[PATCH 0/2] Support for Texas Instruments OPT4001 Ambient Light Sensor

[PATCH 0/2] Support for Texas Instruments OPT4001 Ambient Light Sensor

[Stefan Windfeldt-Prytz]

This series adds support for Texas Instruments OPT4001 Ambient light sensor.

The light sensor has a i2c interface and supports continuous, oneshot and
interruptdriven measurements and has configurable conversion time and range.

This driver uses the sensors continuous mode so it always has a updated light
value available. The conversion time which is
 (integration time + time to set registers) which is used to configure
integration time through sysfs. The chip also has a configurable light
range which this driver sets to Auto where the chip chooses range itself
depending on previously read values.

Since the OPT4001 has different constants used to calculate lux values
depeding on packaging of the chip but uses the same device id, two compatible
string are used depending on the packaging, these are "ti,opt4001-picostar"
and "ti,opt4001-sot-5x3".

Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
---
Stefan Windfeldt-Prytz (2):
      dt-bindings: Document TI OPT4001 light sensor bindings
      iio: light: Add support for TI OPT4001 light sensor

 .../devicetree/bindings/iio/light/ti,opt4001.yaml  |  42 ++
 drivers/iio/light/Kconfig                          |  11 +
 drivers/iio/light/Makefile                         |   1 +
 drivers/iio/light/opt4001.c                        | 487 +++++++++++++++++++++
 4 files changed, 541 insertions(+)
---
base-commit: 60c5238813fdfbe167eb579d58172106916b8db0
change-id: 20230323-add-opt4001-driver-99b9aad69319

Best regards,
-- 
Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>

[PATCH 1/2] dt-bindings: Document TI OPT4001 light sensor bindings

[Stefan Windfeldt-Prytz]

Add devicetree bindings for opt4001 ambient light sensor.

Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
---
 .../devicetree/bindings/iio/light/ti,opt4001.yaml  | 42 ++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml b/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml
new file mode 100644
index 000000000000..cfd6b8b92c17
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/light/ti,opt4001.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments OPT4001 Ambient Light Sensor
+
+maintainers:
+  - Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
+
+description: |
+  Ambient light sensor with an i2c interface.
+  https://www.ti.com/lit/gpn/opt4001
+
+properties:
+  compatible:
+    enum:
+      - ti,opt4001-picostar
+      - ti,opt4001-sot-5x3
+
+  reg:
+    maxItems: 1
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        light-sensor@44 {
+            compatible = "ti,opt4001-picostar";
+            reg = <0x44>;
+        };
+    };
+...

-- 
2.30.2

[PATCH 2/2] iio: light: Add support for TI OPT4001 light sensor

[Stefan Windfeldt-Prytz]

This driver uses the continuous mode of the chip and integration
time can be configured through sysfs.
The constants for calculating lux value differs between packaging
so it uses different compatible string for the two versions
"ti,opt4001-picostar" and "ti,opt4001-sot-5x3" since the device id
is the same.

Datasheet: https://www.ti.com/lit/gpn/opt4001
Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
---
 drivers/iio/light/Kconfig   |  11 +
 drivers/iio/light/Makefile  |   1 +
 drivers/iio/light/opt4001.c | 487 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 499 insertions(+)

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 0d4447df7200..c4064fb35f1f 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -399,6 +399,17 @@ config OPT3001
 	  If built as a dynamically linked module, it will be called
 	  opt3001.
 
