ARM: 6475/1: Introduce asm/hardware/entry-macro-gic.S

This patch is the identical GIC demux implementation
merge V3. Instead of implementing same code over and
over simply share it in entry-macro-gic.S. The shared
code is based on the realview implementation.

Each GIC demux instance still has to setup the base address
of the controller using the get_irqnr_preamble macro. The
rest of the GIC specific code can be shared.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/hardware/entry-macro-gic.S

@@ -0,0 +1,68 @@
+/*
+ * arch/arm/include/asm/hardware/entry-macro-gic.S
+ *
+ * Low-level IRQ helper macros for GIC
+ *
+ * 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>
+
+/*
+ * 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