hwmon: (adt7411) add external thermal diode support

If the EXT_TDM bit is set, the chip supports a second temperature sensor
instead of two voltage sensors.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/adt7411.c

@@ -7,8 +7,7 @@
  *  it under the terms of the GNU General Public License version 2 as
  *  published by the Free Software Foundation.
  *
- *  TODO: SPI, support for external temperature sensor
- *	  use power-down mode for suspend?, interrupt handling?
+ *  TODO: SPI, use power-down mode for suspend?, interrupt handling?
  */
 
 #include <linux/kernel.h>
@@ -31,6 +30,7 @@
 #define ADT7411_REG_CFG1			0x18
 #define ADT7411_CFG1_START_MONITOR		(1 << 0)
 #define ADT7411_CFG1_RESERVED_BIT1		(1 << 1)
+#define ADT7411_CFG1_EXT_TDM			(1 << 2)
 #define ADT7411_CFG1_RESERVED_BIT3		(1 << 3)
 
 #define ADT7411_REG_CFG2			0x19
@@ -57,6 +57,7 @@ struct adt7411_data {
 	unsigned long next_update;
 	int vref_cached;
 	struct i2c_client *client;
+	bool use_ext_temp;
 };
 
 /*
@@ -127,11 +128,20 @@ static ssize_t adt7411_show_vdd(struct device *dev,
 static ssize_t adt7411_show_temp(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
+	int nr = to_sensor_dev_attr(attr)->index;
 	struct adt7411_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
-	int val = adt7411_read_10_bit(client, ADT7411_REG_INT_TEMP_VDD_LSB,
-			ADT7411_REG_INT_TEMP_MSB, 0);
-
+	int val;
+	struct {
+		u8 low;
+		u8 high;
+	} reg[2] = {
+		{ ADT7411_REG_INT_TEMP_VDD_LSB, ADT7411_REG_INT_TEMP_MSB },
+		{ ADT7411_REG_EXT_TEMP_AIN14_LSB,
+		  ADT7411_REG_EXT_TEMP_AIN1_MSB },
+	};
+
+	val = adt7411_read_10_bit(client, reg[nr].low, reg[nr].high, 0);
 	if (val < 0)
 		return val;
 
@@ -218,11 +228,13 @@ static ssize_t adt7411_set_bit(struct device *dev,
 	return ret < 0 ? ret : count;
 }
 
+
 #define ADT7411_BIT_ATTR(__name, __reg, __bit) \
 	SENSOR_DEVICE_ATTR_2(__name, S_IRUGO | S_IWUSR, adt7411_show_bit, \
 	adt7411_set_bit, __bit, __reg)
 
-static DEVICE_ATTR(temp1_input, S_IRUGO, adt7411_show_temp, NULL);
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, adt7411_show_temp, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, adt7411_show_temp, NULL, 1);
 static DEVICE_ATTR(in0_input, S_IRUGO, adt7411_show_vdd, NULL);
 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, adt7411_show_input, NULL, 0);
 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, adt7411_show_input, NULL, 1);
@@ -237,7 +249,8 @@ static ADT7411_BIT_ATTR(fast_sampling, ADT7411_REG_CFG3, ADT7411_CFG3_ADC_CLK_22
 static ADT7411_BIT_ATTR(adc_ref_vdd, ADT7411_REG_CFG3, ADT7411_CFG3_REF_VDD);
 
 static struct attribute *adt7411_attrs[] = {
-	&dev_attr_temp1_input.attr,
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp2_input.dev_attr.attr,
 	&dev_attr_in0_input.attr,
 	&sensor_dev_attr_in1_input.dev_attr.attr,
 	&sensor_dev_attr_in2_input.dev_attr.attr,
@@ -253,7 +266,27 @@ static struct attribute *adt7411_attrs[] = {
 	NULL
 };
 
-ATTRIBUTE_GROUPS(adt7411);
+static umode_t adt7411_attrs_visible(struct kobject *kobj,
+				     struct attribute *attr, int index)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct adt7411_data *data = dev_get_drvdata(dev);
+	bool visible = true;
+
+	if (attr == &sensor_dev_attr_temp2_input.dev_attr.attr)
+		visible = data->use_ext_temp;
+	else if (attr == &sensor_dev_attr_in1_input.dev_attr.attr ||
+		 attr == &sensor_dev_attr_in2_input.dev_attr.attr)
+		visible = !data->use_ext_temp;
+
+	return visible ? attr->mode : 0;
+}
+
+static const struct attribute_group adt7411_group = {
+	.attrs = adt7411_attrs,
+	.is_visible = adt7411_attrs_visible,
+};
+__ATTRIBUTE_GROUPS(adt7411);
 
 static int adt7411_detect(struct i2c_client *client,
 			  struct i2c_board_info *info)
@@ -309,6 +342,8 @@ static int adt7411_init_device(struct adt7411_data *data)
 	if (ret < 0)
 		return ret;
 
+	data->use_ext_temp = ret & ADT7411_CFG1_EXT_TDM;
+
 	/*
 	 * We must only write zero to bit 1 and only one to bit 3 according to
 	 * the datasheet.