Commit 5c1350bd authored by Joseph Lo's avatar Joseph Lo Committed by Stephen Warren
Browse files

ARM: tegra20: cpuidle: add powered-down state for secondary CPU 



The powered-down state of Tegra20 requires power gating both CPU cores.
When the secondary CPU requests to enter powered-down state, it saves
its own contexts and then enters WFI. The Tegra20 had a limition to
power down both CPU cores. The secondary CPU must waits for CPU0 in
powered-down state too. If the secondary CPU be woken up before CPU0
entering powered-down state, then it needs to restore its CPU states
and waits for next chance.

Be aware of that, you may see the legacy power state "LP2" in the code
which is exactly the same meaning of "CPU power down".

Based on the work by:
Colin Cross <ccross@android.com>
Gary King <gking@nvidia.com>

Signed-off-by: default avatarJoseph Lo <josephl@nvidia.com>
Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
parent d4b92fb2

arch/arm/mach-tegra/cpuidle-tegra20.c

+86 −4
Original line number Diff line number Diff line
@@ -22,21 +22,99 @@ 
#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/cpuidle.h>

#include <linux/cpu_pm.h>

#include <linux/clockchips.h>



#include <asm/cpuidle.h>

#include <asm/proc-fns.h>

#include <asm/suspend.h>

#include <asm/smp_plat.h>



#include "pm.h"

#include "sleep.h"



#ifdef CONFIG_PM_SLEEP

static int tegra20_idle_lp2(struct cpuidle_device *dev,

			    struct cpuidle_driver *drv,

			    int index);

#endif



static struct cpuidle_state tegra_idle_states[] = {

	[0] = ARM_CPUIDLE_WFI_STATE_PWR(600),

#ifdef CONFIG_PM_SLEEP

	[1] = {

		.enter			= tegra20_idle_lp2,

		.exit_latency		= 5000,

		.target_residency	= 10000,

		.power_usage		= 0,

		.flags			= CPUIDLE_FLAG_TIME_VALID,

		.name			= "powered-down",

		.desc			= "CPU power gated",

	},

#endif

};



static struct cpuidle_driver tegra_idle_driver = {

	.name = "tegra_idle",

	.owner = THIS_MODULE,

	.en_core_tk_irqen = 1,

	.state_count = 1,

	.states = {

		[0] = ARM_CPUIDLE_WFI_STATE_PWR(600),

	},

};



static DEFINE_PER_CPU(struct cpuidle_device, tegra_idle_device);



#ifdef CONFIG_PM_SLEEP

#ifdef CONFIG_SMP

static bool tegra20_idle_enter_lp2_cpu_1(struct cpuidle_device *dev,

					 struct cpuidle_driver *drv,

					 int index)

{

	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);



	cpu_suspend(0, tegra20_sleep_cpu_secondary_finish);



	tegra20_cpu_clear_resettable();



	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);



	return true;

}

#else

static inline bool tegra20_idle_enter_lp2_cpu_1(struct cpuidle_device *dev,

						struct cpuidle_driver *drv,

						int index)

{

	return true;

}

#endif



static int tegra20_idle_lp2(struct cpuidle_device *dev,

			    struct cpuidle_driver *drv,

			    int index)

{

	u32 cpu = is_smp() ? cpu_logical_map(dev->cpu) : dev->cpu;

	bool entered_lp2 = false;



	local_fiq_disable();



	tegra_set_cpu_in_lp2(cpu);

	cpu_pm_enter();



	if (cpu == 0)

		cpu_do_idle();

	else

		entered_lp2 = tegra20_idle_enter_lp2_cpu_1(dev, drv, index);



	cpu_pm_exit();

	tegra_clear_cpu_in_lp2(cpu);



	local_fiq_enable();



	smp_rmb();



	return entered_lp2 ? index : 0;

}

#endif



int __init tegra20_cpuidle_init(void)

{

	int ret;
@@ -44,6 +122,10 @@ int __init tegra20_cpuidle_init(void) 
	struct cpuidle_device *dev;

	struct cpuidle_driver *drv = &tegra_idle_driver;



	drv->state_count = ARRAY_SIZE(tegra_idle_states);

	memcpy(drv->states, tegra_idle_states,

			drv->state_count * sizeof(drv->states[0]));



	ret = cpuidle_register_driver(&tegra_idle_driver);

	if (ret) {

		pr_err("CPUidle driver registration failed\n");

arch/arm/mach-tegra/pm.c

+3 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include "iomap.h"