+config OPT4001
+	tristate "Texas Instruments OPT4001 Light Sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say Y or M here, you get support for Texas Instruments
+	  OPT4001 Ambient Light Sensor.
+
+	  If built as a dynamically linked module, it will be called
+	  opt4001.
+
 config PA12203001
 	tristate "TXC PA12203001 light and proximity sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index 6f23817fae6f..4e0a908948db 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_MAX44000)		+= max44000.o
 obj-$(CONFIG_MAX44009)		+= max44009.o
 obj-$(CONFIG_NOA1305)		+= noa1305.o
 obj-$(CONFIG_OPT3001)		+= opt3001.o
+obj-$(CONFIG_OPT4001)		+= opt4001.o
 obj-$(CONFIG_PA12203001)	+= pa12203001.o
 obj-$(CONFIG_RPR0521)		+= rpr0521.o
 obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
diff --git a/drivers/iio/light/opt4001.c b/drivers/iio/light/opt4001.c
new file mode 100644
index 000000000000..1ddcb10e997b
--- /dev/null
+++ b/drivers/iio/light/opt4001.c
@@ -0,0 +1,487 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Axis Communications AB
+ *
+ * Datasheet: https://www.ti.com/lit/gpn/opt4001
+ *
+ * Device driver for the Texas Instruments OPT4001.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+/* OPT4001 register set */
+#define OPT4001_LIGHT1_MSB    0x00
+#define OPT4001_LIGHT1_LSB    0x01
+#define OPT4001_CTRL          0x0A
+#define OPT4001_DEVICE_ID     0x11
+
+/* OPT4001 register mask */
+#define OPT4001_EXPONENT_MASK    GENMASK(15, 12)
+#define OPT4001_MSB_MASK         GENMASK(11, 0)
+#define OPT4001_LSB_MASK         GENMASK(15, 8)
+#define OPT4001_COUNTER_MASK     GENMASK(7, 4)
+#define OPT4001_CRC_MASK         GENMASK(3, 0)
+
+/* OPT4001 device id mask */
+#define OPT4001_DEVICE_ID_MASK   GENMASK(11, 0)
+
+/* OPT4001 control registers mask */
+#define OPT4001_CTRL_QWAKE_MASK          GENMASK(15, 15)
+#define OPT4001_CTRL_RANGE_MASK          GENMASK(13, 10)
+#define OPT4001_CTRL_CONV_TIME_MASK      GENMASK(9, 6)
+#define OPT4001_CTRL_OPER_MODE_MASK      GENMASK(5, 4)
+#define OPT4001_CTRL_LATCH_MASK          GENMASK(3, 3)
+#define OPT4001_CTRL_INT_POL_MASK        GENMASK(2, 2)
+#define OPT4001_CTRL_FAULT_COUNT         GENMASK(0, 1)
+
+/* OPT4001 constants */
+#define OPT4001_DEVICE_ID_VAL            0x121
+/* OPT4001 needs different constants to calculate lux for different packaging */
+#define OPT4001_PICOSTAR_MUL_CONST       3125
+#define OPT4001_SOT_5x3_MUL_CONST        4375
+#define OPT4001_PACKAGE_DIV_CONST        10000000
+
+/* OPT4001 operating modes */
+#define OPT4001_CTRL_OPER_MODE_OFF        0x0
+#define OPT4001_CTRL_OPER_MODE_FORCED     0x1
+#define OPT4001_CTRL_OPER_MODE_ONE_SHOT   0x2
+#define OPT4001_CTRL_OPER_MODE_CONTINUOUS 0x3
+
+/* OPT4001 conversion control register definitions */
+#define OPT4001_CTRL_CONVERSION_0_6MS   0x0
+#define OPT4001_CTRL_CONVERSION_1MS     0x1
+#define OPT4001_CTRL_CONVERSION_1_8MS   0x2
+#define OPT4001_CTRL_CONVERSION_3_4MS   0x3
+#define OPT4001_CTRL_CONVERSION_6_5MS   0x4
+#define OPT4001_CTRL_CONVERSION_12_7MS  0x5
+#define OPT4001_CTRL_CONVERSION_25MS    0x6
+#define OPT4001_CTRL_CONVERSION_50MS    0x7
+#define OPT4001_CTRL_CONVERSION_100MS   0x8
+#define OPT4001_CTRL_CONVERSION_200MS   0x9
+#define OPT4001_CTRL_CONVERSION_400MS   0xa
+#define OPT4001_CTRL_CONVERSION_800MS   0xb
+
+/* OPT4001 scale light level range definitions */
+#define OPT4001_CTRL_LIGHT_SCALE_AUTO   12
+
+/* OPT4001 default values */
+#define OPT4001_DEFAULT_CONVERSION_TIME OPT4001_CTRL_CONVERSION_800MS
+
+struct opt4001_package_const {
+	int mul;
+	int div;
+};
+
+struct opt4001_settings {
+	/* Index of the chosen integration time */
+	u8 int_time;
+	u8 chip_type;
+};
+
+struct opt4001_chip {
+	struct opt4001_settings light_settings;
+	struct regmap *regmap;
+	struct i2c_client *client;
+	const struct opt4001_package_const *package_constants;
+	/*
+	 * Keep light_settings in sync with hardware state
+	 * and ensure multiple readers are serialized.
+	 */
+	struct mutex als_mutex;
+};
+
+static const struct opt4001_package_const opt4001_sot_5x3_const = {
+	.mul = OPT4001_SOT_5x3_MUL_CONST,
+	.div = OPT4001_PACKAGE_DIV_CONST,
+};
+
+static const struct opt4001_package_const opt4001_picostar_const = {
+	.mul = OPT4001_PICOSTAR_MUL_CONST,
+	.div = OPT4001_PACKAGE_DIV_CONST,
+};
+
+static const int opt4001_int_time_available[][2] = {
+	{ 0,    600 },
+	{ 0,   1000 },
+	{ 0,   1800 },
+	{ 0,   3400 },
+	{ 0,   6500 },
+	{ 0,  12700 },
+	{ 0,  25000 },
