diff options
| author | Per Dalén <per.dalen@appeartv.com> | 2011-05-26 09:08:53 -0400 |
|---|---|---|
| committer | Guenter Roeck <guenter.roeck@ericsson.com> | 2011-06-04 10:34:28 -0700 |
| commit | 942c1a927bf296fd64fd49f04c5a8f66bb14446b (patch) | |
| tree | 58020f9137fd23755a918eca1ad0621109123a80 /drivers/hwmon/max6642.c | |
| parent | bb9973e4e73f43bd86698483d0c3f7a362ff94ce (diff) | |
| download | lwn-942c1a927bf296fd64fd49f04c5a8f66bb14446b.tar.gz lwn-942c1a927bf296fd64fd49f04c5a8f66bb14446b.zip | |
hwmon: (max6642): Better chip detection schema
Improve detection of MAX6642 by reading non existing registers (0x04, 0x06
and 0xff). Reading those registers returns the previously read value.
Signed-off-by: Per Dalen <per.dalen@appeartv.com>
[guenter.roeck@ericsson.com: added second set of register reads]
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Diffstat (limited to 'drivers/hwmon/max6642.c')
| -rw-r--r-- | drivers/hwmon/max6642.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/hwmon/max6642.c b/drivers/hwmon/max6642.c index 0f30e1bb366f..e855d3b0bd1f 100644 --- a/drivers/hwmon/max6642.c +++ b/drivers/hwmon/max6642.c @@ -136,15 +136,29 @@ static int max6642_detect(struct i2c_client *client, if (man_id != 0x4D) return -ENODEV; + /* sanity check */ + if (i2c_smbus_read_byte_data(client, 0x04) != 0x4D + || i2c_smbus_read_byte_data(client, 0x06) != 0x4D + || i2c_smbus_read_byte_data(client, 0xff) != 0x4D) + return -ENODEV; + /* * We read the config and status register, the 4 lower bits in the * config register should be zero and bit 5, 3, 1 and 0 should be * zero in the status register. */ reg_config = i2c_smbus_read_byte_data(client, MAX6642_REG_R_CONFIG); + if ((reg_config & 0x0f) != 0x00) + return -ENODEV; + + /* in between, another round of sanity checks */ + if (i2c_smbus_read_byte_data(client, 0x04) != reg_config + || i2c_smbus_read_byte_data(client, 0x06) != reg_config + || i2c_smbus_read_byte_data(client, 0xff) != reg_config) + return -ENODEV; + reg_status = i2c_smbus_read_byte_data(client, MAX6642_REG_R_STATUS); - if (((reg_config & 0x0f) != 0x00) || - ((reg_status & 0x2b) != 0x00)) + if ((reg_status & 0x2b) != 0x00) return -ENODEV; strlcpy(info->type, "max6642", I2C_NAME_SIZE); |