hwmon: (max6697) Allow max6581 to create tempX_offset

Add tempX_offset attribute support to max6697 driver.
Temperature offsets are only supported for MAX6581.

Testing:
echo 16250 > temp2_offset
cat temp2_offset
16250

echo 17500 > temp3_offset
cat temp3_offset
17500
cat temp4_offset
0
cat temp2_offset
17500

echo 0 > temp2_offset
cat temp2_offset
0
cat temp3_offset
17500

echo -0 > temp2_offset
cat temp2_offset
0

echo -100000 > temp2_offset
cat temp2_input
4875

echo 10000 > temp2_offset
cat temp2_input
47125

echo -2000 > temp2_offset
cat temp2_input
34875

echo -0 > temp2_offset
cat temp2_input
37000
Signed-off-by: Chu Lin <linchuyuan@google.com>
Link: https://lore.kernel.org/r/20200707171528.2929275-1-linchuyuan@google.com
[groeck: Fixed checkpatch warning (unnecessary { })]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/max6697.c

@@ -57,6 +57,8 @@ static const u8 MAX6697_REG_CRIT[] = {
 #define MAX6581_REG_IDEALITY_SELECT	0x4c
 #define MAX6581_REG_OFFSET		0x4d
 #define MAX6581_REG_OFFSET_SELECT	0x4e
+#define MAX6581_OFFSET_MIN		-31750
+#define MAX6581_OFFSET_MAX		31750
 
 #define MAX6697_CONV_TIME		156	/* ms per channel, worst case */
 
@@ -172,6 +174,11 @@ static const struct max6697_chip_data max6697_chip_data[] = {
 	},
 };
 
+static inline int max6581_offset_to_millic(int val)
+{
+	return sign_extend32(val, 7) * 250;
+}
+
 static struct max6697_data *max6697_update_device(struct device *dev)
 {
 	struct max6697_data *data = dev_get_drvdata(dev);
@@ -317,6 +324,70 @@ static ssize_t temp_store(struct device *dev,
 	return ret < 0 ? ret : count;
 }
 
+static ssize_t offset_store(struct device *dev, struct device_attribute *devattr, const char *buf,
+			    size_t count)
+{
+	int val, ret, index, select;
+	struct max6697_data *data;
+	bool channel_enabled;
+	long temp;
+
+	index = to_sensor_dev_attr(devattr)->index;
+	data = dev_get_drvdata(dev);
+	ret = kstrtol(buf, 10, &temp);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&data->update_lock);
+	select = i2c_smbus_read_byte_data(data->client, MAX6581_REG_OFFSET_SELECT);
+	if (select < 0) {
+		ret = select;
+		goto abort;
+	}
+	channel_enabled = (select & (1 << (index - 1)));
+	temp = clamp_val(temp, MAX6581_OFFSET_MIN, MAX6581_OFFSET_MAX);
+	val = DIV_ROUND_CLOSEST(temp, 250);
+	/* disable the offset for channel if the new offset is 0 */
+	if (val == 0) {
+		if (channel_enabled)
+			ret = i2c_smbus_write_byte_data(data->client, MAX6581_REG_OFFSET_SELECT,
+							select & ~(1 << (index - 1)));
+		ret = ret < 0 ? ret : count;
+		goto abort;
+	}
+	if (!channel_enabled) {
+		ret = i2c_smbus_write_byte_data(data->client, MAX6581_REG_OFFSET_SELECT,
+						select | (1 << (index - 1)));
+		if (ret < 0)
+			goto abort;
+	}
+	ret = i2c_smbus_write_byte_data(data->client, MAX6581_REG_OFFSET, val);
+	ret = ret < 0 ? ret : count;
+
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static ssize_t offset_show(struct device *dev, struct device_attribute *devattr, char *buf)
+{
+	struct max6697_data *data;
+	int select, ret, index;
+
+	index = to_sensor_dev_attr(devattr)->index;
+	data = dev_get_drvdata(dev);
+	mutex_lock(&data->update_lock);
+	select = i2c_smbus_read_byte_data(data->client, MAX6581_REG_OFFSET_SELECT);
+	if (select < 0)
+		ret = select;
+	else if (select & (1 << (index - 1)))
+		ret = i2c_smbus_read_byte_data(data->client, MAX6581_REG_OFFSET);
+	else
+		ret = 0;
+	mutex_unlock(&data->update_lock);
+	return ret < 0 ? ret : sprintf(buf, "%d\n", max6581_offset_to_millic(ret));
+}
+
 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
 static SENSOR_DEVICE_ATTR_2_RW(temp1_max, temp, 0, MAX6697_TEMP_MAX);
 static SENSOR_DEVICE_ATTR_2_RW(temp1_crit, temp, 0, MAX6697_TEMP_CRIT);
@@ -375,6 +446,15 @@ static SENSOR_DEVICE_ATTR_RO(temp6_fault, alarm, 5);
 static SENSOR_DEVICE_ATTR_RO(temp7_fault, alarm, 6);
 static SENSOR_DEVICE_ATTR_RO(temp8_fault, alarm, 7);
 
