diff options
| -rw-r--r-- | drivers/i2c/i2c-core.c | 59 | ||||
| -rw-r--r-- | include/linux/i2c.h | 6 |
2 files changed, 64 insertions, 1 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index cd3fcb85ca7f..96da22e9a5a4 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -296,6 +296,50 @@ void i2c_unregister_device(struct i2c_client *client) EXPORT_SYMBOL_GPL(i2c_unregister_device); +static int dummy_nop(struct i2c_client *client) +{ + return 0; +} + +static struct i2c_driver dummy_driver = { + .driver.name = "dummy", + .probe = dummy_nop, + .remove = dummy_nop, +}; + +/** + * i2c_new_dummy - return a new i2c device bound to a dummy driver + * @adapter: the adapter managing the device + * @address: seven bit address to be used + * @type: optional label used for i2c_client.name + * Context: can sleep + * + * This returns an I2C client bound to the "dummy" driver, intended for use + * with devices that consume multiple addresses. Examples of such chips + * include various EEPROMS (like 24c04 and 24c08 models). + * + * These dummy devices have two main uses. First, most I2C and SMBus calls + * except i2c_transfer() need a client handle; the dummy will be that handle. + * And second, this prevents the specified address from being bound to a + * different driver. + * + * This returns the new i2c client, which should be saved for later use with + * i2c_unregister_device(); or NULL to indicate an error. + */ +struct i2c_client * +i2c_new_dummy(struct i2c_adapter *adapter, u16 address, const char *type) +{ + struct i2c_board_info info = { + .driver_name = "dummy", + .addr = address, + }; + + if (type) + strlcpy(info.type, type, sizeof info.type); + return i2c_new_device(adapter, &info); +} +EXPORT_SYMBOL_GPL(i2c_new_dummy); + /* ------------------------------------------------------------------------- */ /* I2C bus adapters -- one roots each I2C or SMBUS segment */ @@ -841,11 +885,24 @@ static int __init i2c_init(void) retval = bus_register(&i2c_bus_type); if (retval) return retval; - return class_register(&i2c_adapter_class); + retval = class_register(&i2c_adapter_class); + if (retval) + goto bus_err; + retval = i2c_add_driver(&dummy_driver); + if (retval) + goto class_err; + return 0; + +class_err: + class_unregister(&i2c_adapter_class); +bus_err: + bus_unregister(&i2c_bus_type); + return retval; } static void __exit i2c_exit(void) { + i2c_del_driver(&dummy_driver); class_unregister(&i2c_adapter_class); bus_unregister(&i2c_bus_type); } diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 731928ae972c..76014f8f3c60 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -259,6 +259,12 @@ i2c_new_probed_device(struct i2c_adapter *adap, struct i2c_board_info *info, unsigned short const *addr_list); +/* For devices that use several addresses, use i2c_new_dummy() to make + * client handles for the extra addresses. + */ +extern struct i2c_client * +i2c_new_dummy(struct i2c_adapter *adap, u16 address, const char *type); + extern void i2c_unregister_device(struct i2c_client *); /* Mainboard arch_initcall() code should register all its I2C devices. |