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ARM: OMAP4: PM: Add CPUX OFF mode support

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This patch adds the CPU0 and CPU1 off mode support. CPUX close switch
retention (CSWR) is not supported by hardware design.

The CPUx OFF mode isn't supported on OMAP4430 ES1.0

CPUx sleep code is common for hotplug, suspend and CPUilde.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
This commit is contained in:
Santosh Shilimkar 2010-06-16 22:19:48 +05:30 committed by Kevin Hilman
parent fcf6efa3ff
commit b2b9762f76
8 changed files with 595 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/arm/mach-omap2/Makefile
View File

@ -25,11 +25,13 @@ obj-$(CONFIG_TWL4030_CORE) += omap_twl.o
obj-$(CONFIG_SMP) += omap-smp.o omap-headsmp.o
obj-$(CONFIG_LOCAL_TIMERS) += timer-mpu.o
obj-$(CONFIG_HOTPLUG_CPU) += omap-hotplug.o
obj-$(CONFIG_ARCH_OMAP4) += omap4-common.o omap-wakeupgen.o
obj-$(CONFIG_ARCH_OMAP4) += omap4-common.o omap-wakeupgen.o \
sleep44xx.o
plus_sec := $(call as-instr,.arch_extension sec,+sec)
AFLAGS_omap-headsmp.o :=-Wa,-march=armv7-a$(plus_sec)
AFLAGS_omap-smc.o :=-Wa,-march=armv7-a$(plus_sec)
AFLAGS_sleep44xx.o :=-Wa,-march=armv7-a$(plus_sec)
# Functions loaded to SRAM
obj-$(CONFIG_SOC_OMAP2420) += sram242x.o
@ -63,7 +65,7 @@ obj-$(CONFIG_ARCH_OMAP2) += pm24xx.o
obj-$(CONFIG_ARCH_OMAP2) += sleep24xx.o
obj-$(CONFIG_ARCH_OMAP3) += pm34xx.o sleep34xx.o \
cpuidle34xx.o
obj-$(CONFIG_ARCH_OMAP4) += pm44xx.o
obj-$(CONFIG_ARCH_OMAP4) += pm44xx.o omap-mpuss-lowpower.o
obj-$(CONFIG_PM_DEBUG) += pm-debug.o
obj-$(CONFIG_OMAP_SMARTREFLEX) += sr_device.o smartreflex.o
obj-$(CONFIG_OMAP_SMARTREFLEX_CLASS3) += smartreflex-class3.o

30
arch/arm/mach-omap2/common.h
View File

@ -24,9 +24,11 @@
#ifndef __ARCH_ARM_MACH_OMAP2PLUS_COMMON_H
#define __ARCH_ARM_MACH_OMAP2PLUS_COMMON_H
#ifndef __ASSEMBLER__
#include <linux/delay.h>
#include <plat/common.h>
#include <asm/proc-fns.h>
#ifdef CONFIG_SOC_OMAP2420
extern void omap242x_map_common_io(void);
@ -183,6 +185,7 @@ static inline void __iomem *omap4_get_scu_base(void)
extern void __init gic_init_irq(void);
extern void omap_smc1(u32 fn, u32 arg);
extern void __iomem *omap4_get_sar_ram_base(void);
extern void omap_do_wfi(void);
#ifdef CONFIG_SMP
/* Needed for secondary core boot */
@ -192,4 +195,31 @@ extern void omap_auxcoreboot_addr(u32 cpu_addr);
extern u32 omap_read_auxcoreboot0(void);
#endif
#if defined(CONFIG_SMP) && defined(CONFIG_PM)
extern int omap4_mpuss_init(void);
extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state);
extern int omap4_finish_suspend(unsigned long cpu_state);
extern void omap4_cpu_resume(void);
#else
static inline int omap4_enter_lowpower(unsigned int cpu,
unsigned int power_state)
{
cpu_do_idle();
return 0;
}
static inline int omap4_mpuss_init(void)
{
return 0;
}
static inline int omap4_finish_suspend(unsigned long cpu_state)
{
return 0;
}
static inline void omap4_cpu_resume(void)
{}
#endif
#endif /* __ASSEMBLER__ */
#endif /* __ARCH_ARM_MACH_OMAP2PLUS_COMMON_H */