+/* There is no offset for local temperature so starting from temp2 */
+static SENSOR_DEVICE_ATTR_RW(temp2_offset, offset, 1);
+static SENSOR_DEVICE_ATTR_RW(temp3_offset, offset, 2);
+static SENSOR_DEVICE_ATTR_RW(temp4_offset, offset, 3);
+static SENSOR_DEVICE_ATTR_RW(temp5_offset, offset, 4);
+static SENSOR_DEVICE_ATTR_RW(temp6_offset, offset, 5);
+static SENSOR_DEVICE_ATTR_RW(temp7_offset, offset, 6);
+static SENSOR_DEVICE_ATTR_RW(temp8_offset, offset, 7);
+
 static DEVICE_ATTR(dummy, 0, NULL, NULL);
 
 static umode_t max6697_is_visible(struct kobject *kobj, struct attribute *attr,
@@ -383,8 +463,8 @@ static umode_t max6697_is_visible(struct kobject *kobj, struct attribute *attr,
 	struct device *dev = container_of(kobj, struct device, kobj);
 	struct max6697_data *data = dev_get_drvdata(dev);
 	const struct max6697_chip_data *chip = data->chip;
-	int channel = index / 6;	/* channel number */
-	int nr = index % 6;		/* attribute index within channel */
+	int channel = index / 7;	/* channel number */
+	int nr = index % 7;		/* attribute index within channel */
 
 	if (channel >= chip->channels)
 		return 0;
@@ -393,6 +473,10 @@ static umode_t max6697_is_visible(struct kobject *kobj, struct attribute *attr,
 		return 0;
 	if (nr == 5 && !(chip->have_fault & (1 << channel)))
 		return 0;
+	/* offset reg is only supported on max6581 remote channels */
+	if (nr == 6)
+		if (data->type != max6581 || channel == 0)
+			return 0;
 
 	return attr->mode;
 }
@@ -409,6 +493,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp1_crit.dev_attr.attr,
 	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 	&dev_attr_dummy.attr,
+	&dev_attr_dummy.attr,
 
 	&sensor_dev_attr_temp2_input.dev_attr.attr,
 	&sensor_dev_attr_temp2_max.dev_attr.attr,
@@ -416,6 +501,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp2_crit.dev_attr.attr,
 	&sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp2_fault.dev_attr.attr,
+	&sensor_dev_attr_temp2_offset.dev_attr.attr,
 
 	&sensor_dev_attr_temp3_input.dev_attr.attr,
 	&sensor_dev_attr_temp3_max.dev_attr.attr,
@@ -423,6 +509,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp3_crit.dev_attr.attr,
 	&sensor_dev_attr_temp3_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp3_fault.dev_attr.attr,
+	&sensor_dev_attr_temp3_offset.dev_attr.attr,
 
 	&sensor_dev_attr_temp4_input.dev_attr.attr,
 	&sensor_dev_attr_temp4_max.dev_attr.attr,
@@ -430,6 +517,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp4_crit.dev_attr.attr,
 	&sensor_dev_attr_temp4_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp4_fault.dev_attr.attr,
+	&sensor_dev_attr_temp4_offset.dev_attr.attr,
 
 	&sensor_dev_attr_temp5_input.dev_attr.attr,
 	&sensor_dev_attr_temp5_max.dev_attr.attr,
@@ -437,6 +525,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp5_crit.dev_attr.attr,
 	&sensor_dev_attr_temp5_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp5_fault.dev_attr.attr,
+	&sensor_dev_attr_temp5_offset.dev_attr.attr,
 
 	&sensor_dev_attr_temp6_input.dev_attr.attr,
 	&sensor_dev_attr_temp6_max.dev_attr.attr,
@@ -444,6 +533,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp6_crit.dev_attr.attr,
 	&sensor_dev_attr_temp6_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp6_fault.dev_attr.attr,
+	&sensor_dev_attr_temp6_offset.dev_attr.attr,
 
 	&sensor_dev_attr_temp7_input.dev_attr.attr,
 	&sensor_dev_attr_temp7_max.dev_attr.attr,
@@ -451,6 +541,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp7_crit.dev_attr.attr,
 	&sensor_dev_attr_temp7_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp7_fault.dev_attr.attr,
+	&sensor_dev_attr_temp7_offset.dev_attr.attr,
 
 	&sensor_dev_attr_temp8_input.dev_attr.attr,
 	&sensor_dev_attr_temp8_max.dev_attr.attr,
@@ -458,6 +549,7 @@ static struct attribute *max6697_attributes[] = {
 	&sensor_dev_attr_temp8_crit.dev_attr.attr,
 	&sensor_dev_attr_temp8_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp8_fault.dev_attr.attr,
+	&sensor_dev_attr_temp8_offset.dev_attr.attr,
 	NULL
 };