From 667f4bab81ea8357d260aa14bb6fb1a4834248d5 Mon Sep 17 00:00:00 2001 From: Chris Packham Date: Wed, 5 Oct 2016 10:40:54 +1300 Subject: 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: Chris Packham Signed-off-by: Guenter Roeck diff --git a/drivers/hwmon/adm9240.c b/drivers/hwmon/adm9240.c index 98114ce..2fe1828 100644 --- a/drivers/hwmon/adm9240.c +++ b/drivers/hwmon/adm9240.c @@ -194,10 +194,10 @@ static struct adm9240_data *adm9240_update_device(struct device *dev) * 0.5'C per two measurement cycles thus ignore possible * 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) | i2c_smbus_read_byte_data(client, - ADM9240_REG_TEMP_CONF)) / 128; + ADM9240_REG_TEMP_CONF); for (i = 0; i < 2; i++) { /* read fans */ 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) { 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, -- cgit v0.10.2