[PATCH 02/13] OMAP3: PM: Errata i581 suppport: dll kick strategy

[Nishanth Menon <nm@ti.com>]

From: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>

Errata i581 impacts OMAP3 platforms.
PRCM DPLL control FSM removes SDRC_IDLEREQ before DPLL3 locks causing
the DPLL not to be locked at times.

IMPORTANT: this is not a complete workaround implementation as recommended
by the silicon errata. this is a support logic for detecting lockups and
attempting to recover where possible and is known to provide stability
in multiple platforms.

Signed-off-by: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
---
 arch/arm/mach-omap2/sleep34xx.S |   52 +++++++++++++++++++++++++++++++++++---
 1 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
index 8f207b2..5a4468f 100644
--- a/arch/arm/mach-omap2/sleep34xx.S
+++ b/arch/arm/mach-omap2/sleep34xx.S
@@ -42,6 +42,7 @@
 				OMAP3430_PM_PREPWSTST)
 #define PM_PWSTCTRL_MPU_P	OMAP3430_PRM_BASE + MPU_MOD + OMAP2_PM_PWSTCTRL
 #define CM_IDLEST1_CORE_V	OMAP34XX_CM_REGADDR(CORE_MOD, CM_IDLEST1)
+#define CM_IDLEST_CKGEN_V	OMAP34XX_CM_REGADDR(PLL_MOD, CM_IDLEST)
 #define SRAM_BASE_P		0x40200000
 #define CONTROL_STAT		0x480022F0
 #define SCRATCHPAD_MEM_OFFS	0x310 /* Move this as correct place is
@@ -554,31 +555,67 @@ skip_l2_inval:
 
 /* Make sure SDRC accesses are ok */
 wait_sdrc_ok:
+
+/* DPLL3 must be locked before accessing the SDRC. Maybe the HW ensures this. */
+	ldr	r4, cm_idlest_ckgen
+wait_dpll3_lock:
+	ldr	r5, [r4]
+	tst	r5, #1
+	beq	wait_dpll3_lock
+
         ldr     r4, cm_idlest1_core
+wait_sdrc_ready:
         ldr     r5, [r4]
-        and     r5, r5, #0x2
-        cmp     r5, #0
-        bne     wait_sdrc_ok
+        tst     r5, #0x2
+        bne     wait_sdrc_ready
+	/* allow DLL powerdown upon hw idle req */
         ldr     r4, sdrc_power
         ldr     r5, [r4]
         bic     r5, r5, #0x40
         str     r5, [r4]
-wait_dll_lock:
+is_dll_in_lock_mode:
+
         /* Is dll in lock mode? */
         ldr     r4, sdrc_dlla_ctrl
         ldr     r5, [r4]
         tst     r5, #0x4
         bxne    lr
         /* wait till dll locks */
-        ldr     r4, sdrc_dlla_status
+wait_dll_lock_timed:
+	ldr	r4, wait_dll_lock_counter
+	add	r4, r4, #1
+	str	r4, wait_dll_lock_counter
+	ldr	r4, sdrc_dlla_status
+        mov	r6, #8		/* Wait 20uS for lock */
+wait_dll_lock:
+	subs	r6, r6, #0x1
+	beq	kick_dll
         ldr     r5, [r4]
         and     r5, r5, #0x4
         cmp     r5, #0x4
         bne     wait_dll_lock
         bx      lr
 
+	/* disable/reenable DLL if not locked */
+kick_dll:
+	ldr	r4, sdrc_dlla_ctrl
+	ldr	r5, [r4]
+	mov	r6, r5
+	bic	r6, #(1<<3)	/* disable dll */
+	str	r6, [r4]
+	dsb
+	orr	r6, r6, #(1<<3)	/* enable dll */
+	str	r6, [r4]
+	dsb
+	ldr	r4, kick_counter
+	add	r4, r4, #1
+	str	r4, kick_counter
+	b	wait_dll_lock_timed
+
 cm_idlest1_core:
 	.word	CM_IDLEST1_CORE_V
+cm_idlest_ckgen:
+	.word	CM_IDLEST_CKGEN_V
 sdrc_dlla_status:
 	.word	SDRC_DLLA_STATUS_V
 sdrc_dlla_ctrl:
@@ -615,5 +652,10 @@ control_stat:
 	.word	CONTROL_STAT
 kernel_flush:
 	.word v7_flush_dcache_all
+	/* these 2 words need to be at the end !!! */
+kick_counter:
+	.word	0
+wait_dll_lock_counter:
+	.word	0
 ENTRY(omap34xx_cpu_suspend_sz)
 	.word	. - omap34xx_cpu_suspend
-- 
1.6.3.3