[PATCH 1/2] dt-bindings: iio: light: add ltr390

[PATCH 1/2] dt-bindings: iio: light: add ltr390

[Anshul Dalal]

Add binding for Lite-On LTR390 which is an Ambient/UV light sensor that
communicates over i2c with an address of 0x53.

Datasheet:
  https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf

Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
---
 .../bindings/iio/light/liteon,ltr390.yaml     | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/light/liteon,ltr390.yaml

diff --git a/Documentation/devicetree/bindings/iio/light/liteon,ltr390.yaml b/Documentation/devicetree/bindings/iio/light/liteon,ltr390.yaml
new file mode 100644
index 000000000000..90c20076b6c5
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/light/liteon,ltr390.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/light/liteon,ltr390.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Lite-On LTR390 ALS and UV Sensor
+
+description: |
+  The Lite-On LTR390 is an ALS (Ambient Light Sensor) and a UV sensor in a
+  single package with i2c address of 0x53.
+
+  Datasheet: https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
+
+maintainers:
+  - Anshul Dalal <anshulusr@gmail.com>
+
+properties:
+  compatible:
+    enum:
+      - liteon,ltr390
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Level interrupt pin with open drain output.
+      The sensor pulls this pin low when the measured reading is greater than
+      some configured threshold.
+
+  vdd-supply: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        light-sensor@53 {
+            compatible = "liteon,ltr390";
+            reg = <0x53>;
+        };
+    };
-- 
2.42.0

[PATCH 2/2] iio: light: driver for Lite-On ltr390

[Anshul Dalal]

Implements driver for the Ambient/UV Light sensor LTR390.
The driver exposes two ways of getting sensor readings:
  1. Raw UV Counts directly from the sensor
  2. The computed UV Index value with a percision of 2 decimal places

NOTE: Ambient light sensing has not been implemented yet.

Datasheet:
  https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf

Driver tested on RPi Zero 2W

Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
---
 MAINTAINERS                |   7 ++
 drivers/iio/light/Kconfig  |  11 ++
 drivers/iio/light/Makefile |   1 +
 drivers/iio/light/ltr390.c | 224 +++++++++++++++++++++++++++++++++++++
 4 files changed, 243 insertions(+)
 create mode 100644 drivers/iio/light/ltr390.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 81d5fc0bba68..c9f2238673f0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12484,6 +12484,13 @@ S:	Maintained
 W:	http://linux-test-project.github.io/
 T:	git https://github.com/linux-test-project/ltp.git
 
+LTR390 AMBIENT/UV LIGHT SENSOR DRIVER
+M:	Anshul Dalal <anshulusr@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/light/liteon,ltr390.yaml
+F:	drivers/iio/light/ltr390.c
+
 LYNX 28G SERDES PHY DRIVER
 M:	Ioana Ciornei <ioana.ciornei@nxp.com>
 L:	netdev@vger.kernel.org
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 45edba797e4c..61993ae79afe 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -347,6 +347,17 @@ config SENSORS_LM3533
 	  changes. The ALS-control output values can be set per zone for the
 	  three current output channels.
 
