rfkill: rewrite

This patch completely rewrites the rfkill core to address
the following deficiencies:

 * all rfkill drivers need to implement polling where necessary
   rather than having one central implementation

 * updating the rfkill state cannot be done from arbitrary
   contexts, forcing drivers to use schedule_work and requiring
   lots of code

 * rfkill drivers need to keep track of soft/hard blocked
   internally -- the core should do this

 * the rfkill API has many unexpected quirks, for example being
   asymmetric wrt. alloc/free and register/unregister

 * rfkill can call back into a driver from within a function the
   driver called -- this is prone to deadlocks and generally
   should be avoided

 * rfkill-input pointlessly is a separate module

 * drivers need to #ifdef rfkill functions (unless they want to
   depend on or select RFKILL) -- rfkill should provide inlines
   that do nothing if it isn't compiled in

 * the rfkill structure is not opaque -- drivers need to initialise
   it correctly (lots of sanity checking code required) -- instead
   force drivers to pass the right variables to rfkill_alloc()

 * the documentation is hard to read because it always assumes the
   reader is completely clueless and contains way TOO MANY CAPS

 * the rfkill code needlessly uses a lot of locks and atomic
   operations in locked sections

 * fix LED trigger to actually change the LED when the radio state
   changes -- this wasn't done before

Tested-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> [thinkpad]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 252 insertions, 74 deletions

diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index 3f0eaa397ef..7e09c5c1ed0 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -311,6 +311,7 @@ unifdef-y += ptrace.h
 unifdef-y += qnx4_fs.h
 unifdef-y += quota.h
 unifdef-y += random.h
+unifdef-y += rfkill.h
 unifdef-y += irqnr.h
 unifdef-y += reboot.h
 unifdef-y += reiserfs_fs.h
diff --git a/include/linux/rfkill.h b/include/linux/rfkill.h
index de18ef227e0..090852c8de7 100644
--- a/include/linux/rfkill.h
+++ b/include/linux/rfkill.h
@@ -4,6 +4,7 @@
 /*
  * Copyright (C) 2006 - 2007 Ivo van Doorn
  * Copyright (C) 2007 Dmitry Torokhov
+ * Copyright 2009 Johannes Berg <johannes@sipsolutions.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -21,6 +22,24 @@
  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
+
+/* define userspace visible states */
+#define RFKILL_STATE_SOFT_BLOCKED       0
+#define RFKILL_STATE_UNBLOCKED          1
+#define RFKILL_STATE_HARD_BLOCKED       2
+
+/* and that's all userspace gets */
+#ifdef __KERNEL__
+/* don't allow anyone to use these in the kernel */
+enum rfkill_user_states {
+        RFKILL_USER_STATE_SOFT_BLOCKED  = RFKILL_STATE_SOFT_BLOCKED,
+        RFKILL_USER_STATE_UNBLOCKED     = RFKILL_STATE_UNBLOCKED,
+        RFKILL_USER_STATE_HARD_BLOCKED  = RFKILL_STATE_HARD_BLOCKED,
+};
+#undef RFKILL_STATE_SOFT_BLOCKED
+#undef RFKILL_STATE_UNBLOCKED
+#undef RFKILL_STATE_HARD_BLOCKED
+
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
@@ -30,109 +49,267 @@
 
 /**
  * enum rfkill_type - type of rfkill switch.
- * RFKILL_TYPE_WLAN: switch is on a 802.11 wireless network device.
- * RFKILL_TYPE_BLUETOOTH: switch is on a bluetooth device.
- * RFKILL_TYPE_UWB: switch is on a ultra wideband device.
- * RFKILL_TYPE_WIMAX: switch is on a WiMAX device.
- * RFKILL_TYPE_WWAN: switch is on a wireless WAN device.
+ *
+ * @RFKILL_TYPE_WLAN: switch is on a 802.11 wireless network device.
+ * @RFKILL_TYPE_BLUETOOTH: switch is on a bluetooth device.
+ * @RFKILL_TYPE_UWB: switch is on a ultra wideband device.
+ * @RFKILL_TYPE_WIMAX: switch is on a WiMAX device.
+ * @RFKILL_TYPE_WWAN: switch is on a wireless WAN device.
+ * @NUM_RFKILL_TYPES: number of defined rfkill types
  */
 enum rfkill_type {
-        RFKILL_TYPE_WLAN ,
+        RFKILL_TYPE_WLAN,
         RFKILL_TYPE_BLUETOOTH,
         RFKILL_TYPE_UWB,
         RFKILL_TYPE_WIMAX,
         RFKILL_TYPE_WWAN,
-        RFKILL_TYPE_MAX,
+        NUM_RFKILL_TYPES,
 };
 
