iio: magnetometer: ak8974: support AMI306 variant

Add support for AMI306 magnetometer - very similar to AMI305.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/magnetometer/Kconfig

@@ -13,8 +13,8 @@ config AK8974
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	help
-	  Say yes here to build support for Asahi Kasei AK8974 or
-	  AMI305 I2C-based 3-axis magnetometer chips.
+	  Say yes here to build support for Asahi Kasei AK8974, AMI305 or
+	  AMI306 I2C-based 3-axis magnetometer chips.
 
 	  To compile this driver as a module, choose M here: the module
 	  will be called ak8974.

drivers/iio/magnetometer/ak8974.c

@@ -36,7 +36,7 @@
  * and MSB is at the next higher address.
  */
 
-/* These registers are common for AK8974 and AMI305 */
+/* These registers are common for AK8974 and AMI30x */
 #define AK8974_SELFTEST		0x0C
 #define AK8974_SELFTEST_IDLE	0x55
 #define AK8974_SELFTEST_OK	0xAA
@@ -44,6 +44,7 @@
 #define AK8974_INFO		0x0D
 
 #define AK8974_WHOAMI		0x0F
+#define AK8974_WHOAMI_VALUE_AMI306 0x46
 #define AK8974_WHOAMI_VALUE_AMI305 0x47
 #define AK8974_WHOAMI_VALUE_AK8974 0x48
 
@@ -73,6 +74,35 @@
 #define AK8974_TEMP		0x31
 #define AMI305_TEMP		0x60
 
+/* AMI306-specific control register */
+#define AMI306_CTRL4		0x5C
+
+/* AMI306 factory calibration data */
+
+/* fine axis sensitivity */
+#define AMI306_FINEOUTPUT_X	0x90
+#define AMI306_FINEOUTPUT_Y	0x92
+#define AMI306_FINEOUTPUT_Z	0x94
+
+/* axis sensitivity */
+#define AMI306_SENS_X		0x96
+#define AMI306_SENS_Y		0x98
+#define AMI306_SENS_Z		0x9A
+
+/* axis cross-interference */
+#define AMI306_GAIN_PARA_XZ	0x9C
+#define AMI306_GAIN_PARA_XY	0x9D
+#define AMI306_GAIN_PARA_YZ	0x9E
+#define AMI306_GAIN_PARA_YX	0x9F
+#define AMI306_GAIN_PARA_ZY	0xA0
+#define AMI306_GAIN_PARA_ZX	0xA1
+
+/* offset at ZERO magnetic field */
+#define AMI306_OFFZERO_X	0xF8
+#define AMI306_OFFZERO_Y	0xFA
+#define AMI306_OFFZERO_Z	0xFC
+
+
 #define AK8974_INT_X_HIGH	BIT(7) /* Axis over +threshold  */
 #define AK8974_INT_Y_HIGH	BIT(6)
 #define AK8974_INT_Z_HIGH	BIT(5)
@@ -158,6 +188,26 @@ struct ak8974 {
 static const char ak8974_reg_avdd[] = "avdd";
 static const char ak8974_reg_dvdd[] = "dvdd";
 
+static int ak8974_get_u16_val(struct ak8974 *ak8974, u8 reg, u16 *val)
+{
+	int ret;
+	__le16 bulk;
+
+	ret = regmap_bulk_read(ak8974->map, reg, &bulk, 2);
+	if (ret)
+		return ret;
+	*val = le16_to_cpu(bulk);
+
+	return 0;
+}
+
+static int ak8974_set_u16_val(struct ak8974 *ak8974, u8 reg, u16 val)
+{
+	__le16 bulk = cpu_to_le16(val);
+
+	return regmap_bulk_write(ak8974->map, reg, &bulk, 2);
+}
+
 static int ak8974_set_power(struct ak8974 *ak8974, bool mode)
 {
 	int ret;
@@ -209,6 +259,12 @@ static int ak8974_configure(struct ak8974 *ak8974)
 	ret = regmap_write(ak8974->map, AK8974_CTRL3, 0);
 	if (ret)
 		return ret;
+	if (ak8974->variant == AK8974_WHOAMI_VALUE_AMI306) {
+		/* magic from datasheet: set high-speed measurement mode */
+		ret = ak8974_set_u16_val(ak8974, AMI306_CTRL4, 0xA07E);
+		if (ret)
+			return ret;
+	}
 	ret = regmap_write(ak8974->map, AK8974_INT_CTRL, AK8974_INT_CTRL_POL);
 	if (ret)
 		return ret;
@@ -388,19 +444,6 @@ static int ak8974_selftest(struct ak8974 *ak8974)
 	return 0;
 }
 
-static int ak8974_get_u16_val(struct ak8974 *ak8974, u8 reg, u16 *val)
-{
-	int ret;
-	__le16 bulk;
-
-	ret = regmap_bulk_read(ak8974->map, reg, &bulk, 2);
-	if (ret)
-		return ret;
-	*val = le16_to_cpu(bulk);
-
-	return 0;
-}
-
 static int ak8974_detect(struct ak8974 *ak8974)
 {
 	unsigned int whoami;
@@ -413,9 +456,13 @@ static int ak8974_detect(struct ak8974 *ak8974)
 	if (ret)
 		return ret;
 
+	name = "ami305";
+
 	switch (whoami) {
+	case AK8974_WHOAMI_VALUE_AMI306:
+		name = "ami306";
+		/* fall-through */
 	case AK8974_WHOAMI_VALUE_AMI305:
-		name = "ami305";
 		ret = regmap_read(ak8974->map, AMI305_VER, &fw);
 		if (ret)
 			return ret;
@@ -602,9 +649,11 @@ static bool ak8974_writeable_reg(struct device *dev, unsigned int reg)
 	case AMI305_OFFSET_Y + 1:
 	case AMI305_OFFSET_Z:
 	case AMI305_OFFSET_Z + 1:
-		if (ak8974->variant == AK8974_WHOAMI_VALUE_AMI305)
-			return true;
-		return false;
+		return ak8974->variant == AK8974_WHOAMI_VALUE_AMI305 ||
+		       ak8974->variant == AK8974_WHOAMI_VALUE_AMI306;
+	case AMI306_CTRL4:
+	case AMI306_CTRL4 + 1:
+		return ak8974->variant == AK8974_WHOAMI_VALUE_AMI306;
 	default:
 		return false;
 	}
@@ -678,7 +727,7 @@ static int ak8974_probe(struct i2c_client *i2c,
 
 	ret = ak8974_detect(ak8974);
 	if (ret) {
-		dev_err(&i2c->dev, "neither AK8974 nor AMI305 found\n");
+		dev_err(&i2c->dev, "neither AK8974 nor AMI30x found\n");
 		goto power_off;
 	}
 
@@ -827,6 +876,7 @@ static const struct dev_pm_ops ak8974_dev_pm_ops = {
 
 static const struct i2c_device_id ak8974_id[] = {
 	{"ami305", 0 },
+	{"ami306", 0 },
 	{"ak8974", 0 },
 	{}
 };
@@ -850,7 +900,7 @@ static struct i2c_driver ak8974_driver = {
 };
 module_i2c_driver(ak8974_driver);
 
-MODULE_DESCRIPTION("AK8974 and AMI305 3-axis magnetometer driver");
+MODULE_DESCRIPTION("AK8974 and AMI30x 3-axis magnetometer driver");
 MODULE_AUTHOR("Samu Onkalo");
 MODULE_AUTHOR("Linus Walleij");
 MODULE_LICENSE("GPL v2");