metag: IRQ handling

Add core IRQ handling for metag. The code in irq.c exposes the TBX
signal numbers as Linux IRQs.

Signed-off-by: James Hogan <james.hogan@imgtec.com>

arch/metag/include/asm/irq.h

@@ -0,0 +1,32 @@
+#ifndef __ASM_METAG_IRQ_H
+#define __ASM_METAG_IRQ_H
+
+#ifdef CONFIG_4KSTACKS
+extern void irq_ctx_init(int cpu);
+extern void irq_ctx_exit(int cpu);
+# define __ARCH_HAS_DO_SOFTIRQ
+#else
+# define irq_ctx_init(cpu) do { } while (0)
+# define irq_ctx_exit(cpu) do { } while (0)
+#endif
+
+void tbi_startup_interrupt(int);
+void tbi_shutdown_interrupt(int);
+
+struct pt_regs;
+
+int tbisig_map(unsigned int hw);
+extern void do_IRQ(int irq, struct pt_regs *regs);
+
+#ifdef CONFIG_METAG_SUSPEND_MEM
+int traps_save_context(void);
+int traps_restore_context(void);
+#endif
+
+#include <asm-generic/irq.h>
+
+#ifdef CONFIG_HOTPLUG_CPU
+extern void migrate_irqs(void);
+#endif
+
+#endif /* __ASM_METAG_IRQ_H */

arch/metag/include/asm/irqflags.h

@@ -0,0 +1,94 @@
+/*
+ * IRQ flags handling
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() functions from the lowlevel headers.
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/core_reg.h>
+#include <asm/metag_regs.h>
+
+#define INTS_OFF_MASK TXSTATI_BGNDHALT_BIT
+
+#ifdef CONFIG_SMP
+extern unsigned int get_trigger_mask(void);
+#else
+
+extern unsigned int global_trigger_mask;
+
+static inline unsigned int get_trigger_mask(void)
+{
+	return global_trigger_mask;
+}
+#endif
+
+static inline unsigned long arch_local_save_flags(void)
+{
+	return __core_reg_get(TXMASKI);
+}
+
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+	return (flags & ~INTS_OFF_MASK) == 0;
+}
+
+static inline int arch_irqs_disabled(void)
+{
+	unsigned long flags = arch_local_save_flags();
+
+	return arch_irqs_disabled_flags(flags);
+}
+
+static inline unsigned long __irqs_disabled(void)
+{
+	/*
+	 * We shouldn't enable exceptions if they are not already
+	 * enabled. This is required for chancalls to work correctly.
+	 */
+	return arch_local_save_flags() & INTS_OFF_MASK;
+}
+
+/*
+ * For spinlocks, etc:
+ */
+static inline unsigned long arch_local_irq_save(void)
+{
+	unsigned long flags = __irqs_disabled();
+
+	asm volatile("SWAP %0,TXMASKI\n" : "=r" (flags) : "0" (flags)
+		     : "memory");
+
+	return flags;
+}
+
+static inline void arch_local_irq_restore(unsigned long flags)
+{
+	asm volatile("MOV TXMASKI,%0\n" : : "r" (flags) : "memory");
+}
+
+static inline void arch_local_irq_disable(void)
+{
+	unsigned long flags = __irqs_disabled();
+
+	asm volatile("MOV TXMASKI,%0\n" : : "r" (flags) : "memory");
+}
+
+static inline void arch_local_irq_enable(void)
+{
+#ifdef CONFIG_SMP
+	preempt_disable();
+	arch_local_irq_restore(get_trigger_mask());
+	preempt_enable_no_resched();
+#else
+	arch_local_irq_restore(get_trigger_mask());
+#endif
+}
+
+#endif /* (__ASSEMBLY__) */
+
+#endif /* !(_ASM_IRQFLAGS_H) */