From: Jeroen De Wachter <jeroen.de_wachter....@nokia.com>
tmp401 separately read/wrote high and low bytes of temperature values while
the hardware supports reading/writing those values in one operation. Driver
has been modified to use word operations where possible.
Tested with a tmp432 sensor on a mips64 platform.
Signed-off-by: Jeroen De Wachter <jeroen.de_wachter....@nokia.com>
---
drivers/hwmon/tmp401.c | 48 +++++++++++++++++++++++++++++-------------------
1 file changed, 29 insertions(+), 19 deletions(-)
diff --git a/drivers/hwmon/tmp401.c b/drivers/hwmon/tmp401.c
index eeeed2c..88b17e4 100644
--- a/drivers/hwmon/tmp401.c
+++ b/drivers/hwmon/tmp401.c
@@ -213,25 +213,29 @@ static int tmp401_update_device_reg16(struct i2c_client
*client,
for (i = 0; i < num_sensors; i++) { /* local / r1 / r2 */
for (j = 0; j < num_regs; j++) { /* temp / low / ... */
u8 regaddr;
- /*
- * High byte must be read first immediately followed
- * by the low byte
- */
+
regaddr = data->kind == tmp432 ?
TMP432_TEMP_MSB_READ[j][i] :
TMP401_TEMP_MSB_READ[j][i];
- val = i2c_smbus_read_byte_data(client, regaddr);
- if (val < 0)
- return val;
- data->temp[j][i] = val << 8;
- if (j == 3) /* crit is msb only */
- continue;
- regaddr = data->kind == tmp432 ? TMP432_TEMP_LSB[j][i]
- : TMP401_TEMP_LSB[j][i];
- val = i2c_smbus_read_byte_data(client, regaddr);
+ if (j == 3) { /* crit is msb only */
+ val = i2c_smbus_read_byte_data(client, regaddr);
+ } else {
+ /*
+ * Hardware provides big endian data. However,
+ * the smbus protocol expects the LSB first in
+ * I2C_SMBUS_WORD_DATA operations.
+ * i2c_smbus_read_word_swapped swaps the bytes
+ * in the value it receives from
+ * i2c_smbus_read_word_data before returning the
+ * data, so we get the correct value.
+ */
+ val = i2c_smbus_read_word_swapped(client,
+ regaddr);
+ }
if (val < 0)
return val;
- data->temp[j][i] |= val;
+
+ data->temp[j][i] = j == 3 ? val << 8 : val;
}
}
return 0;
@@ -373,11 +377,17 @@ static ssize_t store_temp(struct device *dev, struct
device_attribute *devattr,
regaddr = data->kind == tmp432 ? TMP432_TEMP_MSB_WRITE[nr][index]
: TMP401_TEMP_MSB_WRITE[nr][index];
- i2c_smbus_write_byte_data(client, regaddr, reg >> 8);
- if (nr != 3) {
- regaddr = data->kind == tmp432 ? TMP432_TEMP_LSB[nr][index]
- : TMP401_TEMP_LSB[nr][index];
- i2c_smbus_write_byte_data(client, regaddr, reg & 0xFF);
+ if (nr == 3) { /* crit is msb only */
+ i2c_smbus_write_byte_data(client, regaddr, reg >> 8);
+ } else {
+ /*
+ * Hardware expects big endian data. However, the smbus protocol
+ * puts the LSB first in I2C_SMBUS_WORD_DATA operations.
+ * i2c_smbus_write_word_data_swapped will swap the bytes before
+ * passing them to i2c_smbus_write_word_data, so the hardware
+ * will receive the MSB first, as expected.
+ */
+ i2c_smbus_write_word_swapped(client, regaddr, reg);
}
data->temp[nr][index] = reg;
--
1.8.3.1
