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hwmon: (lm92) Do not try to detect MAX6635

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Maxim MAX663x family are mostly compatible with LM92, but they lack any
identification register. Weakening the detect function would make it prone
to false positives, and current one doesn't detect all chips.  Therefore,
the detect function for max6635 devices is removed in favor of explicit
device instatiation.

Signed-off-by: Alvaro Gamez Machado <alvaro.gamez@hazent.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Alvaro G. M 2018-03-21 16:04:52 +01:00 committed by Guenter Roeck
parent 72816cb06e
commit 05993e226a
2 changed files with 1 additions and 61 deletions
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4
Documentation/hwmon/lm92
View File

@ -12,9 +12,7 @@ Supported chips:
Datasheet: http://www.national.com/pf/LM/LM76.html
* Maxim MAX6633/MAX6634/MAX6635
Prefix: 'lm92'
Addresses scanned: I2C 0x48 - 0x4b
MAX6633 with address in 0x40 - 0x47, 0x4c - 0x4f needs force parameter
and MAX6634 with address in 0x4c - 0x4f needs force parameter
Addresses scanned: none, force parameter needed
Datasheet: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074
Authors:

58
drivers/hwmon/lm92.c
View File

@ -259,62 +259,6 @@ static void lm92_init_client(struct i2c_client *client)
config & 0xFE);
}
/*
* The MAX6635 has no identification register, so we have to use tricks
* to identify it reliably. This is somewhat slow.
* Note that we do NOT rely on the 2 MSB of the configuration register
* always reading 0, as suggested by the datasheet, because it was once
* reported not to be true.
*/
static int max6635_check(struct i2c_client *client)
{
u16 temp_low, temp_high, temp_hyst, temp_crit;
u8 conf;
int i;
/*
* No manufacturer ID register, so a read from this address will
* always return the last read value.
*/
temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
return 0;
temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
return 0;
/* Limits are stored as integer values (signed, 9-bit). */
if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
return 0;
temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
return 0;
/*
* Registers addresses were found to cycle over 16-byte boundaries.
* We don't test all registers with all offsets so as to save some
* reads and time, but this should still be sufficient to dismiss
* non-MAX6635 chips.
*/
conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
for (i = 16; i < 96; i *= 2) {
if (temp_hyst != i2c_smbus_read_word_data(client,
LM92_REG_TEMP_HYST + i - 16)
|| temp_crit != i2c_smbus_read_word_data(client,
LM92_REG_TEMP_CRIT + i)
|| temp_low != i2c_smbus_read_word_data(client,
LM92_REG_TEMP_LOW + i + 16)
|| temp_high != i2c_smbus_read_word_data(client,
LM92_REG_TEMP_HIGH + i + 32)
|| conf != i2c_smbus_read_byte_data(client,
LM92_REG_CONFIG + i))
return 0;
}
return 1;
}
static struct attribute *lm92_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_temp1_crit.dev_attr.attr,
@ -348,8 +292,6 @@ static int lm92_detect(struct i2c_client *new_client,
if ((config & 0xe0) == 0x00 && man_id == 0x0180)
pr_info("lm92: Found National Semiconductor LM92 chip\n");
else if (max6635_check(new_client))
pr_info("lm92: Found Maxim MAX6635 chip\n");
else
return -ENODEV;