1 /*
2 * processor_idle - idle state cpuidle driver.
3 * Adapted from drivers/idle/intel_idle.c and
4 * drivers/acpi/processor_idle.c
5 *
6 */
7
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
15 #include <asm/paca.h>
16 #include <asm/reg.h>
17 #include <asm/machdep.h>
18 #include <asm/firmware.h>
19 #include <asm/runlatch.h>
20
21 #include "plpar_wrappers.h"
22 #include "pseries.h"
23
24 struct cpuidle_driver pseries_idle_driver = {
25 .name = "pseries_idle",
26 .owner = THIS_MODULE,
27 };
28
29 #define MAX_IDLE_STATE_COUNT 2
30
31 static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
32 static struct cpuidle_device __percpu *pseries_cpuidle_devices;
33 static struct cpuidle_state *cpuidle_state_table;
34
update_smt_snooze_delay(int snooze)35 void update_smt_snooze_delay(int snooze)
36 {
37 struct cpuidle_driver *drv = cpuidle_get_driver();
38 if (drv)
39 drv->states[0].target_residency = snooze;
40 }
41
idle_loop_prolog(unsigned long * in_purr,ktime_t * kt_before)42 static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before)
43 {
44
45 *kt_before = ktime_get_real();
46 *in_purr = mfspr(SPRN_PURR);
47 /*
48 * Indicate to the HV that we are idle. Now would be
49 * a good time to find other work to dispatch.
50 */
51 get_lppaca()->idle = 1;
52 }
53
idle_loop_epilog(unsigned long in_purr,ktime_t kt_before)54 static inline s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before)
55 {
56 get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
57 get_lppaca()->idle = 0;
58
59 return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
60 }
61
snooze_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)62 static int snooze_loop(struct cpuidle_device *dev,
63 struct cpuidle_driver *drv,
64 int index)
65 {
66 unsigned long in_purr;
67 ktime_t kt_before;
68 unsigned long start_snooze;
69 long snooze = drv->states[0].target_residency;
70
71 idle_loop_prolog(&in_purr, &kt_before);
72
73 if (snooze) {
74 start_snooze = get_tb() + snooze * tb_ticks_per_usec;
75 local_irq_enable();
76 set_thread_flag(TIF_POLLING_NRFLAG);
77
78 while ((snooze < 0) || (get_tb() < start_snooze)) {
79 if (need_resched() || cpu_is_offline(dev->cpu))
80 goto out;
81 ppc64_runlatch_off();
82 HMT_low();
83 HMT_very_low();
84 }
85
86 HMT_medium();
87 clear_thread_flag(TIF_POLLING_NRFLAG);
88 smp_mb();
89 local_irq_disable();
90 }
91
92 out:
93 HMT_medium();
94 dev->last_residency =
95 (int)idle_loop_epilog(in_purr, kt_before);
96 return index;
97 }
98
check_and_cede_processor(void)99 static void check_and_cede_processor(void)
100 {
101 /*
102 * Ensure our interrupt state is properly tracked,
103 * also checks if no interrupt has occurred while we
104 * were soft-disabled
105 */
106 if (prep_irq_for_idle()) {
107 cede_processor();
108 #ifdef CONFIG_TRACE_IRQFLAGS
109 /* Ensure that H_CEDE returns with IRQs on */
110 if (WARN_ON(!(mfmsr() & MSR_EE)))
111 __hard_irq_enable();
112 #endif
113 }
114 }
115
dedicated_cede_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)116 static int dedicated_cede_loop(struct cpuidle_device *dev,
117 struct cpuidle_driver *drv,
118 int index)
119 {
120 unsigned long in_purr;
121 ktime_t kt_before;
122
123 idle_loop_prolog(&in_purr, &kt_before);
124 get_lppaca()->donate_dedicated_cpu = 1;
125
126 ppc64_runlatch_off();
127 HMT_medium();
128 check_and_cede_processor();
129
130 get_lppaca()->donate_dedicated_cpu = 0;
131 dev->last_residency =
132 (int)idle_loop_epilog(in_purr, kt_before);
133 return index;
134 }
135
shared_cede_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)136 static int shared_cede_loop(struct cpuidle_device *dev,
137 struct cpuidle_driver *drv,
138 int index)
139 {
140 unsigned long in_purr;
141 ktime_t kt_before;
142
143 idle_loop_prolog(&in_purr, &kt_before);
144
145 /*
146 * Yield the processor to the hypervisor. We return if
147 * an external interrupt occurs (which are driven prior
148 * to returning here) or if a prod occurs from another
149 * processor. When returning here, external interrupts
150 * are enabled.
151 */
152 check_and_cede_processor();
153
154 dev->last_residency =
155 (int)idle_loop_epilog(in_purr, kt_before);
156 return index;
157 }
158
159 /*
160 * States for dedicated partition case.