+config LTR390
+	tristate "LTR-390UV-01 ambient light and UV sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the Lite-On LTR-390UV-01
+	  ambient light and UV sensor.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ltr390.
+
 config LTR501
 	tristate "LTR-501ALS-01 light sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index c0db4c4c36ec..550f8b408bc2 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_SENSORS_ISL29028)	+= isl29028.o
 obj-$(CONFIG_ISL29125)		+= isl29125.o
 obj-$(CONFIG_JSA1212)		+= jsa1212.o
 obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
+obj-$(CONFIG_LTR390)		+= ltr390.o
 obj-$(CONFIG_LTR501)		+= ltr501.o
 obj-$(CONFIG_LTRF216A)		+= ltrf216a.o
 obj-$(CONFIG_LV0104CS)		+= lv0104cs.o
diff --git a/drivers/iio/light/ltr390.c b/drivers/iio/light/ltr390.c
new file mode 100644
index 000000000000..1445f944bfd0
--- /dev/null
+++ b/drivers/iio/light/ltr390.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * IIO driver for Lite-On LTR390 ALS and UV sensor
+ * (7-bit I2C slave address 0x53)
+ *
+ * Based on the work of:
+ *   Shreeya Patel and Shi Zhigang (LTRF216 Driver)
+ *
+ * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
+ *
+ * Datasheet: https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
+ *
+ * TODO:
+ *   - Support for configurable gain and resolution
+ *   - Sensor suspend/resume support
+ *   - Add support for reading the ALS
+ *   - Interrupt support
+ */
+
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/math.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+
+#define LTR390_DEVICE_NAME	   "ltr390"
+
+#define LTR390_MAIN_CTRL	   0x00
+#define LTR390_PART_ID		   0x06
+#define LTR390_UVS_DATA		   0x10
+
+#define LTR390_SW_RESET		   BIT(4)
+#define LTR390_UVS_MODE		   BIT(3)
+#define LTR390_SENSOR_ENABLE	   BIT(1)
+
+#define LTR390_PART_NUMBER_ID	   0xb
+#define LTR390_FRCTIONAL_PERCISION 100
+
+/*
+ * At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of
+ * the sensor are equal to 1 UV Index [Datasheet Page#8].
+ *
+ * For the default resolution of 18-bit (integration time: 100ms) and default
+ * gain of 3x, the counts/uvi are calculated as follows:
+ * 2300 / ((3/18) * (100/400)) = 95.83
+ */
+#define LTR390_COUNTS_PER_UVI 96
+
+/*
+ * Window Factor is needed when the device is under Window glass with coated
+ * tinted ink. This is to compensate for the light loss due to the lower
+ * transmission rate of the window glass and helps * in calculating lux.
+ */
+#define LTR390_WINDOW_FACTOR 1
+
+struct ltr390_data {
+	struct regmap *regmap;
+	struct i2c_client *client;
+	struct mutex lock;
+};
+
+static const struct regmap_config ltr390_regmap_config = {
+	.name = LTR390_DEVICE_NAME,
+	.reg_bits = 8,
+	.reg_stride = 1,
+	.val_bits = 8,
+};
+
+static int ltr390_register_read(struct ltr390_data *data, u8 register_address)
+{
+	struct device *dev = &data->client->dev;
+	int ret;
+	u8 recieve_buffer[3];
+
+	mutex_lock(&data->lock);
+
+	ret = regmap_bulk_read(data->regmap, register_address, recieve_buffer,
+			       sizeof(recieve_buffer));
+	if (ret) {
+		dev_err(dev, "failed to read measurement data: %d\n", ret);
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	mutex_unlock(&data->lock);
+	return get_unaligned_le24(recieve_buffer);
