2 * processor_idle - idle state cpuidle driver.
3 * Adapted from drivers/idle/intel_idle.c and
4 * drivers/acpi/processor_idle.c
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/moduleparam.h>
12 #include <linux/cpuidle.h>
13 #include <linux/cpu.h>
14 #include <linux/notifier.h>
18 #include <asm/machdep.h>
19 #include <asm/firmware.h>
20 #include <asm/runlatch.h>
22 #include "plpar_wrappers.h"
25 struct cpuidle_driver pseries_idle_driver = {
26 .name = "pseries_idle",
30 #define MAX_IDLE_STATE_COUNT 2
32 static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
33 static struct cpuidle_device __percpu *pseries_cpuidle_devices;
34 static struct cpuidle_state *cpuidle_state_table;
36 void update_smt_snooze_delay(int snooze)
38 struct cpuidle_driver *drv = cpuidle_get_driver();
40 drv->states[0].target_residency = snooze;
43 static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before)
46 *kt_before = ktime_get_real();
47 *in_purr = mfspr(SPRN_PURR);
49 * Indicate to the HV that we are idle. Now would be
50 * a good time to find other work to dispatch.
52 get_lppaca()->idle = 1;
55 static inline s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before)
57 get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
58 get_lppaca()->idle = 0;
60 return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
63 static int snooze_loop(struct cpuidle_device *dev,
64 struct cpuidle_driver *drv,
67 unsigned long in_purr;
69 unsigned long start_snooze;
70 long snooze = drv->states[0].target_residency;
72 idle_loop_prolog(&in_purr, &kt_before);
75 start_snooze = get_tb() + snooze * tb_ticks_per_usec;
77 set_thread_flag(TIF_POLLING_NRFLAG);
79 while ((snooze < 0) || (get_tb() < start_snooze)) {
80 if (need_resched() || cpu_is_offline(dev->cpu))
88 clear_thread_flag(TIF_POLLING_NRFLAG);
96 (int)idle_loop_epilog(in_purr, kt_before);
100 static void check_and_cede_processor(void)
103 * Ensure our interrupt state is properly tracked,
104 * also checks if no interrupt has occurred while we
107 if (prep_irq_for_idle()) {
109 #ifdef CONFIG_TRACE_IRQFLAGS
110 /* Ensure that H_CEDE returns with IRQs on */
111 if (WARN_ON(!(mfmsr() & MSR_EE)))
117 static int dedicated_cede_loop(struct cpuidle_device *dev,
118 struct cpuidle_driver *drv,
121 unsigned long in_purr;
124 idle_loop_prolog(&in_purr, &kt_before);
125 get_lppaca()->donate_dedicated_cpu = 1;
127 ppc64_runlatch_off();
129 check_and_cede_processor();
131 get_lppaca()->donate_dedicated_cpu = 0;
132 dev->last_residency =
133 (int)idle_loop_epilog(in_purr, kt_before);
137 static int shared_cede_loop(struct cpuidle_device *dev,
138 struct cpuidle_driver *drv,
141 unsigned long in_purr;
144 idle_loop_prolog(&in_purr, &kt_before);
147 * Yield the processor to the hypervisor. We return if
148 * an external interrupt occurs (which are driven prior
149 * to returning here) or if a prod occurs from another
150 * processor. When returning here, external interrupts
153 check_and_cede_processor();
155 dev->last_residency =
156 (int)idle_loop_epilog(in_purr, kt_before);
161 * States for dedicated partition case.
163 static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
167 .flags = CPUIDLE_FLAG_TIME_VALID,
169 .target_residency = 0,
170 .enter = &snooze_loop },
174 .flags = CPUIDLE_FLAG_TIME_VALID,
176 .target_residency = 10,
177 .enter = &dedicated_cede_loop },
181 * States for shared partition case.
