ARC: irqflags - Interrupt enabling/disabling at in-core intc

ARC700 has an in-core intc which provides 2 priorities (a.k.a.) "levels"
of interrupts (per IRQ) hencforth referred to as L1/L2 interrupts.

CPU flags register STATUS32 has Interrupt Enable bits per level (E1/E2)
to globally enable (or disable) all IRQs at a level. Hence the
implementation of arch_local_irq_{save,restore,enable,disable}( )

The STATUS32 reg can be r/w only using the AUX Interface of ARC, hence
the use of LR/SR instructions. Further, E1/E2 bits in there can only be
updated using the FLAG insn.

The intc supports 32 interrupts - and per IRQ enabling is controlled by
a bit in the AUX_IENABLE register, hence the implmentation of
arch_{,un}mask_irq( ) routines.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/arc/kernel/irq.c b/arch/arc/kernel/irq.c
new file mode 100644
index 000000000000..c4e9b25d305f
--- /dev/null
+++ b/arch/arc/kernel/irq.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2011-12 Synopsys, Inc. (www.synopsys.com)
+ *
+ * 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.
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <asm/irqflags.h>
+#include <asm/arcregs.h>
+
+void arch_local_irq_enable(void)
+{
+        unsigned long flags;
+
+        /*
+         * ARC IDE Drivers tries to re-enable interrupts from hard-isr
+         * context which is simply wrong
+         */
+        if (in_irq()) {
+                WARN_ONCE(1, "IRQ enabled from hard-isr");
+                return;
+        }
+
+        flags = arch_local_save_flags();
+        flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
+        arch_local_irq_restore(flags);
+}
+EXPORT_SYMBOL(arch_local_irq_enable);