iio: accel: st_accel: Add support for Silan SC7A20

This chip appears to be register-compatible with the LIS2DH. The new
description is a copy of the LIS2DH's description with a different WAI
value.

Datasheet: http://linux-chenxing.org/silan/SC7A20-SilanMicroelectronics.pdf
Datasheet: http://www.siitek.com.cn/Upfiles/down/SC7A20说明书_0.92(智能穿戴).pdfSigned-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220202235049.8051-4-samuel@sholland.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/st_accel.h

@@ -36,6 +36,7 @@ enum st_accel_type {
 	LIS3DHH,
 	LIS2DE12,
 	LIS2HH12,
+	SC7A20,
 	ST_ACCEL_MAX,
 };
 
@@ -61,6 +62,7 @@ enum st_accel_type {
 #define LIS3DE_ACCEL_DEV_NAME		"lis3de"
 #define LIS2DE12_ACCEL_DEV_NAME		"lis2de12"
 #define LIS2HH12_ACCEL_DEV_NAME		"lis2hh12"
+#define SC7A20_ACCEL_DEV_NAME		"sc7a20"
 
 #ifdef CONFIG_IIO_BUFFER
 int st_accel_allocate_ring(struct iio_dev *indio_dev);

drivers/iio/accel/st_accel_core.c

@@ -1087,6 +1087,89 @@ static const struct st_sensor_settings st_accel_sensors_settings[] = {
 		.multi_read_bit = true,
 		.bootime = 2,
 	},
+	{
+		/*
+		 * Not an ST part. Register-compatible with the LIS2DH, even
+		 * though the WAI value is different.
+		 */
+		.wai = 0x11,
+		.wai_addr = ST_SENSORS_DEFAULT_WAI_ADDRESS,
+		.sensors_supported = {
+			[0] = SC7A20_ACCEL_DEV_NAME,
+		},
+		.ch = (struct iio_chan_spec *)st_accel_12bit_channels,
+		.odr = {
+			.addr = 0x20,
+			.mask = 0xf0,
+			.odr_avl = {
+				{ .hz = 1, .value = 0x01, },
+				{ .hz = 10, .value = 0x02, },
+				{ .hz = 25, .value = 0x03, },
+				{ .hz = 50, .value = 0x04, },
+				{ .hz = 100, .value = 0x05, },
+				{ .hz = 200, .value = 0x06, },
+				{ .hz = 400, .value = 0x07, },
+				{ .hz = 1600, .value = 0x08, },
+			},
+		},
+		.pw = {
+			.addr = 0x20,
+			.mask = 0xf0,
+			.value_off = ST_SENSORS_DEFAULT_POWER_OFF_VALUE,
+		},
+		.enable_axis = {
+			.addr = ST_SENSORS_DEFAULT_AXIS_ADDR,
+			.mask = ST_SENSORS_DEFAULT_AXIS_MASK,
+		},
+		.fs = {
+			.addr = 0x23,
+			.mask = 0x30,
+			.fs_avl = {
+				[0] = {
+					.num = ST_ACCEL_FS_AVL_2G,
+					.value = 0x00,
+					.gain = IIO_G_TO_M_S_2(1000),
+				},
+				[1] = {
+					.num = ST_ACCEL_FS_AVL_4G,
+					.value = 0x01,
+					.gain = IIO_G_TO_M_S_2(2000),
+				},
+				[2] = {
+					.num = ST_ACCEL_FS_AVL_8G,
+					.value = 0x02,
+					.gain = IIO_G_TO_M_S_2(4000),
+				},
+				[3] = {
+					.num = ST_ACCEL_FS_AVL_16G,
+					.value = 0x03,
+					.gain = IIO_G_TO_M_S_2(12000),
+				},
+			},
+		},
+		.bdu = {
+			.addr = 0x23,
+			.mask = 0x80,
+		},
+		.drdy_irq = {
+			.int1 = {
+				.addr = 0x22,
+				.mask = 0x10,
+			},
+			.addr_ihl = 0x25,
+			.mask_ihl = 0x02,
+			.stat_drdy = {
+				.addr = ST_SENSORS_DEFAULT_STAT_ADDR,
+				.mask = 0x07,
+			},
+		},
+		.sim = {
+			.addr = 0x23,
+			.value = BIT(0),
+		},
+		.multi_read_bit = true,
+		.bootime = 2,
+	},
 };
 
 /* Default accel DRDY is available on INT1 pin */

drivers/iio/accel/st_accel_i2c.c

@@ -107,6 +107,10 @@ static const struct of_device_id st_accel_of_match[] = {
 		.compatible = "st,lis2hh12",
 		.data = LIS2HH12_ACCEL_DEV_NAME,
 	},
+	{
+		.compatible = "silan,sc7a20",
+		.data = SC7A20_ACCEL_DEV_NAME,
+	},
 	{},
 };
 MODULE_DEVICE_TABLE(of, st_accel_of_match);
@@ -142,6 +146,7 @@ static const struct i2c_device_id st_accel_id_table[] = {
 	{ LIS3DE_ACCEL_DEV_NAME },
 	{ LIS2DE12_ACCEL_DEV_NAME },
 	{ LIS2HH12_ACCEL_DEV_NAME },
+	{ SC7A20_ACCEL_DEV_NAME },
 	{},
 };
 MODULE_DEVICE_TABLE(i2c, st_accel_id_table);