ARM: l2c: provide common PL310 early resume code

Provide a common assembly implementation for PL310 resume code.  Certain
platforms need to re-initialise the L2C cache early as it may preserve
data across a S2RAM cycle, and therefore must be enabled along with the
L1 cache and MMU.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/Makefile

@@ -97,6 +97,6 @@ AFLAGS_proc-v7.o	:=-Wa,-march=armv7-a
 
 obj-$(CONFIG_OUTER_CACHE)	+= l2c-common.o
 obj-$(CONFIG_CACHE_FEROCEON_L2)	+= cache-feroceon-l2.o
-obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o
+obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o l2c-l2x0-resume.o
 obj-$(CONFIG_CACHE_XSC3L2)	+= cache-xsc3l2.o
 obj-$(CONFIG_CACHE_TAUROS2)	+= cache-tauros2.o

arch/arm/mm/l2c-l2x0-resume.S

+/*
+ * L2C-310 early resume code.  This can be used by platforms to restore
+ * the settings of their L2 cache controller before restoring the
+ * processor state.
+ *
+ * This code can only be used to if you are running in the secure world.
+ */
+#include <linux/linkage.h>
+#include <asm/hardware/cache-l2x0.h>
+
+	.text
+
+ENTRY(l2c310_early_resume)
+	adr	r0, 1f
+	ldr	r2, [r0]
+	add	r0, r2, r0
+
+	ldmia	r0, {r1, r2, r3, r4, r5, r6, r7, r8}
+	@ r1 = phys address of L2C-310 controller
+	@ r2 = aux_ctrl
+	@ r3 = tag_latency
+	@ r4 = data_latency
+	@ r5 = filter_start
+	@ r6 = filter_end
+	@ r7 = prefetch_ctrl
+	@ r8 = pwr_ctrl
+
+	@ Check that the address has been initialised
+	teq	r1, #0
+	moveq	pc, lr
+
+	@ The prefetch and power control registers are revision dependent
+	@ and can be written whether or not the L2 cache is enabled
+	ldr	r0, [r1, #L2X0_CACHE_ID]
+	and	r0, r0, #L2X0_CACHE_ID_RTL_MASK
+	cmp	r0, #L310_CACHE_ID_RTL_R2P0
+	strcs	r7, [r1, #L310_PREFETCH_CTRL]
+	cmp	r0, #L310_CACHE_ID_RTL_R3P0
+	strcs	r8, [r1, #L310_POWER_CTRL]
+
+	@ Don't setup the L2 cache if it is already enabled
+	ldr	r0, [r1, #L2X0_CTRL]
+	tst	r0, #L2X0_CTRL_EN
+	movne	pc, lr
+
+	str	r3, [r1, #L310_TAG_LATENCY_CTRL]
+	str	r4, [r1, #L310_DATA_LATENCY_CTRL]
+	str	r6, [r1, #L310_ADDR_FILTER_END]
+	str	r5, [r1, #L310_ADDR_FILTER_START]
+
+	str	r2, [r1, #L2X0_AUX_CTRL]
+	mov	r9, #L2X0_CTRL_EN
+	str	r9, [r1, #L2X0_CTRL]
+	mov	pc, lr
+ENDPROC(l2c310_early_resume)
+
+	.align
+1:	.long	l2x0_saved_regs - .