Message-Id: <20241020-veml3235-v2-2-4bc7cfad7e0b@gmail.com>
Date: Sun, 20 Oct 2024 21:12:17 +0200
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Jonathan Cameron <jic23@...nel.org>, 
 Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Rishi Gupta <gupt21@...il.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Javier Carrasco <javier.carrasco.cruz@...il.com>
Subject: [PATCH v2 2/2] iio: light: add support for veml3235

The Vishay veml3235 is a low-power ambient light sensor with I2C
interface. It provides a minimum detectable intensity of
0.0021 lx/cnt, configurable integration time and gain, and an additional
white channel to distinguish between different light sources.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
---
 MAINTAINERS                  |   6 +
 drivers/iio/light/Kconfig    |  11 +
 drivers/iio/light/Makefile   |   1 +
 drivers/iio/light/veml3235.c | 540 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 558 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5ed860685cd1..ae7cb38fb64e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -24798,6 +24798,12 @@ S:	Maintained
 F:	drivers/input/serio/userio.c
 F:	include/uapi/linux/userio.h
 
+VISHAY VEML3235 AMBIENT LIGHT SENSOR DRIVER
+M:	Javier Carrasco <javier.carrasco.cruz@...il.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/light/vishay,veml6030.yaml
+F:	drivers/iio/light/veml3235.c
+
 VISHAY VEML6030 AMBIENT LIGHT SENSOR DRIVER
 M:	Javier Carrasco <javier.carrasco.cruz@...il.com>
 S:	Maintained
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index c38b3c603ab4..c6b7ed0c61a1 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -670,6 +670,17 @@ config VCNL4035
 	  To compile this driver as a module, choose M here: the
 	  module will be called vcnl4035.
 
+config VEML3235
+	tristate "VEML3235 ambient light sensor"
+	select REGMAP_I2C
+	depends on I2C
+	help
+	  Say Y here if you want to build a driver for the Vishay VEML3235
+	  ambient light sensor.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called veml3235.
+
 config VEML6030
 	tristate "VEML6030 and VEML6035 ambient light sensors"
 	select REGMAP_I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index 321010fc0b93..f14a37442712 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_TSL4531)		+= tsl4531.o
 obj-$(CONFIG_US5182D)		+= us5182d.o
 obj-$(CONFIG_VCNL4000)		+= vcnl4000.o
 obj-$(CONFIG_VCNL4035)		+= vcnl4035.o
+obj-$(CONFIG_VEML3235)		+= veml3235.o
 obj-$(CONFIG_VEML6030)		+= veml6030.o
 obj-$(CONFIG_VEML6040)		+= veml6040.o
 obj-$(CONFIG_VEML6070)		+= veml6070.o
diff --git a/drivers/iio/light/veml3235.c b/drivers/iio/light/veml3235.c
new file mode 100644
index 000000000000..fa2141cced8f
--- /dev/null
+++ b/drivers/iio/light/veml3235.c
@@ -0,0 +1,540 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * VEML3235 Ambient Light Sensor
+ *
+ * Copyright (c) 2024, Javier Carrasco <javier.carrasco.cruz@...il.com>
+ *
+ * Datasheet: https://www.vishay.com/docs/80131/veml3235.pdf
+ * Appnote-80222: https://www.vishay.com/docs/80222/designingveml3235.pdf
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+#define VEML3235_REG_CONF       0x00
+#define VEML3235_REG_WH_DATA    0x04
+#define VEML3235_REG_ALS_DATA   0x05
+#define VEML3235_REG_ID         0x09
+
+#define VEML3235_CONF_SD        BIT(0)
+#define VEML3235_CONF_SD0       BIT(8)
+
+struct veml3235_rf {
+	struct regmap_field *it;
+	struct regmap_field *gain;
+	struct regmap_field *id;
+};
+
+struct veml3235_data {
+	struct i2c_client *client;
+	struct device *dev;
+	struct regmap *regmap;
+	struct veml3235_rf rf;
+	int gain;
+	int it;
+	int resolution;
+};
+
+static const int veml3235_it_times[][2] = {
+	{ 0, 50000 },
+	{ 0, 100000 },
+	{ 0, 200000 },
+	{ 0, 400000 },
+	{ 0, 800000 },
+};
+