+	{ 0,  50000 },
+	{ 0, 100000 },
+	{ 0, 200000 },
+	{ 0, 400000 },
+	{ 0, 800000 },
+};
+
+/*
+ * Conversion time is integration time + time to set register
+ * this is used as integration time.
+ */
+static const int opt4001_int_time_reg[][2] = {
+	{    600,  OPT4001_CTRL_CONVERSION_0_6MS  },
+	{   1000,  OPT4001_CTRL_CONVERSION_1MS    },
+	{   1800,  OPT4001_CTRL_CONVERSION_1_8MS  },
+	{   3400,  OPT4001_CTRL_CONVERSION_3_4MS  },
+	{   6500,  OPT4001_CTRL_CONVERSION_6_5MS  },
+	{  12700,  OPT4001_CTRL_CONVERSION_12_7MS },
+	{  25000,  OPT4001_CTRL_CONVERSION_25MS   },
+	{  50000,  OPT4001_CTRL_CONVERSION_50MS   },
+	{ 100000,  OPT4001_CTRL_CONVERSION_100MS  },
+	{ 200000,  OPT4001_CTRL_CONVERSION_200MS  },
+	{ 400000,  OPT4001_CTRL_CONVERSION_400MS  },
+	{ 800000,  OPT4001_CTRL_CONVERSION_800MS  },
+};
+
+static int opt4001_als_time_to_index(const u32 als_integration_time)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(opt4001_int_time_available); i++) {
+		if (als_integration_time == opt4001_int_time_available[i][1])
+			return i;
+	}
+
+	return -EINVAL;
+}
+
+static int opt4001_calculate_crc(int exp, int mantissa, int count)
+{
+	int crc;
+
+	crc = (hweight32(mantissa) + hweight32(exp) + hweight32(count)) % 2;
+	crc |= ((hweight32(mantissa & 0xAAAAA) + hweight32(exp & 0xA)
+		 + hweight32(count & 0xA)) % 2) << 1;
+	crc |= ((hweight32(mantissa & 0x88888) + hweight32(exp & 0x8)
+		 + hweight32(count & 0x8)) % 2) << 2;
+	crc |= (hweight32(mantissa & 0x80808) % 2) << 3;
+	return crc;
+}
+
+static int opt4001_read_lux_value(struct iio_dev *indio_dev,
+				  int *val, int *val2)
+{
+	struct opt4001_chip *chip = iio_priv(indio_dev);
+	struct device *dev = &chip->client->dev;
+	uint light1;
+	uint light2;
+	uint msb;
+	uint lsb;
+	uint exp;
+	uint count;
+	uint crc;
+	uint calc_crc;
+	unsigned long long lux_raw;
+	int ret;
+
+	ret = regmap_read(chip->regmap, OPT4001_LIGHT1_MSB, &light1);
+	if (ret < 0) {
+		dev_err(dev, "Failed to read data bytes");
+		return ret;
+	}
+
+	ret = regmap_read(chip->regmap, OPT4001_LIGHT1_LSB, &light2);
+	if (ret < 0) {
+		dev_err(dev, "Failed to read data bytes");
+		return ret;
+	}
+
+	count = (OPT4001_COUNTER_MASK & light2) >> 4;
+	exp = (OPT4001_EXPONENT_MASK & light1) >> 12;
+	crc = (OPT4001_CRC_MASK & light2);
+	msb = (OPT4001_MSB_MASK & light1);
+	lsb = (OPT4001_LSB_MASK & light2) >> 8;
+	lux_raw = (msb << 8) + lsb;
+	calc_crc = opt4001_calculate_crc(exp, lux_raw, count);
+	if (calc_crc != crc)
+		return -EIO;
+
+	lux_raw = lux_raw << exp;
+	lux_raw = lux_raw * chip->package_constants->mul;
+	*val = div_u64_rem(lux_raw, chip->package_constants->div, val2);
+	*val2 = *val2 * 100;
+
+	return IIO_VAL_INT_PLUS_NANO;
+}
+
+static int opt4001_set_conf(struct opt4001_chip *chip)
+{
+	struct opt4001_settings light_settings = chip->light_settings;
+	struct device *dev = &chip->client->dev;
+	u16 reg;
+	int ret;
+
+	reg = FIELD_PREP(OPT4001_CTRL_RANGE_MASK, OPT4001_CTRL_LIGHT_SCALE_AUTO);
+	reg |= FIELD_PREP(OPT4001_CTRL_CONV_TIME_MASK, light_settings.int_time);
+	reg |= FIELD_PREP(OPT4001_CTRL_OPER_MODE_MASK, OPT4001_CTRL_OPER_MODE_CONTINUOUS);
+
+	ret = regmap_write(chip->regmap, OPT4001_CTRL, reg);
+	if (ret)
+		dev_err(dev, "Failed to set configuration\n");
+
+	return ret;
+}
+
+static int opt4001_power_down(struct opt4001_chip *chip)
+{
+	int ret;
+	struct device *dev = &chip->client->dev;
+	uint reg;
+
+	ret = regmap_read(chip->regmap, OPT4001_DEVICE_ID, &reg);
+	if (ret) {
+		dev_err(dev, "Failed to read configuration\n");
+		return ret;
+	}
+
+	/* MODE_OFF is 0x0 so just set bits to 0 */
+	reg &= ~OPT4001_CTRL_OPER_MODE_MASK;
+
+	ret = regmap_write(chip->regmap, OPT4001_CTRL, reg);
+	if (ret)
+		dev_err(dev, "Failed to set configuration to power down\n");
+
+	return ret;
+}
+
+static const struct iio_chan_spec opt4001_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME)
+	},
+};
+
+static int opt4001_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct opt4001_chip *chip = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&chip->als_mutex);
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = opt4001_read_lux_value(indio_dev, val, val2);
+		break;
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = opt4001_int_time_reg[chip->light_settings.int_time][0];
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&chip->als_mutex);
+
+	return ret;
+}
+
+static int opt4001_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct opt4001_chip *chip = iio_priv(indio_dev);
