[02/21] ARM: shmobile: Convert to hotplug state machine
diff mbox

Message ID 20160906170457.32393-3-bigeasy@linutronix.de
State New
Headers show

Commit Message

Sebastian Andrzej Siewior Sept. 6, 2016, 5:04 p.m. UTC
Install the callbacks via the state machine.

Cc: Simon Horman <horms@verge.net.au>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-sh@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 arch/arm/mach-shmobile/platsmp-scu.c | 26 ++++++++------------------
 include/linux/cpuhotplug.h           |  1 +
 2 files changed, 9 insertions(+), 18 deletions(-)

Comments

Geert Uytterhoeven Sept. 6, 2016, 6:05 p.m. UTC | #1
Hi Sebastian,

CC linux-renesas-soc

On Tue, Sep 6, 2016 at 7:04 PM, Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
> Install the callbacks via the state machine.

Please describe why this is desirable.

> Cc: Simon Horman <horms@verge.net.au>
> Cc: Magnus Damm <magnus.damm@gmail.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-sh@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  arch/arm/mach-shmobile/platsmp-scu.c | 26 ++++++++------------------
>  include/linux/cpuhotplug.h           |  1 +
>  2 files changed, 9 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm/mach-shmobile/platsmp-scu.c b/arch/arm/mach-shmobile/platsmp-scu.c
> index 8d478f1da265..d1ecaf37d142 100644
> --- a/arch/arm/mach-shmobile/platsmp-scu.c
> +++ b/arch/arm/mach-shmobile/platsmp-scu.c
> @@ -21,26 +21,14 @@
>  static phys_addr_t shmobile_scu_base_phys;
>  static void __iomem *shmobile_scu_base;
>
> -static int shmobile_smp_scu_notifier_call(struct notifier_block *nfb,
> -                                         unsigned long action, void *hcpu)
> +static int shmobile_scu_cpu_prepare(unsigned int cpu)
>  {
> -       unsigned int cpu = (long)hcpu;
> -
> -       switch (action) {
> -       case CPU_UP_PREPARE:
> -               /* For this particular CPU register SCU SMP boot vector */
> -               shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
> -                                 shmobile_scu_base_phys);
> -               break;
> -       };
> -
> -       return NOTIFY_OK;
> +       /* For this particular CPU register SCU SMP boot vector */
> +       shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
> +                         shmobile_scu_base_phys);
> +       return 0;
>  }
>
> -static struct notifier_block shmobile_smp_scu_notifier = {
> -       .notifier_call = shmobile_smp_scu_notifier_call,
> -};
> -
>  void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
>                                           unsigned int max_cpus)
>  {
> @@ -54,7 +42,9 @@ void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
>         scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
>
>         /* Use CPU notifier for reset vector control */
> -       register_cpu_notifier(&shmobile_smp_scu_notifier);
> +       cpuhp_setup_state_nocalls(CPUHP_ARM_SHMOBILE_SCU_PREPARE,
> +                                 "arm/shmobile-scu:prepare",
> +                                 shmobile_scu_cpu_prepare, NULL);
>  }
>
>  #ifdef CONFIG_HOTPLUG_CPU
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index 0da071ff36d2..008eed0c0787 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -35,6 +35,7 @@ enum cpuhp_state {
>         CPUHP_POWERPC_PMAC_PREPARE,
>         CPUHP_POWERPC_MMU_CTX_PREPARE,
>         CPUHP_NOTIFY_PREPARE,
> +       CPUHP_ARM_SHMOBILE_SCU_PREPARE,
>         CPUHP_TIMERS_DEAD,
>         CPUHP_BRINGUP_CPU,
>         CPUHP_AP_IDLE_DEAD,

What's the rationale behind adding all these numbers and always
iterating over all
of them, even though most/all of them cannot be used at the same time
(e.g. CPUHP_SH_SH3X_PREPARE is for SuperH, while
 CPUHP_ARM_SHMOBILE_SCU_PREPARE is for ARM)?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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Sebastian Andrzej Siewior Sept. 7, 2016, 1:58 p.m. UTC | #2
On 2016-09-06 20:05:37 [+0200], Geert Uytterhoeven wrote:
> Hi Sebastian,
Hi Geert,

> Please describe why this is desirable.

