dt-bindings: vendor-prefixes: add aosong

Add bindings for Aosong AGS02MA TVOC sensor.

The sensor communicates over i2c with the default address 0x1a. TVOC values can be read in the units of ppb and ug/m^3 at register 0x00.

Datasheet:
https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf
Product-Page:
http://www.aosong.com/m/en/products-33.html

Signed-off-by Anshul Dalal <[email protected]>

Add bindings for Aosong AGS02MA TVOC sensor.

The sensor communicates over i2c with the default address 0x1a. TVOC values can be read in the units of ppb and ug/m^3 at register 0x00.

Datasheet:
https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf
Product-Page:
http://www.aosong.com/m/en/products-33.html

Signed-off-by Anshul Dalal <[email protected]>

---

Changes for v4:
- Changed node name from 'light-sensor' to 'voc-sensor'

v3: https://lore.kernel.org/lkml/[email protected]/

Changes for v3:
- Fixed commit message
- Removed "asair,ags02ma" compatible

v2: https://lore.kernel.org/lkml/[email protected]/

Changes for v2:
- Removed device from trivial-devices
- Added standalone binding with vdd-supply property

v1: https://lore.kernel.org/lkml/[email protected]/

---
 .../bindings/iio/chemical/aosong,ags02ma.yaml | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/aosong,ags02ma.yaml

Documentation/devicetree/bindings/iio/chemical/aosong,ags02ma.yaml new file +17 -0

new file mode 100644
index 000000000000..c176a6e102ac
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/chemical/aosong,ags02ma.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Aosong AGS02MA VOC Sensor
+
+description: |
+  AGS02MA is an TVOC (Total Volatile Organic Compounds) i2c sensor with default
+  address of 0x1a.
+
+  Datasheet:
+    https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf
+
+maintainers:
+  - Anshul Dalal <[email protected]>

Documentation/devicetree/bindings/iio/chemical/aosong,ags02ma.yaml new file +19 -0

+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        voc-sensor@1a {
+            compatible = "aosong,ags02ma";
+            reg = <0x1a>;
+            vdd-supply = <&vdd_regulator>;
+        };
+    };

A simple driver for the TVOC (Total Volatile Organic Compounds) sensor from Aosong: AGS02MA

Steps in reading the VOC sensor value over i2c:
1. Read 5 bytes from the register AGS02MA_TVOC_READ_REG [0x00]
2. The first 4 bytes are taken as the big endian sensor data with final byte being the CRC
3. The CRC is verified and the value is returned over an IIO_CHAN_INFO_RAW channel as percents

Tested on Raspberry Pi Zero 2W

Datasheet:
https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf

Product-Page:
http://www.aosong.com/m/en/products-33.html

Signed-off-by Anshul Dalal <[email protected]>

drivers/iio/chemical/ags02ma.c new file +3 -0

new file mode 100644
index 000000000000..b23160eac99f
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 Anshul Dalal <[email protected]>

drivers/iio/chemical/ags02ma.c new file +42 -0

+ */
+
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+
+#define AGS02MA_DEVICE_NAME		   "ags02ma"
+
+#define AGS02MA_TVOC_READ_REG		   0x00
+#define AGS02MA_VERSION_REG		   0x11
+
+#define AGS02MA_VERSION_PROCESSING_DELAY   30
+#define AGS02MA_TVOC_READ_PROCESSING_DELAY 1500
+
+#define AGS02MA_CRC8_INIT		   0xff
+#define AGS02MA_CRC8_POLYNOMIAL		   0x31
+#define AGS02MA_PPB_PERCENT_CONVERSION     10000000
+
+DECLARE_CRC8_TABLE(ags02ma_crc8_table);
+
+struct ags02ma_data {
+	struct i2c_client *client;
+};
+
+struct ags02ma_reading {
+	__be32 data;
+	u8 crc;
+} __packed;
+
+static u32 ags02ma_register_read(struct i2c_client *client, u8 reg, u16 delay)
+{
+	int ret;
+	u8 crc;
+	struct ags02ma_reading read_buffer;
+
+	ret = i2c_master_send(client, &reg, sizeof(reg));
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"Failed to send data to register 0x%x: %d", reg, ret);
+		return ret;

drivers/iio/chemical/ags02ma.c new file +17 -0

+	}
+
+	crc = crc8(ags02ma_crc8_table, (u8 *)&read_buffer.data,
+		   sizeof(read_buffer.data), AGS02MA_CRC8_INIT);
+	if (crc != read_buffer.crc) {
+		dev_err(&client->dev, "CRC error\n");
+		return -EIO;
+	}
+
+	return be32_to_cpu(read_buffer.data);
 
+}
+
+static int ags02ma_read_raw(struct iio_dev *iio_device,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	int ret;

drivers/iio/chemical/ags02ma.c new file +10 -0

+};
+
+static int ags02ma_probe(struct i2c_client *client)
+{
+	int ret;
+	struct ags02ma_data *data;
+	struct iio_dev *indio_dev;
+	u32 version;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));

Aosong Electronic Co., LTD. is a supplier for MEMS sensors such as AHT20 temperature and humidity sensor under the brand name Asair

Signed-off-by Anshul Dalal <[email protected]>

---