diff options
| -rw-r--r-- | arch/arm/common/mcpm_entry.c | 91 | ||||
| -rw-r--r-- | arch/arm/include/asm/mcpm.h | 92 |
2 files changed, 183 insertions, 0 deletions
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 <linux/kernel.h> +#include <linux/init.h> +#include <linux/irqflags.h> + #include <asm/mcpm.h> #include <asm/cacheflush.h> +#include <asm/idmap.h> 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; +} diff --git a/arch/arm/include/asm/mcpm.h b/arch/arm/include/asm/mcpm.h index 470a417d1351..627761fce780 100644 --- a/arch/arm/include/asm/mcpm.h +++ b/arch/arm/include/asm/mcpm.h @@ -38,5 +38,97 @@ extern void mcpm_entry_point(void); */ void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr); +/* + * CPU/cluster power operations API for higher subsystems to use. + */ + +/** + * mcpm_cpu_power_up - make given CPU in given cluster runable + * + * @cpu: CPU number within given cluster + * @cluster: cluster number for the CPU + * + * The identified CPU is brought out of reset. If the cluster was powered + * down then it is brought up as well, taking care not to let the other CPUs + * in the cluster run, and ensuring appropriate cluster setup. + * + * Caller must ensure the appropriate entry vector is initialized with + * mcpm_set_entry_vector() prior to calling this. + * + * This must be called in a sleepable context. However, the implementation + * is strongly encouraged to return early and let the operation happen + * asynchronously, especially when significant delays are expected. + * + * If the operation cannot be performed then an error code is returned. + */ +int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster); + +/** + * mcpm_cpu_power_down - power the calling CPU down + * + * The calling CPU is powered down. + * + * If this CPU is found to be the "last man standing" in the cluster + * then the cluster is prepared for power-down too. + * + * This must be called with interrupts disabled. + * + * This does not return. Re-entry in the kernel is expected via + * mcpm_entry_point. + */ +void mcpm_cpu_power_down(void); + +/** + * mcpm_cpu_suspend - bring the calling CPU in a suspended state + * + * @expected_residency: duration in microseconds the CPU is expected + * to remain suspended, or 0 if unknown/infinity. + * + * The calling CPU is suspended. The expected residency argument is used + * as a hint by the platform specific backend to implement the appropriate + * sleep state level according to the knowledge it has on wake-up latency + * for the given hardware. + * + * If this CPU is found to be the "last man standing" in the cluster + * then the cluster may be prepared for power-down too, if the expected + * residency makes it worthwhile. + * + * This must be called with interrupts disabled. + * + * This does not return. Re-entry in the kernel is expected via + * mcpm_entry_point. + */ +void mcpm_cpu_suspend(u64 expected_residency); + +/** + * mcpm_cpu_powered_up - housekeeping workafter a CPU has been powered up + * + * This lets the platform specific backend code perform needed housekeeping + * work. This must be called by the newly activated CPU as soon as it is + * fully operational in kernel space, before it enables interrupts. + * + * If the operation cannot be performed then an error code is returned. + */ +int mcpm_cpu_powered_up(void); + +/* + * Platform specific methods used in the implementation of the above API. + */ +struct mcpm_platform_ops { + int (*power_up)(unsigned int cpu, unsigned int cluster); + void (*power_down)(void); + void (*suspend)(u64); + void (*powered_up)(void); +}; + +/** + * mcpm_platform_register - register platform specific power methods + * + * @ops: mcpm_platform_ops structure to register + * + * An error is returned if the registration has been done previously. + */ +int __init mcpm_platform_register(const struct mcpm_platform_ops *ops); + #endif /* ! __ASSEMBLY__ */ #endif |