+static const int veml3235_scale_vals[] = { 1, 2, 4, 8 };
+
+static int veml3235_power_on(struct veml3235_data *data)
+{
+	int ret;
+
+	ret = regmap_clear_bits(data->regmap, VEML3235_REG_CONF,
+				VEML3235_CONF_SD | VEML3235_CONF_SD0);
+	if (ret)
+		return ret;
+
+	/* Wait 4 ms to let processor & oscillator start correctly */
+	fsleep(4000);
+
+	return 0;
+}
+
+static int veml3235_shut_down(struct veml3235_data *data)
+{
+	return regmap_set_bits(data->regmap, VEML3235_REG_CONF,
+			       VEML3235_CONF_SD | VEML3235_CONF_SD0);
+}
+
+static void veml3235_shut_down_action(void *data)
+{
+	veml3235_shut_down(data);
+}
+
+enum veml3235_chan {
+	CH_ALS,
+	CH_WHITE,
+};
+
+static const struct iio_chan_spec veml3235_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.channel = CH_ALS,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_PROCESSED),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME) |
+					   BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) |
+						     BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_INTENSITY,
+		.channel = CH_WHITE,
+		.modified = 1,
+		.channel2 = IIO_MOD_LIGHT_BOTH,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME) |
+					   BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) |
+						     BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static const struct regmap_config veml3235_regmap_config = {
+	.name = "veml3235_regmap",
+	.reg_bits = 8,
+	.val_bits = 16,
+	.max_register = VEML3235_REG_ID,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+static int veml3235_get_it(struct veml3235_data *data, int *val, int *val2)
+{
+	int ret, reg;
+
+	ret = regmap_field_read(data->rf.it, &reg);
+	if (ret)
+		return ret;
+
+	switch (reg) {
+	case 0:
+		*val2 = 50000;
+		break;
+	case 1:
+		*val2 = 100000;
+		break;
+	case 2:
+		*val2 = 200000;
+		break;
+	case 3:
+		*val2 = 400000;
+		break;
+	case 4:
+		*val2 = 800000;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	*val = 0;
+
+	return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int veml3235_set_it(struct iio_dev *indio_dev, int val, int val2)
+{
+	struct veml3235_data *data = iio_priv(indio_dev);
+	int ret, new_it, it_idx;
+
+	if (val)
+		return -EINVAL;
+
+	switch (val2) {
+	case 50000:
+		new_it = 0x00;
+		it_idx = 4;
+		break;
+	case 100000:
+		new_it = 0x01;
+		it_idx = 3;
+		break;
+	case 200000:
+		new_it = 0x02;
+		it_idx = 2;
+		break;
+	case 400000:
+		new_it = 0x03;
+		it_idx = 1;
+		break;
+	case 800000:
+		new_it = 0x04;
+		it_idx = 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_field_write(data->rf.it, new_it);
+	if (ret) {
+		dev_err(data->dev,
+			"failed to update integration time: %d\n", ret);
+		return ret;
+	}
+
+	if (data->it < it_idx)
+		data->resolution <<= it_idx - data->it;
+	else if (data->it > it_idx)
+		data->resolution >>= data->it - it_idx;
+
+	data->it = it_idx;
+
+	return 0;
+}
+
+static int veml3235_set_gain(struct iio_dev *indio_dev, int val, int val2)
+{
+	struct veml3235_data *data = iio_priv(indio_dev);
+	int ret, new_gain, gain_idx;
+
+	if (val2 != 0)
+		return -EINVAL;
+
+	switch (val) {
+	case 1:
+		new_gain = 0x00;
+		gain_idx = 3;
+		break;
+	case 2:
+		new_gain = 0x01;
+		gain_idx = 2;
+		break;
+	case 4:
+		new_gain = 0x03;
+		gain_idx = 1;
+		break;
+	case 8:
+		new_gain = 0x07;
+		gain_idx = 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_field_write(data->rf.gain, new_gain);
+	if (ret) {
+		dev_err(data->dev, "failed to set gain: %d\n", ret);
+		return ret;
+	}
+
+	if (data->gain < gain_idx)
+		data->resolution <<= gain_idx - data->gain;
+	else if (data->gain > gain_idx)
+		data->resolution >>= data->gain - gain_idx;
+
+	data->gain = gain_idx;
+
+	return 0;
+}
+
+static int veml3235_get_gain(struct veml3235_data *data, int *val)
+{