+	int int_time;
+	int ret = 0;
+
+	mutex_lock(&chip->als_mutex);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		int_time = opt4001_als_time_to_index(val2);
+		if (int_time < 0) {
+			ret = int_time;
+		} else {
+			chip->light_settings.int_time = int_time;
+			ret = opt4001_set_conf(chip);
+		}
+
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+
+	mutex_unlock(&chip->als_mutex);
+	return ret;
+}
+
+static int opt4001_read_available(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:
+		*length = ARRAY_SIZE(opt4001_int_time_available) * 2;
+		*vals = (const int *)opt4001_int_time_available;
+		*type = IIO_VAL_INT_PLUS_MICRO;
+		return IIO_AVAIL_LIST;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info opt4001_info_no_irq = {
+	.read_raw = opt4001_read_raw,
+	.write_raw = opt4001_write_raw,
+	.read_avail = opt4001_read_available,
+};
+
+static int opt4001_load_defaults(struct opt4001_chip *chip)
+{
+	chip->light_settings.int_time = OPT4001_DEFAULT_CONVERSION_TIME;
+
+	return opt4001_set_conf(chip);
+}
+
+static bool opt4001_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case OPT4001_LIGHT1_MSB:
+	case OPT4001_LIGHT1_LSB:
+	case OPT4001_CTRL:
+	case OPT4001_DEVICE_ID:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool opt4001_writable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case OPT4001_CTRL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool opt4001_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case OPT4001_LIGHT1_MSB:
+	case OPT4001_LIGHT1_LSB:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config opt4001_regmap_config = {
+	.name = "opt4001",
+	.reg_bits = 8,
+	.val_bits = 16,
+	.cache_type = REGCACHE_RBTREE,
+	.max_register = OPT4001_DEVICE_ID,
+	.readable_reg = opt4001_readable_reg,
+	.writeable_reg = opt4001_writable_reg,
+	.volatile_reg = opt4001_volatile_reg,
+	.disable_locking = true,
+	.val_format_endian = REGMAP_ENDIAN_BIG,
+};
+
+/*
+ * The compatible string determines which constants to use depending on
+ * opt4001 packaging
+ */
+static const struct of_device_id opt4001_of_match[] = {
+	{ .compatible = "ti,opt4001-sot-5x3", .data = &opt4001_sot_5x3_const},
+	{ .compatible = "ti,opt4001-picostar", .data = &opt4001_picostar_const},
+	{}
+};
+MODULE_DEVICE_TABLE(of, opt4001_of_match);
+
+static int opt4001_probe(struct i2c_client *client)
+{
+	struct opt4001_chip *chip;
+	struct iio_dev *indio_dev;
+	const struct of_device_id *of_id;
+	int ret;
+	uint dev_id;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	chip = iio_priv(indio_dev);
+
+	chip->regmap = devm_regmap_init_i2c(client, &opt4001_regmap_config);
+	if (IS_ERR(chip->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
+				     "regmap initialization failed\n");
+
+	i2c_set_clientdata(client, indio_dev);
+	chip->client = client;
+
+	indio_dev->info = &opt4001_info_no_irq;
+
+	mutex_init(&chip->als_mutex);
+
+	ret = regmap_reinit_cache(chip->regmap, &opt4001_regmap_config);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "failed to reinit regmap cache\n");
+
+	ret = regmap_read(chip->regmap, OPT4001_DEVICE_ID, &dev_id);
+	if (ret < 0)
+		return dev_err_probe(&client->dev, ret,
+			"Failed to read the device ID register\n");
+
+	dev_id = FIELD_GET(OPT4001_DEVICE_ID_MASK, dev_id);
+	if (dev_id != OPT4001_DEVICE_ID_VAL) {
+		dev_err(&client->dev, "Device ID: %#04x unknown\n", dev_id);
+		return -EINVAL;
+	}
+
+	indio_dev->channels = opt4001_channels;
+	indio_dev->num_channels = ARRAY_SIZE(opt4001_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->name = chip->client->name;
+
+	of_id = of_match_device(of_match_ptr(opt4001_of_match), &client->dev);
+	chip->package_constants = of_id->data;
+
+	ret = opt4001_load_defaults(chip);
+	if (ret < 0)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to set sensor defaults\n");
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static void opt4001_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct opt4001_chip *chip = iio_priv(indio_dev);
+
+	opt4001_power_down(chip);
+}
+
+static struct i2c_driver opt4001_driver = {
+	.driver = {
+		.name = "opt4001",
+		.of_match_table = of_match_ptr(opt4001_of_match),
+	},
+	.probe_new = opt4001_probe,
+	.remove = opt4001_remove
+};
+module_i2c_driver(opt4001_driver);
+
+MODULE_AUTHOR("Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>");
+MODULE_DESCRIPTION("Texas Instruments opt4001 ambient light sensor driver");
+MODULE_LICENSE("GPL");

