diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/hwmon/lm90.c | 72 |
1 files changed, 43 insertions, 29 deletions
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c index c24fe36ac78..73a1c622fb7 100644 --- a/drivers/hwmon/lm90.c +++ b/drivers/hwmon/lm90.c @@ -1,7 +1,7 @@ /* * lm90.c - Part of lm_sensors, Linux kernel modules for hardware * monitoring - * Copyright (C) 2003-2006 Jean Delvare <khali@linux-fr.org> + * Copyright (C) 2003-2008 Jean Delvare <khali@linux-fr.org> * * Based on the lm83 driver. The LM90 is a sensor chip made by National * Semiconductor. It reports up to two temperatures (its own plus up to @@ -736,6 +736,38 @@ static int lm90_remove(struct i2c_client *client) return 0; } +static int lm90_read16(struct i2c_client *client, u8 regh, u8 regl, u16 *value) +{ + int err; + u8 oldh, newh, l; + + /* + * There is a trick here. We have to read two registers to have the + * sensor temperature, but we have to beware a conversion could occur + * inbetween the readings. The datasheet says we should either use + * the one-shot conversion register, which we don't want to do + * (disables hardware monitoring) or monitor the busy bit, which is + * impossible (we can't read the values and monitor that bit at the + * exact same time). So the solution used here is to read the high + * byte once, then the low byte, then the high byte again. If the new + * high byte matches the old one, then we have a valid reading. Else + * we have to read the low byte again, and now we believe we have a + * correct reading. + */ + if ((err = lm90_read_reg(client, regh, &oldh)) + || (err = lm90_read_reg(client, regl, &l)) + || (err = lm90_read_reg(client, regh, &newh))) + return err; + if (oldh != newh) { + err = lm90_read_reg(client, regl, &l); + if (err) + return err; + } + *value = (newh << 8) | l; + + return 0; +} + static struct lm90_data *lm90_update_device(struct device *dev) { struct i2c_client *client = to_i2c_client(dev); @@ -744,7 +776,7 @@ static struct lm90_data *lm90_update_device(struct device *dev) mutex_lock(&data->update_lock); if (time_after(jiffies, data->last_updated + HZ * 2) || !data->valid) { - u8 oldh, newh, l; + u8 h, l; dev_dbg(&client->dev, "Updating lm90 data.\n"); lm90_read_reg(client, LM90_REG_R_LOCAL_TEMP, &data->temp8[0]); @@ -754,39 +786,21 @@ static struct lm90_data *lm90_update_device(struct device *dev) lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT, &data->temp8[4]); lm90_read_reg(client, LM90_REG_R_TCRIT_HYST, &data->temp_hyst); - /* - * There is a trick here. We have to read two registers to - * have the remote sensor temperature, but we have to beware - * a conversion could occur inbetween the readings. The - * datasheet says we should either use the one-shot - * conversion register, which we don't want to do (disables - * hardware monitoring) or monitor the busy bit, which is - * impossible (we can't read the values and monitor that bit - * at the exact same time). So the solution used here is to - * read the high byte once, then the low byte, then the high - * byte again. If the new high byte matches the old one, - * then we have a valid reading. Else we have to read the low - * byte again, and now we believe we have a correct reading. - */ - if (lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPH, &oldh) == 0 - && lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPL, &l) == 0 - && lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPH, &newh) == 0 - && (newh == oldh - || lm90_read_reg(client, LM90_REG_R_REMOTE_TEMPL, &l) == 0)) - data->temp11[0] = (newh << 8) | l; - - if (lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH, &newh) == 0 + lm90_read16(client, LM90_REG_R_REMOTE_TEMPH, + LM90_REG_R_REMOTE_TEMPL, &data->temp11[0]); + + if (lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH, &h) == 0 && lm90_read_reg(client, LM90_REG_R_REMOTE_LOWL, &l) == 0) - data->temp11[1] = (newh << 8) | l; - if (lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH, &newh) == 0 + data->temp11[1] = (h << 8) | l; + if (lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH, &h) == 0 && lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHL, &l) == 0) - data->temp11[2] = (newh << 8) | l; + data->temp11[2] = (h << 8) | l; if (data->kind != max6657) { if (lm90_read_reg(client, LM90_REG_R_REMOTE_OFFSH, - &newh) == 0 + &h) == 0 && lm90_read_reg(client, LM90_REG_R_REMOTE_OFFSL, &l) == 0) - data->temp11[3] = (newh << 8) | l; + data->temp11[3] = (h << 8) | l; } lm90_read_reg(client, LM90_REG_R_STATUS, &data->alarms); |