9
arch/arm/mach-omap2/include/mach/omap-secure.h
View File

@ -35,9 +35,18 @@
#define OMAP4_HAL_SAVEALL_INDEX 0x1c
#define OMAP4_HAL_SAVEGIC_INDEX 0x1d
/* Secure Monitor mode APIs */
#define OMAP4_MON_SCU_PWR_INDEX 0x108
/* Secure PPA(Primary Protected Application) APIs */
#define OMAP4_PPA_CPU_ACTRL_SMP_INDEX 0x25
#ifndef __ASSEMBLER__
extern u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs,
u32 arg1, u32 arg2, u32 arg3, u32 arg4);
extern u32 omap_smc2(u32 id, u32 falg, u32 pargs);
extern phys_addr_t omap_secure_ram_mempool_base(void);
#endif /* __ASSEMBLER__ */
#endif /* OMAP_ARCH_OMAP_SECURE_H */

248
arch/arm/mach-omap2/omap-mpuss-lowpower.c Normal file
View File

@ -0,0 +1,248 @@
/*
* OMAP MPUSS low power code
*
* Copyright (C) 2011 Texas Instruments, Inc.
* Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* OMAP4430 MPUSS mainly consists of dual Cortex-A9 with per-CPU
* Local timer and Watchdog, GIC, SCU, PL310 L2 cache controller,
* CPU0 and CPU1 LPRM modules.
* CPU0, CPU1 and MPUSS each have there own power domain and
* hence multiple low power combinations of MPUSS are possible.
*
* The CPU0 and CPU1 can't support Closed switch Retention (CSWR)
* because the mode is not supported by hw constraints of dormant
* mode. While waking up from the dormant mode, a reset signal
* to the Cortex-A9 processor must be asserted by the external
* power controller.
*
* With architectural inputs and hardware recommendations, only
* below modes are supported from power gain vs latency point of view.
*
* CPU0 CPU1 MPUSS
* ----------------------------------------------
* ON ON ON
* ON(Inactive) OFF ON(Inactive)
* OFF OFF CSWR
* OFF OFF OSWR (*TBD)
* OFF OFF OFF* (*TBD)
* ----------------------------------------------
*
* Note: CPU0 is the master core and it is the last CPU to go down
* and first to wake-up when MPUSS low power states are excercised
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/errno.h>
#include <linux/linkage.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/smp_scu.h>
#include <asm/system.h>
#include <asm/pgalloc.h>
#include <asm/suspend.h>
#include <plat/omap44xx.h>
#include "common.h"
#include "omap4-sar-layout.h"
#include "pm.h"
#include "powerdomain.h"
#ifdef CONFIG_SMP
struct omap4_cpu_pm_info {
struct powerdomain *pwrdm;
void __iomem *scu_sar_addr;
void __iomem *wkup_sar_addr;
};
static DEFINE_PER_CPU(struct omap4_cpu_pm_info, omap4_pm_info);
/*
* Program the wakeup routine address for the CPU0 and CPU1
* used for OFF or DORMANT wakeup.
*/
static inline void set_cpu_wakeup_addr(unsigned int cpu_id, u32 addr)
{
struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu_id);
__raw_writel(addr, pm_info->wkup_sar_addr);
}
/*
* Set the CPUx powerdomain's previous power state
*/
static inline void set_cpu_next_pwrst(unsigned int cpu_id,
unsigned int power_state)
{
struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu_id);
pwrdm_set_next_pwrst(pm_info->pwrdm, power_state);
}
/*
* Read CPU's previous power state
*/
static inline unsigned int read_cpu_prev_pwrst(unsigned int cpu_id)
{
struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu_id);
return pwrdm_read_prev_pwrst(pm_info->pwrdm);
}
/*
* Clear the CPUx powerdomain's previous power state
*/
static inline void clear_cpu_prev_pwrst(unsigned int cpu_id)
{
struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu_id);
pwrdm_clear_all_prev_pwrst(pm_info->pwrdm);
