isl29125.o
 obj-$(CONFIG_JSA1212)		+= jsa1212.o
 obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
 obj-$(CONFIG_LTR501)		+= ltr501.o
+obj-$(CONFIG_LV0104CS)		+= lv0104cs.o
 obj-$(CONFIG_MAX44000)		+= max44000.o
 obj-$(CONFIG_OPT3001)		+= opt3001.o
 obj-$(CONFIG_PA12203001)	+= pa12203001.o
diff --git a/drivers/iio/light/lv0104cs.c b/drivers/iio/light/lv0104cs.c
new file mode 100644
index 000000000000..55b8e2855647
--- /dev/null
+++ b/drivers/iio/light/lv0104cs.c
@@ -0,0 +1,531 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * lv0104cs.c: LV0104CS Ambient Light Sensor Driver
+ *
+ * Copyright (C) 2018
+ * Author: Jeff LaBundy <jeff@labundy.com>
+ *
+ * 7-bit I2C slave address: 0x13
+ *
+ * Link to data sheet: http://www.onsemi.com/pub/Collateral/LV0104CS-D.PDF
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define LV0104CS_REGVAL_MEASURE		0xE0
+#define LV0104CS_REGVAL_SLEEP		0x00
+
+#define LV0104CS_SCALE_0_25X		0
+#define LV0104CS_SCALE_1X		1
+#define LV0104CS_SCALE_2X		2
+#define LV0104CS_SCALE_8X		3
+#define LV0104CS_SCALE_SHIFT		3
+
+#define LV0104CS_INTEG_12_5MS		0
+#define LV0104CS_INTEG_100MS		1
+#define LV0104CS_INTEG_200MS		2
+#define LV0104CS_INTEG_SHIFT		1
+
+#define LV0104CS_CALIBSCALE_UNITY	31
+
+struct lv0104cs_private {
+	struct i2c_client *client;
+	struct mutex lock;
+	u8 calibscale;
+	u8 scale;
+	u8 int_time;
+};
+
+struct lv0104cs_mapping {
+	int val;
+	int val2;
+	u8 regval;
+};
+
+static const struct lv0104cs_mapping lv0104cs_calibscales[] = {
+	{ 0, 666666, 0x81 },
+	{ 0, 800000, 0x82 },
+	{ 0, 857142, 0x83 },
+	{ 0, 888888, 0x84 },
+	{ 0, 909090, 0x85 },
+	{ 0, 923076, 0x86 },
+	{ 0, 933333, 0x87 },
+	{ 0, 941176, 0x88 },
+	{ 0, 947368, 0x89 },
+	{ 0, 952380, 0x8A },
+	{ 0, 956521, 0x8B },
+	{ 0, 960000, 0x8C },
+	{ 0, 962962, 0x8D },
+	{ 0, 965517, 0x8E },
+	{ 0, 967741, 0x8F },
+	{ 0, 969696, 0x90 },
+	{ 0, 971428, 0x91 },
+	{ 0, 972972, 0x92 },
+	{ 0, 974358, 0x93 },
+	{ 0, 975609, 0x94 },
+	{ 0, 976744, 0x95 },
+	{ 0, 977777, 0x96 },
+	{ 0, 978723, 0x97 },
+	{ 0, 979591, 0x98 },
+	{ 0, 980392, 0x99 },
+	{ 0, 981132, 0x9A },
+	{ 0, 981818, 0x9B },
+	{ 0, 982456, 0x9C },
+	{ 0, 983050, 0x9D },
+	{ 0, 983606, 0x9E },
+	{ 0, 984126, 0x9F },
+	{ 1, 0, 0x80 },
+	{ 1, 16129, 0xBF },
+	{ 1, 16666, 0xBE },
+	{ 1, 17241, 0xBD },
+	{ 1, 17857, 0xBC },
+	{ 1, 18518, 0xBB },
+	{ 1, 19230, 0xBA },
+	{ 1, 20000, 0xB9 },
+	{ 1, 20833, 0xB8 },
+	{ 1, 21739, 0xB7 },
+	{ 1, 22727, 0xB6 },
+	{ 1, 23809, 0xB5 },
+	{ 1, 24999, 0xB4 },
+	{ 1, 26315, 0xB3 },
+	{ 1, 27777, 0xB2 },
+	{ 1, 29411, 0xB1 },
+	{ 1, 31250, 0xB0 },
+	{ 1, 33333, 0xAF },
+	{ 1, 35714, 0xAE },
+	{ 1, 38461, 0xAD },
+	{ 1, 41666, 0xAC },
+	{ 1, 45454, 0xAB },
+	{ 1, 50000, 0xAA },
+	{ 1, 55555, 0xA9 },
+	{ 1, 62500, 0xA8 },
+	{ 1, 71428, 0xA7 },
+	{ 1, 83333, 0xA6 },
+	{ 1, 100000, 0xA5 },
+	{ 1, 125000, 0xA4 },
+	{ 1, 166666, 0xA3 },
+	{ 1, 250000, 0xA2 },
+	{ 1, 500000, 0xA1 },
+};
+
+static const struct lv0104cs_mapping lv0104cs_scales[] = {
+	{ 0, 250000, LV0104CS_SCALE_0_25X << LV0104CS_SCALE_SHIFT },
