ARM: make a common low level IRQ helper macros for GIC based platforms

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+/*
+ * Low-level IRQ helper macros for GIC based platforms
+ *
+ * This file is licensed under  the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+#include <asm/hardware/gic.h>
+
+	.macro	disable_fiq
+	.endm
+
+	.macro  get_irqnr_preamble, base, tmp
+	ldr	\base, =gic_cpu_base_addr
+	ldr	\base, [\base]
+	.endm
+
+	.macro  arch_ret_to_user, tmp1, tmp2
+	.endm
+
+	/*
+	 * The interrupt numbering scheme is defined in the
+	 * interrupt controller spec.  To wit:
+	 *
+	 * Interrupts 0-15 are IPI
+	 * 16-28 are reserved
+	 * 29-31 are local.  We allow 30 to be used for the watchdog.
+	 * 32-1020 are global
+	 * 1021-1022 are reserved
+	 * 1023 is "spurious" (no interrupt)
+	 *
+	 * For now, we ignore all local interrupts so only return an interrupt if it's
+	 * between 30 and 1020.  The test_for_ipi routine below will pick up on IPIs.
+	 *
+	 * A simple read from the controller will tell us the number of the highest
+	 * priority enabled interrupt.  We then just need to check whether it is in the
+	 * valid range for an IRQ (30-1020 inclusive).
+	 */
+
+	.macro  get_irqnr_and_base, irqnr, irqstat, base, tmp
+	ldr     \irqstat, [\base, #GIC_CPU_INTACK] /* bits 12-10 = src CPU, 9-0 = int # */
+	ldr	\tmp, =1021
+	bic     \irqnr, \irqstat, #0x1c00
+	cmp     \irqnr, #29
+	cmpcc	\irqnr, \irqnr
+	cmpne	\irqnr, \tmp
+	cmpcs	\irqnr, \irqnr
+	.endm
+
+	/*
+	 * We assume that irqstat (the raw value of the IRQ acknowledge
+	 * register) is preserved from the macro above.
+	 * If there is an IPI, we immediately signal end of interrupt on the
+	 * controller, since this requires the original irqstat value which
+	 * we won't easily be able to recreate later.
+	 */
+
+	.macro test_for_ipi, irqnr, irqstat, base, tmp
+	bic	\irqnr, \irqstat, #0x1c00
+	cmp	\irqnr, #16
+	strcc	\irqstat, [\base, #GIC_CPU_EOI]
+	cmpcs	\irqnr, \irqnr
+	.endm
+
+	/* As above, this assumes that irqstat and base are preserved.. */
+
+	.macro test_for_ltirq, irqnr, irqstat, base, tmp
+	bic	\irqnr, \irqstat, #0x1c00
+	mov 	\tmp, #0
+	cmp	\irqnr, #29
+	moveq	\tmp, #1
+	streq	\irqstat, [\base, #GIC_CPU_EOI]
+	cmp	\tmp, #0
+	.endm

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