Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 942c1a92 authored by Per Dalén's avatar Per Dalén Committed by Guenter Roeck
Browse files

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: default avatarPer Dalen <per.dalen@appeartv.com>
[guenter.roeck@ericsson.com: added second set of register reads]
Signed-off-by: default avatarGuenter Roeck <guenter.roeck@ericsson.com>
parent bb9973e4

drivers/hwmon/max6642.c

+16 −2
Original line number Diff line number Diff line
@@ -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);