+	int ret, reg;
+
+	ret = regmap_field_read(data->rf.gain, &reg);
+	if (ret) {
+		dev_err(data->dev, "failed to read gain %d\n", ret);
+		return ret;
+	}
+
+	switch (reg & 0x03) {
+	case 0:
+		*val = 1;
+		break;
+	case 1:
+		*val = 2;
+		break;
+	case 3:
+		*val = 4;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Double gain */
+	if (reg & 0x04)
+		*val *= 2;
+
+	return IIO_VAL_INT;
+}
+
+static int veml3235_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int *val,
+			     int *val2, long mask)
+{
+	struct veml3235_data *data = iio_priv(indio_dev);
+	struct regmap *regmap = data->regmap;
+	int ret, reg;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (chan->type) {
+		case IIO_LIGHT:
+			ret = regmap_read(regmap, VEML3235_REG_ALS_DATA, &reg);
+			if (ret < 0)
+				return ret;
+
+			if (mask == IIO_CHAN_INFO_PROCESSED) {
+				*val = (reg * data->resolution) / 100000;
+				*val2 = (reg * data->resolution) % 100000 * 10;
+				return IIO_VAL_INT_PLUS_MICRO;
+			}
+			*val = reg;
+			return IIO_VAL_INT;
+		case IIO_INTENSITY:
+			ret = regmap_read(regmap, VEML3235_REG_WH_DATA, &reg);
+			if (ret < 0)
+				return ret;
+
+			*val = reg;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_INT_TIME:
+		return veml3235_get_it(data, val, val2);
+	case IIO_CHAN_INFO_SCALE:
+		return veml3235_get_gain(data, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int veml3235_read_avail(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       const int **vals, int *type, int *length,
+			       long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		*vals = (int *)&veml3235_it_times;
+		*length = 2 * ARRAY_SIZE(veml3235_it_times);
+		*type = IIO_VAL_INT_PLUS_MICRO;
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_SCALE:
+		*vals = (int *)&veml3235_scale_vals;
+		*length = ARRAY_SIZE(veml3235_scale_vals);
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int veml3235_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		return veml3235_set_it(indio_dev, val, val2);
+	case IIO_CHAN_INFO_SCALE:
+		return veml3235_set_gain(indio_dev, val, val2);
+	}
+
+	return -EINVAL;
+}
+
+static void veml3235_read_id(struct veml3235_data *data)
+{
+	int ret, reg;
+
+	ret = regmap_field_read(data->rf.id,  &reg);
+	if (ret) {
+		dev_info(data->dev, "failed to read ID\n");
+		return;
+	}
+
+	if (reg != 0x35)
+		dev_info(data->dev, "Unknown ID %d\n", reg);
+}
+
+static const struct reg_field veml3235_rf_it =
+	REG_FIELD(VEML3235_REG_CONF, 4, 6);
+
+static const struct reg_field veml3235_rf_gain =
+	REG_FIELD(VEML3235_REG_CONF, 11, 13);
+
+static const struct reg_field veml3235_rf_id =
+	REG_FIELD(VEML3235_REG_ID, 0, 7);
+
+static int veml3235_regfield_init(struct veml3235_data *data)
+{
+	struct regmap *regmap = data->regmap;
+	struct device *dev = data->dev;
+	struct regmap_field *rm_field;
+	struct veml3235_rf *rf = &data->rf;
+
+	rm_field = devm_regmap_field_alloc(dev, regmap, veml3235_rf_it);
+	if (IS_ERR(rm_field))
+		return PTR_ERR(rm_field);
+	rf->it = rm_field;
+
+	rm_field = devm_regmap_field_alloc(dev, regmap, veml3235_rf_gain);
+	if (IS_ERR(rm_field))
+		return PTR_ERR(rm_field);
+	rf->gain = rm_field;
+
+	rm_field = devm_regmap_field_alloc(dev, regmap, veml3235_rf_id);
+	if (IS_ERR(rm_field))
+		return PTR_ERR(rm_field);
+	rf->id = rm_field;
+
+	return 0;
+}
+
+static int veml3235_hw_init(struct iio_dev *indio_dev)
+{
+	struct veml3235_data *data = iio_priv(indio_dev);
+	struct device *dev = data->dev;
+	int ret;
+
+	ret = regmap_write(data->regmap, VEML3235_REG_CONF, 0x1001);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to set configuration\n");
+
+	/*
+	 * Set gain to 1, integration time to 100 ms, and the resulting
+	 * resolution in (lux/cnt * 100000) according to the typical value
+	 * from the datasheet.