+}
+
+static int ltr390_get_uv_index(struct ltr390_data *data)
+{
+	int ret;
+	int uv_index;
+
+	ret = ltr390_register_read(data, LTR390_UVS_DATA);
+	if (ret < 0)
+		return ret;
+
+	uv_index = DIV_ROUND_CLOSEST(ret * LTR390_FRCTIONAL_PERCISION *
+					     LTR390_WINDOW_FACTOR,
+				     LTR390_COUNTS_PER_UVI);
+
+	return uv_index;
+}
+
+static int ltr390_read_raw(struct iio_dev *iio_device,
+			   struct iio_chan_spec const *chan, int *val,
+			   int *val2, long mask)
+{
+	int ret;
+	struct ltr390_data *data = iio_priv(iio_device);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = ltr390_get_uv_index(data);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		*val2 = LTR390_FRCTIONAL_PERCISION;
+		return IIO_VAL_FRACTIONAL;
+	case IIO_CHAN_INFO_RAW:
+		ret = ltr390_register_read(data, LTR390_UVS_DATA);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info ltr390_info = {
+	.read_raw = ltr390_read_raw,
+};
+
+static const struct iio_chan_spec ltr390_channels[] = {
+	{
+		.type = IIO_UVINDEX,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED)
+	},
+	{
+		.type = IIO_INTENSITY,
+		.channel2 = IIO_MOD_LIGHT_UV,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
+	},
+};
+
+static int ltr390_probe(struct i2c_client *client)
+{
+	struct ltr390_data *data;
+	struct iio_dev *indio_dev;
+	int ret, part_number;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+
+	data->regmap = devm_regmap_init_i2c(client, &ltr390_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "regmap initialization failed\n");
+
+	data->client = client;
+	i2c_set_clientdata(client, indio_dev);
+	mutex_init(&data->lock);
+
+	indio_dev->info = &ltr390_info;
+	indio_dev->channels = ltr390_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ltr390_channels);
+	indio_dev->name = LTR390_DEVICE_NAME;
+
+	ret = regmap_read(data->regmap, LTR390_PART_ID, &part_number);
+	if (ret) {
+		dev_err(&client->dev, "failed to get sensor's part id: %d",
+			ret);
+		return ret;
+	}
+	/* Lower 4 bits of `part_number` change with hardware revisions */
+	if (part_number >> 4 != LTR390_PART_NUMBER_ID) {
+		dev_err(&client->dev, "received invalid product id: 0x%x",
+			part_number);
+		return -ENODEV;
+	}
+	dev_dbg(&client->dev, "LTR390, product id: 0x%x\n", part_number);
+
+	/* reset sensor, chip fails to respond to this, so ignore any errors */
+	regmap_set_bits(data->regmap, LTR390_MAIN_CTRL, LTR390_SW_RESET);
+
+	/* Wait for the registers to reset before proceeding */
+	usleep_range(1000, 2000);
+
+	ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL,
+			      LTR390_SENSOR_ENABLE | LTR390_UVS_MODE);
+	if (ret) {
+		dev_err(&client->dev, "failed to enable the sensor: %d\n", ret);
+		return ret;
+	}
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id ltr390_id[] = {
+	{ LTR390_DEVICE_NAME, 0 },
+	{ /* Sentinel */ },
+};
+MODULE_DEVICE_TABLE(i2c, ltr390_id);
+
+static struct i2c_driver ltr390_driver = {
+	.driver = {
+		.name = LTR390_DEVICE_NAME,
+	},
+	.probe = ltr390_probe,
+	.id_table = ltr390_id,
+};
+
+module_i2c_driver(ltr390_driver);
+
+MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
+MODULE_DESCRIPTION("Lite-On LTR390 ALS and UV sensor Driver");
+MODULE_LICENSE("GPL");
-- 
2.42.0

