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>

1 files changed, 342 insertions, 0 deletions

diff --git a/net/rfkill/input.c b/net/rfkill/input.c
new file mode 100644
index 000000000000..a7295ad5f9cb
--- /dev/null
+++ b/net/rfkill/input.c
@@ -0,0 +1,342 @@
+/*
+ * Input layer to RF Kill interface connector
+ *
+ * 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 version 2 as published
+ * by the Free Software Foundation.
+ *
+ * If you ever run into a situation in which you have a SW_ type rfkill
+ * input device, then you can revive code that was removed in the patch
+ * "rfkill-input: remove unused code".
+ */
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/init.h>
+#include <linux/rfkill.h>
+#include <linux/sched.h>
+
+#include "rfkill.h"
+
+enum rfkill_input_master_mode {
+	RFKILL_INPUT_MASTER_UNLOCK = 0,
+	RFKILL_INPUT_MASTER_RESTORE = 1,
+	RFKILL_INPUT_MASTER_UNBLOCKALL = 2,
+	NUM_RFKILL_INPUT_MASTER_MODES
+};
+
+/* Delay (in ms) between consecutive switch ops */
+#define RFKILL_OPS_DELAY 200
+
+static enum rfkill_input_master_mode rfkill_master_switch_mode =
+					RFKILL_INPUT_MASTER_UNBLOCKALL;
+module_param_named(master_switch_mode, rfkill_master_switch_mode, uint, 0);
+MODULE_PARM_DESC(master_switch_mode,
+	"SW_RFKILL_ALL ON should: 0=do nothing (only unlock); 1=restore; 2=unblock all");
+
+static spinlock_t rfkill_op_lock;
+static bool rfkill_op_pending;
+static unsigned long rfkill_sw_pending[BITS_TO_LONGS(NUM_RFKILL_TYPES)];
+static unsigned long rfkill_sw_state[BITS_TO_LONGS(NUM_RFKILL_TYPES)];
+
+enum rfkill_sched_op {
+	RFKILL_GLOBAL_OP_EPO = 0,
+	RFKILL_GLOBAL_OP_RESTORE,
+	RFKILL_GLOBAL_OP_UNLOCK,
+	RFKILL_GLOBAL_OP_UNBLOCK,
+};
+
+static enum rfkill_sched_op rfkill_master_switch_op;
+static enum rfkill_sched_op rfkill_op;
+
+static void __rfkill_handle_global_op(enum rfkill_sched_op op)
+{
+	unsigned int i;
+
+	switch (op) {
+	case RFKILL_GLOBAL_OP_EPO:
+		rfkill_epo();
+		break;
+	case RFKILL_GLOBAL_OP_RESTORE:
+		rfkill_restore_states();
+		break;
+	case RFKILL_GLOBAL_OP_UNLOCK:
+		rfkill_remove_epo_lock();
+		break;
+	case RFKILL_GLOBAL_OP_UNBLOCK:
+		rfkill_remove_epo_lock();
+		for (i = 0; i < NUM_RFKILL_TYPES; i++)
+			rfkill_switch_all(i, false);
+		break;
+	default:
+		/* memory corruption or bug, fail safely */
+		rfkill_epo();
+		WARN(1, "Unknown requested operation %d! "
+			"rfkill Emergency Power Off activated\n",
+			op);
+	}
+}
+
+static void __rfkill_handle_normal_op(const enum rfkill_type type,
+				      const bool complement)
+{
+	bool blocked;
+
+	blocked = rfkill_get_global_sw_state(type);
+	if (complement)
+		blocked = !blocked;
+
+	rfkill_switch_all(type, blocked);
+}
+
+static void rfkill_op_handler(struct work_struct *work)
+{
+	unsigned int i;
+	bool c;
+
+	spin_lock_irq(&rfkill_op_lock);
+	do {
+		if (rfkill_op_pending) {
+			enum rfkill_sched_op op = rfkill_op;
+			rfkill_op_pending = false;
+			memset(rfkill_sw_pending, 0,
+				sizeof(rfkill_sw_pending));
+			spin_unlock_irq(&rfkill_op_lock);
+
+			__rfkill_handle_global_op(op);
+
+			spin_lock_irq(&rfkill_op_lock);
+
+			/*
+			 * handle global ops first -- during unlocked period
+			 * we might have gotten a new global op.