}
/*
* Store the SCU power status value to scratchpad memory
*/
static void scu_pwrst_prepare(unsigned int cpu_id, unsigned int cpu_state)
{
struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu_id);
u32 scu_pwr_st;
switch (cpu_state) {
case PWRDM_POWER_RET:
scu_pwr_st = SCU_PM_DORMANT;
break;
case PWRDM_POWER_OFF:
scu_pwr_st = SCU_PM_POWEROFF;
break;
case PWRDM_POWER_ON:
case PWRDM_POWER_INACTIVE:
default:
scu_pwr_st = SCU_PM_NORMAL;
break;
}
__raw_writel(scu_pwr_st, pm_info->scu_sar_addr);
}
/**
* omap4_enter_lowpower: OMAP4 MPUSS Low Power Entry Function
* The purpose of this function is to manage low power programming
* of OMAP4 MPUSS subsystem
* @cpu : CPU ID
* @power_state: Low power state.
*/
int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
{
unsigned int save_state = 0;
unsigned int wakeup_cpu;
if (omap_rev() == OMAP4430_REV_ES1_0)
return -ENXIO;
switch (power_state) {
case PWRDM_POWER_ON:
case PWRDM_POWER_INACTIVE:
save_state = 0;
break;
case PWRDM_POWER_OFF:
save_state = 1;
break;
case PWRDM_POWER_RET:
default:
/*
* CPUx CSWR is invalid hardware state. Also CPUx OSWR
* doesn't make much scense, since logic is lost and $L1
* needs to be cleaned because of coherency. This makes
* CPUx OSWR equivalent to CPUX OFF and hence not supported
*/
WARN_ON(1);
return -ENXIO;
}
clear_cpu_prev_pwrst(cpu);
set_cpu_next_pwrst(cpu, power_state);
set_cpu_wakeup_addr(cpu, virt_to_phys(omap4_cpu_resume));
scu_pwrst_prepare(cpu, power_state);
/*
* Call low level function with targeted low power state.
*/
cpu_suspend(save_state, omap4_finish_suspend);
/*
* Restore the CPUx power state to ON otherwise CPUx
* power domain can transitions to programmed low power
* state while doing WFI outside the low powe code. On
* secure devices, CPUx does WFI which can result in
* domain transition
*/
wakeup_cpu = smp_processor_id();
set_cpu_next_pwrst(wakeup_cpu, PWRDM_POWER_ON);
return 0;
}
/*
* Initialise OMAP4 MPUSS
*/
int __init omap4_mpuss_init(void)
{
struct omap4_cpu_pm_info *pm_info;
void __iomem *sar_base = omap4_get_sar_ram_base();
if (omap_rev() == OMAP4430_REV_ES1_0) {
WARN(1, "Power Management not supported on OMAP4430 ES1.0\n");
return -ENODEV;
}
/* Initilaise per CPU PM information */
pm_info = &per_cpu(omap4_pm_info, 0x0);
pm_info->scu_sar_addr = sar_base + SCU_OFFSET0;
pm_info->wkup_sar_addr = sar_base + CPU0_WAKEUP_NS_PA_ADDR_OFFSET;
pm_info->pwrdm = pwrdm_lookup("cpu0_pwrdm");
if (!pm_info->pwrdm) {
pr_err("Lookup failed for CPU0 pwrdm\n");
return -ENODEV;
}
/* Clear CPU previous power domain state */
pwrdm_clear_all_prev_pwrst(pm_info->pwrdm);
/* Initialise CPU0 power domain state to ON */
pwrdm_set_next_pwrst(pm_info->pwrdm, PWRDM_POWER_ON);
pm_info = &per_cpu(omap4_pm_info, 0x1);
pm_info->scu_sar_addr = sar_base + SCU_OFFSET1;
pm_info->wkup_sar_addr = sar_base + CPU1_WAKEUP_NS_PA_ADDR_OFFSET;
pm_info->pwrdm = pwrdm_lookup("cpu1_pwrdm");
if (!pm_info->pwrdm) {
pr_err("Lookup failed for CPU1 pwrdm\n");
return -ENODEV;
}
/* Clear CPU previous power domain state */
pwrdm_clear_all_prev_pwrst(pm_info->pwrdm);
/* Initialise CPU1 power domain state to ON */
pwrdm_set_next_pwrst(pm_info->pwrdm, PWRDM_POWER_ON);
/* Save device type on scratchpad for low level code to use */
if (omap_type() != OMAP2_DEVICE_TYPE_GP)
__raw_writel(1, sar_base + OMAP_TYPE_OFFSET);
else
__raw_writel(0, sar_base + OMAP_TYPE_OFFSET);
return 0;
}
#endif

