From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [patch 2.6.24-rc5-git] add i2c_new_dummy() utility Date: Sat, 22 Dec 2007 21:11:09 -0800 Message-ID: <200712222111.09471.david-b@pacbell.net> References: <200712222108.51292.david-b@pacbell.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200712222108.51292.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: i2c-bounces-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org Errors-To: i2c-bounces-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org To: Jean Delvare Cc: timtimred-f/KTTADhmRsdnm+yROfE0A@public.gmane.org, i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org List-Id: linux-i2c@vger.kernel.org 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 --- Updated to match Jean's feedback. Tested with 24c00 EEPROM, which takes eight addresses (but stores only 16 bytes total). drivers/i2c/i2c-core.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++- include/linux/i2c.h | 6 ++++ 2 files changed, 65 insertions(+), 1 deletion(-) --- a/drivers/i2c/i2c-core.c 2007-12-22 13:54:04.000000000 -0800 +++ b/drivers/i2c/i2c-core.c 2007-12-22 13:57:15.000000000 -0800 @@ -276,6 +276,51 @@ void i2c_unregister_device(struct i2c_cl 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 */ @@ -848,11 +893,24 @@ 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); } --- a/include/linux/i2c.h 2007-12-22 13:54:04.000000000 -0800 +++ b/include/linux/i2c.h 2007-12-22 13:57:15.000000000 -0800 @@ -261,6 +261,12 @@ i2c_new_probed_device(struct i2c_adapter 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.