From 7c2b860534d02d11923dd0504b961f21508173f1 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Thu, 20 Sep 2012 16:05:37 -0400 Subject: ARM: mcpm: introduce the CPU/cluster power API This is the basic API used to handle the powering up/down of individual CPUs in a (multi-)cluster system. The platform specific backend implementation has the responsibility to also handle the cluster level power as well when the first/last CPU in a cluster is brought up/down. Signed-off-by: Nicolas Pitre Reviewed-by: Santosh Shilimkar Reviewed-by: Will Deacon --- arch/arm/common/mcpm_entry.c | 91 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) (limited to 'arch/arm/common') diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c index 7cbf70051ea7..5d72889a58a4 100644 --- a/arch/arm/common/mcpm_entry.c +++ b/arch/arm/common/mcpm_entry.c @@ -9,8 +9,13 @@ * published by the Free Software Foundation. */ +#include +#include +#include + #include #include +#include extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER]; @@ -20,3 +25,89 @@ void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr) mcpm_entry_vectors[cluster][cpu] = val; sync_cache_w(&mcpm_entry_vectors[cluster][cpu]); } + +static const struct mcpm_platform_ops *platform_ops; + +int __init mcpm_platform_register(const struct mcpm_platform_ops *ops) +{ + if (platform_ops) + return -EBUSY; + platform_ops = ops; + return 0; +} + +int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster) +{ + if (!platform_ops) + return -EUNATCH; /* try not to shadow power_up errors */ + might_sleep(); + return platform_ops->power_up(cpu, cluster); +} + +typedef void (*phys_reset_t)(unsigned long); + +void mcpm_cpu_power_down(void) +{ + phys_reset_t phys_reset; + + BUG_ON(!platform_ops); + BUG_ON(!irqs_disabled()); + + /* + * Do this before calling into the power_down method, + * as it might not always be safe to do afterwards. + */ + setup_mm_for_reboot(); + + platform_ops->power_down(); + + /* + * It is possible for a power_up request to happen concurrently + * with a power_down request for the same CPU. In this case the + * power_down method might not be able to actually enter a + * powered down state with the WFI instruction if the power_up + * method has removed the required reset condition. The + * power_down method is then allowed to return. We must perform + * a re-entry in the kernel as if the power_up method just had + * deasserted reset on the CPU. + * + * To simplify race issues, the platform specific implementation + * must accommodate for the possibility of unordered calls to + * power_down and power_up with a usage count. Therefore, if a + * call to power_up is issued for a CPU that is not down, then + * the next call to power_down must not attempt a full shutdown + * but only do the minimum (normally disabling L1 cache and CPU + * coherency) and return just as if a concurrent power_up request + * had happened as described above. + */ + + phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset); + phys_reset(virt_to_phys(mcpm_entry_point)); + + /* should never get here */ + BUG(); +} + +void mcpm_cpu_suspend(u64 expected_residency) +{ + phys_reset_t phys_reset; + + BUG_ON(!platform_ops); + BUG_ON(!irqs_disabled()); + + /* Very similar to mcpm_cpu_power_down() */ + setup_mm_for_reboot(); + platform_ops->suspend(expected_residency); + phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset); + phys_reset(virt_to_phys(mcpm_entry_point)); + BUG(); +} + +int mcpm_cpu_powered_up(void) +{ + if (!platform_ops) + return -EUNATCH; + if (platform_ops->powered_up) + platform_ops->powered_up(); + return 0; +} -- cgit v1.2.3