ARM: pm: preallocate a page table for suspend/resume

Preallocate a page table and setup an identity mapping for the MMU
enable code.  This means we don't have to "borrow" a page table to
do this, avoiding complexities with L2 cache coherency.

Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 61 insertions, 22 deletions

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index f7887dc53c1f..787b88823a56 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -29,7 +29,7 @@ obj-$(CONFIG_MODULES)		+= armksyms.o module.o
 obj-$(CONFIG_ARTHUR)            += arthur.o
 obj-$(CONFIG_ISA_DMA)           += dma-isa.o
 obj-$(CONFIG_PCI)               += bios32.o isa.o
-obj-$(CONFIG_PM_SLEEP)          += sleep.o
+obj-$(CONFIG_PM_SLEEP)          += sleep.o suspend.o
 obj-$(CONFIG_HAVE_SCHED_CLOCK)  += sched_clock.o
 obj-$(CONFIG_SMP)               += smp.o smp_tlb.o
 obj-$(CONFIG_HAVE_ARM_SCU)      += smp_scu.o
diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index 46a9f460db83..8cf13de1e368 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -27,7 +27,7 @@ ENTRY(__cpu_suspend)
         sub     sp, sp, r5              @ allocate CPU state on stack
         mov     r0, sp                  @ save pointer to CPU save block
         add     ip, ip, r1              @ convert resume fn to phys
-        stmfd   sp!, {r1, r6, ip}       @ save v:p, virt SP, phys resume fn
+        stmfd   sp!, {r6, ip}           @ save virt SP, phys resume fn
         ldr     r5, =sleep_save_sp
         add     r6, sp, r1              @ convert SP to phys
         stmfd   sp!, {r2, r3}           @ save suspend func arg and pointer
@@ -60,7 +60,7 @@ ENDPROC(__cpu_suspend)
         .ltorg
 
 cpu_suspend_abort:
-        ldmia   sp!, {r1 - r3}          @ pop v:p, virt SP, phys resume fn
+        ldmia   sp!, {r2 - r3}          @ pop virt SP, phys resume fn
         teq     r0, #0
         moveq   r0, #1                  @ force non-zero value
         mov     sp, r2
@@ -74,28 +74,19 @@ ENDPROC(cpu_suspend_abort)
  * 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
+ENTRY(cpu_resume_turn_mmu_on)
+        mcr     p15, 0, r0, c1, c0, 0   @ turn on MMU, I-cache, etc
+        mrc     p15, 0, r0, c0, c0, 0   @ read id reg
+        mov     r0, r0
+        mov     r0, r0
         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
         bl      cpu_init                @ restore the und/abt/irq banked regs
         mov     r0, #0                  @ return zero on success
         ldmfd   sp!, {r4 - r11, pc}
@@ -121,11 +112,11 @@ ENTRY(cpu_resume)
         ldr     r0, sleep_save_sp       @ stack phys addr
 #endif
         setmode PSR_I_BIT | PSR_F_BIT | SVC_MODE, r1  @ set SVC, irqs off
-        @ load v:p, stack, resume fn
-  ARM(  ldmia   r0!, {r1, sp, pc}       )
-THUMB(  ldmia   r0!, {r1, r2, r3}       )
-THUMB(  mov     sp, r2                  )
-THUMB(  bx      r3                      )
+        @ load stack, resume fn
+  ARM(  ldmia   r0!, {sp, pc}   )
+THUMB(  ldmia   r0!, {r2, r3}   )
+THUMB(  mov     sp, r2          )
+THUMB(  bx      r3              )
 ENDPROC(cpu_resume)
 
 sleep_save_sp:
diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
new file mode 100644
index 000000000000..0a33f109549d
--- /dev/null
+++ b/arch/arm/kernel/suspend.c
@@ -0,0 +1,48 @@
+#include <linux/init.h>
+
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/memory.h>
+#include <asm/suspend.h>
+#include <asm/tlbflush.h>
+
+static pgd_t *suspend_pgd;
+
+extern int __cpu_suspend(int, long, unsigned long, int (*)(unsigned long));
+extern void cpu_resume_turn_mmu_on(void);
+
+/*
+ * Hide the first two arguments to __cpu_suspend - these are an implementation
+ * detail which platform code shouldn't have to know about.
+ */
+int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
+{
+        struct mm_struct *mm = current->active_mm;
+        int ret;
+
+        if (!suspend_pgd)
+                return -EINVAL;
+
+        /*
+         * Temporarily switch the page tables to our suspend page
+         * tables, which contain the temporary identity mapping
+         * required for resuming.
+         */
+        cpu_switch_mm(suspend_pgd, mm);
+        ret = __cpu_suspend(0, PHYS_OFFSET - PAGE_OFFSET, arg, fn);
+        cpu_switch_mm(mm->pgd, mm);
+        local_flush_tlb_all();
+
+        return ret;
+}
+
+static int __init cpu_suspend_init(void)
+{
+        suspend_pgd = pgd_alloc(&init_mm);
+        if (suspend_pgd) {
+                unsigned long addr = virt_to_phys(cpu_resume_turn_mmu_on);
+                identity_mapping_add(suspend_pgd, addr, addr + SECTION_SIZE);
+        }
+        return suspend_pgd ? 0 : -ENOMEM;
+}
+core_initcall(cpu_suspend_init);