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[ARM] S3C: Tidy sleep code path to fix call flow

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As noted by Russell King, the sleep code path is not
elegant and makes use of leaving items on the stack
between calls.

Change the code that does the following:

        if (s3c_cpu_save(regs_save) == 0) {
                flush_cache_all();
                S3C_PMDBG("preparing to sleep\n");
                pm_cpu_sleep();
        }

to simply call s3c_cpu_save, and let that do the
necessary calls to quiesce and sleep the system.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
This commit is contained in:
Ben Dooks 2009-03-10 11:48:07 +00:00
parent aa8aba6944
commit fff94cd9f5
3 changed files with 28 additions and 25 deletions
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8
arch/arm/plat-s3c/include/plat/pm.h
View File

@ -162,5 +162,13 @@ extern void s3c_pm_restore_gpios(void);
*/
extern void s3c_pm_save_gpios(void);
/**
* s3c_pm_cb_flushcache - callback for assembly code
*
* Callback to issue flush_cache_all() as this call is
* not a directly callable object.
*/
extern void s3c_pm_cb_flushcache(void);
extern void s3c_pm_save_core(void);
extern void s3c_pm_restore_core(void);

20
arch/arm/plat-s3c/pm.c
View File

@ -229,7 +229,7 @@ void (*pm_cpu_sleep)(void);
static int s3c_pm_enter(suspend_state_t state)
{
unsigned long regs_save[16];
static unsigned long regs_save[16];
/* ensure the debug is initialised (if enabled) */
@ -289,15 +289,11 @@ static int s3c_pm_enter(suspend_state_t state)
s3c_pm_arch_stop_clocks();
/* s3c2410_cpu_save will also act as our return point from when
* we resume as it saves its own register state, so use the return
* code to differentiate return from save and return from sleep */
/* s3c_cpu_save will also act as our return point from when
* we resume as it saves its own register state and restores it
* during the resume. */
if (s3c_cpu_save(regs_save) == 0) {
flush_cache_all();
S3C_PMDBG("preparing to sleep\n");
pm_cpu_sleep();
}
s3c_cpu_save(regs_save);
/* restore the cpu state using the kernel's cpu init code. */
@ -325,6 +321,12 @@ static int s3c_pm_enter(suspend_state_t state)
return 0;
}
/* callback from assembly code */
void s3c_pm_cb_flushcache(void)
{
flush_cache_all();
}
static int s3c_pm_prepare(void)
{
/* prepare check area if configured */

25
arch/arm/plat-s3c24xx/sleep.S
View File

@ -42,21 +42,9 @@
.text
/* s3c_cpu_save
*
* save enough of the CPU state to allow us to re-start
* pm.c code. as we store items like the sp/lr, we will
* end up returning from this function when the cpu resumes
* so the return value is set to mark this.
*
* This arangement means we avoid having to flush the cache
* from this code.
*
* entry:
* r0 = pointer to save block
*
* exit:
* r0 = 0 => we stored everything
* 1 => resumed from sleep
* r0 = save address (virtual addr of s3c_sleep_save_phys)
*/
ENTRY(s3c_cpu_save)
@ -71,14 +59,19 @@ ENTRY(s3c_cpu_save)
stmia r0, { r4 - r13 }
mov r0, #0
ldmfd sp, { r4 - r12, pc }
@@ write our state back to RAM
bl s3c_pm_cb_flushcache
@@ jump to final code to send system to sleep
ldr r0, =pm_cpu_sleep
@@ldr pc, [ r0 ]
ldr r0, [ r0 ]
mov pc, r0
@@ return to the caller, after having the MMU
@@ turned on, this restores the last bits from the
@@ stack
resume_with_mmu:
mov r0, #1
ldmfd sp!, { r4 - r12, pc }
.ltorg