2 * cpuidle-powernv - idle state cpuidle driver.
3 * Adapted from drivers/cpuidle/cpuidle-pseries
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/init.h>
10 #include <linux/moduleparam.h>
11 #include <linux/cpuidle.h>
12 #include <linux/cpu.h>
13 #include <linux/notifier.h>
14 #include <linux/clockchips.h>
17 #include <asm/machdep.h>
18 #include <asm/firmware.h>
19 #include <asm/runlatch.h>
21 /* Flags and constants used in PowerNV platform */
23 #define MAX_POWERNV_IDLE_STATES 8
24 #define IDLE_USE_INST_NAP 0x00010000 /* Use nap instruction */
25 #define IDLE_USE_INST_SLEEP 0x00020000 /* Use sleep instruction */
27 struct cpuidle_driver powernv_idle_driver = {
28 .name = "powernv_idle",
32 static int max_idle_state;
33 static struct cpuidle_state *cpuidle_state_table;
35 static int snooze_loop(struct cpuidle_device *dev,
36 struct cpuidle_driver *drv,
40 set_thread_flag(TIF_POLLING_NRFLAG);
43 while (!need_resched()) {
50 clear_thread_flag(TIF_POLLING_NRFLAG);
55 static int nap_loop(struct cpuidle_device *dev,
56 struct cpuidle_driver *drv,
65 static int fastsleep_loop(struct cpuidle_device *dev,
66 struct cpuidle_driver *drv,
69 unsigned long old_lpcr = mfspr(SPRN_LPCR);
70 unsigned long new_lpcr;
72 if (unlikely(system_state < SYSTEM_RUNNING))
76 /* Do not exit powersave upon decrementer as we've setup the timer
79 new_lpcr &= ~LPCR_PECE1;
81 mtspr(SPRN_LPCR, new_lpcr);
84 mtspr(SPRN_LPCR, old_lpcr);
90 * States for dedicated partition case.
92 static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
96 .flags = CPUIDLE_FLAG_TIME_VALID,
98 .target_residency = 0,
99 .enter = &snooze_loop },
102 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
103 unsigned long action, void *hcpu)
105 int hotcpu = (unsigned long)hcpu;
106 struct cpuidle_device *dev =
107 per_cpu(cpuidle_devices, hotcpu);
109 if (dev && cpuidle_get_driver()) {
112 case CPU_ONLINE_FROZEN:
113 cpuidle_pause_and_lock();
114 cpuidle_enable_device(dev);
115 cpuidle_resume_and_unlock();
119 case CPU_DEAD_FROZEN:
120 cpuidle_pause_and_lock();
121 cpuidle_disable_device(dev);
122 cpuidle_resume_and_unlock();
132 static struct notifier_block setup_hotplug_notifier = {
133 .notifier_call = powernv_cpuidle_add_cpu_notifier,
137 * powernv_cpuidle_driver_init()
139 static int powernv_cpuidle_driver_init(void)
142 struct cpuidle_driver *drv = &powernv_idle_driver;
144 drv->state_count = 0;
146 for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
147 /* Is the state not enabled? */
148 if (cpuidle_state_table[idle_state].enter == NULL)
151 drv->states[drv->state_count] = /* structure copy */
152 cpuidle_state_table[idle_state];
154 drv->state_count += 1;
160 static int powernv_add_idle_states(void)
162 struct device_node *power_mgt;
163 int nr_idle_states = 1; /* Snooze */
165 const __be32 *idle_state_flags;
166 const __be32 *idle_state_latency;
167 u32 len_flags, flags, latency_ns;
170 /* Currently we have snooze statically defined */
172 power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
174 pr_warn("opal: PowerMgmt Node not found\n");
175 return nr_idle_states;
178 idle_state_flags = of_get_property(power_mgt, "ibm,cpu-idle-state-flags", &len_flags);
179 if (!idle_state_flags) {
180 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
181 return nr_idle_states;
184 idle_state_latency = of_get_property(power_mgt,
185 "ibm,cpu-idle-state-latencies-ns", NULL);
186 if (!idle_state_latency) {
187 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
188 return nr_idle_states;
191 dt_idle_states = len_flags / sizeof(u32);
193 for (i = 0; i < dt_idle_states; i++) {
195 flags = be32_to_cpu(idle_state_flags[i]);
197 /* Cpuidle accepts exit_latency in us and we estimate
198 * target residency to be 10x exit_latency
200 latency_ns = be32_to_cpu(idle_state_latency[i]);
201 if (flags & IDLE_USE_INST_NAP) {
203 strcpy(powernv_states[nr_idle_states].name, "Nap");
204 strcpy(powernv_states[nr_idle_states].desc, "Nap");
205 powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
206 powernv_states[nr_idle_states].exit_latency =
207 ((unsigned int)latency_ns) / 1000;
208 powernv_states[nr_idle_states].target_residency =
209 ((unsigned int)latency_ns / 100);
210 powernv_states[nr_idle_states].enter = &nap_loop;
214 if (flags & IDLE_USE_INST_SLEEP) {
215 /* Add FASTSLEEP state */
216 strcpy(powernv_states[nr_idle_states].name, "FastSleep");
217 strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
218 powernv_states[nr_idle_states].flags =
219 CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
220 powernv_states[nr_idle_states].exit_latency =
221 ((unsigned int)latency_ns) / 1000;
222 powernv_states[nr_idle_states].target_residency =
223 ((unsigned int)latency_ns / 100);
224 powernv_states[nr_idle_states].enter = &fastsleep_loop;
229 return nr_idle_states;
233 * powernv_idle_probe()
234 * Choose state table for shared versus dedicated partition
236 static int powernv_idle_probe(void)
238 if (cpuidle_disable != IDLE_NO_OVERRIDE)
241 if (firmware_has_feature(FW_FEATURE_OPALv3)) {
242 cpuidle_state_table = powernv_states;
243 /* Device tree can indicate more idle states */
244 max_idle_state = powernv_add_idle_states();
251 static int __init powernv_processor_idle_init(void)
255 retval = powernv_idle_probe();
259 powernv_cpuidle_driver_init();
260 retval = cpuidle_register(&powernv_idle_driver, NULL);
262 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
266 register_cpu_notifier(&setup_hotplug_notifier);
267 printk(KERN_DEBUG "powernv_idle_driver registered\n");
271 device_initcall(powernv_processor_idle_init);