Re: [PATCH v3 2/2] cpuidle: exynos: add coupled cpuidle support for Exynos4210

From: Kukjin Kim
Date: Thu Jan 29 2015 - 18:38:18 EST

On 01/26/15 20:53, Krzysztof Kozlowski wrote:
> On pon, 2015-01-26 at 12:33 +0100, Bartlomiej Zolnierkiewicz wrote:
>> Hi,
>>
>> On Monday, January 26, 2015 09:16:48 AM Krzysztof Kozlowski wrote:
>>> On piÄ, 2015-01-23 at 17:24 +0100, Bartlomiej Zolnierkiewicz wrote:
>>>> The following patch adds coupled cpuidle support for Exynos4210 to
>>>> an existing cpuidle-exynos driver. As a result it enables AFTR mode
>>>> to be used by default on Exynos4210 without the need to hot unplug
>>>> CPU1 first.
>>>>
>>>> The patch is heavily based on earlier cpuidle-exynos4210 driver from
>>>> Daniel Lezcano:
>>>>
>>>> http://www.spinics.net/lists/linux-samsung-soc/msg28134.html
>>>>
>>>> Changes from Daniel's code include:
>>>> - porting code to current kernels
>>>> - fixing it to work on my setup (by using S5P_INFORM register
>>>> instead of S5P_VA_SYSRAM one on Revison 1.1 and retrying poking
>>>> CPU1 out of the BOOT ROM if necessary)
>>>> - fixing rare lockup caused by waiting for CPU1 to get stuck in
>>>> the BOOT ROM (CPU hotplug code in arch/arm/mach-exynos/platsmp.c
>>>> doesn't require this and works fine)
>>>> - moving Exynos specific code to arch/arm/mach-exynos/pm.c
>>>> - using cpu_boot_reg_base() helper instead of BOOT_VECTOR macro
>>>> - using exynos_cpu_*() helpers instead of accessing registers
>>>> directly
>>>> - using arch_send_wakeup_ipi_mask() instead of dsb_sev()
>>>> (this matches CPU hotplug code in arch/arm/mach-exynos/platsmp.c)
>>>> - integrating separate exynos4210-cpuidle driver into existing
>>>> exynos-cpuidle one
>>>>
>>>> Cc: Colin Cross <ccross@xxxxxxxxxx>
>>>> Cc: Kukjin Kim <kgene.kim@xxxxxxxxxxx>
>>>> Cc: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
>>>> Cc: Tomasz Figa <tomasz.figa@xxxxxxxxx>
>>>> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
>>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
>>>> Acked-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
>>>
>>> I've seen the patch during internal review and now looks good... except
>>> minor issues below.
>>>
>>>> ---
>>>> arch/arm/mach-exynos/common.h | 4 +
>>>> arch/arm/mach-exynos/exynos.c | 4 +
>>>> arch/arm/mach-exynos/platsmp.c | 2 +-
>>>> arch/arm/mach-exynos/pm.c | 122 +++++++++++++++++++++++++++
>>>> drivers/cpuidle/Kconfig.arm | 1 +
>>>> drivers/cpuidle/cpuidle-exynos.c | 76 +++++++++++++++--
>>>> include/linux/platform_data/cpuidle-exynos.h | 20 +++++
>>>> 7 files changed, 223 insertions(+), 6 deletions(-)
>>>> create mode 100644 include/linux/platform_data/cpuidle-exynos.h
>>>>
>>>> diff --git a/arch/arm/mach-exynos/common.h b/arch/arm/mach-exynos/common.h
>>>> index 865f878..f70eca7 100644
>>>> --- a/arch/arm/mach-exynos/common.h
>>>> +++ b/arch/arm/mach-exynos/common.h
>>>> @@ -13,6 +13,7 @@
>>>> #define __ARCH_ARM_MACH_EXYNOS_COMMON_H
>>>>
>>>> #include <linux/of.h>
>>>> +#include <linux/platform_data/cpuidle-exynos.h>
>>>>
>>>> #define EXYNOS3250_SOC_ID 0xE3472000
>>>> #define EXYNOS3_SOC_MASK 0xFFFFF000
>>>> @@ -150,8 +151,11 @@ extern void exynos_pm_central_suspend(void);
>>>> extern int exynos_pm_central_resume(void);
>>>> extern void exynos_enter_aftr(void);
>>>>
>>>> +extern struct cpuidle_exynos_data cpuidle_coupled_exynos_data;
>>>> +
>>>> extern void s5p_init_cpu(void __iomem *cpuid_addr);
>>>> extern unsigned int samsung_rev(void);
>>>> +extern void __iomem *cpu_boot_reg_base(void);
>>>>
>>>> static inline void pmu_raw_writel(u32 val, u32 offset)
>>>> {
>>>> diff --git a/arch/arm/mach-exynos/exynos.c b/arch/arm/mach-exynos/exynos.c
>>>> index 78eca99b..2013f73 100644