161 */
162 static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
163 { /* Snooze */
164 .name = "snooze",
165 .desc = "snooze",
166 .flags = CPUIDLE_FLAG_TIME_VALID,
167 .exit_latency = 0,
168 .target_residency = 0,
169 .enter = &snooze_loop },
170 { /* CEDE */
171 .name = "CEDE",
172 .desc = "CEDE",
173 .flags = CPUIDLE_FLAG_TIME_VALID,
174 .exit_latency = 1,
175 .target_residency = 10,
176 .enter = &dedicated_cede_loop },
177 };
178
179 /*
180 * States for shared partition case.
181 */
182 static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
183 { /* Shared Cede */
184 .name = "Shared Cede",
185 .desc = "Shared Cede",
186 .flags = CPUIDLE_FLAG_TIME_VALID,
187 .exit_latency = 0,
188 .target_residency = 0,
189 .enter = &shared_cede_loop },
190 };
191
pseries_notify_cpuidle_add_cpu(int cpu)192 int pseries_notify_cpuidle_add_cpu(int cpu)
193 {
194 struct cpuidle_device *dev =
195 per_cpu_ptr(pseries_cpuidle_devices, cpu);
196 if (dev && cpuidle_get_driver()) {
197 cpuidle_disable_device(dev);
198 cpuidle_enable_device(dev);
199 }
200 return 0;
201 }
202
203 /*
204 * pseries_cpuidle_driver_init()
205 */
pseries_cpuidle_driver_init(void)206 static int pseries_cpuidle_driver_init(void)
207 {
208 int idle_state;
209 struct cpuidle_driver *drv = &pseries_idle_driver;
210
211 drv->state_count = 0;
212
213 for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
214
215 if (idle_state > max_idle_state)
216 break;
217
218 /* is the state not enabled? */
219 if (cpuidle_state_table[idle_state].enter == NULL)
220 continue;
221
222 drv->states[drv->state_count] = /* structure copy */
223 cpuidle_state_table[idle_state];
224
225 if (cpuidle_state_table == dedicated_states)
226 drv->states[drv->state_count].target_residency =
227 __get_cpu_var(smt_snooze_delay);
228
229 drv->state_count += 1;
230 }
231
232 return 0;
233 }
234
235 /* pseries_idle_devices_uninit(void)
236 * unregister cpuidle devices and de-allocate memory
237 */
pseries_idle_devices_uninit(void)238 static void pseries_idle_devices_uninit(void)
239 {
240 int i;
241 struct cpuidle_device *dev;
242
243 for_each_possible_cpu(i) {
244 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
245 cpuidle_unregister_device(dev);
246 }
247
248 free_percpu(pseries_cpuidle_devices);
249 return;
250 }
251
252 /* pseries_idle_devices_init()
253 * allocate, initialize and register cpuidle device
254 */
pseries_idle_devices_init(void)255 static int pseries_idle_devices_init(void)
256 {
257 int i;
258 struct cpuidle_driver *drv = &pseries_idle_driver;
259 struct cpuidle_device *dev;
260
261 pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device);
262 if (pseries_cpuidle_devices == NULL)
263 return -ENOMEM;
264
265 for_each_possible_cpu(i) {
266 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
267 dev->state_count = drv->state_count;
268 dev->cpu = i;
269 if (cpuidle_register_device(dev)) {
270 printk(KERN_DEBUG \
271 "cpuidle_register_device %d failed!\n", i);
272 return -EIO;
273 }
274 }
275
276 return 0;
277 }
278
279 /*
280 * pseries_idle_probe()
281 * Choose state table for shared versus dedicated partition
282 */
pseries_idle_probe(void)283 static int pseries_idle_probe(void)
284 {
285
286 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
287 return -ENODEV;
288
289 if (cpuidle_disable != IDLE_NO_OVERRIDE)
290 return -ENODEV;
291
292 if (max_idle_state == 0) {
293 printk(KERN_DEBUG "pseries processor idle disabled.\n");
294 return -EPERM;
295 }
296
297 if (get_lppaca()->shared_proc)
298 cpuidle_state_table = shared_states;
299 else
300 cpuidle_state_table = dedicated_states;
301
302 return 0;
303 }
304
pseries_processor_idle_init(void)305 static int __init pseries_processor_idle_init(void)
306 {
307 int retval;
308
309 retval = pseries_idle_probe();
310 if (retval)
311 return retval;
312
313 pseries_cpuidle_driver_init();
314 retval = cpuidle_register_driver(&pseries_idle_driver);
315 if (retval) {
316 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
317 return retval;
318 }
319
320 retval = pseries_idle_devices_init();
321 if (retval) {
322 pseries_idle_devices_uninit();
323 cpuidle_unregister_driver(&pseries_idle_driver);
324 return retval;
325 }
326
327 printk(KERN_DEBUG "pseries_idle_driver registered\n");
328
329 return 0;
330 }
331
pseries_processor_idle_exit(void)332 static void __exit pseries_processor_idle_exit(void)
333 {
334
335 pseries_idle_devices_uninit();
336 cpuidle_unregister_driver(&pseries_idle_driver);
337
338 return;
339 }
340
341 module_init(pseries_processor_idle_init);
342 module_exit(pseries_processor_idle_exit);
343
344 MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
345 MODULE_DESCRIPTION("Cpuidle driver for POWER");
346 MODULE_LICENSE("GPL");
347