+			 */
+			if (rfkill_op_pending)
+				continue;
+		}
+
+		if (rfkill_is_epo_lock_active())
+			continue;
+
+		for (i = 0; i < NUM_RFKILL_TYPES; i++) {
+			if (__test_and_clear_bit(i, rfkill_sw_pending)) {
+				c = __test_and_clear_bit(i, rfkill_sw_state);
+				spin_unlock_irq(&rfkill_op_lock);
+
+				__rfkill_handle_normal_op(i, c);
+
+				spin_lock_irq(&rfkill_op_lock);
+			}
+		}
+	} while (rfkill_op_pending);
+	spin_unlock_irq(&rfkill_op_lock);
+}
+
+static DECLARE_DELAYED_WORK(rfkill_op_work, rfkill_op_handler);
+static unsigned long rfkill_last_scheduled;
+
+static unsigned long rfkill_ratelimit(const unsigned long last)
+{
+	const unsigned long delay = msecs_to_jiffies(RFKILL_OPS_DELAY);
+	return (time_after(jiffies, last + delay)) ? 0 : delay;
+}
+
+static void rfkill_schedule_ratelimited(void)
+{
+	if (delayed_work_pending(&rfkill_op_work))
+		return;
+	schedule_delayed_work(&rfkill_op_work,
+			      rfkill_ratelimit(rfkill_last_scheduled));
+	rfkill_last_scheduled = jiffies;
+}
+
+static void rfkill_schedule_global_op(enum rfkill_sched_op op)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rfkill_op_lock, flags);
+	rfkill_op = op;
+	rfkill_op_pending = true;
+	if (op == RFKILL_GLOBAL_OP_EPO && !rfkill_is_epo_lock_active()) {
+		/* bypass the limiter for EPO */
+		cancel_delayed_work(&rfkill_op_work);
+		schedule_delayed_work(&rfkill_op_work, 0);
+		rfkill_last_scheduled = jiffies;
+	} else
+		rfkill_schedule_ratelimited();
+	spin_unlock_irqrestore(&rfkill_op_lock, flags);
+}
+
+static void rfkill_schedule_toggle(enum rfkill_type type)
+{
+	unsigned long flags;
+
+	if (rfkill_is_epo_lock_active())
+		return;
+
+	spin_lock_irqsave(&rfkill_op_lock, flags);
+	if (!rfkill_op_pending) {
+		__set_bit(type, rfkill_sw_pending);
+		__change_bit(type, rfkill_sw_state);
+		rfkill_schedule_ratelimited();
+	}
+	spin_unlock_irqrestore(&rfkill_op_lock, flags);
+}
+
+static void rfkill_schedule_evsw_rfkillall(int state)
+{
+	if (state)
+		rfkill_schedule_global_op(rfkill_master_switch_op);
+	else
+		rfkill_schedule_global_op(RFKILL_GLOBAL_OP_EPO);
+}
+
+static void rfkill_event(struct input_handle *handle, unsigned int type,
+			unsigned int code, int data)
+{
+	if (type == EV_KEY && data == 1) {
+		switch (code) {
+		case KEY_WLAN:
+			rfkill_schedule_toggle(RFKILL_TYPE_WLAN);
+			break;
+		case KEY_BLUETOOTH:
+			rfkill_schedule_toggle(RFKILL_TYPE_BLUETOOTH);
+			break;
+		case KEY_UWB:
+			rfkill_schedule_toggle(RFKILL_TYPE_UWB);
+			break;
+		case KEY_WIMAX:
+			rfkill_schedule_toggle(RFKILL_TYPE_WIMAX);
+			break;
+		}
+	} else if (type == EV_SW && code == SW_RFKILL_ALL)
+		rfkill_schedule_evsw_rfkillall(data);
+}
+
+static int rfkill_connect(struct input_handler *handler, struct input_dev *dev,
+			  const struct input_device_id *id)
+{
+	struct input_handle *handle;
+	int error;
+
+	handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
+	if (!handle)
+		return -ENOMEM;
+
+	handle->dev = dev;
+	handle->handler = handler;
+	handle->name = "rfkill";
+
+	/* causes rfkill_start() to be called */
+	error = input_register_handle(handle);
+	if (error)
+		goto err_free_handle;
+
+	error = input_open_device(handle);
+	if (error)
+		goto err_unregister_handle;
+
+	return 0;
+
+ err_unregister_handle:
+	input_unregister_handle(handle);
+ err_free_handle:
+	kfree(handle);
+	return error;
+}
+
+static void rfkill_start(struct input_handle *handle)
+{
+	/*
+	 * Take event_lock to guard against configuration changes, we
+	 * should be able to deal with concurrency with rfkill_event()
+	 * just fine (which event_lock will also avoid).