+	 */
+	ret = regmap_field_write(data->rf.gain, 0x00);
+	if (ret)
+		return dev_err_probe(data->dev, ret, "failed to set gain\n");
+
+	ret = regmap_field_write(data->rf.it, 0x01);
+	if (ret)
+		return dev_err_probe(data->dev, ret,
+				     "failed to set integration time\n");
+
+	data->gain = 3;
+	data->it = 3;
+	data->resolution = 13632;
+
+	ret = veml3235_power_on(data);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to power on\n");
+
+	return devm_add_action_or_reset(dev, veml3235_shut_down_action, data);
+}
+
+static const struct iio_info veml3235_info = {
+	.read_raw  = veml3235_read_raw,
+	.read_avail  = veml3235_read_avail,
+	.write_raw = veml3235_write_raw,
+};
+
+static int veml3235_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct veml3235_data *data;
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = devm_regmap_init_i2c(client, &veml3235_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap),
+				     "failed to setup regmap\n");
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	data->dev = dev;
+	data->regmap = regmap;
+
+	ret = veml3235_regfield_init(data);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to init regfield\n");
+
+	ret = devm_regulator_get_enable(dev, "vdd");
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable regulator\n");
+
+	indio_dev->name = "veml3235";
+	indio_dev->channels = veml3235_channels;
+	indio_dev->num_channels = ARRAY_SIZE(veml3235_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &veml3235_info;
+
+	veml3235_read_id(data);
+
+	ret = veml3235_hw_init(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static int veml3235_runtime_suspend(struct device *dev)
+{
+	struct veml3235_data *data = iio_priv(dev_get_drvdata(dev));
+	int ret;
+
+	ret = veml3235_shut_down(data);
+	if (ret < 0)
+		dev_err(data->dev, "failed to suspend: %d\n", ret);
+
+	return ret;
+}
+
+static int veml3235_runtime_resume(struct device *dev)
+{
+	struct veml3235_data *data = iio_priv(dev_get_drvdata(dev));
+	int ret;
+
+	ret = veml3235_power_on(data);
+	if (ret < 0)
+		dev_err(data->dev, "failed to resume: %d\n", ret);
+
+	return ret;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(veml3235_pm_ops, veml3235_runtime_suspend,
+				 veml3235_runtime_resume, NULL);
+
+static const struct of_device_id veml3235_of_match[] = {
+	{ .compatible = "vishay,veml3235" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, veml3235_of_match);
+
+static const struct i2c_device_id veml3235_id[] = {
+	{ "veml3235" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, veml3235_id);
+
+static struct i2c_driver veml3235_driver = {
+	.driver = {
+		.name = "veml3235",
+		.of_match_table = veml3235_of_match,
+		.pm = pm_ptr(&veml3235_pm_ops),
+	},
+	.probe = veml3235_probe,
+	.id_table = veml3235_id,
+};
+module_i2c_driver(veml3235_driver);
+
+MODULE_AUTHOR("Javier Carrasco <javier.carrasco.cruz@...il.com>");
+MODULE_DESCRIPTION("VEML3235 Ambient Light Sensor");
+MODULE_LICENSE("GPL");

-- 
2.43.0

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