Messages in this thread Patch in this message |  | | From | Chris Packham <> | Subject | [PATCHv2] hwmon: adm9240: handle temperature readings below 0 | Date | Wed, 5 Oct 2016 10:40:54 +1300 |
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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 <chris.packham@alliedtelesis.co.nz> --- Changes in v2: - Simplify as per feedback from Guenter. - Re-word commit message.
drivers/hwmon/adm9240.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/adm9240.c b/drivers/hwmon/adm9240.c index 98114ce..8d8ede8 100644 --- a/drivers/hwmon/adm9240.c +++ b/drivers/hwmon/adm9240.c @@ -197,7 +197,7 @@ static struct adm9240_data *adm9240_update_device(struct device *dev) 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, -- 2.10.1
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