+	{ 1, 0, LV0104CS_SCALE_1X << LV0104CS_SCALE_SHIFT },
+	{ 2, 0, LV0104CS_SCALE_2X << LV0104CS_SCALE_SHIFT },
+	{ 8, 0, LV0104CS_SCALE_8X << LV0104CS_SCALE_SHIFT },
+};
+
+static const struct lv0104cs_mapping lv0104cs_int_times[] = {
+	{ 0, 12500, LV0104CS_INTEG_12_5MS << LV0104CS_INTEG_SHIFT },
+	{ 0, 100000, LV0104CS_INTEG_100MS << LV0104CS_INTEG_SHIFT },
+	{ 0, 200000, LV0104CS_INTEG_200MS << LV0104CS_INTEG_SHIFT },
+};
+
+static int lv0104cs_write_reg(struct i2c_client *client, u8 regval)
+{
+	int ret;
+
+	ret = i2c_master_send(client, (char *)&regval, sizeof(regval));
+	if (ret < 0)
+		return ret;
+	if (ret != sizeof(regval))
+		return -EIO;
+
+	return 0;
+}
+
+static int lv0104cs_read_adc(struct i2c_client *client, u16 *adc_output)
+{
+	__be16 regval;
+	int ret;
+
+	ret = i2c_master_recv(client, (char *)&regval, sizeof(regval));
+	if (ret < 0)
+		return ret;
+	if (ret != sizeof(regval))
+		return -EIO;
+
+	*adc_output = be16_to_cpu(regval);
+
+	return 0;
+}
+
+static int lv0104cs_get_lux(struct lv0104cs_private *lv0104cs,
+				int *val, int *val2)
+{
+	u8 regval = LV0104CS_REGVAL_MEASURE;
+	u16 adc_output;
+	int ret;
+
+	regval |= lv0104cs_scales[lv0104cs->scale].regval;
+	regval |= lv0104cs_int_times[lv0104cs->int_time].regval;
+	ret = lv0104cs_write_reg(lv0104cs->client, regval);
+	if (ret)
+		return ret;
+
+	/* wait for integration time to pass (with margin) */
+	switch (lv0104cs->int_time) {
+	case LV0104CS_INTEG_12_5MS:
+		msleep(50);
+		break;
+
+	case LV0104CS_INTEG_100MS:
+		msleep(150);
+		break;
+
+	case LV0104CS_INTEG_200MS:
+		msleep(250);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	ret = lv0104cs_read_adc(lv0104cs->client, &adc_output);
+	if (ret)
+		return ret;
+
+	ret = lv0104cs_write_reg(lv0104cs->client, LV0104CS_REGVAL_SLEEP);
+	if (ret)
+		return ret;
+
+	/* convert ADC output to lux */
+	switch (lv0104cs->scale) {
+	case LV0104CS_SCALE_0_25X:
+		*val = adc_output * 4;
+		*val2 = 0;
+		return 0;
+
+	case LV0104CS_SCALE_1X:
+		*val = adc_output;
+		*val2 = 0;
+		return 0;
+
+	case LV0104CS_SCALE_2X:
+		*val = adc_output / 2;
+		*val2 = (adc_output % 2) * 500000;
+		return 0;
+
+	case LV0104CS_SCALE_8X:
+		*val = adc_output / 8;
+		*val2 = (adc_output % 8) * 125000;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int lv0104cs_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct lv0104cs_private *lv0104cs = iio_priv(indio_dev);
+	int ret;
+
+	if (chan->type != IIO_LIGHT)
+		return -EINVAL;
+
+	mutex_lock(&lv0104cs->lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = lv0104cs_get_lux(lv0104cs, val, val2);
+		if (ret)
+			goto err_mutex;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+
+	case IIO_CHAN_INFO_CALIBSCALE:
+		*val = lv0104cs_calibscales[lv0104cs->calibscale].val;
+		*val2 = lv0104cs_calibscales[lv0104cs->calibscale].val2;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = lv0104cs_scales[lv0104cs->scale].val;
+		*val2 = lv0104cs_scales[lv0104cs->scale].val2;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = lv0104cs_int_times[lv0104cs->int_time].val;