#include "reset.h"

#include "flowctrl.h"

#include "fuse.h"

#include "sleep.h"



#define TEGRA_POWER_CPU_PWRREQ_OE	(1 << 16)  /* CPU pwr req enable */
@@ -173,6 +174,8 @@ bool tegra_set_cpu_in_lp2(int phy_cpu_id) 


	if ((phy_cpu_id == 0) && cpumask_equal(cpu_lp2_mask, cpu_online_mask))

		last_cpu = true;

	else if (tegra_chip_id == TEGRA20 && phy_cpu_id == 1)

		tegra20_cpu_set_resettable_soon();



	spin_unlock(&tegra_lp2_lock);

	return last_cpu;

arch/arm/mach-tegra/sleep-tegra20.S

+147 −0
Original line number Diff line number Diff line
@@ -21,6 +21,8 @@ 
#include <linux/linkage.h>



#include <asm/assembler.h>

#include <asm/proc-fns.h>

#include <asm/cp15.h>



#include "sleep.h"

#include "flowctrl.h"
@@ -75,3 +77,148 @@ ENTRY(tegra20_cpu_shutdown) 
	mov	pc, lr

ENDPROC(tegra20_cpu_shutdown)

#endif



#ifdef CONFIG_PM_SLEEP

/*

 * tegra_pen_lock

 *

 * spinlock implementation with no atomic test-and-set and no coherence

 * using Peterson's algorithm on strongly-ordered registers

 * used to synchronize a cpu waking up from wfi with entering lp2 on idle

 *

 * The reference link of Peterson's algorithm:

 * http://en.wikipedia.org/wiki/Peterson's_algorithm

 *

 * SCRATCH37 = r1 = !turn (inverted from Peterson's algorithm)

 * on cpu 0:

 * r2 = flag[0] (in SCRATCH38)

 * r3 = flag[1] (in SCRATCH39)

 * on cpu1:

 * r2 = flag[1] (in SCRATCH39)

 * r3 = flag[0] (in SCRATCH38)

 *

 * must be called with MMU on

 * corrupts r0-r3, r12

 */

ENTRY(tegra_pen_lock)

	mov32	r3, TEGRA_PMC_VIRT

	cpu_id	r0

	add	r1, r3, #PMC_SCRATCH37

	cmp	r0, #0

	addeq	r2, r3, #PMC_SCRATCH38

	addeq	r3, r3, #PMC_SCRATCH39

	addne	r2, r3, #PMC_SCRATCH39

	addne	r3, r3, #PMC_SCRATCH38



	mov	r12, #1

	str	r12, [r2]		@ flag[cpu] = 1

	dsb

	str	r12, [r1]		@ !turn = cpu

1:	dsb

	ldr	r12, [r3]

	cmp	r12, #1			@ flag[!cpu] == 1?

	ldreq	r12, [r1]

	cmpeq	r12, r0			@ !turn == cpu?

	beq	1b			@ while !turn == cpu && flag[!cpu] == 1



	mov	pc, lr			@ locked

ENDPROC(tegra_pen_lock)



ENTRY(tegra_pen_unlock)

	dsb

	mov32	r3, TEGRA_PMC_VIRT

	cpu_id	r0

	cmp	r0, #0

	addeq	r2, r3, #PMC_SCRATCH38

	addne	r2, r3, #PMC_SCRATCH39

	mov	r12, #0

	str	r12, [r2]

	mov     pc, lr

ENDPROC(tegra_pen_unlock)



/*

 * tegra20_cpu_clear_resettable(void)

 *

 * Called to clear the "resettable soon" flag in PMC_SCRATCH41 when

 * it is expected that the secondary CPU will be idle soon.

 */

ENTRY(tegra20_cpu_clear_resettable)

	mov32	r1, TEGRA_PMC_VIRT + PMC_SCRATCH41

	mov	r12, #CPU_NOT_RESETTABLE

	str	r12, [r1]

	mov	pc, lr

ENDPROC(tegra20_cpu_clear_resettable)



/*

 * tegra20_cpu_set_resettable_soon(void)

 *

 * Called to set the "resettable soon" flag in PMC_SCRATCH41 when

 * it is expected that the secondary CPU will be idle soon.