Re: [PATCH 2/2] iio: light: driver for Lite-On ltr390

[Linus Walleij]

Hi Anshul,

thanks for your patch!

Overall this looks good to me.

On Thu, Nov 9, 2023 at 10:07 AM Anshul Dalal <anshulusr@gmail.com> wrote:

> Implements driver for the Ambient/UV Light sensor LTR390.
> The driver exposes two ways of getting sensor readings:
>   1. Raw UV Counts directly from the sensor
>   2. The computed UV Index value with a percision of 2 decimal places
>
> NOTE: Ambient light sensing has not been implemented yet.
>
> Datasheet:
>   https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
>
> Driver tested on RPi Zero 2W
>
> Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
(...)

> +#define LTR390_FRCTIONAL_PERCISION 100

This define is just too hard for me to read, can you rename it?

Does it mean LTR390_FRACTIONAL_PRECISION? It's fine to spell it out like
that instead.

Yours,
Linus Walleij

Re: [PATCH 2/2] iio: light: driver for Lite-On ltr390

[Anshul Dalal]

Hello Linus,

On 11/9/23 14:49, Linus Walleij wrote:
> Hi Anshul,
> 
> thanks for your patch!
> 
> Overall this looks good to me.
> 
> On Thu, Nov 9, 2023 at 10:07 AM Anshul Dalal <anshulusr@gmail.com> wrote:
> 
>> Implements driver for the Ambient/UV Light sensor LTR390.
>> The driver exposes two ways of getting sensor readings:
>>   1. Raw UV Counts directly from the sensor
>>   2. The computed UV Index value with a percision of 2 decimal places
>>
>> NOTE: Ambient light sensing has not been implemented yet.
>>
>> Datasheet:
>>   https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
>>
>> Driver tested on RPi Zero 2W
>>
>> Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
> (...)
> 
>> +#define LTR390_FRCTIONAL_PERCISION 100
> 
> This define is just too hard for me to read, can you rename it?
> 
> Does it mean LTR390_FRACTIONAL_PRECISION? It's fine to spell it out like
> that instead.

Yes indeed, that typo would be fixed in the next revision.

Thanks for the review.

Best wishes,
Anshul

Re: [PATCH 1/2] dt-bindings: iio: light: add ltr390

[Krzysztof Kozlowski]

On 09/11/2023 10:04, Anshul Dalal wrote:
> Add binding for Lite-On LTR390 which is an Ambient/UV light sensor that
> communicates over i2c with an address of 0x53.
> 
> Datasheet:
>   https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
> 
> Signed-off-by: Anshul Dalal <anshulusr@gmail.com>


> +  interrupts:
> +    maxItems: 1
> +    description: |
> +      Level interrupt pin with open drain output.
> +      The sensor pulls this pin low when the measured reading is greater than
> +      some configured threshold.
> +
> +  vdd-supply: true
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        light-sensor@53 {
> +            compatible = "liteon,ltr390";
> +            reg = <0x53>;

Please extend the example to be complete - interrupts and vdd-supply.

Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: iio: light: add ltr390

[Anshul Dalal]

Hello Krzysztof,

On 11/9/23 15:57, Krzysztof Kozlowski wrote:
> On 09/11/2023 10:04, Anshul Dalal wrote:
>> Add binding for Lite-On LTR390 which is an Ambient/UV light sensor that
>> communicates over i2c with an address of 0x53.
>>
>> Datasheet:
>>   https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
>>
>> Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
> 
> 
>> +  interrupts:
>> +    maxItems: 1
>> +    description: |
>> +      Level interrupt pin with open drain output.
>> +      The sensor pulls this pin low when the measured reading is greater than
>> +      some configured threshold.
>> +
>> +  vdd-supply: true
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    i2c {
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        light-sensor@53 {
>> +            compatible = "liteon,ltr390";
>> +            reg = <0x53>;
> 
> Please extend the example to be complete - interrupts and vdd-supply.

Could the following be used as a suitable example.

#include <dt-bindings/interrupt-controller/irq.h>

i2c {
    #address-cells = <1>;
    #size-cells = <0>;

    light-sensor@53 {
        compatible = "liteon,ltr390";
        reg = <0x53>;
        interrupts = <18 IRQ_TYPE_EDGE_FALLING>;
        vdd-supply = <&vdd_regulator>;
    };
};

Thanks for the review.

Best regards,
Anshul

Re: [PATCH 1/2] dt-bindings: iio: light: add ltr390

[Krzysztof Kozlowski]

On 09/11/2023 11:35, Anshul Dalal wrote:
>>> +examples:
>>> +  - |
>>> +    i2c {
>>> +        #address-cells = <1>;
>>> +        #size-cells = <0>;
>>> +
>>> +        light-sensor@53 {
>>> +            compatible = "liteon,ltr390";
>>> +            reg = <0x53>;
>>
>> Please extend the example to be complete - interrupts and vdd-supply.
> 
> Could the following be used as a suitable example.
> 

Yes

Best regards,
Krzysztof