-enum rfkill_state {
-        RFKILL_STATE_SOFT_BLOCKED = 0,  /* Radio output blocked */
-        RFKILL_STATE_UNBLOCKED    = 1,  /* Radio output allowed */
-        RFKILL_STATE_HARD_BLOCKED = 2,  /* Output blocked, non-overrideable */
-        RFKILL_STATE_MAX,               /* marker for last valid state */
+/* this is opaque */
+struct rfkill;
+
+/**
+ * struct rfkill_ops - rfkill driver methods
+ *
+ * @poll: poll the rfkill block state(s) -- only assign this method
+ *      when you need polling. When called, simply call one of the
+ *      rfkill_set{,_hw,_sw}_state family of functions. If the hw
+ *      is getting unblocked you need to take into account the return
+ *      value of those functions to make sure the software block is
+ *      properly used.
+ * @query: query the rfkill block state(s) and call exactly one of the
+ *      rfkill_set{,_hw,_sw}_state family of functions. Assign this
+ *      method if input events can cause hardware state changes to make
+ *      the rfkill core query your driver before setting a requested
+ *      block.
+ * @set_block: turn the transmitter on (blocked == false) or off
+ *      (blocked == true) -- this is called only while the transmitter
+ *      is not hard-blocked, but note that the core's view of whether
+ *      the transmitter is hard-blocked might differ from your driver's
+ *      view due to race conditions, so it is possible that it is still
+ *      called at the same time as you are calling rfkill_set_hw_state().
+ *      This callback must be assigned.
+ */
+struct rfkill_ops {
+        void    (*poll)(struct rfkill *rfkill, void *data);
+        void    (*query)(struct rfkill *rfkill, void *data);
+        int     (*set_block)(void *data, bool blocked);
 };
 
+#if defined(CONFIG_RFKILL) || defined(CONFIG_RFKILL_MODULE)
 /**
- * struct rfkill - rfkill control structure.
- * @name: Name of the switch.
- * @type: Radio type which the button controls, the value stored
- *      here should be a value from enum rfkill_type.
- * @state: State of the switch, "UNBLOCKED" means radio can operate.
- * @mutex: Guards switch state transitions.  It serializes callbacks
- *      and also protects the state.
- * @data: Pointer to the RF button drivers private data which will be
- *      passed along when toggling radio state.
- * @toggle_radio(): Mandatory handler to control state of the radio.
- *      only RFKILL_STATE_SOFT_BLOCKED and RFKILL_STATE_UNBLOCKED are
- *      valid parameters.
- * @get_state(): handler to read current radio state from hardware,
- *      may be called from atomic context, should return 0 on success.
- *      Either this handler OR judicious use of rfkill_force_state() is
- *      MANDATORY for any driver capable of RFKILL_STATE_HARD_BLOCKED.
- * @led_trigger: A LED trigger for this button's LED.
- * @dev: Device structure integrating the switch into device tree.
- * @node: Used to place switch into list of all switches known to the
- *      the system.
- *
- * This structure represents a RF switch located on a network device.
+ * rfkill_alloc - allocate rfkill structure
+ * @name: name of the struct -- the string is not copied internally
+ * @parent: device that has rf switch on it
+ * @type: type of the switch (RFKILL_TYPE_*)
+ * @ops: rfkill methods
+ * @ops_data: data passed to each method
+ *
+ * This function should be called by the transmitter driver to allocate an
+ * rfkill structure. Returns %NULL on failure.
  */
-struct rfkill {
-        const char *name;
-        enum rfkill_type type;
-
-        /* the mutex serializes callbacks and also protects
-         * the state */
-        struct mutex mutex;
-        enum rfkill_state state;
-        void *data;
-        int (*toggle_radio)(void *data, enum rfkill_state state);
-        int (*get_state)(void *data, enum rfkill_state *state);
+struct rfkill * __must_check rfkill_alloc(const char *name,
+                                          struct device *parent,
+                                          const enum rfkill_type type,
+                                          const struct rfkill_ops *ops,
+                                          void *ops_data);
 
-#ifdef CONFIG_RFKILL_LEDS
-        struct led_trigger led_trigger;
-#endif
+/**
+ * rfkill_register - Register a rfkill structure.
+ * @rfkill: rfkill structure to be registered
+ *
+ * This function should be called by the transmitter driver to register
+ * the rfkill structure needs to be registered. Before calling this function
+ * the driver needs to be ready to service method calls from rfkill.
+ */
+int __must_check rfkill_register(struct rfkill *rfkill);
 
-        struct device dev;
-        struct list_head node;
-        enum rfkill_state state_for_resume;
-};
-#define to_rfkill(d)    container_of(d, struct rfkill, dev)
+/**
+ * rfkill_pause_polling(struct rfkill *rfkill)
+ *
+ * Pause polling -- say transmitter is off for other reasons.
+ * NOTE: not necessary for suspend/resume -- in that case the
+ * core stops polling anyway
+ */
+void rfkill_pause_polling(struct rfkill *rfkill);
 
-struct rfkill * __must_check rfkill_allocate(struct device *parent,
-                                             enum rfkill_type type);
-void rfkill_free(struct rfkill *rfkill);
-int __must_check rfkill_register(struct rfkill *rfkill);
+/**
+ * rfkill_resume_polling(struct rfkill *rfkill)
+ *
+ * Pause polling -- say transmitter is off for other reasons.
+ * NOTE: not necessary for suspend/resume -- in that case the
+ * core stops polling anyway
+ */