13
arch/arm/mach-omap2/omap-smp.c
View File

@ -24,6 +24,7 @@
#include <asm/hardware/gic.h>
#include <asm/smp_scu.h>
#include <mach/hardware.h>
#include <mach/omap-secure.h>
#include "common.h"
@ -39,6 +40,18 @@ void __iomem *omap4_get_scu_base(void)
void __cpuinit platform_secondary_init(unsigned int cpu)
{
/*
* Configure ACTRL and enable NS SMP bit access on CPU1 on HS device.
* OMAP44XX EMU/HS devices - CPU0 SMP bit access is enabled in PPA
* init and for CPU1, a secure PPA API provided. CPU0 must be ON
* while executing NS_SMP API on CPU1 and PPA version must be 1.4.0+.
* OMAP443X GP devices- SMP bit isn't accessible.
* OMAP446X GP devices - SMP bit access is enabled on both CPUs.
*/
if (cpu_is_omap443x() && (omap_type() != OMAP2_DEVICE_TYPE_GP))
omap_secure_dispatcher(OMAP4_PPA_CPU_ACTRL_SMP_INDEX,
4, 0, 0, 0, 0, 0);
/*
* If any interrupts are already enabled for the primary
* core (e.g. timer irq), then they will not have been enabled

9
arch/arm/mach-omap2/omap4-sar-layout.h
View File

@ -19,4 +19,13 @@
#define SAR_BANK3_OFFSET 0x2000
#define SAR_BANK4_OFFSET 0x3000
/* Scratch pad memory offsets from SAR_BANK1 */
#define SCU_OFFSET0 0xd00
#define SCU_OFFSET1 0xd04
#define OMAP_TYPE_OFFSET 0xd10
/* CPUx Wakeup Non-Secure Physical Address offsets in SAR_BANK3 */
#define CPU0_WAKEUP_NS_PA_ADDR_OFFSET 0xa04
#define CPU1_WAKEUP_NS_PA_ADDR_OFFSET 0xa08
#endif

6
arch/arm/mach-omap2/pm44xx.c
View File

@ -163,6 +163,12 @@ static int __init omap4_pm_init(void)
goto err2;
}
ret = omap4_mpuss_init();
if (ret) {
pr_err("Failed to initialise OMAP4 MPUSS\n");
goto err2;
}
(void) clkdm_for_each(clkdms_setup, NULL);
#ifdef CONFIG_SUSPEND

