extcon: Remove porting compatibility of swich class

This patch removes the porting compatibility for switch class
because there is no any usage and requirement of swich class
over a couple of years.
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

Documentation/extcon/porting-android-switch-class

-
-	Staging/Android Switch Class Porting Guide
-	(linux/drivers/staging/android/switch)
-	(c) Copyright 2012 Samsung Electronics
-
-AUTHORS
-MyungJoo Ham <myungjoo.ham@samsung.com>
-
-/*****************************************************************
- * CHAPTER 1.                                                    *
- * PORTING SWITCH CLASS DEVICE DRIVERS                           *
- *****************************************************************/
-
-****** STEP 1. Basic Functionality
-	No extcon extended feature, but switch features only.
-
-- struct switch_dev (fed to switch_dev_register/unregister)
-    @name: no change
-    @dev: no change
-    @index: drop (not used in switch device driver side anyway)
-    @state: no change
-	If you have used @state with magic numbers, keep it
-	at this step.
-    @print_name: no change but type change (switch_dev->extcon_dev)
-    @print_state: no change but type change (switch_dev->extcon_dev)
-
-- switch_dev_register(sdev, dev)
-	=> extcon_dev_register(edev)
-	: type change (sdev->edev)
-	: remove second param('dev'). if edev has parent device, should store
-	  'dev' to 'edev.dev.parent' before registering extcon device
-- switch_dev_unregister(sdev)
-	=> extcon_dev_unregister(edev)
-	: no change but type change (sdev->edev)
-- switch_get_state(sdev)
-	=> extcon_get_state(edev)
-	: no change but type change (sdev->edev) and (return: int->u32)
-- switch_set_state(sdev, state)
-	=> extcon_set_state(edev, state)
-	: no change but type change (sdev->edev) and (state: int->u32)
-
-With this changes, the ex-switch extcon class device works as it once
-worked as switch class device. However, it will now have additional
-interfaces (both ABI and in-kernel API) and different ABI locations.
-However, if CONFIG_ANDROID is enabled without CONFIG_ANDROID_SWITCH,
-/sys/class/switch/* will be symbolically linked to /sys/class/extcon/
-so that they are still compatible with legacy userspace processes.
-
-****** STEP 2. Multistate (no more magic numbers in state value)
-	Extcon's extended features for switch device drivers with
-	complex features usually required magic numbers in state
-	value of switch_dev. With extcon, such magic numbers that
-	support multiple cables are no more required or supported.
-
-  1. Define cable names at edev->supported_cable.
-  2. (Recommended) remove print_state callback.
-  3. Use extcon_get_cable_state_(edev, index) or
-   extcon_get_cable_state(edev, cable_name) instead of
-   extcon_get_state(edev) if you intend to get a state of a specific
-   cable. Same for set_state. This way, you can remove the usage of
-   magic numbers in state value.
-  4. Use extcon_update_state() if you are updating specific bits of
-   the state value.
-
-Example: a switch device driver w/ magic numbers for two cables.
-	"0x00": no cables connected.
-	"0x01": cable 1 connected
-	"0x02": cable 2 connected
-	"0x03": cable 1 and 2 connected
-  1. edev->supported_cable = {"1", "2", NULL};
-  2. edev->print_state = NULL;
-  3. extcon_get_cable_state_(edev, 0) shows cable 1's state.
-     extcon_get_cable_state(edev, "1") shows cable 1's state.
-     extcon_set_cable_state_(edev, 1) sets cable 2's state.
-     extcon_set_cable_state(edev, "2") sets cable 2's state
-  4. extcon_update_state(edev, 0x01, 0) sets the least bit's 0.
-
-****** STEP 3. Notify other device drivers
-
-  You can notify others of the cable attach/detach events with
-notifier chains.
-
-  At the side of other device drivers (the extcon device itself
-does not need to get notified of its own events), there are two
-methods to register notifier_block for cable events:
-(a) for a specific cable or (b) for every cable.
-
-  (a) extcon_register_interest(obj, extcon_name, cable_name, nb)
-	Example: want to get news of "MAX8997_MUIC"'s "USB" cable
-
-	obj = kzalloc(sizeof(struct extcon_specific_cable_nb),
-		      GFP_KERNEL);
-	nb->notifier_call = the_callback_to_handle_usb;
-
-	extcon_register_intereset(obj, "MAX8997_MUIC", "USB", nb);
-
-  (b) extcon_register_notifier(edev, nb)
-	Call nb for any changes in edev.
-
-  Please note that in order to properly behave with method (a),
-the extcon device driver should support multistate feature (STEP 2).
-
-****** STEP 4. Inter-cable relation (mutually exclusive)
-
-  You can provide inter-cable mutually exclusiveness information
-for an extcon device. When cables A and B are declared to be mutually
-exclusive, the two cables cannot be in ATTACHED state simulteneously.
-
-
-/*****************************************************************
- * CHAPTER 2.                                                    *
- * PORTING USERSPACE w/ SWITCH CLASS DEVICE SUPPORT              *
- *****************************************************************/
-
-****** ABI Location
-
-  If "CONFIG_ANDROID" is enabled, /sys/class/switch/* are created
-as symbolic links to /sys/class/extcon/*.
-
-  The two files of switch class, name and state, are provided with
-extcon, too. When the multistate support (STEP 2 of CHAPTER 1.) is
-not enabled or print_state callback is supplied, the output of
-state ABI is same with switch class.

drivers/extcon/extcon.c

@@ -230,9 +230,6 @@ struct extcon_cable {
 };
 
 static struct class *extcon_class;
-#if defined(CONFIG_ANDROID)
-static struct class_compat *switch_class;
-#endif /* CONFIG_ANDROID */
 
 static LIST_HEAD(extcon_dev_list);
 static DEFINE_MUTEX(extcon_dev_list_lock);
@@ -1032,12 +1029,6 @@ static int create_extcon_class(void)
 		if (IS_ERR(extcon_class))
 			return PTR_ERR(extcon_class);
 		extcon_class->dev_groups = extcon_groups;
-
-#if defined(CONFIG_ANDROID)
-		switch_class = class_compat_register("switch");
-		if (WARN(!switch_class, "cannot allocate"))
-			return -ENOMEM;
-#endif /* CONFIG_ANDROID */
 	}
 
 	return 0;
@@ -1259,10 +1250,6 @@ int extcon_dev_register(struct extcon_dev *edev)
 		put_device(&edev->dev);
 		goto err_dev;
 	}
-#if defined(CONFIG_ANDROID)
-	if (switch_class)
-		ret = class_compat_create_link(switch_class, &edev->dev, NULL);
-#endif /* CONFIG_ANDROID */
 
 	spin_lock_init(&edev->lock);
 
@@ -1350,10 +1337,6 @@ void extcon_dev_unregister(struct extcon_dev *edev)
 		kfree(edev->cables);
 	}
 
-#if defined(CONFIG_ANDROID)
-	if (switch_class)
-		class_compat_remove_link(switch_class, &edev->dev, NULL);
-#endif
 	put_device(&edev->dev);
 }
 EXPORT_SYMBOL_GPL(extcon_dev_unregister);
@@ -1424,9 +1407,6 @@ module_init(extcon_class_init);
 
 static void __exit extcon_class_exit(void)
 {
-#if defined(CONFIG_ANDROID)
-	class_compat_unregister(switch_class);
-#endif
 	class_destroy(extcon_class);
 }
 module_exit(extcon_class_exit);