zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/kernel/irq_work.c b/ap/os/linux/linux-3.4.x/kernel/irq_work.c
new file mode 100644
index 0000000..170c2ea
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/kernel/irq_work.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * Provides a framework for enqueueing and running callbacks from hardirq
+ * context. The enqueueing is NMI-safe.
+ */
+
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/irq_work.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <linux/irqflags.h>
+#include <asm/processor.h>
+
+/*
+ * An entry can be in one of four states:
+ *
+ * free NULL, 0 -> {claimed} : free to be used
+ * claimed NULL, 3 -> {pending} : claimed to be enqueued
+ * pending next, 3 -> {busy} : queued, pending callback
+ * busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed
+ */
+
+#define IRQ_WORK_PENDING 1UL
+#define IRQ_WORK_BUSY 2UL
+#define IRQ_WORK_FLAGS 3UL
+
+static DEFINE_PER_CPU(struct llist_head, irq_work_list);
+
+/*
+ * Claim the entry so that no one else will poke at it.
+ */
+static bool irq_work_claim(struct irq_work *work)
+{
+ unsigned long flags, nflags;
+
+ for (;;) {
+ flags = work->flags;
+ if (flags & IRQ_WORK_PENDING)
+ return false;
+ nflags = flags | IRQ_WORK_FLAGS;
+ if (cmpxchg(&work->flags, flags, nflags) == flags)
+ break;
+ cpu_relax();
+ }
+
+ return true;
+}
+
+void __weak arch_irq_work_raise(void)
+{
+ /*
+ * Lame architectures will get the timer tick callback
+ */
+}
+
+/*
+ * Queue the entry and raise the IPI if needed.
+ */
+static void __irq_work_queue(struct irq_work *work)
+{
+ bool empty;
+
+ preempt_disable();
+
+ empty = llist_add(&work->llnode, &__get_cpu_var(irq_work_list));
+ /* The list was empty, raise self-interrupt to start processing. */
+ if (empty)
+ arch_irq_work_raise();
+
+ preempt_enable();
+}
+
+/*
+ * Enqueue the irq_work @entry, returns true on success, failure when the
+ * @entry was already enqueued by someone else.
+ *
+ * Can be re-enqueued while the callback is still in progress.
+ */
+bool irq_work_queue(struct irq_work *work)
+{
+ if (!irq_work_claim(work)) {
+ /*
+ * Already enqueued, can't do!
+ */
+ return false;
+ }
+
+ __irq_work_queue(work);
+ return true;
+}
+EXPORT_SYMBOL_GPL(irq_work_queue);
+
+/*
+ * Run the irq_work entries on this cpu. Requires to be ran from hardirq
+ * context with local IRQs disabled.
+ */
+void irq_work_run(void)
+{
+ struct irq_work *work;
+ struct llist_head *this_list;
+ struct llist_node *llnode;
+
+ this_list = &__get_cpu_var(irq_work_list);
+ if (llist_empty(this_list))
+ return;
+
+#ifndef CONFIG_PREEMPT_RT_FULL
+ BUG_ON(!in_irq());
+ BUG_ON(!irqs_disabled());
+#endif
+
+ llnode = llist_del_all(this_list);
+ while (llnode != NULL) {
+ work = llist_entry(llnode, struct irq_work, llnode);
+
+ llnode = llist_next(llnode);
+
+ /*
+ * Clear the PENDING bit, after this point the @work
+ * can be re-used.
+ */
+ work->flags = IRQ_WORK_BUSY;
+ work->func(work);
+ /*
+ * Clear the BUSY bit and return to the free state if
+ * no-one else claimed it meanwhile.
+ */
+ (void)cmpxchg(&work->flags, IRQ_WORK_BUSY, 0);
+ }
+}
+EXPORT_SYMBOL_GPL(irq_work_run);
+
+/*
+ * Synchronize against the irq_work @entry, ensures the entry is not
+ * currently in use.
+ */
+void irq_work_sync(struct irq_work *work)
+{
+ WARN_ON_ONCE(irqs_disabled());
+
+ while (work->flags & IRQ_WORK_BUSY)
+ cpu_relax();
+}
+EXPORT_SYMBOL_GPL(irq_work_sync);