276
arch/arm/mach-omap2/sleep44xx.S Normal file
View File

@ -0,0 +1,276 @@
/*
* OMAP44xx sleep code.
*
* Copyright (C) 2011 Texas Instruments, Inc.
* Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* This program is free software,you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <asm/system.h>
#include <asm/smp_scu.h>
#include <asm/memory.h>
#include <asm/hardware/cache-l2x0.h>
#include <plat/omap44xx.h>
#include <mach/omap-secure.h>
#include "common.h"
#include "omap4-sar-layout.h"
#if defined(CONFIG_SMP) && defined(CONFIG_PM)
.macro DO_SMC
dsb
smc #0
dsb
.endm
ppa_zero_params:
.word 0x0
/*
* =============================
* == CPU suspend finisher ==
* =============================
*
* void omap4_finish_suspend(unsigned long cpu_state)
*
* This function code saves the CPU context and performs the CPU
* power down sequence. Calling WFI effectively changes the CPU
* power domains states to the desired target power state.
*
* @cpu_state : contains context save state (r0)
* 0 - No context lost
* 1 - CPUx L1 and logic lost: MPUSS CSWR
* 2 - CPUx L1 and logic lost + GIC lost: MPUSS OSWR
* 3 - CPUx L1 and logic lost + GIC + L2 lost: MPUSS OFF
* @return: This function never returns for CPU OFF and DORMANT power states.
* Post WFI, CPU transitions to DORMANT or OFF power state and on wake-up
* from this follows a full CPU reset path via ROM code to CPU restore code.
* The restore function pointer is stored at CPUx_WAKEUP_NS_PA_ADDR_OFFSET.
* It returns to the caller for CPU INACTIVE and ON power states or in case
* CPU failed to transition to targeted OFF/DORMANT state.
*/
ENTRY(omap4_finish_suspend)
stmfd sp!, {lr}
cmp r0, #0x0
beq do_WFI @ No lowpower state, jump to WFI
/*
* Flush all data from the L1 data cache before disabling
* SCTLR.C bit.
*/
bl omap4_get_sar_ram_base
ldr r9, [r0, #OMAP_TYPE_OFFSET]
cmp r9, #0x1 @ Check for HS device
bne skip_secure_l1_clean
mov r0, #SCU_PM_NORMAL
mov r1, #0xFF @ clean seucre L1
stmfd r13!, {r4-r12, r14}
ldr r12, =OMAP4_MON_SCU_PWR_INDEX
DO_SMC
ldmfd r13!, {r4-r12, r14}
skip_secure_l1_clean:
bl v7_flush_dcache_all
/*
* Clear the SCTLR.C bit to prevent further data cache
* allocation. Clearing SCTLR.C would make all the data accesses
* strongly ordered and would not hit the cache.
*/
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #(1 << 2) @ Disable the C bit
mcr p15, 0, r0, c1, c0, 0
isb
/*
* Invalidate L1 data cache. Even though only invalidate is
* necessary exported flush API is used here. Doing clean
* on already clean cache would be almost NOP.
*/
bl v7_flush_dcache_all
/*
* Switch the CPU from Symmetric Multiprocessing (SMP) mode
* to AsymmetricMultiprocessing (AMP) mode by programming
* the SCU power status to DORMANT or OFF mode.
* This enables the CPU to be taken out of coherency by
* preventing the CPU from receiving cache, TLB, or BTB
* maintenance operations broadcast by other CPUs in the cluster.
*/
bl omap4_get_sar_ram_base
mov r8, r0
ldr r9, [r8, #OMAP_TYPE_OFFSET]
cmp r9, #0x1 @ Check for HS device
bne scu_gp_set
mrc p15, 0, r0, c0, c0, 5 @ Read MPIDR
ands r0, r0, #0x0f
ldreq r0, [r8, #SCU_OFFSET0]
ldrne r0, [r8, #SCU_OFFSET1]
mov r1, #0x00
stmfd r13!, {r4-r12, r14}
ldr r12, =OMAP4_MON_SCU_PWR_INDEX
DO_SMC
ldmfd r13!, {r4-r12, r14}
b skip_scu_gp_set
scu_gp_set:
mrc p15, 0, r0, c0, c0, 5 @ Read MPIDR
ands r0, r0, #0x0f
ldreq r1, [r8, #SCU_OFFSET0]
ldrne r1, [r8, #SCU_OFFSET1]