-- 
2.30.2

Re: [PATCH 1/2] dt-bindings: Document TI OPT4001 light sensor bindings

[Rob Herring]

On Tue, Apr 04, 2023 at 11:07:42AM +0200, Stefan Windfeldt-Prytz wrote:
> Add devicetree bindings for opt4001 ambient light sensor.
> 
> Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
> ---
>  .../devicetree/bindings/iio/light/ti,opt4001.yaml  | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml b/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml
> new file mode 100644
> index 000000000000..cfd6b8b92c17
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml
> @@ -0,0 +1,42 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/light/ti,opt4001.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Texas Instruments OPT4001 Ambient Light Sensor
> +
> +maintainers:
> +  - Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
> +
> +description: |
> +  Ambient light sensor with an i2c interface.
> +  https://www.ti.com/lit/gpn/opt4001
> +
> +properties:
> +  compatible:
> +    enum:
> +      - ti,opt4001-picostar
> +      - ti,opt4001-sot-5x3

Please explain in the commit message or description of the device what 
picostar and sot-5x3 mean.

> +
> +  reg:
> +    maxItems: 1
> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        light-sensor@44 {
> +            compatible = "ti,opt4001-picostar";
> +            reg = <0x44>;
> +        };
> +    };
> +...
> 
> -- 
> 2.30.2
> 

Re: [PATCH 1/2] dt-bindings: Document TI OPT4001 light sensor bindings

[Jonathan Cameron]

On Tue, 4 Apr 2023 11:07:42 +0200
Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com> wrote:

> Add devicetree bindings for opt4001 ambient light sensor.
> 
> Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>

Hi Stefan,

Please add the VDD regulator and interrupt pin to the DT binding.
Whilst the driver might not use them, the binding should describe the device
fully anyway both so that we can potentially enable control of the regulator
and use of interrupt in Linux and because other software picks up these
bindings and might need them.