+		*val2 = lv0104cs_int_times[lv0104cs->int_time].val2;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+
+	default:
+		ret = -EINVAL;
+	}
+
+err_mutex:
+	mutex_unlock(&lv0104cs->lock);
+
+	return ret;
+}
+
+static int lv0104cs_set_calibscale(struct lv0104cs_private *lv0104cs,
+				int val, int val2)
+{
+	int calibscale = val * 1000000 + val2;
+	int floor, ceil, mid;
+	int ret, i, index;
+
+	/* round to nearest quantized calibscale (sensitivity) */
+	for (i = 0; i < ARRAY_SIZE(lv0104cs_calibscales) - 1; i++) {
+		floor = lv0104cs_calibscales[i].val * 1000000
+				+ lv0104cs_calibscales[i].val2;
+		ceil = lv0104cs_calibscales[i + 1].val * 1000000
+				+ lv0104cs_calibscales[i + 1].val2;
+		mid = (floor + ceil) / 2;
+
+		/* round down */
+		if (calibscale >= floor && calibscale < mid) {
+			index = i;
+			break;
+		}
+
+		/* round up */
+		if (calibscale >= mid && calibscale <= ceil) {
+			index = i + 1;
+			break;
+		}
+	}
+
+	if (i == ARRAY_SIZE(lv0104cs_calibscales) - 1)
+		return -EINVAL;
+
+	mutex_lock(&lv0104cs->lock);
+
+	/* set calibscale (sensitivity) */
+	ret = lv0104cs_write_reg(lv0104cs->client,
+			lv0104cs_calibscales[index].regval);
+	if (ret)
+		goto err_mutex;
+
+	lv0104cs->calibscale = index;
+
+err_mutex:
+	mutex_unlock(&lv0104cs->lock);
+
+	return ret;
+}
+
+static int lv0104cs_set_scale(struct lv0104cs_private *lv0104cs,
+				int val, int val2)
+{
+	int i;
+
+	/* hard matching */
+	for (i = 0; i < ARRAY_SIZE(lv0104cs_scales); i++) {
+		if (val != lv0104cs_scales[i].val)
+			continue;
+
+		if (val2 == lv0104cs_scales[i].val2)
+			break;
+	}
+
+	if (i == ARRAY_SIZE(lv0104cs_scales))
+		return -EINVAL;
+
+	mutex_lock(&lv0104cs->lock);
+	lv0104cs->scale = i;
+	mutex_unlock(&lv0104cs->lock);
+
+	return 0;
+}
+
+static int lv0104cs_set_int_time(struct lv0104cs_private *lv0104cs,
+				int val, int val2)
+{
+	int i;
+
+	/* hard matching */
+	for (i = 0; i < ARRAY_SIZE(lv0104cs_int_times); i++) {
+		if (val != lv0104cs_int_times[i].val)
+			continue;
+
+		if (val2 == lv0104cs_int_times[i].val2)
+			break;
+	}
+
+	if (i == ARRAY_SIZE(lv0104cs_int_times))
+		return -EINVAL;
+
+	mutex_lock(&lv0104cs->lock);
+	lv0104cs->int_time = i;
+	mutex_unlock(&lv0104cs->lock);
+
+	return 0;
+}
+
+static int lv0104cs_write_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int val, int val2, long mask)
+{
+	struct lv0104cs_private *lv0104cs = iio_priv(indio_dev);
+
+	if (chan->type != IIO_LIGHT)
+		return -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBSCALE:
+		return lv0104cs_set_calibscale(lv0104cs, val, val2);
+
+	case IIO_CHAN_INFO_SCALE:
+		return lv0104cs_set_scale(lv0104cs, val, val2);
+
+	case IIO_CHAN_INFO_INT_TIME:
+		return lv0104cs_set_int_time(lv0104cs, val, val2);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static ssize_t lv0104cs_show_calibscale_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(lv0104cs_calibscales); i++) {
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d.%06d ",
