RE: [PATCH 2/2] ARM: S5PV310: Update CPU hotplug implementation

[Kukjin Kim <kgene.kim@samsung.com>]

Kukjin Kim wrote:
> 
> From: Changhwan Youn <chaos.youn@samsung.com>
> 
> This patch updates CPU hotplug implementation to reduce CPU power
> consumption
> and will turn off the CPU power when CPU1 is unplugged while previous CPU
> hotplug
> used CPU idle.
> This patch removes init memory freeing code to use CPU boot code when CPU1
is
> plugged-in again and adds vfp_enable() call to allow to access CP10 and
CP11.
> 
> Signed-off-by: Changhwan Youn <chaos.youn@samsung.com>
> Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
> Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Colin Cross <ccross@android.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Olof Johansson <olof@lixom.net>

Hi all,

Please check changing of arch/arm/mm/init.c and arch/arm/vfp/vfpmodule.c.
- Removed init memory freeing code to use CPU boot code when CPU1 is
plugged-in again.
- Added vfp_enable() call to allow to access CP10 and CP11.

> ---
>  arch/arm/mach-s5pv310/hotplug.c |   12 +++++++-----
>  arch/arm/mach-s5pv310/platsmp.c |   34
> ++++++++++++++++++++++++++++++++++
>  arch/arm/mm/init.c              |    2 ++
>  arch/arm/vfp/vfpmodule.c        |    2 +-
>  4 files changed, 44 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm/mach-s5pv310/hotplug.c
b/arch/arm/mach-s5pv310/hotplug.c
> index 03652c3..0e188fe 100644
> --- a/arch/arm/mach-s5pv310/hotplug.c
> +++ b/arch/arm/mach-s5pv310/hotplug.c
> @@ -14,9 +14,12 @@
>  #include <linux/errno.h>
>  #include <linux/smp.h>
>  #include <linux/completion.h>
> +#include <linux/io.h>
> 
>  #include <asm/cacheflush.h>
> 
> +#include <mach/regs-pmu.h>
> +
>  extern volatile int pen_release;
> 
>  static DECLARE_COMPLETION(cpu_killed);
> @@ -61,12 +64,11 @@ static inline void cpu_leave_lowpower(void)
> 
>  static inline void platform_do_lowpower(unsigned int cpu)
>  {
> -	/*
> -	 * there is no power-control hardware on this platform, so all
> -	 * we can do is put the core into WFI; this is safe as the calling
> -	 * code will have already disabled interrupts
> -	 */
>  	for (;;) {
> +		/* make cpu1 to be turned off at next WFI command */
> +		if (cpu == 1)
> +			__raw_writel(0, S5PV310_ARM_CORE1_CONF);
> +
>  		/*
>  		 * here's the WFI
>  		 */
> diff --git a/arch/arm/mach-s5pv310/platsmp.c
b/arch/arm/mach-s5pv310/platsmp.c
> index d357c19..d10c4ad 100644
> --- a/arch/arm/mach-s5pv310/platsmp.c
> +++ b/arch/arm/mach-s5pv310/platsmp.c
> @@ -28,8 +28,10 @@
> 
>  #include <mach/hardware.h>
>  #include <mach/regs-clock.h>
> +#include <mach/regs-pmu.h>
> 
>  extern void s5pv310_secondary_startup(void);
> +extern void vfp_enable(void *unused);
> 
>  /*
>   * control for which core is the next to come out of the secondary
> @@ -47,6 +49,10 @@ static DEFINE_SPINLOCK(boot_lock);
> 
>  void __cpuinit platform_secondary_init(unsigned int cpu)
>  {
> +#ifdef CONFIG_VFP
> +	vfp_enable(NULL);
> +#endif
> +
>  	trace_hardirqs_off();
> 
>  	/*
> @@ -92,6 +98,27 @@ int __cpuinit boot_secondary(unsigned int cpu, struct
> task_struct *idle)
>  	__cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
>  	outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
> 
> +	if (!(__raw_readl(S5PV310_ARM_CORE1_STAT) &
> S5PV310_CORE_PWR_EN)) {
> +		__raw_writel(S5PV310_CORE_PWR_EN,
> +			     S5PV310_ARM_CORE1_CONF);
> +
> +		timeout = 10;
> +
> +		/* wait max 10 ms until cpu1 is on */
> +		while ((__raw_readl(S5PV310_ARM_CORE1_STAT)
> +			& S5PV310_CORE_PWR_EN) !=
> S5PV310_CORE_PWR_EN) {
> +			if (timeout-- == 0)
> +				break;
> +
> +			mdelay(1);
> +		}
> +
> +		if (timeout == 0) {
> +			printk(KERN_ERR "cpu1 power-up failed");
> +			return -ETIMEDOUT;
> +		}
> +	}
> +
>  	/*
>  	 * Send the secondary CPU a soft interrupt, thereby causing
>  	 * the boot monitor to read the system wide flags register,
> @@ -102,6 +129,13 @@ int __cpuinit boot_secondary(unsigned int cpu, struct
> task_struct *idle)
>  	timeout = jiffies + (1 * HZ);
>  	while (time_before(jiffies, timeout)) {
>  		smp_rmb();
> +
> +		if (!__raw_readl(S5P_VA_SYSRAM)) {
> +
> 	__raw_writel(BSYM(virt_to_phys(s5pv310_secondary_startup)),
> +				     S5P_VA_SYSRAM);
> +			smp_cross_call(cpumask_of(cpu));
> +		}
> +
>  		if (pen_release == -1)
>  			break;
> 
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 7185b00..57c4c5c 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -589,10 +589,12 @@ void free_initmem(void)
>  				    "TCM link");
>  #endif
> 
> +#ifndef CONFIG_HOTPLUG_CPU
>  	if (!machine_is_integrator() && !machine_is_cintegrator())
>  		totalram_pages +=
free_area(__phys_to_pfn(__pa(__init_begin)),
>  					    __phys_to_pfn(__pa(__init_end)),
>  					    "init");
> +#endif
>  }
> 
>  #ifdef CONFIG_BLK_DEV_INITRD
> diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
> index 8063a32..eee8f67 100644
> --- a/arch/arm/vfp/vfpmodule.c
> +++ b/arch/arm/vfp/vfpmodule.c
> @@ -364,7 +364,7 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs
> *regs)
>  	preempt_enable();
>  }
> 
> -static void vfp_enable(void *unused)
> +void vfp_enable(void *unused)
>  {
>  	u32 access = get_copro_access();
> 
> --


Thanks.

Best regards,
Kgene.
--
Kukjin Kim <kgene.kim@samsung.com>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.