The regulator is easy to handle in the driver now we have
devm_regulator_get_enable() so that probably is worth supporting from the start
even if your board has it hard wired on.

Thanks,

Jonathan

> ---
>  .../devicetree/bindings/iio/light/ti,opt4001.yaml  | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml b/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml
> new file mode 100644
> index 000000000000..cfd6b8b92c17
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/light/ti,opt4001.yaml
> @@ -0,0 +1,42 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/light/ti,opt4001.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Texas Instruments OPT4001 Ambient Light Sensor
> +
> +maintainers:
> +  - Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
> +
> +description: |
> +  Ambient light sensor with an i2c interface.
> +  https://www.ti.com/lit/gpn/opt4001
> +
> +properties:
> +  compatible:
> +    enum:
> +      - ti,opt4001-picostar
> +      - ti,opt4001-sot-5x3
> +
> +  reg:
> +    maxItems: 1
> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        light-sensor@44 {
> +            compatible = "ti,opt4001-picostar";
> +            reg = <0x44>;
> +        };
> +    };
> +...
> 

Re: [PATCH 2/2] iio: light: Add support for TI OPT4001 light sensor

[Jonathan Cameron]

On Tue, 4 Apr 2023 11:07:43 +0200
Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com> wrote:

> This driver uses the continuous mode of the chip and integration
> time can be configured through sysfs.
> The constants for calculating lux value differs between packaging
> so it uses different compatible string for the two versions
> "ti,opt4001-picostar" and "ti,opt4001-sot-5x3" since the device id
> is the same.
> 
> Datasheet: https://www.ti.com/lit/gpn/opt4001
> Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
> ---
Hi Stefan,

Various comments inline.

Thanks,

Jonathan

> diff --git a/drivers/iio/light/opt4001.c b/drivers/iio/light/opt4001.c
> new file mode 100644
> index 000000000000..1ddcb10e997b
> --- /dev/null
> +++ b/drivers/iio/light/opt4001.c
> @@ -0,0 +1,487 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2023 Axis Communications AB
> + *
> + * Datasheet: https://www.ti.com/lit/gpn/opt4001
> + *
> + * Device driver for the Texas Instruments OPT4001.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/math64.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_device.h>

As below, use property.h functions instead that work for lots of types of
firmware including OF.

> +#include <linux/regmap.h>

..

> +/* OPT4001 constants */
> +#define OPT4001_DEVICE_ID_VAL            0x121
> +/* OPT4001 needs different constants to calculate lux for different packaging */
> +#define OPT4001_PICOSTAR_MUL_CONST       3125
> +#define OPT4001_SOT_5x3_MUL_CONST        4375
> +#define OPT4001_PACKAGE_DIV_CONST        10000000
> +

...


> +
> +/* OPT4001 default values */
> +#define OPT4001_DEFAULT_CONVERSION_TIME OPT4001_CTRL_CONVERSION_800MS
> +
> +struct opt4001_package_const {
I would would include other things about the device variants in here.
If you want the naming to reflect which one of these you have then
a const char *name would make that easy to do.

> +	int mul;
> +	int div;
> +};
> +
> +struct opt4001_settings {
> +	/* Index of the chosen integration time */
> +	u8 int_time;
> +	u8 chip_type;
> +};
> +
> +struct opt4001_chip {
> +	struct opt4001_settings light_settings;
> +	struct regmap *regmap;
> +	struct i2c_client *client;
> +	const struct opt4001_package_const *package_constants;
> +	/*
> +	 * Keep light_settings in sync with hardware state
> +	 * and ensure multiple readers are serialized.
Multiple readers will be serialized with the underlying bus lock.
If you need to handle multiple part accesses together that's
what you should highlight here.

> +	 */
> +	struct mutex als_mutex;
> +};
> +
> +static const struct opt4001_package_const opt4001_sot_5x3_const = {
> +	.mul = OPT4001_SOT_5x3_MUL_CONST,
> +	.div = OPT4001_PACKAGE_DIV_CONST,
> +};
> +
> +static const struct opt4001_package_const opt4001_picostar_const = {
> +	.mul = OPT4001_PICOSTAR_MUL_CONST,

Unless used in multiple places, just having numbers here will be more readable
than giving them names.

