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i2c: Add i2c_new_dummy() utility 

This adds a i2c_new_dummy() primitive to help work with devices
that consume multiple addresses, which include many I2C eeproms
and at least one RTC.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
hifive-unleashed-5.1
David Brownell 2008-01-27 18:14:52 +01:00 committed by Jean Delvare
parent 0b987dcd3a
commit e9f1373b64
2 changed files with 64 additions and 1 deletions
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59
drivers/i2c/i2c-core.c
View File

@ -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);
}

6
include/linux/i2c.h
View File

@ -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.