| Message ID | 1483980458-28202-1-git-send-email-jeroen.de_wachter.ext@nokia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, Jan 09, 2017 at 05:47:37PM +0100, jeroen.de_wachter.ext@nokia.com wrote: > From: Jeroen De Wachter <jeroen.de_wachter.ext@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.ext@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. > + */ Please drop the comment or make it shorter (such as "Hardware provides big endian data"). > + 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. Comment in one place is enough. Unless I am missing something, TMP432_TEMP_LSB and TMP401_TEMP_LSB are now unused and can be removed. Thanks, Guenter > + */ > + i2c_smbus_write_word_swapped(client, regaddr, reg); > } > data->temp[nr][index] = reg; > > -- > 1.8.3.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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;