linux-kernel - Re: [RFC PATCH 5/9] soc: samsung: pm: Add support for suspend-to-ram of Exynos5433

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Message-ID: <CAJKOXPdL7EbhaWkKCV7vMMnX2Z9vTr=r7UyDNx6E7ZLUikXy_Q@mail.gmail.com>
Date:   Tue, 9 Jan 2018 13:45:15 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Chanwoo Choi <cw00.choi@...sung.com>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>, kgene@...nel.org,
        Tomasz Figa <tomasz.figa@...il.com>, chanwoo@...nel.org,
        Jaehoon Chung <jh80.chung@...sung.com>,
        Inki Dae <inki.dae@...sung.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Jonghwa Lee <jonghwa3.lee@...sung.com>
Subject: Re: [RFC PATCH 5/9] soc: samsung: pm: Add support for suspend-to-ram
 of Exynos5433

On Tue, Jan 9, 2018 at 8:59 AM, Chanwoo Choi <cw00.choi@...sung.com> wrote:
> This patch adds the specific exynos_pm_data instance for Exynos5433
> in order to support the suspend-to-ram. Exynos5433 SoC need to write
> the 'cpu_resume' poiter address and the specific magic number
> for suspend mode.
>
> Signed-off-by: Jonghwa Lee <jonghwa3.lee@...sung.com>
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> ---
>  drivers/soc/samsung/exynos-pm.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/drivers/soc/samsung/exynos-pm.c b/drivers/soc/samsung/exynos-pm.c
> index 45d84bbe5e61..70d949ba5cab 100644
> --- a/drivers/soc/samsung/exynos-pm.c
> +++ b/drivers/soc/samsung/exynos-pm.c
> @@ -12,6 +12,7 @@
>  #include <linux/regulator/machine.h>
>  #include <linux/syscore_ops.h>
>  #include <linux/suspend.h>
> +#include <linux/psci.h>
>
>  #include <asm/cpuidle.h>
>  #include <asm/io.h>
> @@ -123,7 +124,44 @@ static void exynos_pm_finish(void)
>  #define exynos_pm_data_arm_ptr(data)   NULL
>  #endif
>
> +static int exynos5433_pm_suspend(unsigned long unused)
> +{
> +       /*
> +        * Exynos5433 uses PSCI v0.1 which provides the only one
> +        * entry point (psci_ops.cpu_suspend) for both cpuidle and
> +        * suspend-to-RAM. Also, PSCI v0.1 needs the specific 'power_state'
> +        * parameter for the suspend mode. In order to enter suspend mode,
> +        * Exynos5433 calls the 'psci_ops.cpu_suspend' with '0x3010000'
> +        * power_state parameter.
> +        *
> +        * '0x3010000' means that both cluster and system are going to enter
> +        * the power-down state as following:
> +        * - [25:24] 0x3 : Indicate the cluster and system.
> +        * - [16]    0x1 : Indicate power-down state.

Define them, it will be more readable (name of define given just as an example):

EXYNOS5433_PCSI_SUSPEND_SYSTEM (0x3 << 24)
(or even split per system and cluser and use BIT() if this is real meaning)
and probably reuse existing S5P_CENTRAL_LOWPWR_CFG

> +        */
> +       return psci_ops.cpu_suspend(0x3010000, __pa_symbol(cpu_resume));
> +}
> +
> +static int exynos5433_pm_suspend_enter(suspend_state_t state)
> +{
> +       if (!sysram_ns_base_addr)
> +               return -EINVAL;
> +
> +       __raw_writel(virt_to_phys(cpu_resume), sysram_ns_base_addr + 0x8);
> +       __raw_writel(EXYNOS_SLEEP_MAGIC, sysram_ns_base_addr + 0xc);

Document them in Documentation/arm/Samsung/Bootloader-interface.txt.

Best regards,
Krzysztof

> +
> +       return cpu_suspend(0, exynos5433_pm_suspend);
> +}
> +
> +const struct exynos_pm_data exynos5433_pm_data = {
> +       .enter          = exynos5433_pm_suspend_enter,
> +};
> +
>  static const struct of_device_id exynos_pm_of_device_ids[] = {
> +       {
> +               .compatible = "samsung,exynos5433-pmu",
> +               .data = exynos_pm_data_arm_ptr(exynos5433_pm_data),
> +       },
>         { /*sentinel*/ },
>  };
>
> --
> 1.9.1
>