We have now an old and new infrastructure in place to handle hotplug
notifications while a CPU goes up and/or down. We want to get rid of the
old infrastructure and are converting its users away. 

> > diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> > index 0da071ff36d2..008eed0c0787 100644
> > --- a/include/linux/cpuhotplug.h
> > +++ b/include/linux/cpuhotplug.h
> > @@ -35,6 +35,7 @@ enum cpuhp_state {
> >         CPUHP_POWERPC_PMAC_PREPARE,
> >         CPUHP_POWERPC_MMU_CTX_PREPARE,
> >         CPUHP_NOTIFY_PREPARE,
> > +       CPUHP_ARM_SHMOBILE_SCU_PREPARE,
> >         CPUHP_TIMERS_DEAD,
> >         CPUHP_BRINGUP_CPU,
> >         CPUHP_AP_IDLE_DEAD,
> 
> What's the rationale behind adding all these numbers and always
> iterating over all
> of them, even though most/all of them cannot be used at the same time
> (e.g. CPUHP_SH_SH3X_PREPARE is for SuperH, while
>  CPUHP_ARM_SHMOBILE_SCU_PREPARE is for ARM)?

PREPARE + STARTING states require static ids. The online callback has
dynamic allocations of ids since it was assumed that this is the most
common one.
We will most likely evaluate the situation once we done and total number
of IDS are not acceptable.

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

Sebastian
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Patch
diff mbox

diff --git a/arch/arm/mach-shmobile/platsmp-scu.c b/arch/arm/mach-shmobile/platsmp-scu.c
index 8d478f1da265..d1ecaf37d142 100644
--- a/arch/arm/mach-shmobile/platsmp-scu.c
+++ b/arch/arm/mach-shmobile/platsmp-scu.c
@@ -21,26 +21,14 @@ 
 static phys_addr_t shmobile_scu_base_phys;
 static void __iomem *shmobile_scu_base;
 
-static int shmobile_smp_scu_notifier_call(struct notifier_block *nfb,
-					  unsigned long action, void *hcpu)
+static int shmobile_scu_cpu_prepare(unsigned int cpu)
 {
-	unsigned int cpu = (long)hcpu;
-
-	switch (action) {
-	case CPU_UP_PREPARE:
-		/* For this particular CPU register SCU SMP boot vector */
-		shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
-				  shmobile_scu_base_phys);
-		break;
-	};
-
-	return NOTIFY_OK;
+	/* For this particular CPU register SCU SMP boot vector */
+	shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
+			  shmobile_scu_base_phys);
+	return 0;
 }
 
-static struct notifier_block shmobile_smp_scu_notifier = {
-	.notifier_call = shmobile_smp_scu_notifier_call,
-};
-
 void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
 					  unsigned int max_cpus)
 {
@@ -54,7 +42,9 @@  void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
 	scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
 
 	/* Use CPU notifier for reset vector control */
-	register_cpu_notifier(&shmobile_smp_scu_notifier);
+	cpuhp_setup_state_nocalls(CPUHP_ARM_SHMOBILE_SCU_PREPARE,
+				  "arm/shmobile-scu:prepare",
+				  shmobile_scu_cpu_prepare, NULL);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 0da071ff36d2..008eed0c0787 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -35,6 +35,7 @@  enum cpuhp_state {
 	CPUHP_POWERPC_PMAC_PREPARE,
 	CPUHP_POWERPC_MMU_CTX_PREPARE,
 	CPUHP_NOTIFY_PREPARE,
+	CPUHP_ARM_SHMOBILE_SCU_PREPARE,
 	CPUHP_TIMERS_DEAD,
 	CPUHP_BRINGUP_CPU,
 	CPUHP_AP_IDLE_DEAD,