Re: [Xen-devel] [PATCH v3] [RFC] arm: use PSCI if available

[Rob Herring <robherring2@xxxxxxxxx>]

On 03/27/2013 07:50 AM, Stefano Stabellini wrote:
> Check for the presence of PSCI before setting smp_ops, use PSCI if it is
> available.
> 
> This is useful because at least when running on Xen it's possible to have a
> PSCI node for example on a Versatile Express or an Exynos5 machine. In these
> cases the PSCI SMP calls should be the ones to be called.

I have a similar patch in my tree. I thought I had sent it out, but
looks like I didn't. I didn't make smp_ops default to this or change
mach-virt, so we should go with yours.

[...]

> @@ -36,7 +38,11 @@ enum psci_function {
>       PSCI_FN_MAX,
>  };
>  
> -static u32 psci_function_id[PSCI_FN_MAX];
> +struct psci_function_desc {
> +     enum psci_function func;
> +     bool valid;

Why can't you use a NULL function ptr or a 0 psci_function_id to
indicate not valid?

> +};
> +static struct psci_function_desc psci_function_id[PSCI_FN_MAX];
>  
>  #define PSCI_RET_SUCCESS             0
>  #define PSCI_RET_EOPNOTSUPP          -1
> @@ -116,7 +122,10 @@ static int psci_cpu_suspend(struct psci_power_state 
> state,
>       int err;
>       u32 fn, power_state;
>  
> -     fn = psci_function_id[PSCI_FN_CPU_SUSPEND];
> +     if (!psci_function_id[PSCI_FN_CPU_SUSPEND].valid)
> +             return -ENOSYS;
> +
> +     fn = psci_function_id[PSCI_FN_CPU_SUSPEND].func;
>       power_state = psci_power_state_pack(state);
>       err = invoke_psci_fn(fn, power_state, entry_point, 0);
>       return psci_to_linux_errno(err);
> @@ -127,7 +136,10 @@ static int psci_cpu_off(struct psci_power_state state)
>       int err;
>       u32 fn, power_state;
>  
> -     fn = psci_function_id[PSCI_FN_CPU_OFF];
> +     if (!psci_function_id[PSCI_FN_CPU_OFF].valid)
> +             return -ENOSYS;
> +
> +     fn = psci_function_id[PSCI_FN_CPU_OFF].func;
>       power_state = psci_power_state_pack(state);
>       err = invoke_psci_fn(fn, power_state, 0, 0);
>       return psci_to_linux_errno(err);
> @@ -138,7 +150,10 @@ static int psci_cpu_on(unsigned long cpuid, unsigned 
> long entry_point)
>       int err;
>       u32 fn;
>  
> -     fn = psci_function_id[PSCI_FN_CPU_ON];
> +     if (!psci_function_id[PSCI_FN_CPU_ON].valid)
> +             return -ENOSYS;
> +
> +     fn = psci_function_id[PSCI_FN_CPU_ON].func;
>       err = invoke_psci_fn(fn, cpuid, entry_point, 0);
>       return psci_to_linux_errno(err);
>  }
> @@ -148,25 +163,64 @@ static int psci_migrate(unsigned long cpuid)
>       int err;
>       u32 fn;
>  
> -     fn = psci_function_id[PSCI_FN_MIGRATE];
> +     if (!psci_function_id[PSCI_FN_MIGRATE].valid)
> +             return -ENOSYS;
> +
> +     fn = psci_function_id[PSCI_FN_MIGRATE].func;
>       err = invoke_psci_fn(fn, cpuid, 0, 0);
>       return psci_to_linux_errno(err);
>  }
>  
> +struct psci_operations psci_ops = {
> +     .cpu_suspend = psci_cpu_suspend,
> +     .cpu_off     = psci_cpu_off,
> +     .cpu_on      = psci_cpu_on,
> +     .migrate     = psci_migrate,
> +};
> +
> +#ifdef CONFIG_SMP
> +static void __init psci_smp_init_cpus(void)
> +{
> +}
> +
> +static void __init psci_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +}

You can leave these 2 functions as NULL.

> +
> +static int __cpuinit psci_boot_secondary(unsigned int cpu,
> +                                      struct task_struct *idle)
> +{
> +     return psci_cpu_on(cpu_logical_map(cpu), __pa(secondary_startup));
> +}
> +
> +static void __cpuinit psci_secondary_init(unsigned int cpu)
> +{
> +     gic_secondary_init(0);
> +}
> +
> +struct smp_operations __initdata psci_smp_ops = {
> +     .smp_init_cpus          = psci_smp_init_cpus,
> +     .smp_prepare_cpus       = psci_smp_prepare_cpus,
> +     .smp_secondary_init     = psci_secondary_init,
> +     .smp_boot_secondary     = psci_boot_secondary,

You should also include hotplug. Here's what I had:

#ifdef CONFIG_HOTPLUG_CPU
void __ref psci_cpu_die(unsigned int cpu)
{
       const struct psci_power_state ps = {
               .type = PSCI_POWER_STATE_TYPE_POWER_DOWN,
       };

       if (psci_ops.cpu_off)
               psci_ops.cpu_off(ps);

       /* We should never return */
       panic("psci: cpu %d failed to shutdown\n", cpu);
}
#else
#define psci_cpu_die NULL
#endif


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel