ARM: pm: add generic CPU suspend/resume support

This adds core support for saving and restoring CPU coprocessor
registers for suspend/resume support.  This contains support for suspend
with ARM920, ARM926, SA11x0, PXA25x, PXA27x, PXA3xx, V6 and V7 CPUs.
Tested on Assabet and Tegra 2.

Tested-by: Colin Cross <ccross@android.com>
Tested-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 109 insertions, 0 deletions

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
new file mode 100644
index 000000000000..2ba17946619e
--- /dev/null
+++ b/arch/arm/kernel/sleep.S
@@ -0,0 +1,109 @@
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/assembler.h>
+#include <asm/glue-cache.h>
+#include <asm/glue-proc.h>
+#include <asm/system.h>
+        .text
+
+/*
+ * Save CPU state for a suspend
+ *  r1 = v:p offset
+ *  r3 = virtual return function
+ * Note: sp is decremented to allocate space for CPU state on stack
+ * r0-r3,r9,r10,lr corrupted
+ */
+ENTRY(cpu_suspend)
+        mov     r9, lr
+#ifdef MULTI_CPU
+        ldr     r10, =processor
+        mov     r2, sp                  @ current virtual SP
+        ldr     r0, [r10, #CPU_SLEEP_SIZE] @ size of CPU sleep state
+        ldr     ip, [r10, #CPU_DO_RESUME] @ virtual resume function
+        sub     sp, sp, r0              @ allocate CPU state on stack
+        mov     r0, sp                  @ save pointer
+        add     ip, ip, r1              @ convert resume fn to phys
+        stmfd   sp!, {r1, r2, r3, ip}   @ save v:p, virt SP, retfn, phys resume fn
+        ldr     r3, =sleep_save_sp
+        add     r2, sp, r1              @ convert SP to phys
+        str     r2, [r3]                @ save phys SP
+        mov     lr, pc
+        ldr     pc, [r10, #CPU_DO_SUSPEND] @ save CPU state
+#else
+        mov     r2, sp                  @ current virtual SP
+        ldr     r0, =cpu_suspend_size
+        sub     sp, sp, r0              @ allocate CPU state on stack
+        mov     r0, sp                  @ save pointer
+        stmfd   sp!, {r1, r2, r3}       @ save v:p, virt SP, return fn
+        ldr     r3, =sleep_save_sp
+        add     r2, sp, r1              @ convert SP to phys
+        str     r2, [r3]                @ save phys SP
+        bl      cpu_do_suspend
+#endif
+
+        @ flush data cache
+#ifdef MULTI_CACHE
+        ldr     r10, =cpu_cache
+        mov     lr, r9
+        ldr     pc, [r10, #CACHE_FLUSH_KERN_ALL]
+#else
+        mov     lr, r9
+        b       __cpuc_flush_kern_all
+#endif
+ENDPROC(cpu_suspend)
+        .ltorg
+
+/*
+ * r0 = control register value
+ * r1 = v:p offset (preserved by cpu_do_resume)
+ * r2 = phys page table base
+ * r3 = L1 section flags
+ */
+ENTRY(cpu_resume_mmu)
+        adr     r4, cpu_resume_turn_mmu_on
+        mov     r4, r4, lsr #20
+        orr     r3, r3, r4, lsl #20
+        ldr     r5, [r2, r4, lsl #2]    @ save old mapping
+        str     r3, [r2, r4, lsl #2]    @ setup 1:1 mapping for mmu code
+        sub     r2, r2, r1
+        ldr     r3, =cpu_resume_after_mmu
+        bic     r1, r0, #CR_C           @ ensure D-cache is disabled
+        b       cpu_resume_turn_mmu_on
+ENDPROC(cpu_resume_mmu)
+        .ltorg
+        .align  5
+cpu_resume_turn_mmu_on:
+        mcr     p15, 0, r1, c1, c0, 0   @ turn on MMU, I-cache, etc
+        mrc     p15, 0, r1, c0, c0, 0   @ read id reg
+        mov     r1, r1
+        mov     r1, r1
+        mov     pc, r3                  @ jump to virtual address
+ENDPROC(cpu_resume_turn_mmu_on)
+cpu_resume_after_mmu:
+        str     r5, [r2, r4, lsl #2]    @ restore old mapping
+        mcr     p15, 0, r0, c1, c0, 0   @ turn on D-cache
+        mov     pc, lr
+ENDPROC(cpu_resume_after_mmu)
+
+/*
+ * Note: Yes, part of the following code is located into the .data section.
+ *       This is to allow sleep_save_sp to be accessed with a relative load
+ *       while we can't rely on any MMU translation.  We could have put
+ *       sleep_save_sp in the .text section as well, but some setups might
+ *       insist on it to be truly read-only.
+ */
+        .data
+        .align
+ENTRY(cpu_resume)
+        ldr     r0, sleep_save_sp       @ stack phys addr
+        msr     cpsr_c, #PSR_I_BIT | PSR_F_BIT | SVC_MODE @ set SVC, irqs off
+#ifdef MULTI_CPU
+        ldmia   r0!, {r1, sp, lr, pc}   @ load v:p, stack, return fn, resume fn
+#else
+        ldmia   r0!, {r1, sp, lr}       @ load v:p, stack, return fn
+        b       cpu_do_resume
+#endif
+ENDPROC(cpu_resume)
+
+sleep_save_sp:
+        .word   0                               @ preserve stack phys ptr here