linux-kernel - Re: [PATCH v2 4/5] ARM: EXYNOS: add exynos_get_boot

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Date:	Wed, 18 Mar 2015 16:18:23 +0100
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Kukjin Kim <kgene.kim@...sung.com>, Kukjin Kim <kgene@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Colin Cross <ccross@...gle.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Russell King <rmk+kernel@....linux.org.uk>
Subject: Re: [PATCH v2 4/5] ARM: EXYNOS: add exynos_get_boot_addr() helper

On Wednesday, March 18, 2015 02:43:49 PM Krzysztof Kozlowski wrote:
> 2015-03-18 14:09 GMT+01:00 Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>:
> > Add get_cpu_boot_addr() firmware operation and then
> > exynos_get_boot_addr() helper.
> >
> > This is a preparation for adding coupled cpuidle support
> > for Exynos3250 SoC.
> >
> > There should be no functional changes caused by this patch.
> >
> > Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> > Cc: Russell King <rmk+kernel@....linux.org.uk>
> > Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> > ---
> >  arch/arm/include/asm/firmware.h |  4 ++++
> >  arch/arm/mach-exynos/firmware.c | 17 +++++++++++++++++
> >  arch/arm/mach-exynos/platsmp.c  | 25 +++++++++++++++++++++++++
> >  3 files changed, 46 insertions(+)
> >
> > diff --git a/arch/arm/include/asm/firmware.h b/arch/arm/include/asm/firmware.h
> > index 89aefe1..34c1d96 100644
> > --- a/arch/arm/include/asm/firmware.h
> > +++ b/arch/arm/include/asm/firmware.h
> > @@ -34,6 +34,10 @@ struct firmware_ops {
> >          */
> >         int (*set_cpu_boot_addr)(int cpu, unsigned long boot_addr);
> >         /*
> > +        * Gets boot address of specified physical CPU
> > +        */
> > +       int (*get_cpu_boot_addr)(int cpu, unsigned long *boot_addr);
> > +       /*
> >          * Boots specified physical CPU
> >          */
> >         int (*cpu_boot)(int cpu);
> > diff --git a/arch/arm/mach-exynos/firmware.c b/arch/arm/mach-exynos/firmware.c
> > index f236877..c9e4481 100644
> > --- a/arch/arm/mach-exynos/firmware.c
> > +++ b/arch/arm/mach-exynos/firmware.c
> > @@ -104,6 +104,22 @@ static int exynos_set_cpu_boot_addr(int cpu, unsigned long boot_addr)
> >         return 0;
> >  }
> >
> > +static int exynos_get_cpu_boot_addr(int cpu, unsigned long *boot_addr)
> > +{
> > +       void __iomem *boot_reg;
> > +
> > +       if (!sysram_ns_base_addr)
> > +               return -ENODEV;
> > +
> > +       boot_reg = sysram_ns_base_addr + 0x1c;
> > +
> > +       if (soc_is_exynos4412())
> > +               boot_reg += 4 * cpu;
> > +
> > +       *boot_addr = __raw_readl(boot_reg);
> > +       return 0;
> > +}
> > +
> >  static int exynos_cpu_suspend(unsigned long arg)
> >  {
> >         flush_cache_all();
> > @@ -138,6 +154,7 @@ static int exynos_resume(void)
> >  static const struct firmware_ops exynos_firmware_ops = {
> >         .do_idle                = IS_ENABLED(CONFIG_EXYNOS_CPU_SUSPEND) ? exynos_do_idle : NULL,
> >         .set_cpu_boot_addr      = exynos_set_cpu_boot_addr,
> > +       .get_cpu_boot_addr      = exynos_get_cpu_boot_addr,
> >         .cpu_boot               = exynos_cpu_boot,
> >         .suspend                = IS_ENABLED(CONFIG_PM_SLEEP) ? exynos_suspend : NULL,
> >         .resume                 = IS_ENABLED(CONFIG_EXYNOS_CPU_SUSPEND) ? exynos_resume : NULL,
> > diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
> > index b7cfcdc..449edd1 100644
> > --- a/arch/arm/mach-exynos/platsmp.c
> > +++ b/arch/arm/mach-exynos/platsmp.c
> > @@ -272,6 +272,31 @@ fail:
> >         return ret;
> >  }
> >
> > +static int exynos_get_boot_addr(u32 core_id, unsigned long *boot_addr)
> > +{
> > +       int ret;
> > +
> > +       /*
> > +        * Try to get boot address using firmware first
> > +        * and fall back to boot register if it fails.
> > +        */
> > +       ret = call_firmware_op(get_cpu_boot_addr, core_id, boot_addr);
> > +       if (ret && ret != -ENOSYS)
> > +               goto fail;
> 
> The exynos_get_cpu_boot_addr() returns ENODEV. Do you really want to
> check for ENOSYS here?

Yes.  When secure firmware is not present on the board the call_firmware_op()
itself returns -ENOSYS (exynos_get_cpu_boot_addr() is not called in this
case) and it needs to be handled in a special way.

> > +       if (ret == -ENOSYS) {
> > +               void __iomem *boot_reg = cpu_boot_reg(core_id);
> > +
> > +               if (IS_ERR(boot_reg)) {
> > +                       ret = PTR_ERR(boot_reg);
> > +                       goto fail;
> > +               }

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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