[PATCH v6 02/15] ARM: SoC: Add per SoC SMP and CPU hotplug operations

[Nicolas Pitre]

On Wed, 8 Feb 2012, Marc Zyngier wrote:

> Populate the SoC descriptor structure with the SMP and CPU hotplug
> operations. To allow the kernel to continue building, the platform
> hooks are defined as weak symbols which are overrided by the
> platform code. Once all platforms are converted, the "weak" attribute
> will be removed and the function made static.
> 
> Cc: Arnd Bergmann <arnd at arndb.de>
> Cc: Nicolas Pitre <nico at fluxnic.net>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>

You should be able to replace __attribute__((weak)) with simply __weak.

Otherwise:

Acked-by: Nicolas Pitre <nico at linaro.org>


> ---
>  arch/arm/include/asm/soc.h |   45 ++++++++++++++++++++++++++++
>  arch/arm/kernel/setup.c    |    1 +
>  arch/arm/kernel/smp.c      |   69 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 115 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/include/asm/soc.h b/arch/arm/include/asm/soc.h
> index 2d73e35..1bcc58c 100644
> --- a/arch/arm/include/asm/soc.h
> +++ b/arch/arm/include/asm/soc.h
> @@ -12,8 +12,53 @@
>  #ifndef __ASM_ARM_SOC_H
>  #define __ASM_ARM_SOC_H
>  
> +struct task_struct;
> +
> +struct arm_soc_smp_init_ops {
> +	/*
> +	 * Setup the set of possible CPUs (via set_cpu_possible)
> +	 */
> +	void (*smp_init_cpus)(void);
> +	/*
> +	 * Initialize cpu_possible map, and enable coherency
> +	 */
> +	void (*smp_prepare_cpus)(unsigned int max_cpus);
> +};
> +
> +struct arm_soc_smp_ops {
> +	/*
> +	 * Perform platform specific initialisation of the specified CPU.
> +	 */
> +	void (*smp_secondary_init)(unsigned int cpu);
> +	/*
> +	 * Boot a secondary CPU, and assign it the specified idle task.
> +	 * This also gives us the initial stack to use for this CPU.
> +	 */
> +	int  (*smp_boot_secondary)(unsigned int cpu, struct task_struct *idle);
> +#ifdef CONFIG_HOTPLUG_CPU
> +	int  (*cpu_kill)(unsigned int cpu);
> +	void (*cpu_die)(unsigned int cpu);
> +	int  (*cpu_disable)(unsigned int cpu);
> +#endif
> +};
> +
>  struct arm_soc_desc {
>  	const char			*name;
> +#ifdef CONFIG_SMP
> +	struct arm_soc_smp_init_ops	*smp_init_ops;
> +	struct arm_soc_smp_ops		*smp_ops;
> +#endif
>  };
>  
> +#ifdef CONFIG_SMP
> +#define soc_smp_init_ops(ops)		.smp_init_ops = &(ops),
> +#define soc_smp_ops(ops)		.smp_ops = &(ops),
> +extern void soc_smp_ops_register(struct arm_soc_smp_init_ops *,
> +				 struct arm_soc_smp_ops *);
> +#else
> +#define soc_smp_init_ops(ops)		/* empty */
> +#define soc_smp_ops(ops)		/* empty */
> +#define soc_smp_ops_register(a,b)	do {} while(0)
> +#endif
> +
>  #endif	/* __ASM_ARM_SOC_H */
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index 69ac002..bf30274 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -927,6 +927,7 @@ void __init setup_arch(char **cmdline_p)
>  	if (mdesc->soc) {
>  		soc_desc = mdesc->soc;
>  		pr_info("SoC: %s\n", soc_desc->name);
> +		soc_smp_ops_register(soc_desc->smp_init_ops, soc_desc->smp_ops);
>  	} else
>  		soc_desc = NULL;
>  
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index cdeb727..49a904d 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -27,6 +27,7 @@
>  #include <linux/completion.h>
>  
>  #include <linux/atomic.h>
> +#include <asm/soc.h>
>  #include <asm/cacheflush.h>
>  #include <asm/cpu.h>
>  #include <asm/cputype.h>
> @@ -127,9 +128,77 @@ int __cpuinit __cpu_up(unsigned int cpu)
>  	return ret;
>  }
>  
> +/* SoC helpers */
> +static const struct arm_soc_smp_init_ops *soc_smp_init_ops  __initdata;
> +static const struct arm_soc_smp_ops *soc_smp_ops  __cpuinitdata;
> +static struct arm_soc_smp_ops __soc_smp_ops __cpuinitdata;
> +
> +void __init soc_smp_ops_register(struct arm_soc_smp_init_ops *smp_init_ops,
> +				 struct arm_soc_smp_ops *smp_ops)
> +{
> +	if (smp_init_ops)
> +		soc_smp_init_ops = smp_init_ops;
> +
> +	/*
> +	 * Warning: we're copying an __initdata structure into a
> +	 * __cpuinitdata structure. We *know* it is valid because only
> +	 * __cpuinit (or more persistant) functions should be pointed
> +	 * to by soc_smp_ops. Still, this is borderline ugly.
> +	 */
> +	if (smp_ops) {
> +		__soc_smp_ops = *smp_ops;
> +		soc_smp_ops = &__soc_smp_ops;
> +	}
> +}
> +
> +void __attribute__((weak)) __init smp_init_cpus(void)
> +{
> +	if (soc_smp_init_ops && soc_smp_init_ops->smp_init_cpus)
> +		soc_smp_init_ops->smp_init_cpus();
> +}
> +
> +void __attribute__((weak)) __init platform_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +	if (soc_smp_ops && soc_smp_init_ops->smp_prepare_cpus)
> +		soc_smp_init_ops->smp_prepare_cpus(max_cpus);
> +}
> +
> +void __attribute__((weak)) __cpuinit platform_secondary_init(unsigned int cpu)
> +{
> +	if (soc_smp_ops && soc_smp_ops->smp_secondary_init)
> +		soc_smp_ops->smp_secondary_init(cpu);
> +}
> +
> +int __attribute__((weak)) __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
> +{
> +	if (soc_smp_ops && soc_smp_ops->smp_boot_secondary)
> +		return soc_smp_ops->smp_boot_secondary(cpu, idle);
> +	return -ENOSYS;
> +}
> +
>  #ifdef CONFIG_HOTPLUG_CPU
>  static void percpu_timer_stop(void);
>  
> +int __attribute__((weak)) __cpuinit platform_cpu_kill(unsigned int cpu)
> +{
> +	if (soc_smp_ops && soc_smp_ops->cpu_kill)
> +		return soc_smp_ops->cpu_kill(cpu);
> +	return 0;
> +}
> +
> +void __attribute__((weak)) __cpuinit platform_cpu_die(unsigned int cpu)
> +{
> +	if (soc_smp_ops && soc_smp_ops->cpu_die)
> +		soc_smp_ops->cpu_die(cpu);
> +}
> +
> +int __attribute__((weak)) __cpuinit platform_cpu_disable(unsigned int cpu)
> +{
> +	if (soc_smp_ops && soc_smp_ops->cpu_disable)
> +		return soc_smp_ops->cpu_disable(cpu);
> +	return -EPERM;
> +}
> +
>  /*
>   * __cpu_disable runs on the processor to be shutdown.
>   */
> -- 
> 1.7.3.4
>