> +	.div = OPT4001_PACKAGE_DIV_CONST,
> +};

> +static int opt4001_read_lux_value(struct iio_dev *indio_dev,
> +				  int *val, int *val2)
> +{
> +	struct opt4001_chip *chip = iio_priv(indio_dev);
> +	struct device *dev = &chip->client->dev;
> +	uint light1;
> +	uint light2;
> +	uint msb;
> +	uint lsb;
> +	uint exp;
> +	uint count;
> +	uint crc;
> +	uint calc_crc;

Would prefer fixed width types or unsigned int

> +	unsigned long long lux_raw;

u64 

> +	int ret;
> +
> +	ret = regmap_read(chip->regmap, OPT4001_LIGHT1_MSB, &light1);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to read data bytes");
> +		return ret;
> +	}
> +
> +	ret = regmap_read(chip->regmap, OPT4001_LIGHT1_LSB, &light2);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to read data bytes");
> +		return ret;
> +	}
> +
> +	count = (OPT4001_COUNTER_MASK & light2) >> 4;
> +	exp = (OPT4001_EXPONENT_MASK & light1) >> 12;
> +	crc = (OPT4001_CRC_MASK & light2);

FIELD_GET() for all these so no need to go look to see
if the field is aligned to LSB.

> +	msb = (OPT4001_MSB_MASK & light1);
> +	lsb = (OPT4001_LSB_MASK & light2) >> 8;
> +	lux_raw = (msb << 8) + lsb;
> +	calc_crc = opt4001_calculate_crc(exp, lux_raw, count);
> +	if (calc_crc != crc)
> +		return -EIO;
> +
> +	lux_raw = lux_raw << exp;
> +	lux_raw = lux_raw * chip->package_constants->mul;
> +	*val = div_u64_rem(lux_raw, chip->package_constants->div, val2);
> +	*val2 = *val2 * 100;
> +
> +	return IIO_VAL_INT_PLUS_NANO;
> +}


...


> +
> +static int opt4001_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct opt4001_chip *chip = iio_priv(indio_dev);
> +	int int_time;
> +	int ret = 0;

Set in all paths that I can see so don't set it here.


> +
> +	mutex_lock(&chip->als_mutex);

Might as well move the mutex into the case statement and simplify things
a little.

> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_INT_TIME:
> +		int_time = opt4001_als_time_to_index(val2);
> +		if (int_time < 0) {
> +			ret = int_time;
> +		} else {
> +			chip->light_settings.int_time = int_time;
> +			ret = opt4001_set_conf(chip);
> +		}
> +
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +
> +	mutex_unlock(&chip->als_mutex);
> +	return ret;
> +}
...

 +/*
> + * The compatible string determines which constants to use depending on
> + * opt4001 packaging
> + */
> +static const struct of_device_id opt4001_of_match[] = {
> +	{ .compatible = "ti,opt4001-sot-5x3", .data = &opt4001_sot_5x3_const},
> +	{ .compatible = "ti,opt4001-picostar", .data = &opt4001_picostar_const},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, opt4001_of_match);
> +
> +static int opt4001_probe(struct i2c_client *client)
> +{
> +	struct opt4001_chip *chip;
> +	struct iio_dev *indio_dev;
> +	const struct of_device_id *of_id;
> +	int ret;
> +	uint dev_id;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	chip = iio_priv(indio_dev);
> +
> +	chip->regmap = devm_regmap_init_i2c(client, &opt4001_regmap_config);
> +	if (IS_ERR(chip->regmap))
> +		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
> +				     "regmap initialization failed\n");
> +
> +	i2c_set_clientdata(client, indio_dev);

Don't think you'll need this after taking the remainder of remove over to
devm_ automatic unwinding.

> +	chip->client = client;
> +
> +	indio_dev->info = &opt4001_info_no_irq;
> +
> +	mutex_init(&chip->als_mutex);
> +
> +	ret = regmap_reinit_cache(chip->regmap, &opt4001_regmap_config);
> +	if (ret)
> +		return dev_err_probe(&client->dev, ret,
> +				     "failed to reinit regmap cache\n");
> +
> +	ret = regmap_read(chip->regmap, OPT4001_DEVICE_ID, &dev_id);
> +	if (ret < 0)
> +		return dev_err_probe(&client->dev, ret,
> +			"Failed to read the device ID register\n");
> +
> +	dev_id = FIELD_GET(OPT4001_DEVICE_ID_MASK, dev_id);
> +	if (dev_id != OPT4001_DEVICE_ID_VAL) {
> +		dev_err(&client->dev, "Device ID: %#04x unknown\n", dev_id);
> +		return -EINVAL;
> +	}
> +
> +	indio_dev->channels = opt4001_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(opt4001_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->name = chip->client->name;

I'd prefer to see the string obtained from the 'package constants' (renamed
to reflect it covers other details of the chip. That tends to remove any
risk of things getting out of sync.


