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author | Deepthi Dharwar <deepthi@linux.vnet.ibm.com> | 2011-11-30 02:46:42 (GMT) |
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committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2011-12-08 02:56:31 (GMT) |
commit | 707827f3387d9b260d50fa697885a4042cea3bf4 (patch) | |
tree | ad6b616d17cab85bf39fd42405dd2ae84123811c /arch/powerpc/platforms/pseries/processor_idle.c | |
parent | 771dae81896855d25f7f8746aaf56c0238deafb6 (diff) | |
download | linux-fsl-qoriq-707827f3387d9b260d50fa697885a4042cea3bf4.tar.xz |
powerpc/cpuidle: cpuidle driver for pSeries
This patch implements a back-end cpuidle driver for pSeries
based on pseries_dedicated_idle_loop and pseries_shared_idle_loop
routines. The driver is built only if CONFIG_CPU_IDLE is set. This
cpuidle driver uses global registration of idle states and
not per-cpu.
Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Trinabh Gupta <g.trinabh@gmail.com>
Signed-off-by: Arun R Bharadwaj <arun.r.bharadwaj@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/platforms/pseries/processor_idle.c')
-rw-r--r-- | arch/powerpc/platforms/pseries/processor_idle.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c new file mode 100644 index 0000000..f7e3e87 --- /dev/null +++ b/arch/powerpc/platforms/pseries/processor_idle.c @@ -0,0 +1,326 @@ +/* + * processor_idle - idle state cpuidle driver. + * Adapted from drivers/idle/intel_idle.c and + * drivers/acpi/processor_idle.c + * + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/moduleparam.h> +#include <linux/cpuidle.h> +#include <linux/cpu.h> + +#include <asm/paca.h> +#include <asm/reg.h> +#include <asm/system.h> +#include <asm/machdep.h> +#include <asm/firmware.h> + +#include "plpar_wrappers.h" +#include "pseries.h" + +struct cpuidle_driver pseries_idle_driver = { + .name = "pseries_idle", + .owner = THIS_MODULE, +}; + +#define MAX_IDLE_STATE_COUNT 2 + +static int max_idle_state = MAX_IDLE_STATE_COUNT - 1; +static struct cpuidle_device __percpu *pseries_cpuidle_devices; +static struct cpuidle_state *cpuidle_state_table; + +void update_smt_snooze_delay(int snooze) +{ + struct cpuidle_driver *drv = cpuidle_get_driver(); + if (drv) + drv->states[0].target_residency = snooze; +} + +static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before) +{ + + *kt_before = ktime_get_real(); + *in_purr = mfspr(SPRN_PURR); + /* + * Indicate to the HV that we are idle. Now would be + * a good time to find other work to dispatch. + */ + get_lppaca()->idle = 1; +} + +static inline s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before) +{ + get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr; + get_lppaca()->idle = 0; + + return ktime_to_us(ktime_sub(ktime_get_real(), kt_before)); +} + +static int snooze_loop(struct cpuidle_device *dev, + struct cpuidle_driver *drv, + int index) +{ + unsigned long in_purr; + ktime_t kt_before; + unsigned long start_snooze; + long snooze = drv->states[0].target_residency; + + idle_loop_prolog(&in_purr, &kt_before); + + if (snooze) { + start_snooze = get_tb() + snooze * tb_ticks_per_usec; + local_irq_enable(); + set_thread_flag(TIF_POLLING_NRFLAG); + + while ((snooze < 0) || (get_tb() < start_snooze)) { + if (need_resched() || cpu_is_offline(dev->cpu)) + goto out; + ppc64_runlatch_off(); + HMT_low(); + HMT_very_low(); + } + + HMT_medium(); + clear_thread_flag(TIF_POLLING_NRFLAG); + smp_mb(); + local_irq_disable(); + } + +out: + HMT_medium(); + dev->last_residency = + (int)idle_loop_epilog(in_purr, kt_before); + return index; +} + +static int dedicated_cede_loop(struct cpuidle_device *dev, + struct cpuidle_driver *drv, + int index) +{ + unsigned long in_purr; + ktime_t kt_before; + + idle_loop_prolog(&in_purr, &kt_before); + get_lppaca()->donate_dedicated_cpu = 1; + + ppc64_runlatch_off(); + HMT_medium(); + cede_processor(); + + get_lppaca()->donate_dedicated_cpu = 0; + dev->last_residency = + (int)idle_loop_epilog(in_purr, kt_before); + return index; +} + +static int shared_cede_loop(struct cpuidle_device *dev, + struct cpuidle_driver *drv, + int index) +{ + unsigned long in_purr; + ktime_t kt_before; + + idle_loop_prolog(&in_purr, &kt_before); + + /* + * Yield the processor to the hypervisor. We return if + * an external interrupt occurs (which are driven prior + * to