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Commit 667f4bab authored by Chris Packham's avatar Chris Packham Committed by Guenter Roeck
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hwmon: (adm9240) handle temperature readings below 0 



Unlike the temperature thresholds the temperature data is a 9-bit signed
value. This allows and additional 0.5 degrees of precision on the
reading but makes handling negative values slightly harder. In order to
have sign-extension applied correctly the 9-bit value is stored in the
upper bits of a signed 16-bit value. When presenting this in sysfs the
value is shifted and scaled appropriately.

Signed-off-by: default avatarChris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 1001354c

drivers/hwmon/adm9240.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -194,10 +194,10 @@ static struct adm9240_data *adm9240_update_device(struct device *dev) 
		 * 0.5'C per two measurement cycles thus ignore possible

		 * 0.5'C per two measurement cycles thus ignore possible

		 * but unlikely aliasing error on lsb reading. --Grant

		 * but unlikely aliasing error on lsb reading. --Grant

		 */

		 */

		data->temp = ((i2c_smbus_read_byte_data(client,

		data->temp = (i2c_smbus_read_byte_data(client,

					ADM9240_REG_TEMP) << 8) |

					ADM9240_REG_TEMP) << 8) |

					i2c_smbus_read_byte_data(client,

					i2c_smbus_read_byte_data(client,

					ADM9240_REG_TEMP_CONF)) / 128;

					ADM9240_REG_TEMP_CONF);





		for (i = 0; i < 2; i++) { /* read fans */

		for (i = 0; i < 2; i++) { /* read fans */

			data->fan[i] = i2c_smbus_read_byte_data(client,

			data->fan[i] = i2c_smbus_read_byte_data(client,
@@ -263,7 +263,7 @@ static ssize_t show_temp(struct device *dev, struct device_attribute *dummy, 
		char *buf)

		char *buf)

{

{

	struct adm9240_data *data = adm9240_update_device(dev);

	struct adm9240_data *data = adm9240_update_device(dev);

	return sprintf(buf, "%d\n", data->temp * 500); /* 9-bit value */

	return sprintf(buf, "%d\n", data->temp / 128 * 500); /* 9-bit value */

}

}





static ssize_t show_max(struct device *dev, struct device_attribute *devattr,

static ssize_t show_max(struct device *dev, struct device_attribute *devattr,