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 static inline void idle_loop_prolog(unsigned long *in_purr)
38 *in_purr = mfspr(SPRN_PURR);
40 * Indicate to the HV that we are idle. Now would be
41 * a good time to find other work to dispatch.
43 get_lppaca()->idle = 1;
46 static inline void idle_loop_epilog(unsigned long in_purr)
48 get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
49 get_lppaca()->idle = 0;
52 static int snooze_loop(struct cpuidle_device *dev,
53 struct cpuidle_driver *drv,
56 unsigned long in_purr;
59 idle_loop_prolog(&in_purr);
61 set_thread_flag(TIF_POLLING_NRFLAG);
63 while ((!need_resched()) && cpu_online(cpu)) {
70 clear_thread_flag(TIF_POLLING_NRFLAG);
73 idle_loop_epilog(in_purr);
78 static void check_and_cede_processor(void)
81 * Ensure our interrupt state is properly tracked,
82 * also checks if no interrupt has occurred while we
85 if (prep_irq_for_idle()) {
87 #ifdef CONFIG_TRACE_IRQFLAGS
88 /* Ensure that H_CEDE returns with IRQs on */
89 if (WARN_ON(!(mfmsr() & MSR_EE)))
95 static int dedicated_cede_loop(struct cpuidle_device *dev,
96 struct cpuidle_driver *drv,
99 unsigned long in_purr;
101 idle_loop_prolog(&in_purr);
102 get_lppaca()->donate_dedicated_cpu = 1;
104 ppc64_runlatch_off();
106 check_and_cede_processor();
108 get_lppaca()->donate_dedicated_cpu = 0;
110 idle_loop_epilog(in_purr);
115 static int shared_cede_loop(struct cpuidle_device *dev,
116 struct cpuidle_driver *drv,
119 unsigned long in_purr;
121 idle_loop_prolog(&in_purr);
124 * Yield the processor to the hypervisor. We return if
125 * an external interrupt occurs (which are driven prior
126 * to returning here) or if a prod occurs from another
127 * processor. When returning here, external interrupts
130 check_and_cede_processor();
132 idle_loop_epilog(in_purr);
138 * States for dedicated partition case.
140 static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
144 .flags = CPUIDLE_FLAG_TIME_VALID,
146 .target_residency = 0,
147 .enter = &snooze_loop },
151 .flags = CPUIDLE_FLAG_TIME_VALID,
153 .target_residency = 100,
154 .enter = &dedicated_cede_loop },
158 * States for shared partition case.
160 static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
162 .name = "Shared Cede",
163 .desc = "Shared Cede",
164 .flags = CPUIDLE_FLAG_TIME_VALID,
166 .target_residency = 0,
167 .enter = &shared_cede_loop },
170 void update_smt_snooze_delay(int cpu, int residency)
172 struct cpuidle_driver *drv = cpuidle_get_driver();
173 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
175 if (cpuidle_state_table != dedicated_states)
179 /* Disable the Nap state on that cpu */
181 dev->states_usage[1].disable = 1;
184 drv->states[1].target_residency = residency;
187 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
188 unsigned long action, void *hcpu)
190 int hotcpu = (unsigned long)hcpu;
191 struct cpuidle_device *dev =
192 per_cpu_ptr(pseries_cpuidle_devices, hotcpu);
194 if (dev && cpuidle_get_driver()) {
197 case CPU_ONLINE_FROZEN:
198 cpuidle_pause_and_lock();
199 cpuidle_enable_device(dev);
200 cpuidle_resume_and_unlock();
204 case CPU_DEAD_FROZEN:
205 cpuidle_pause_and_lock();
206 cpuidle_disable_device(dev);
207 cpuidle_resume_and_unlock();
217 static struct notifier_block setup_hotplug_notifier = {
218 .notifier_call = pseries_cpuidle_add_cpu_notifier,
222 * pseries_cpuidle_driver_init()
224 static int pseries_cpuidle_driver_init(void)
227 struct cpuidle_driver *drv = &pseries_idle_driver;
229 drv->state_count = 0;
231 for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
233 if (idle_state > max_idle_state)
236 /* is the state not enabled? */
237 if (cpuidle_state_table[idle_state].enter == NULL)
240 drv->states[drv->state_count] = /* structure copy */
241 cpuidle_state_table[idle_state];
243 drv->state_count += 1;
249 /* pseries_idle_devices_uninit(void)
250 * unregister cpuidle devices and de-allocate memory
252 static void pseries_idle_devices_uninit(void)
255 struct cpuidle_device *dev;
257 for_each_possible_cpu(i) {
258 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
259 cpuidle_unregister_device(dev);
262 free_percpu(pseries_cpuidle_devices);
266 /* pseries_idle_devices_init()
267 * allocate, initialize and register cpuidle device
269 static int pseries_idle_devices_init(void)
272 struct cpuidle_driver *drv = &pseries_idle_driver;
273 struct cpuidle_device *dev;
275 pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device);
276 if (pseries_cpuidle_devices == NULL)
279 for_each_possible_cpu(i) {
280 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
281 dev->state_count = drv->state_count;
283 if (cpuidle_register_device(dev)) {
285 "cpuidle_register_device %d failed!\n", i);
294 * pseries_idle_probe()
295 * Choose state table for shared versus dedicated partition
297 static int pseries_idle_probe(void)
300 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
303 if (cpuidle_disable != IDLE_NO_OVERRIDE)
306 if (max_idle_state == 0) {
307 printk(KERN_DEBUG "pseries processor idle disabled.\n");
311 if (get_lppaca()->shared_proc)
312 cpuidle_state_table = shared_states;
314 cpuidle_state_table = dedicated_states;
319 static int __init pseries_processor_idle_init(void)
323 retval = pseries_idle_probe();
327 pseries_cpuidle_driver_init();
328 retval = cpuidle_register_driver(&pseries_idle_driver);
330 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
334 retval = pseries_idle_devices_init();
336 pseries_idle_devices_uninit();
337 cpuidle_unregister_driver(&pseries_idle_driver);
341 register_cpu_notifier(&setup_hotplug_notifier);
342 printk(KERN_DEBUG "pseries_idle_driver registered\n");
347 static void __exit pseries_processor_idle_exit(void)
350 unregister_cpu_notifier(&setup_hotplug_notifier);
351 pseries_idle_devices_uninit();
352 cpuidle_unregister_driver(&pseries_idle_driver);
357 module_init(pseries_processor_idle_init);
358 module_exit(pseries_processor_idle_exit);
360 MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
361 MODULE_DESCRIPTION("Cpuidle driver for POWER");
362 MODULE_LICENSE("GPL");