arm: Move chained_irq_(enter|exit) to a generic file

These functions have been introduced by commit 10a8c383 (irq: introduce
entry and exit functions for chained handlers) in asm/mach/irq.h. This
patch moves them to linux/irqchip/chained_irq.h so that generic irqchip
drivers do not rely on architecture specific header files.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
diff --git a/include/linux/irqchip/chained_irq.h b/include/linux/irqchip/chained_irq.h
new file mode 100644
index 0000000..adf4c30
--- /dev/null
+++ b/include/linux/irqchip/chained_irq.h
@@ -0,0 +1,52 @@
+/*
+ * Chained IRQ handlers support.
+ *
+ * Copyright (C) 2011 ARM Ltd.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __IRQCHIP_CHAINED_IRQ_H
+#define __IRQCHIP_CHAINED_IRQ_H
+
+#include <linux/irq.h>
+
+/*
+ * Entry/exit functions for chained handlers where the primary IRQ chip
+ * may implement either fasteoi or level-trigger flow control.
+ */
+static inline void chained_irq_enter(struct irq_chip *chip,
+				     struct irq_desc *desc)
+{
+	/* FastEOI controllers require no action on entry. */
+	if (chip->irq_eoi)
+		return;
+
+	if (chip->irq_mask_ack) {
+		chip->irq_mask_ack(&desc->irq_data);
+	} else {
+		chip->irq_mask(&desc->irq_data);
+		if (chip->irq_ack)
+			chip->irq_ack(&desc->irq_data);
+	}
+}
+
+static inline void chained_irq_exit(struct irq_chip *chip,
+				    struct irq_desc *desc)
+{
+	if (chip->irq_eoi)
+		chip->irq_eoi(&desc->irq_data);
+	else
+		chip->irq_unmask(&desc->irq_data);
+}
+
+#endif /* __IRQCHIP_CHAINED_IRQ_H */