diff options
Diffstat (limited to 'drivers/i2c/i2c-core.c')
| -rw-r--r-- | drivers/i2c/i2c-core.c | 80 |
1 files changed, 40 insertions, 40 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index e0f833cca3f..f744f73e3ff 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1277,6 +1277,41 @@ EXPORT_SYMBOL(i2c_master_recv); * ---------------------------------------------------- */ +/* + * Legacy default probe function, mostly relevant for SMBus. The default + * probe method is a quick write, but it is known to corrupt the 24RF08 + * EEPROMs due to a state machine bug, and could also irreversibly + * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f, + * we use a short byte read instead. Also, some bus drivers don't implement + * quick write, so we fallback to a byte read in that case too. + * On x86, there is another special case for FSC hardware monitoring chips, + * which want regular byte reads (address 0x73.) Fortunately, these are the + * only known chips using this I2C address on PC hardware. + * Returns 1 if probe succeeded, 0 if not. + */ +static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr) +{ + int err; + union i2c_smbus_data dummy; + +#ifdef CONFIG_X86 + if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON) + && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA)) + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE_DATA, &dummy); + else +#endif + if ((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50 + || !i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK)) + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE, &dummy); + else + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0, + I2C_SMBUS_QUICK, NULL); + + return err >= 0; +} + static int i2c_detect_address(struct i2c_client *temp_client, struct i2c_driver *driver) { @@ -1297,23 +1332,8 @@ static int i2c_detect_address(struct i2c_client *temp_client, return 0; /* Make sure there is something at this address */ - if (addr == 0x73 && (adapter->class & I2C_CLASS_HWMON)) { - /* Special probe for FSC hwmon chips */ - union i2c_smbus_data dummy; - - if (i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_READ, 0, - I2C_SMBUS_BYTE_DATA, &dummy) < 0) - return 0; - } else { - if (i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_WRITE, 0, - I2C_SMBUS_QUICK, NULL) < 0) - return 0; - - /* Prevent 24RF08 corruption */ - if ((addr & ~0x0f) == 0x50) - i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_WRITE, 0, - I2C_SMBUS_QUICK, NULL); - } + if (!i2c_default_probe(adapter, addr)) + return 0; /* Finally call the custom detection function */ memset(&info, 0, sizeof(struct i2c_board_info)); @@ -1420,29 +1440,9 @@ i2c_new_probed_device(struct i2c_adapter *adap, continue; } - /* Test address responsiveness - The default probe method is a quick write, but it is known - to corrupt the 24RF08 EEPROMs due to a state machine bug, - and could also irreversibly write-protect some EEPROMs, so - for address ranges 0x30-0x37 and 0x50-0x5f, we use a byte - read instead. Also, some bus drivers don't implement - quick write, so we fallback to a byte read it that case - too. */ - if ((addr_list[i] & ~0x07) == 0x30 - || (addr_list[i] & ~0x0f) == 0x50 - || !i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK)) { - union i2c_smbus_data data; - - if (i2c_smbus_xfer(adap, addr_list[i], 0, - I2C_SMBUS_READ, 0, - I2C_SMBUS_BYTE, &data) >= 0) - break; - } else { - if (i2c_smbus_xfer(adap, addr_list[i], 0, - I2C_SMBUS_WRITE, 0, - I2C_SMBUS_QUICK, NULL) >= 0) - break; - } + /* Test address responsiveness */ + if (i2c_default_probe(adap, addr_list[i])) + break; } if (addr_list[i] == I2C_CLIENT_END) { |