bl omap4_get_scu_base
bl scu_power_mode
skip_scu_gp_set:
mrc p15, 0, r0, c1, c1, 2 @ Read NSACR data
tst r0, #(1 << 18)
mrcne p15, 0, r0, c1, c0, 1
bicne r0, r0, #(1 << 6) @ Disable SMP bit
mcrne p15, 0, r0, c1, c0, 1
isb
dsb
do_WFI:
bl omap_do_wfi
/*
* CPU is here when it failed to enter OFF/DORMANT or
* no low power state was attempted.
*/
mrc p15, 0, r0, c1, c0, 0
tst r0, #(1 << 2) @ Check C bit enabled?
orreq r0, r0, #(1 << 2) @ Enable the C bit
mcreq p15, 0, r0, c1, c0, 0
isb
/*
* Ensure the CPU power state is set to NORMAL in
* SCU power state so that CPU is back in coherency.
* In non-coherent mode CPU can lock-up and lead to
* system deadlock.
*/
mrc p15, 0, r0, c1, c0, 1
tst r0, #(1 << 6) @ Check SMP bit enabled?
orreq r0, r0, #(1 << 6)
mcreq p15, 0, r0, c1, c0, 1
isb
bl omap4_get_sar_ram_base
mov r8, r0
ldr r9, [r8, #OMAP_TYPE_OFFSET]
cmp r9, #0x1 @ Check for HS device
bne scu_gp_clear
mov r0, #SCU_PM_NORMAL
mov r1, #0x00
stmfd r13!, {r4-r12, r14}
ldr r12, =OMAP4_MON_SCU_PWR_INDEX
DO_SMC
ldmfd r13!, {r4-r12, r14}
b skip_scu_gp_clear
scu_gp_clear:
bl omap4_get_scu_base
mov r1, #SCU_PM_NORMAL
bl scu_power_mode
skip_scu_gp_clear:
isb
dsb
ldmfd sp!, {pc}
ENDPROC(omap4_finish_suspend)
/*
* ============================
* == CPU resume entry point ==
* ============================
*
* void omap4_cpu_resume(void)
*
* ROM code jumps to this function while waking up from CPU
* OFF or DORMANT state. Physical address of the function is
* stored in the SAR RAM while entering to OFF or DORMANT mode.
* The restore function pointer is stored at CPUx_WAKEUP_NS_PA_ADDR_OFFSET.
*/
ENTRY(omap4_cpu_resume)
/*
* Configure ACTRL and enable NS SMP bit access on CPU1 on HS device.
* OMAP44XX EMU/HS devices - CPU0 SMP bit access is enabled in PPA
* init and for CPU1, a secure PPA API provided. CPU0 must be ON
* while executing NS_SMP API on CPU1 and PPA version must be 1.4.0+.
* OMAP443X GP devices- SMP bit isn't accessible.
* OMAP446X GP devices - SMP bit access is enabled on both CPUs.
*/
ldr r8, =OMAP44XX_SAR_RAM_BASE
ldr r9, [r8, #OMAP_TYPE_OFFSET]
cmp r9, #0x1 @ Skip if GP device
bne skip_ns_smp_enable
mrc p15, 0, r0, c0, c0, 5
ands r0, r0, #0x0f
beq skip_ns_smp_enable
ppa_actrl_retry:
mov r0, #OMAP4_PPA_CPU_ACTRL_SMP_INDEX
adr r3, ppa_zero_params @ Pointer to parameters
mov r1, #0x0 @ Process ID
mov r2, #0x4 @ Flag
mov r6, #0xff
mov r12, #0x00 @ Secure Service ID
DO_SMC
cmp r0, #0x0 @ API returns 0 on success.
beq enable_smp_bit
b ppa_actrl_retry
enable_smp_bit:
mrc p15, 0, r0, c1, c0, 1
tst r0, #(1 << 6) @ Check SMP bit enabled?
orreq r0, r0, #(1 << 6)
mcreq p15, 0, r0, c1, c0, 1
isb
skip_ns_smp_enable:
b cpu_resume @ Jump to generic resume
ENDPROC(omap4_cpu_resume)
#endif
ENTRY(omap_do_wfi)
stmfd sp!, {lr}
/*
* Execute an ISB instruction to ensure that all of the
* CP15 register changes have been committed.
*/
isb
/*
* Execute a barrier instruction to ensure that all cache,
* TLB and branch predictor maintenance operations issued
* by any CPU in the cluster have completed.
*/
dsb
dmb
/*
* Execute a WFI instruction and wait until the
* STANDBYWFI output is asserted to indicate that the
* CPU is in idle and low power state. CPU can specualatively
* prefetch the instructions so add NOPs after WFI. Sixteen
* NOPs as per Cortex-A9 pipeline.
*/
wfi @ Wait For Interrupt
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
ldmfd sp!, {pc}
ENDPROC(omap_do_wfi)