183 static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
185 .name = "Shared Cede",
186 .desc = "Shared Cede",
187 .flags = CPUIDLE_FLAG_TIME_VALID,
189 .target_residency = 0,
190 .enter = &shared_cede_loop },
193 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
194 unsigned long action, void *hcpu)
196 int hotcpu = (unsigned long)hcpu;
197 struct cpuidle_device *dev =
198 per_cpu_ptr(pseries_cpuidle_devices, hotcpu);
200 if (dev && cpuidle_get_driver()) {
203 case CPU_ONLINE_FROZEN:
204 cpuidle_pause_and_lock();
205 cpuidle_enable_device(dev);
206 cpuidle_resume_and_unlock();
210 case CPU_DEAD_FROZEN:
211 cpuidle_pause_and_lock();
212 cpuidle_disable_device(dev);
213 cpuidle_resume_and_unlock();
223 static struct notifier_block setup_hotplug_notifier = {
224 .notifier_call = pseries_cpuidle_add_cpu_notifier,
228 * pseries_cpuidle_driver_init()
230 static int pseries_cpuidle_driver_init(void)
233 struct cpuidle_driver *drv = &pseries_idle_driver;
235 drv->state_count = 0;
237 for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
239 if (idle_state > max_idle_state)
242 /* is the state not enabled? */
243 if (cpuidle_state_table[idle_state].enter == NULL)
246 drv->states[drv->state_count] = /* structure copy */
247 cpuidle_state_table[idle_state];
249 if (cpuidle_state_table == dedicated_states)
250 drv->states[drv->state_count].target_residency =
251 __get_cpu_var(smt_snooze_delay);
253 drv->state_count += 1;
259 /* pseries_idle_devices_uninit(void)
260 * unregister cpuidle devices and de-allocate memory
262 static void pseries_idle_devices_uninit(void)
265 struct cpuidle_device *dev;
267 for_each_possible_cpu(i) {
268 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
269 cpuidle_unregister_device(dev);
272 free_percpu(pseries_cpuidle_devices);
276 /* pseries_idle_devices_init()
277 * allocate, initialize and register cpuidle device
279 static int pseries_idle_devices_init(void)
282 struct cpuidle_driver *drv = &pseries_idle_driver;
283 struct cpuidle_device *dev;
285 pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device);
286 if (pseries_cpuidle_devices == NULL)
289 for_each_possible_cpu(i) {
290 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
291 dev->state_count = drv->state_count;
293 if (cpuidle_register_device(dev)) {
295 "cpuidle_register_device %d failed!\n", i);
304 * pseries_idle_probe()
305 * Choose state table for shared versus dedicated partition
307 static int pseries_idle_probe(void)
310 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
313 if (cpuidle_disable != IDLE_NO_OVERRIDE)
316 if (max_idle_state == 0) {
317 printk(KERN_DEBUG "pseries processor idle disabled.\n");
321 if (get_lppaca()->shared_proc)
322 cpuidle_state_table = shared_states;
324 cpuidle_state_table = dedicated_states;
329 static int __init pseries_processor_idle_init(void)
333 retval = pseries_idle_probe();
337 pseries_cpuidle_driver_init();
338 retval = cpuidle_register_driver(&pseries_idle_driver);
340 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
344 retval = pseries_idle_devices_init();
346 pseries_idle_devices_uninit();
347 cpuidle_unregister_driver(&pseries_idle_driver);
351 register_cpu_notifier(&setup_hotplug_notifier);
352 printk(KERN_DEBUG "pseries_idle_driver registered\n");
357 static void __exit pseries_processor_idle_exit(void)
360 unregister_cpu_notifier(&setup_hotplug_notifier);
361 pseries_idle_devices_uninit();
362 cpuidle_unregister_driver(&pseries_idle_driver);
367 module_init(pseries_processor_idle_init);
368 module_exit(pseries_processor_idle_exit);
370 MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
371 MODULE_DESCRIPTION("Cpuidle driver for POWER");
372 MODULE_LICENSE("GPL");