> +
> +	of_id = of_match_device(of_match_ptr(opt4001_of_match), &client->dev);

device_get_match_data() from property.h


> +	chip->package_constants = of_id->data;
> +
> +	ret = opt4001_load_defaults(chip);
> +	if (ret < 0)
> +		return dev_err_probe(&client->dev, ret,
> +				     "Failed to set sensor defaults\n");

I assume load defaults powers up the chip. If so, you should
register a callback to power it down here (see below)

> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +static void opt4001_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct opt4001_chip *chip = iio_priv(indio_dev);
> +
> +	opt4001_power_down(chip);

If that's all that needs doing, can we use a devm_add_action_or_reset()
registered custom handler to power this off.

Note that currently you turn the chip off before the userspace interfaces
are removed which is a race we should close. Take things fully devm
managed and that should be automatic.

> +}
> +
> +static struct i2c_driver opt4001_driver = {
> +	.driver = {
> +		.name = "opt4001",
> +		.of_match_table = of_match_ptr(opt4001_of_match),

Don't use of_match_ptr().

Multiple reasons.
1) Will result in unused variable warnings if DT support not built.
2) Prevents other firmware registration paths (in particular ACPI PRP0001
   which uses this from non OF firmware).

> +	},
> +	.probe_new = opt4001_probe,
> +	.remove = opt4001_remove

Add an i2c_device_id table as well as the of one and MODULE_DEVICE_TABLE
for that. I think some auto probing of the driver still needs that.

> +};
> +module_i2c_driver(opt4001_driver);
> +
> +MODULE_AUTHOR("Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>");
> +MODULE_DESCRIPTION("Texas Instruments opt4001 ambient light sensor driver");
> +MODULE_LICENSE("GPL");
> 

Re: [PATCH 2/2] iio: light: Add support for TI OPT4001 light sensor

[Krzysztof Kozlowski]

On 04/04/2023 11:07, Stefan Windfeldt-Prytz wrote:
> This driver uses the continuous mode of the chip and integration
> time can be configured through sysfs.
> The constants for calculating lux value differs between packaging
> so it uses different compatible string for the two versions
> "ti,opt4001-picostar" and "ti,opt4001-sot-5x3" since the device id
> is the same.

Thank you for your patch. There is something to discuss/improve.

> +
> +	indio_dev->channels = opt4001_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(opt4001_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->name = chip->client->name;
> +
> +	of_id = of_match_device(of_match_ptr(opt4001_of_match), &client->dev);

? Drop of_match_ptr

> +	chip->package_constants = of_id->data;
> +
> +	ret = opt4001_load_defaults(chip);
> +	if (ret < 0)
> +		return dev_err_probe(&client->dev, ret,
> +				     "Failed to set sensor defaults\n");
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +static void opt4001_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct opt4001_chip *chip = iio_priv(indio_dev);
> +
> +	opt4001_power_down(chip);
> +}
> +
> +static struct i2c_driver opt4001_driver = {
> +	.driver = {
> +		.name = "opt4001",
> +		.of_match_table = of_match_ptr(opt4001_of_match),

This should sparkle some warnings. Drop of_match_ptr().

Best regards,
Krzysztof

Re: [PATCH 2/2] iio: light: Add support for TI OPT4001 light sensor

[Krzysztof Kozlowski]

On 18/04/2023 18:34, Krzysztof Kozlowski wrote:
> On 04/04/2023 11:07, Stefan Windfeldt-Prytz wrote:
>> This driver uses the continuous mode of the chip and integration
>> time can be configured through sysfs.
>> The constants for calculating lux value differs between packaging
>> so it uses different compatible string for the two versions
>> "ti,opt4001-picostar" and "ti,opt4001-sot-5x3" since the device id
>> is the same.
> 
> Thank you for your patch. There is something to discuss/improve.
> 
>> +
>> +	indio_dev->channels = opt4001_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(opt4001_channels);
>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>> +	indio_dev->name = chip->client->name;
>> +
>> +	of_id = of_match_device(of_match_ptr(opt4001_of_match), &client->dev);
> 
> ? Drop of_match_ptr

Ah, this is old patch... so maybe you already did this.

Best regards,
Krzysztof