returning here) or if a prod occurs from another + * processor. When returning here, external interrupts + * are enabled. + */ + cede_processor(); + + dev->last_residency = + (int)idle_loop_epilog(in_purr, kt_before); + return index; +} + +/* + * States for dedicated partition case. + */ +static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = { + { /* Snooze */ + .name = "snooze", + .desc = "snooze", + .flags = CPUIDLE_FLAG_TIME_VALID, + .exit_latency = 0, + .target_residency = 0, + .enter = &snooze_loop }, + { /* CEDE */ + .name = "CEDE", + .desc = "CEDE", + .flags = CPUIDLE_FLAG_TIME_VALID, + .exit_latency = 1, + .target_residency = 10, + .enter = &dedicated_cede_loop }, +}; + +/* + * States for shared partition case. + */ +static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = { + { /* Shared Cede */ + .name = "Shared Cede", + .desc = "Shared Cede", + .flags = CPUIDLE_FLAG_TIME_VALID, + .exit_latency = 0, + .target_residency = 0, + .enter = &shared_cede_loop }, +}; + +int pseries_notify_cpuidle_add_cpu(int cpu) +{ + struct cpuidle_device *dev = + per_cpu_ptr(pseries_cpuidle_devices, cpu); + if (dev && cpuidle_get_driver()) { + cpuidle_disable_device(dev); + cpuidle_enable_device(dev); + } + return 0; +} + +/* + * pseries_cpuidle_driver_init() + */ +static int pseries_cpuidle_driver_init(void) +{ + int idle_state; + struct cpuidle_driver *drv = &pseries_idle_driver; + + drv->state_count = 0; + + for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) { + + if (idle_state > max_idle_state) + break; + + /* is the state not enabled? */ + if (cpuidle_state_table[idle_state].enter == NULL) + continue; + + drv->states[drv->state_count] = /* structure copy */ + cpuidle_state_table[idle_state]; + + if (cpuidle_state_table == dedicated_states) + drv->states[drv->state_count].target_residency = + __get_cpu_var(smt_snooze_delay); + + drv->state_count += 1; + } + + return 0; +} + +/* pseries_idle_devices_uninit(void) + * unregister cpuidle devices and de-allocate memory + */ +static void pseries_idle_devices_uninit(void) +{ + int i; + struct cpuidle_device *dev; + + for_each_possible_cpu(i) { + dev = per_cpu_ptr(pseries_cpuidle_devices, i); + cpuidle_unregister_device(dev); + } + + free_percpu(pseries_cpuidle_devices); + return; +} + +/* pseries_idle_devices_init() + * allocate, initialize and register cpuidle device + */ +static int pseries_idle_devices_init(void) +{ + int i; + struct cpuidle_driver *drv = &pseries_idle_driver; + struct cpuidle_device *dev; + + pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device); + if (pseries_cpuidle_devices == NULL) + return -ENOMEM; + + for_each_possible_cpu(i) { + dev = per_cpu_ptr(pseries_cpuidle_devices, i); + dev->state_count = drv->state_count; + dev->cpu = i; + if (cpuidle_register_device(dev)) { + printk(KERN_DEBUG \ + "cpuidle_register_device %d failed!\n", i); + return -EIO; + } + } + + return 0; +} + +/* + * pseries_idle_probe() + * Choose state table for shared versus dedicated partition + */ +static int pseries_idle_probe(void) +{ + + if (!firmware_has_feature(FW_FEATURE_SPLPAR)) + return -ENODEV; + + if (max_idle_state == 0) { + printk(KERN_DEBUG "pseries processor idle disabled.\n"); + return -EPERM; + } + + if (get_lppaca()->shared_proc) + cpuidle_state_table = shared_states; + else + cpuidle_state_table = dedicated_states; + + return 0; +} + +static int __init pseries_processor_idle_init(void) +{ + int retval; + + retval = pseries_idle_probe(); + if (retval) + return retval; + + pseries_cpuidle_driver_init(); + retval = cpuidle_register_driver(&pseries_idle_driver); + if (retval) { + printk(KERN_DEBUG "Registration of pseries driver failed.\n"); + return retval; + } + + retval = pseries_idle_devices_init(); + if (retval) { + pseries_idle_devices_uninit(); + cpuidle_unregister_driver(&pseries_idle_driver); + return retval; + } + + printk(KERN_DEBUG "pseries_idle_driver registered\n"); + + return 0; +} + +static void __exit pseries_processor_idle_exit(void) +{ + + pseries_idle_devices_uninit(); + cpuidle_unregister_driver(&pseries_idle_driver); + + return; +} + +module_init(pseries_processor_idle_init); +module_exit(pseries_processor_idle_exit); + +MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>"); +MODULE_DESCRIPTION("Cpuidle driver for POWER"); +MODULE_LICENSE("GPL"); |