+	 */
+	spin_lock_irq(&handle->dev->event_lock);
+
+	if (test_bit(EV_SW, handle->dev->evbit) &&
+	    test_bit(SW_RFKILL_ALL, handle->dev->swbit))
+		rfkill_schedule_evsw_rfkillall(test_bit(SW_RFKILL_ALL,
+							handle->dev->sw));
+
+	spin_unlock_irq(&handle->dev->event_lock);
+}
+
+static void rfkill_disconnect(struct input_handle *handle)
+{
+	input_close_device(handle);
+	input_unregister_handle(handle);
+	kfree(handle);
+}
+
+static const struct input_device_id rfkill_ids[] = {
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
+		.evbit = { BIT_MASK(EV_KEY) },
+		.keybit = { [BIT_WORD(KEY_WLAN)] = BIT_MASK(KEY_WLAN) },
+	},
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
+		.evbit = { BIT_MASK(EV_KEY) },
+		.keybit = { [BIT_WORD(KEY_BLUETOOTH)] = BIT_MASK(KEY_BLUETOOTH) },
+	},
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
+		.evbit = { BIT_MASK(EV_KEY) },
+		.keybit = { [BIT_WORD(KEY_UWB)] = BIT_MASK(KEY_UWB) },
+	},
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT,
+		.evbit = { BIT_MASK(EV_KEY) },
+		.keybit = { [BIT_WORD(KEY_WIMAX)] = BIT_MASK(KEY_WIMAX) },
+	},
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_SWBIT,
+		.evbit = { BIT(EV_SW) },
+		.swbit = { [BIT_WORD(SW_RFKILL_ALL)] = BIT_MASK(SW_RFKILL_ALL) },
+	},
+	{ }
+};
+
+static struct input_handler rfkill_handler = {
+	.name =	"rfkill",
+	.event = rfkill_event,
+	.connect = rfkill_connect,
+	.start = rfkill_start,
+	.disconnect = rfkill_disconnect,
+	.id_table = rfkill_ids,
+};
+
+int __init rfkill_handler_init(void)
+{
+	switch (rfkill_master_switch_mode) {
+	case RFKILL_INPUT_MASTER_UNBLOCKALL:
+		rfkill_master_switch_op = RFKILL_GLOBAL_OP_UNBLOCK;
+		break;
+	case RFKILL_INPUT_MASTER_RESTORE:
+		rfkill_master_switch_op = RFKILL_GLOBAL_OP_RESTORE;
+		break;
+	case RFKILL_INPUT_MASTER_UNLOCK:
+		rfkill_master_switch_op = RFKILL_GLOBAL_OP_UNLOCK;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	spin_lock_init(&rfkill_op_lock);
+
+	/* Avoid delay at first schedule */
+	rfkill_last_scheduled =
+			jiffies - msecs_to_jiffies(RFKILL_OPS_DELAY) - 1;
+	return input_register_handler(&rfkill_handler);
+}
+
+void __exit rfkill_handler_exit(void)
+{
+	input_unregister_handler(&rfkill_handler);
+	cancel_delayed_work_sync(&rfkill_op_work);
+}