 */

ENTRY(tegra20_cpu_set_resettable_soon)

	mov32	r1, TEGRA_PMC_VIRT + PMC_SCRATCH41

	mov	r12, #CPU_RESETTABLE_SOON

	str	r12, [r1]

	mov	pc, lr

ENDPROC(tegra20_cpu_set_resettable_soon)



/*

 * tegra20_sleep_cpu_secondary_finish(unsigned long v2p)

 *

 * Enters WFI on secondary CPU by exiting coherency.

 */

ENTRY(tegra20_sleep_cpu_secondary_finish)

	stmfd	sp!, {r4-r11, lr}



	mrc	p15, 0, r11, c1, c0, 1  @ save actlr before exiting coherency



	/* Flush and disable the L1 data cache */

	bl	tegra_disable_clean_inv_dcache



	mov32	r0, TEGRA_PMC_VIRT + PMC_SCRATCH41

	mov	r3, #CPU_RESETTABLE

	str	r3, [r0]



	bl	cpu_do_idle



	/*

	 * cpu may be reset while in wfi, which will return through

	 * tegra_resume to cpu_resume

	 * or interrupt may wake wfi, which will return here

	 * cpu state is unchanged - MMU is on, cache is on, coherency

	 * is off, and the data cache is off

	 *

	 * r11 contains the original actlr

	 */



	bl	tegra_pen_lock



	mov32	r3, TEGRA_PMC_VIRT

	add	r0, r3, #PMC_SCRATCH41

	mov	r3, #CPU_NOT_RESETTABLE

	str	r3, [r0]



	bl	tegra_pen_unlock



	/* Re-enable the data cache */

	mrc	p15, 0, r10, c1, c0, 0

	orr	r10, r10, #CR_C

	mcr	p15, 0, r10, c1, c0, 0

	isb



	mcr	p15, 0, r11, c1, c0, 1	@ reenable coherency



	/* Invalidate the TLBs & BTAC */

	mov	r1, #0

	mcr	p15, 0, r1, c8, c3, 0	@ invalidate shared TLBs

	mcr	p15, 0, r1, c7, c1, 6	@ invalidate shared BTAC

	dsb

	isb



	/* the cpu was running with coherency disabled,

	 * caches may be out of date */

	bl	v7_flush_kern_cache_louis



	ldmfd	sp!, {r4 - r11, pc}

ENDPROC(tegra20_sleep_cpu_secondary_finish)

#endif

arch/arm/mach-tegra/sleep.h

+23 −0
Original line number Diff line number Diff line
@@ -25,6 +25,19 @@ 
					+ IO_PPSB_VIRT)

#define TEGRA_CLK_RESET_VIRT (TEGRA_CLK_RESET_BASE - IO_PPSB_PHYS \

					+ IO_PPSB_VIRT)

#define TEGRA_PMC_VIRT	(TEGRA_PMC_BASE - IO_APB_PHYS + IO_APB_VIRT)



/* PMC_SCRATCH37-39 and 41 are used for tegra_pen_lock and idle */

#define PMC_SCRATCH37	0x130

#define PMC_SCRATCH38	0x134

#define PMC_SCRATCH39	0x138

#define PMC_SCRATCH41	0x140



#ifdef CONFIG_ARCH_TEGRA_2x_SOC

#define CPU_RESETTABLE		2

#define CPU_RESETTABLE_SOON	1

#define CPU_NOT_RESETTABLE	0

#endif



#ifdef __ASSEMBLY__

/* returns the offset of the flow controller halt register for a cpu */
@@ -104,6 +117,8 @@ exit_l2_resume: 
.endm

#endif /* CONFIG_CACHE_L2X0 */

#else

void tegra_pen_lock(void);

void tegra_pen_unlock(void);

void tegra_resume(void);

int tegra_sleep_cpu_finish(unsigned long);

void tegra_disable_clean_inv_dcache(void);
@@ -116,6 +131,14 @@ static inline void tegra20_hotplug_init(void) {} 
static inline void tegra30_hotplug_init(void) {}

#endif



void tegra20_cpu_clear_resettable(void);

#ifdef CONFIG_ARCH_TEGRA_2x_SOC

void tegra20_cpu_set_resettable_soon(void);

#else

static inline void tegra20_cpu_set_resettable_soon(void) {}

#endif



int tegra20_sleep_cpu_secondary_finish(unsigned long);

int tegra30_sleep_cpu_secondary_finish(unsigned long);

void tegra30_tear_down_cpu(void);

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