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hwmon: (pcf8591) Don't attempt to detect devices 

The PCF8591 can't be detected, don't even try. There are plenty of
other means to instantiate i2c devices these days.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Reviewed-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Jean Delvare 2010-10-28 20:31:50 +02:00 committed by Jean Delvare
parent 4275fcd65d
commit 6dfee85397
2 changed files with 8 additions and 36 deletions
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18
Documentation/hwmon/pcf8591
View File

@ -4,7 +4,7 @@ Kernel driver pcf8591
Supported chips:
* Philips/NXP PCF8591
Prefix: 'pcf8591'
Addresses scanned: I2C 0x48 - 0x4f
Addresses scanned: none
Datasheet: Publicly available at the NXP website
http://www.nxp.com/pip/PCF8591_6.html
@ -58,18 +58,16 @@ Module parameters
Accessing PCF8591 via /sys interface
-------------------------------------
! Be careful !
The PCF8591 is plainly impossible to detect! Stupid chip.
So every chip with address in the interval [0x48..0x4f] is
detected as PCF8591. If you have other chips in this address
range, the workaround is to load this module after the one
for your others chips.
The PCF8591 is plainly impossible to detect! Thus the driver won't even
try. You have to explicitly instantiate the device at the relevant
address (in the interval [0x48..0x4f]) either through platform data, or
using the sysfs interface. See Documentation/i2c/instantiating-devices
for details.
On detection (i.e. insmod, modprobe et al.), directories are being
created for each detected PCF8591:
Directories are being created for each instantiated PCF8591:
/sys/bus/i2c/devices/<0>-<1>/
where <0> is the bus the chip was detected on (e. g. i2c-0)
where <0> is the bus the chip is connected to (e. g. i2c-0)
and <1> the chip address ([48..4f])
Inside these directories, there are such files:

26
drivers/hwmon/pcf8591.c
View File

@ -26,10 +26,6 @@
#include <linux/err.h>
#include <linux/hwmon.h>
/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
/* Insmod parameters */
static int input_mode;
@ -170,24 +166,6 @@ static const struct attribute_group pcf8591_attr_group_opt = {
* Real code
*/
/* Return 0 if detection is successful, -ENODEV otherwise */
static int pcf8591_detect(struct i2c_client *client,
struct i2c_board_info *info)
{
struct i2c_adapter *adapter = client->adapter;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE
| I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
return -ENODEV;
/* Now, we would do the remaining detection. But the PCF8591 is plainly
impossible to detect! Stupid chip. */
strlcpy(info->type, "pcf8591", I2C_NAME_SIZE);
return 0;
}
static int pcf8591_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
@ -307,10 +285,6 @@ static struct i2c_driver pcf8591_driver = {
.probe = pcf8591_probe,
.remove = pcf8591_remove,
.id_table = pcf8591_id,
.class = I2C_CLASS_HWMON, /* Nearest choice */
.detect = pcf8591_detect,
.address_list = normal_i2c,
};
static int __init pcf8591_init(void)