This patch implements locking using the semaphore in scratchpad
memory preventing any concurrent access to scratchpad from OMAP
and Baseband/Modem processor.
Signed-off-by: Rajendra Nayak <rnayak@xxxxxx>
---
arch/arm/mach-omap2/resource34xx.c | 6 +++++-
arch/arm/mach-omap2/resource34xx.h | 2 ++
arch/arm/mach-omap2/sleep34xx.S | 32 ++++++++++++++++++++++++++++++++
3 files changed, 39 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mach-omap2/resource34xx.c b/arch/arm/mach-omap2/resource34xx.c
index 82405b6..408d3ab 100644
--- a/arch/arm/mach-omap2/resource34xx.c
+++ b/arch/arm/mach-omap2/resource34xx.c
@@ -236,6 +236,7 @@ static int program_opp_freq(int res, int target_level, int current_level)
int ret = 0, l3_div;
int *curr_opp;
+ lock_scratchpad_sem();
if (res == VDD1_OPP) {
curr_opp = &curr_vdd1_opp;
clk_set_rate(dpll1_clk, mpu_opps[target_level].rate);
@@ -253,11 +254,14 @@ static int program_opp_freq(int res, int target_level, int current_level)
ret = clk_set_rate(dpll3_clk,
l3_opps[target_level].rate * l3_div);
}
- if (ret)
+ if (ret) {
+ unlock_scratchpad_sem();
return current_level;
+ }
#ifdef CONFIG_PM
omap3_save_scratchpad_contents();
#endif
+ unlock_scratchpad_sem();
*curr_opp = target_level;
return target_level;
diff --git a/arch/arm/mach-omap2/resource34xx.h b/arch/arm/mach-omap2/resource34xx.h
index a160665..5b5618a 100644
--- a/arch/arm/mach-omap2/resource34xx.h
+++ b/arch/arm/mach-omap2/resource34xx.h
@@ -29,6 +29,8 @@
#include <mach/omap34xx.h>
extern int sr_voltagescale_vcbypass(u32 t_opp, u32 c_opp, u8 t_vsel, u8 c_vsel);
+extern void lock_scratchpad_sem();
+extern void unlock_scratchpad_sem();
/*
* mpu_latency/core_latency are used to control the cpuidle C state.
diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
index 38aa3fd..aedcf94 100644
--- a/arch/arm/mach-omap2/sleep34xx.S
+++ b/arch/arm/mach-omap2/sleep34xx.S
@@ -39,6 +39,7 @@
#define PM_PREPWSTST_MPU_V OMAP34XX_PRM_REGADDR(MPU_MOD, \
OMAP3430_PM_PREPWSTST)
#define CM_IDLEST1_CORE_V OMAP34XX_CM_REGADDR(CORE_MOD, CM_IDLEST1)
+#define SDRC_SCRATCHPAD_SEM_V 0xd800291C
/*
* This is the physical address of the register as specified
@@ -62,6 +63,37 @@
#define SDRC_DLLA_STATUS_V OMAP34XX_SDRC_REGADDR(SDRC_DLLA_STATUS)
#define SDRC_DLLA_CTRL_V OMAP34XX_SDRC_REGADDR(SDRC_DLLA_CTRL)
+ .text
+/* Function to aquire the semaphore in scratchpad */
+ENTRY(lock_scratchpad_sem)
+ stmfd sp!, {lr} @ save registers on stack
+wait_sem:
+ mov r0,#1
+ ldr r1, sdrc_scratchpad_sem
+wait_loop:
+ ldr r2, [r1] @ load the lock value
+ cmp r2, r0 @ is the lock free ?
+ beq wait_loop @ not free...
+ swp r2, r0, [r1] @ semaphore free so lock it and proceed
+ cmp r2, r0 @ did we succeed ?
+ beq wait_sem @ no - try again
+ ldmfd sp!, {pc} @ restore regs and return
+sdrc_scratchpad_sem:
+ .word SDRC_SCRATCHPAD_SEM_V
+ENTRY(lock_scratchpad_sem_sz)
+ .word . - lock_scratchpad_sem
+
+ .text
+/* Function to release the scratchpad semaphore */
+ENTRY(unlock_scratchpad_sem)
+ stmfd sp!, {lr} @ save registers on stack
+ ldr r3, sdrc_scratchpad_sem
+ mov r2,#0
+ str r2,[r3]
+ ldmfd sp!, {pc} @ restore regs and return
+ENTRY(unlock_scratchpad_sem_sz)
+ .word . - unlock_scratchpad_sem
+
.text
/* Function call to get the restore pointer for resume from OFF */
ENTRY(get_restore_pointer)
--
1.5.4.7
--
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