+				lv0104cs_calibscales[i].val,
+				lv0104cs_calibscales[i].val2);
+	}
+
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t lv0104cs_show_scale_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(lv0104cs_scales); i++) {
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d.%06d ",
+				lv0104cs_scales[i].val,
+				lv0104cs_scales[i].val2);
+	}
+
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t lv0104cs_show_int_time_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(lv0104cs_int_times); i++) {
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d.%06d ",
+				lv0104cs_int_times[i].val,
+				lv0104cs_int_times[i].val2);
+	}
+
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR(calibscale_available, 0444,
+				lv0104cs_show_calibscale_avail, NULL, 0);
+static IIO_DEVICE_ATTR(scale_available, 0444,
+				lv0104cs_show_scale_avail, NULL, 0);
+static IIO_DEV_ATTR_INT_TIME_AVAIL(lv0104cs_show_int_time_avail);
+
+static struct attribute *lv0104cs_attributes[] = {
+	&iio_dev_attr_calibscale_available.dev_attr.attr,
+	&iio_dev_attr_scale_available.dev_attr.attr,
+	&iio_dev_attr_integration_time_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group lv0104cs_attribute_group = {
+	.attrs = lv0104cs_attributes,
+};
+
+static const struct iio_info lv0104cs_info = {
+	.attrs = &lv0104cs_attribute_group,
+	.read_raw = &lv0104cs_read_raw,
+	.write_raw = &lv0104cs_write_raw,
+};
+
+static const struct iio_chan_spec lv0104cs_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+				      BIT(IIO_CHAN_INFO_CALIBSCALE) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_INT_TIME),
+	},
+};
+
+static int lv0104cs_probe(struct i2c_client *client,
+				const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct lv0104cs_private *lv0104cs;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*lv0104cs));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	lv0104cs = iio_priv(indio_dev);
+
+	i2c_set_clientdata(client, lv0104cs);
+	lv0104cs->client = client;
+
+	mutex_init(&lv0104cs->lock);
+
+	lv0104cs->calibscale = LV0104CS_CALIBSCALE_UNITY;
+	lv0104cs->scale = LV0104CS_SCALE_1X;
+	lv0104cs->int_time = LV0104CS_INTEG_200MS;
+
+	ret = lv0104cs_write_reg(lv0104cs->client,
+			lv0104cs_calibscales[LV0104CS_CALIBSCALE_UNITY].regval);
+	if (ret)
+		return ret;
+
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->channels = lv0104cs_channels;
+	indio_dev->num_channels = ARRAY_SIZE(lv0104cs_channels);
+	indio_dev->name = client->name;
+	indio_dev->info = &lv0104cs_info;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id lv0104cs_id[] = {
+	{ "lv0104cs", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lv0104cs_id);
+
+static struct i2c_driver lv0104cs_i2c_driver = {
+	.driver = {
+		.name	= "lv0104cs",
+	},
+	.id_table	= lv0104cs_id,
+	.probe		= lv0104cs_probe,
+};
+module_i2c_driver(lv0104cs_i2c_driver);
+
+MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
+MODULE_DESCRIPTION("LV0104CS Ambient Light Sensor Driver");
+MODULE_LICENSE("GPL");