>>>> --- a/arch/arm/mach-exynos/exynos.c
>>>> +++ b/arch/arm/mach-exynos/exynos.c
>>>> @@ -211,6 +211,10 @@ static void __init exynos_dt_machine_init(void)
>>>> if (!IS_ENABLED(CONFIG_SMP))
>>>> exynos_sysram_init();
>>>>
>>>> +#ifdef CONFIG_ARM_EXYNOS_CPUIDLE
>>>> + if (of_machine_is_compatible("samsung,exynos4210"))
>>>> + exynos_cpuidle.dev.platform_data = &cpuidle_coupled_exynos_data;
>>>> +#endif
>>>> if (of_machine_is_compatible("samsung,exynos4210") ||
>>>> of_machine_is_compatible("samsung,exynos4212") ||
>>>> (of_machine_is_compatible("samsung,exynos4412") &&
>>>> diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
>>>> index 7a1ebfe..3f32c47 100644
>>>> --- a/arch/arm/mach-exynos/platsmp.c
>>>> +++ b/arch/arm/mach-exynos/platsmp.c
>>>> @@ -194,7 +194,7 @@ int exynos_cluster_power_state(int cluster)
>>>> S5P_CORE_LOCAL_PWR_EN);
>>>> }
>>>>
>>>> -static inline void __iomem *cpu_boot_reg_base(void)
>>>> +void __iomem *cpu_boot_reg_base(void)
>>>> {
>>>> if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
>>>> return pmu_base_addr + S5P_INFORM5;
>>>> diff --git a/arch/arm/mach-exynos/pm.c b/arch/arm/mach-exynos/pm.c
>>>> index 1a7454d..e6209da 100644
>>>> --- a/arch/arm/mach-exynos/pm.c
>>>> +++ b/arch/arm/mach-exynos/pm.c
>>>> @@ -180,3 +180,125 @@ void exynos_enter_aftr(void)
>>>>
>>>> cpu_pm_exit();
>>>> }
>>>> +
>>>> +static atomic_t cpu1_wakeup = ATOMIC_INIT(0);
>>>> +
>>>> +static int exynos_cpu0_enter_aftr(void)
>>>> +{
>>>> + int ret = -1;
>>>> +
>>>> + /*
>>>> + * If the other cpu is powered on, we have to power it off, because
>>>> + * the AFTR state won't work otherwise
>>>> + */
>>>> + if (cpu_online(1)) {
>>>> + /*
>>>> + * We reach a sync point with the coupled idle state, we know
>>>> + * the other cpu will power down itself or will abort the
>>>> + * sequence, let's wait for one of these to happen
>>>> + */
>>>> + while (exynos_cpu_power_state(1)) {
>>>> + /*
>>>> + * The other cpu may skip idle and boot back
>>>> + * up again
>>>> + */
>>>> + if (atomic_read(&cpu1_wakeup))
>>>> + goto abort;
>>>> +
>>>> + /*
>>>> + * The other cpu may bounce through idle and
>>>> + * boot back up again, getting stuck in the
>>>> + * boot rom code
>>>> + */
>>>> + if (__raw_readl(cpu_boot_reg_base()) == 0)
>>>> + goto abort;
>>>> +
>>>> + cpu_relax();
>>>> + }
>>>> + }
>>>> +
>>>> + exynos_enter_aftr();
>>>> + ret = 0;
>>>> +
>>>> +abort:
>>>> + if (cpu_online(1)) {
>>>> + /*
>>>> + * Set the boot vector to something non-zero
>>>> + */
>>>> + __raw_writel(virt_to_phys(exynos_cpu_resume),
>>>> + cpu_boot_reg_base());
>>>> + dsb();
>>>> +
>>>> + /*
>>>> + * Turn on cpu1 and wait for it to be on
>>>> + */
>>>> + exynos_cpu_power_up(1);
>>>> + while (exynos_cpu_power_state(1) != S5P_CORE_LOCAL_PWR_EN)
>>>> + cpu_relax();
>>>> +
>>>> + while (!atomic_read(&cpu1_wakeup)) {
>>>> + /*
>>>> + * Poke cpu1 out of the boot rom
>>>> + */
>>>> + __raw_writel(virt_to_phys(exynos_cpu_resume),
>>>> + cpu_boot_reg_base());
>>>> +
>>>> + arch_send_wakeup_ipi_mask(cpumask_of(1));
>>>> + }
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int exynos_wfi_finisher(unsigned long flags)
>>>> +{
>>>> + cpu_do_idle();
>>>> +
>>>> + return -1;
>>>> +}
>>>> +
>>>> +static int exynos_cpu1_powerdown(void)
>>>> +{
>>>> + int ret = -1;
>>>> +
>>>> + /*
>>>> + * Idle sequence for cpu1
>>>> + */
>>>> + if (cpu_pm_enter())
>>>> + goto cpu1_aborted;
>>>> +
>>>> + /*
>>>> + * Turn off cpu 1
>>>> + */
>>>> + exynos_cpu_power_down(1);
>>>> +
>>>> + ret = cpu_suspend(0, exynos_wfi_finisher);
>>>> +
>>>> + cpu_pm_exit();
>>>> +
>>>> +cpu1_aborted:
>>>> + dsb();
>>>> + /*
>>>> + * Notify cpu 0 that cpu 1 is awake
>>>> + */
