ARM: pm: omap3: run the ASM sleep code from DDR

Most of the ASM sleep code (in arch/arm/mach-omap2/sleep34xx.S)
is copied to internal SRAM at boot and after wake-up from CORE OFF
mode.  However only a small part of the code really needs to run from
internal SRAM.

This fix lets most of the ASM idle code run from the DDR in order to
minimize the SRAM usage and the overhead in the code copy.

The only pieces of code that are mandatory in SRAM are:
- the i443 erratum WA,
- the i581 erratum WA,
- the security extension code.

SRAM usage:
- original code:
  . 560 bytes for omap3_sram_configure_core_dpll (used by DVFS),
  . 852 bytes for omap_sram_idle (used by suspend/resume in RETention),
  . 124 bytes for es3_sdrc_fix (used by suspend/resume in OFF mode on ES3.x),
  . 108 bytes for save_secure_ram_context (used on HS parts only).

With this fix the usage for suspend/resume in RETention goes down 288
bytes, so the gain in SRAM usage for suspend/resume is 564 bytes.

Also fixed the SRAM initialization sequence to avoid an unnecessary
copy to SRAM at boot time and for readability.

Tested on Beagleboard (ES2.x) in idle with full RET and OFF modes.

Kevin Hilman tested retention and off on 3430/n900, 3530/Overo and
3630/Zoom3

Signed-off-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 11 insertions, 9 deletions

diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 3e9a13e1ac57..e1c79bae7670 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -78,9 +78,8 @@ struct power_state {
 
 static LIST_HEAD(pwrst_list);
 
-static void (*_omap_sram_idle)(u32 *addr, int save_state);
-
 static int (*_omap_save_secure_sram)(u32 *addr);
+void (*omap3_do_wfi_sram)(void);
 
 static struct powerdomain *mpu_pwrdm, *neon_pwrdm;
 static struct powerdomain *core_pwrdm, *per_pwrdm;
@@ -309,7 +308,7 @@ static irqreturn_t prcm_interrupt_handler (int irq, void *dev_id)
 
 static void omap34xx_do_sram_idle(unsigned long save_state)
 {
-        _omap_sram_idle(omap3_arm_context, save_state);
+        omap34xx_cpu_suspend(omap3_arm_context, save_state);
 }
 
 void omap_sram_idle(void)
@@ -328,9 +327,6 @@ void omap_sram_idle(void)
         int core_prev_state, per_prev_state;
         u32 sdrc_pwr = 0;
 
-        if (!_omap_sram_idle)
-                return;
-
         pwrdm_clear_all_prev_pwrst(mpu_pwrdm);
         pwrdm_clear_all_prev_pwrst(neon_pwrdm);
         pwrdm_clear_all_prev_pwrst(core_pwrdm);
@@ -826,10 +822,17 @@ static int __init clkdms_setup(struct clockdomain *clkdm, void *unused)
         return 0;
 }
 
+/*
+ * Push functions to SRAM
+ *
+ * The minimum set of functions is pushed to SRAM for execution:
+ * - omap3_do_wfi for erratum i581 WA,
+ * - save_secure_ram_context for security extensions.
+ */
 void omap_push_sram_idle(void)
 {
-        _omap_sram_idle = omap_sram_push(omap34xx_cpu_suspend,
-                                        omap34xx_cpu_suspend_sz);
+        omap3_do_wfi_sram = omap_sram_push(omap3_do_wfi, omap3_do_wfi_sz);
+
         if (omap_type() != OMAP2_DEVICE_TYPE_GP)
                 _omap_save_secure_sram = omap_sram_push(save_secure_ram_context,
                                 save_secure_ram_context_sz);
@@ -894,7 +897,6 @@ static int __init omap3_pm_init(void)
         per_clkdm = clkdm_lookup("per_clkdm");
         core_clkdm = clkdm_lookup("core_clkdm");
 
-        omap_push_sram_idle();
 #ifdef CONFIG_SUSPEND
         suspend_set_ops(&omap_pm_ops);
 #endif /* CONFIG_SUSPEND */