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/plpar_wrappers.h>
22 struct cpuidle_driver pseries_idle_driver = {
23 .name = "pseries_idle",
27 #define MAX_IDLE_STATE_COUNT 2
29 static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
30 static struct cpuidle_state *cpuidle_state_table;
32 static inline void idle_loop_prolog(unsigned long *in_purr)
34 *in_purr = mfspr(SPRN_PURR);
36 * Indicate to the HV that we are idle. Now would be
37 * a good time to find other work to dispatch.
39 get_lppaca()->idle = 1;
42 static inline void idle_loop_epilog(unsigned long in_purr)
46 wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles);
47 wait_cycles += mfspr(SPRN_PURR) - in_purr;
48 get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles);
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)) {
69 clear_thread_flag(TIF_POLLING_NRFLAG);
72 idle_loop_epilog(in_purr);
77 static void check_and_cede_processor(void)
80 * Ensure our interrupt state is properly tracked,
81 * also checks if no interrupt has occurred while we
84 if (prep_irq_for_idle()) {
86 #ifdef CONFIG_TRACE_IRQFLAGS
87 /* Ensure that H_CEDE returns with IRQs on */
88 if (WARN_ON(!(mfmsr() & MSR_EE)))
94 static int dedicated_cede_loop(struct cpuidle_device *dev,
95 struct cpuidle_driver *drv,
98 unsigned long in_purr;
100 idle_loop_prolog(&in_purr);
101 get_lppaca()->donate_dedicated_cpu = 1;
104 check_and_cede_processor();
106 get_lppaca()->donate_dedicated_cpu = 0;
108 idle_loop_epilog(in_purr);
113 static int shared_cede_loop(struct cpuidle_device *dev,
114 struct cpuidle_driver *drv,
117 unsigned long in_purr;
119 idle_loop_prolog(&in_purr);
122 * Yield the processor to the hypervisor. We return if
123 * an external interrupt occurs (which are driven prior
124 * to returning here) or if a prod occurs from another
125 * processor. When returning here, external interrupts
128 check_and_cede_processor();
130 idle_loop_epilog(in_purr);
136 * States for dedicated partition case.
138 static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
142 .flags = CPUIDLE_FLAG_TIME_VALID,
144 .target_residency = 0,
145 .enter = &snooze_loop },
149 .flags = CPUIDLE_FLAG_TIME_VALID,
151 .target_residency = 100,
152 .enter = &dedicated_cede_loop },
156 * States for shared partition case.
158 static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
160 .name = "Shared Cede",
161 .desc = "Shared Cede",
162 .flags = CPUIDLE_FLAG_TIME_VALID,
164 .target_residency = 0,
165 .enter = &shared_cede_loop },
168 void update_smt_snooze_delay(int cpu, int residency)
170 struct cpuidle_driver *drv = cpuidle_get_driver();
171 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
173 if (cpuidle_state_table != dedicated_states)
177 /* Disable the Nap state on that cpu */
179 dev->states_usage[1].disable = 1;
182 drv->states[1].target_residency = residency;
185 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
186 unsigned long action, void *hcpu)
188 int hotcpu = (unsigned long)hcpu;
189 struct cpuidle_device *dev =
190 per_cpu_ptr(cpuidle_devices, hotcpu);
192 if (dev && cpuidle_get_driver()) {
195 case CPU_ONLINE_FROZEN:
196 cpuidle_pause_and_lock();
197 cpuidle_enable_device(dev);
198 cpuidle_resume_and_unlock();
202 case CPU_DEAD_FROZEN:
203 cpuidle_pause_and_lock();
204 cpuidle_disable_device(dev);
205 cpuidle_resume_and_unlock();
215 static struct notifier_block setup_hotplug_notifier = {
216 .notifier_call = pseries_cpuidle_add_cpu_notifier,
220 * pseries_cpuidle_driver_init()
222 static int pseries_cpuidle_driver_init(void)
225 struct cpuidle_driver *drv = &pseries_idle_driver;
227 drv->state_count = 0;
229 for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
231 if (idle_state > max_idle_state)
234 /* is the state not enabled? */
235 if (cpuidle_state_table[idle_state].enter == NULL)
238 drv->states[drv->state_count] = /* structure copy */
239 cpuidle_state_table[idle_state];
241 drv->state_count += 1;
248 * pseries_idle_probe()
249 * Choose state table for shared versus dedicated partition
251 static int pseries_idle_probe(void)
254 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
257 if (cpuidle_disable != IDLE_NO_OVERRIDE)
260 if (max_idle_state == 0) {
261 printk(KERN_DEBUG "pseries processor idle disabled.\n");
265 if (lppaca_shared_proc(get_lppaca()))
266 cpuidle_state_table = shared_states;
268 cpuidle_state_table = dedicated_states;
273 static int __init pseries_processor_idle_init(void)
277 retval = pseries_idle_probe();
281 pseries_cpuidle_driver_init();
282 retval = cpuidle_register(&pseries_idle_driver, NULL);
284 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
288 register_cpu_notifier(&setup_hotplug_notifier);
289 printk(KERN_DEBUG "pseries_idle_driver registered\n");
294 static void __exit pseries_processor_idle_exit(void)
297 unregister_cpu_notifier(&setup_hotplug_notifier);
298 cpuidle_unregister(&pseries_idle_driver);
303 module_init(pseries_processor_idle_init);
304 module_exit(pseries_processor_idle_exit);
306 MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
307 MODULE_DESCRIPTION("Cpuidle driver for POWER");
308 MODULE_LICENSE("GPL");