Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e9f1373b643887f63878d1169b310c9acc534cd5
Commit:     e9f1373b643887f63878d1169b310c9acc534cd5
Parent:     0b987dcd3ae5626ac006fbbe366e9a8415b303df
Author:     David Brownell <[EMAIL PROTECTED]>
AuthorDate: Sun Jan 27 18:14:52 2008 +0100
Committer:  Jean Delvare <[EMAIL PROTECTED]>
CommitDate: Sun Jan 27 18:14:52 2008 +0100

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Jean Delvare <[EMAIL PROTECTED]>
---
 drivers/i2c/i2c-core.c |   59 +++++++++++++++++++++++++++++++++++++++++++++++-
 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 cd3fcb8..96da22e 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 731928a..76014f8 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.
-
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