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/system.h>
18 #include <asm/machdep.h>
19 #include <asm/firmware.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
dedicated_cede_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)99 static int dedicated_cede_loop(struct cpuidle_device *dev,
100 struct cpuidle_driver *drv,
101 int index)
102 {
103 unsigned long in_purr;
104 ktime_t kt_before;
105
106 idle_loop_prolog(&in_purr, &kt_before);
107 get_lppaca()->donate_dedicated_cpu = 1;
108
109 ppc64_runlatch_off();
110 HMT_medium();
111 cede_processor();
112
113 get_lppaca()->donate_dedicated_cpu = 0;
114 dev->last_residency =
115 (int)idle_loop_epilog(in_purr, kt_before);
116 return index;
117 }
118
shared_cede_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)119 static int shared_cede_loop(struct cpuidle_device *dev,
120 struct cpuidle_driver *drv,
121 int index)
122 {
123 unsigned long in_purr;
124 ktime_t kt_before;
125
126 idle_loop_prolog(&in_purr, &kt_before);
127
128 /*
129 * Yield the processor to the hypervisor. We return if
130 * an external interrupt occurs (which are driven prior
131 * to returning here) or if a prod occurs from another
132 * processor. When returning here, external interrupts
133 * are enabled.
134 */
135 cede_processor();
136
137 dev->last_residency =
138 (int)idle_loop_epilog(in_purr, kt_before);
139 return index;
140 }
141
142 /*
143 * States for dedicated partition case.
144 */
145 static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
146 { /* Snooze */
147 .name = "snooze",
148 .desc = "snooze",
149 .flags = CPUIDLE_FLAG_TIME_VALID,
150 .exit_latency = 0,
151 .target_residency = 0,
152 .enter = &snooze_loop },
153 { /* CEDE */
154 .name = "CEDE",
155 .desc = "CEDE",
156 .flags = CPUIDLE_FLAG_TIME_VALID,
157 .exit_latency = 1,
158 .target_residency = 10,
159 .enter = &dedicated_cede_loop },
160 };
161
162 /*
163 * States for shared partition case.
164 */
165 static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
166 { /* Shared Cede */
167 .name = "Shared Cede",
168 .desc = "Shared Cede",
169 .flags = CPUIDLE_FLAG_TIME_VALID,
170 .exit_latency = 0,
171 .target_residency = 0,
172 .enter = &shared_cede_loop },
173 };
174
pseries_notify_cpuidle_add_cpu(int cpu)175 int pseries_notify_cpuidle_add_cpu(int cpu)
176 {
177 struct cpuidle_device *dev =
178 per_cpu_ptr(pseries_cpuidle_devices, cpu);
179 if (dev && cpuidle_get_driver()) {
180 cpuidle_disable_device(dev);
181 cpuidle_enable_device(dev);
182 }
183 return 0;
184 }
185
186 /*
187 * pseries_cpuidle_driver_init()
188 */
pseries_cpuidle_driver_init(void)189 static int pseries_cpuidle_driver_init(void)
190 {
191 int idle_state;
192 struct cpuidle_driver *drv = &pseries_idle_driver;
193
194 drv->state_count = 0;
195
196 for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
197
198 if (idle_state > max_idle_state)
199 break;
200
201 /* is the state not enabled? */
202 if (cpuidle_state_table[idle_state].enter == NULL)
203 continue;
204
205 drv->states[drv->state_count] = /* structure copy */
206 cpuidle_state_table[idle_state];
207
208 if (cpuidle_state_table == dedicated_states)
209 drv->states[drv->state_count].target_residency =
210 __get_cpu_var(smt_snooze_delay);
211
212 drv->state_count += 1;
213 }
214
215 return 0;
216 }
217
218 /* pseries_idle_devices_uninit(void)
219 * unregister cpuidle devices and de-allocate memory
220 */
pseries_idle_devices_uninit(void)221 static void pseries_idle_devices_uninit(void)
222 {
223 int i;
224 struct cpuidle_device *dev;
225
226 for_each_possible_cpu(i) {
227 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
228 cpuidle_unregister_device(dev);
229 }
230
231 free_percpu(pseries_cpuidle_devices);
232 return;
233 }
234
235 /* pseries_idle_devices_init()
236 * allocate, initialize and register cpuidle device
237 */
pseries_idle_devices_init(void)238 static int pseries_idle_devices_init(void)
239 {
240 int i;
241 struct cpuidle_driver *drv = &pseries_idle_driver;
242 struct cpuidle_device *dev;
243
244 pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device);
245 if (pseries_cpuidle_devices == NULL)
246 return -ENOMEM;
247
248 for_each_possible_cpu(i) {
249 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
250 dev->state_count = drv->state_count;
251 dev->cpu = i;
252 if (cpuidle_register_device(dev)) {
253 printk(KERN_DEBUG \
254 "cpuidle_register_device %d failed!\n", i);
255 return -EIO;
256 }
257 }
258
259 return 0;
260 }
261
262 /*
263 * pseries_idle_probe()
264 * Choose state table for shared versus dedicated partition
265 */
pseries_idle_probe(void)266 static int pseries_idle_probe(void)
267 {
268
269 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
270 return -ENODEV;
271
272 if (cpuidle_disable != IDLE_NO_OVERRIDE)
273 return -ENODEV;
274
275 if (max_idle_state == 0) {
276 printk(KERN_DEBUG "pseries processor idle disabled.\n");
277 return -EPERM;
278 }
279
280 if (get_lppaca()->shared_proc)
281 cpuidle_state_table = shared_states;
282 else
283 cpuidle_state_table = dedicated_states;
284
285 return 0;
286 }
287
pseries_processor_idle_init(void)288 static int __init pseries_processor_idle_init(void)
289 {
290 int retval;
291
292 retval = pseries_idle_probe();
293 if (retval)
294 return retval;
295
296 pseries_cpuidle_driver_init();
297 retval = cpuidle_register_driver(&pseries_idle_driver);
298 if (retval) {
299 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
300 return retval;
301 }
302
303 retval = pseries_idle_devices_init();
304 if (retval) {
305 pseries_idle_devices_uninit();
306 cpuidle_unregister_driver(&pseries_idle_driver);
307 return retval;
308 }
309
310 printk(KERN_DEBUG "pseries_idle_driver registered\n");
311
312 return 0;
313 }
314
pseries_processor_idle_exit(void)315 static void __exit pseries_processor_idle_exit(void)
316 {
317
318 pseries_idle_devices_uninit();
319 cpuidle_unregister_driver(&pseries_idle_driver);
320
321 return;
322 }
323
324 module_init(pseries_processor_idle_init);
325 module_exit(pseries_processor_idle_exit);
326
327 MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
328 MODULE_DESCRIPTION("Cpuidle driver for POWER");
329 MODULE_LICENSE("GPL");
330