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

[Marc Zyngier]

On 27/03/13 12:50, 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.
> 
> Remove virt_smp_ops and platsmp.c from mach-virt because they aren't needed
> anymore.
> 
> 
> 
> This patch was originally part of this series:
> 
> http://marc.info/?l=linux-arm-kernel&m=136430903110734&w=2
> 
> I am keeping it separate now since it is the only non-obvious change and
> it is not Xen related.
> 
> 
> 
> 
> Changes in v3:
> - move the call to psci_init to setup_arch;
> - export psci_smp_ops from psci.h;
> - introduce psci_smp_available;
> - introduce stub functions for psci_init and psci_smp_available ifndef
> CONFIG_ARM_PSCI;
> - only compile psci_smp functions ifdef CONFIG_SMP.
> 
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> CC: will.deacon@xxxxxxx
> CC: arnd@xxxxxxxx
> CC: marc.zyngier@xxxxxxx
> CC: linux@xxxxxxxxxxxxxxxx
> CC: nico@xxxxxxxxxx
> ---
>  arch/arm/include/asm/psci.h  |    9 ++++
>  arch/arm/kernel/psci.c       |   97 ++++++++++++++++++++++++++++++++++--------
>  arch/arm/kernel/setup.c      |    7 +++-
>  arch/arm/mach-virt/Makefile  |    1 -
>  arch/arm/mach-virt/platsmp.c |   58 -------------------------
>  arch/arm/mach-virt/virt.c    |    3 -
>  6 files changed, 94 insertions(+), 81 deletions(-)
>  delete mode 100644 arch/arm/mach-virt/platsmp.c
> 
> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> index ce0dbe7..ddef231 100644
> --- a/arch/arm/include/asm/psci.h
> +++ b/arch/arm/include/asm/psci.h
> @@ -32,5 +32,14 @@ struct psci_operations {
>  };
>  
>  extern struct psci_operations psci_ops;
> +extern struct smp_operations psci_smp_ops;
> +
> +#ifdef CONFIG_ARM_PSCI
> +int psci_init(void);
> +bool psci_smp_available(void);
> +#else
> +static inline int psci_init(void) { return -ENODEV; }
> +static inline bool psci_smp_available(void) { return false; }
> +#endif
>  
>  #endif /* __ASM_ARM_PSCI_H */
> diff --git a/arch/arm/kernel/psci.c b/arch/arm/kernel/psci.c
> index 3653164..90f0839 100644
> --- a/arch/arm/kernel/psci.c
> +++ b/arch/arm/kernel/psci.c
> @@ -16,6 +16,7 @@
>  #define pr_fmt(fmt) "psci: " fmt
>  
>  #include <linux/init.h>
> +#include <linux/irqchip/arm-gic.h>
>  #include <linux/of.h>
>  
>  #include <asm/compiler.h>
> @@ -23,8 +24,9 @@
>  #include <asm/opcodes-sec.h>
>  #include <asm/opcodes-virt.h>
>  #include <asm/psci.h>
> +#include <asm/smp_plat.h>
>  
> -struct psci_operations psci_ops;
> +extern void secondary_startup(void);
>  
>  static int (*invoke_psci_fn)(u32, u32, u32, u32);
>  
> @@ -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;
> +};
> +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)
> +{
> +}
> +
> +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);
> +}

So here we end-up with a dependency between SMP, PSCI, and GIC.
I really can't see that being a good idea, even I like the general
direction of this series.

	M.
-- 
Jazz is not dead. It just smells funny...

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