>>>> + atomic_set(&cpu1_wakeup, 1);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static void exynos_pre_enter_aftr(void)
>>>> +{
>>>> + __raw_writel(virt_to_phys(exynos_cpu_resume), cpu_boot_reg_base());
>>>> +}
>>>> +
>>>> +static void exynos_post_enter_aftr(void)
>>>> +{
>>>> + atomic_set(&cpu1_wakeup, 0);
>>>> +}
>>>> +
>>>> +struct cpuidle_exynos_data cpuidle_coupled_exynos_data = {
>>>> + .cpu0_enter_aftr = exynos_cpu0_enter_aftr,
>>>> + .cpu1_powerdown = exynos_cpu1_powerdown,
>>>> + .pre_enter_aftr = exynos_pre_enter_aftr,
>>>> + .post_enter_aftr = exynos_post_enter_aftr,
>>>> +};
>>>> diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
>>>> index 8c16ab2..8e07c94 100644
>>>> --- a/drivers/cpuidle/Kconfig.arm
>>>> +++ b/drivers/cpuidle/Kconfig.arm
>>>> @@ -55,6 +55,7 @@ config ARM_AT91_CPUIDLE
>>>> config ARM_EXYNOS_CPUIDLE
>>>> bool "Cpu Idle Driver for the Exynos processors"
>>>> depends on ARCH_EXYNOS
>>>> + select ARCH_NEEDS_CPU_IDLE_COUPLED if SMP
>>>> help
>>>> Select this to enable cpuidle for Exynos processors
>>>>
>>>> diff --git a/drivers/cpuidle/cpuidle-exynos.c b/drivers/cpuidle/cpuidle-exynos.c
>>>> index 4003a31..26f5f29 100644
>>>> --- a/drivers/cpuidle/cpuidle-exynos.c
>>>> +++ b/drivers/cpuidle/cpuidle-exynos.c
>>>> @@ -1,8 +1,11 @@
>>>> -/* linux/arch/arm/mach-exynos/cpuidle.c
>>>> - *
>>>> - * Copyright (c) 2011 Samsung Electronics Co., Ltd.
>>>> +/*
>>>> + * Copyright (c) 2011-2014 Samsung Electronics Co., Ltd.
>>>> * http://www.samsung.com
>>>> *
>>>> + * Coupled cpuidle support based on the work of:
>>>> + * Colin Cross <ccross@xxxxxxxxxxx>
>>>> + * Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
>>>> + *
>>>> * 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.
>>>> @@ -13,13 +16,49 @@
>>>> #include <linux/export.h>
>>>> #include <linux/module.h>
>>>> #include <linux/platform_device.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/platform_data/cpuidle-exynos.h>
>>>>
>>>> #include <asm/proc-fns.h>
>>>> #include <asm/suspend.h>
>>>> #include <asm/cpuidle.h>
>>>>
>>>> +static atomic_t exynos_idle_barrier;
>>>> +
>>>> +static struct cpuidle_exynos_data *exynos_cpuidle_pdata;
>>>> static void (*exynos_enter_aftr)(void);
>>>>
>>>> +static int exynos_enter_coupled_lowpower(struct cpuidle_device *dev,
>>>> + struct cpuidle_driver *drv,
>>>> + int index)
>>>> +{
>>>> + int ret;
>>>> +
>>>> + exynos_cpuidle_pdata->pre_enter_aftr();
>>>> +
>>>> + /*
>>>> + * Waiting all cpus to reach this point at the same moment
>>>> + */
>>>> + cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
>>>> +
>>>> + /*
>>>> + * Both cpus will reach this point at the same time
>>>> + */
>>>> + ret = dev->cpu ? exynos_cpuidle_pdata->cpu1_powerdown()
>>>> + : exynos_cpuidle_pdata->cpu0_enter_aftr();
>>>> + if (ret)
>>>> + index = ret;
>>>> +
>>>> + /*
>>>> + * Waiting all cpus to finish the power sequence before going further
>>>> + */
>>>> + cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
>>>> +
>>>> + exynos_cpuidle_pdata->post_enter_aftr();
>>>> +
>>>> + return index;
>>>> +}
>>>> +
>>>> static int exynos_enter_lowpower(struct cpuidle_device *dev,
>>>> struct cpuidle_driver *drv,
>>>> int index)
>>>> @@ -55,13 +94,40 @@ static struct cpuidle_driver exynos_idle_driver = {
>>>> .safe_state_index = 0,
>>>> };
>>>>
>>>> +static struct cpuidle_driver exynos_coupled_idle_driver = {
>>>> + .name = "exynos_coupled_idle",
>>>> + .owner = THIS_MODULE,
>>>> + .states = {
>>>> + [0] = ARM_CPUIDLE_WFI_STATE,
>>>> + [1] = {
>>>> + .enter = exynos_enter_coupled_lowpower,
>>>> + .exit_latency = 5000,
>>>> + .target_residency = 10000,
>>>
>>> Have you measured these numbers? Existing cpuidle has residency of
>>> 100000.
>>
>> These numbers are from the original driver by Daniel. If needed they
>> can be changed later.
>>
>>>> + .flags = CPUIDLE_FLAG_COUPLED |
>>>> + CPUIDLE_FLAG_TIMER_STOP,
>>>> + .name = "C1",
>>>> + .desc = "ARM power down",
>>>> + },
>>>> + },
>>>> + .state_count = 2,
>>>> + .safe_state_index = 0,
>>>> +};
>>>> +
>>>> static int exynos_cpuidle_probe(struct platform_device *pdev)
>>>> {
>>>> int ret;
>>>>
>>>> - exynos_enter_aftr = (void *)(pdev->dev.platform_data);
>>>> + if (of_machine_is_compatible("samsung,exynos4210")) {
>>>> + exynos_cpuidle_pdata = pdev->dev.platform_data;
>>>> +
>>>> + ret = cpuidle_register(&exynos_coupled_idle_driver,
>>>> + cpu_possible_mask);
>>>> + } else {
>>>> + exynos_enter_aftr = (void *)(pdev->dev.platform_data);
>>>> +
>>>> + ret = cpuidle_register(&exynos_idle_driver, NULL);
>>>> + }
>>>>
>>>> - ret = cpuidle_register(&exynos_idle_driver, NULL);
>>>> if (ret) {
>>>> dev_err(&pdev->dev, "failed to register cpuidle driver\n");
>>>> return ret;
>>>> diff --git a/include/linux/platform_data/cpuidle-exynos.h b/include/linux/platform_data/cpuidle-exynos.h
>>>> new file mode 100644
>>>> index 0000000..bfa40e4
>>>> --- /dev/null
>>>> +++ b/include/linux/platform_data/cpuidle-exynos.h
>>>> @@ -0,0 +1,20 @@
>>>> +/*
>>>> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
>>>> + * http://www.samsung.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.
>>>> +*/
>>>> +
>>>> +#ifndef __CPUIDLE_EXYNOS_H
>>>> +#define __CPUIDLE_EXYNOS_H
>>>> +
>>>> +struct cpuidle_exynos_data {
>>>> + int (*cpu0_enter_aftr)(void);
>>>> + int (*cpu1_powerdown)(void);
>>>> + void (*pre_enter_aftr)(void);
>>>> + void (*post_enter_aftr)(void);
>>>
>>> I don't like the names of pre/post_enter_aftr. They are called also on
>>> CPU1 for powerdown. Probably they will be also called for CPU0 to enter
>>
>> powerdown on CPU1 is a part of preparations for system to go into AFTR
>> state.
>>
>>> LPA/LPD/W-AFTR.
>>>
>>> Maybe "pre/post_enter_lowpower"?
>>
>> I agree but it can be changed later when LPA/LPD/W-AFTR support is added.
>
> Sure.
>
>>
>>> Additionally could you add short comment for them (like when they are
>>> called and on which CPU). It is not exynos internal header so one may
>>> not be sure that the raw code is actual documentation for this.
>>
>> It is an Exynos internal header, no generic code uses it. It is a good
>> idea to enhance documentation but lets leave the code as it is for v3.20
>> and update it in the future changes.
>
> OK, I'm fine with that. I saw that Kukjin applied these patches so
> actually I don't oppose them. As I said it was rather nit-picking from
> my side.
>
Thanks, Krzysztof. And we can enhance this stuff next time, soon.

I've applied and merged into for-next just now.

- Kukjin
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