Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * cpuidle-powernv - idle state cpuidle driver.
4 * Adapted from drivers/cpuidle/cpuidle-pseries
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#include <linux/notifier.h>
15#include <linux/clockchips.h>
16#include <linux/of.h>
17#include <linux/slab.h>
18
19#include <asm/machdep.h>
20#include <asm/firmware.h>
21#include <asm/opal.h>
22#include <asm/runlatch.h>
23#include <asm/cpuidle.h>
24
25/*
26 * Expose only those Hardware idle states via the cpuidle framework
27 * that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
28 */
29#define POWERNV_THRESHOLD_LATENCY_NS 200000
30
31static struct cpuidle_driver powernv_idle_driver = {
32 .name = "powernv_idle",
33 .owner = THIS_MODULE,
34};
35
36static int max_idle_state __read_mostly;
37static struct cpuidle_state *cpuidle_state_table __read_mostly;
38
39struct stop_psscr_table {
40 u64 val;
41 u64 mask;
42};
43
44static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;
45
46static u64 default_snooze_timeout __read_mostly;
47static bool snooze_timeout_en __read_mostly;
48
49static u64 get_snooze_timeout(struct cpuidle_device *dev,
50 struct cpuidle_driver *drv,
51 int index)
52{
53 int i;
54
55 if (unlikely(!snooze_timeout_en))
56 return default_snooze_timeout;
57
58 for (i = index + 1; i < drv->state_count; i++) {
59 if (dev->states_usage[i].disable)
60 continue;
61
62 return drv->states[i].target_residency * tb_ticks_per_usec;
63 }
64
65 return default_snooze_timeout;
66}
67
68static int snooze_loop(struct cpuidle_device *dev,
69 struct cpuidle_driver *drv,
70 int index)
71{
72 u64 snooze_exit_time;
73
74 set_thread_flag(TIF_POLLING_NRFLAG);
75
76 local_irq_enable();
77
78 snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
79 dev->poll_time_limit = false;
80 ppc64_runlatch_off();
81 HMT_very_low();
82 while (!need_resched()) {
83 if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
84 /*
85 * Task has not woken up but we are exiting the polling
86 * loop anyway. Require a barrier after polling is
87 * cleared to order subsequent test of need_resched().
88 */
89 clear_thread_flag(TIF_POLLING_NRFLAG);
90 dev->poll_time_limit = true;
91 smp_mb();
92 break;
93 }
94 }
95
96 HMT_medium();
97 ppc64_runlatch_on();
98
99 /* Avoid double clear when breaking */
100 if (!dev->poll_time_limit)
101 clear_thread_flag(TIF_POLLING_NRFLAG);
102
103 local_irq_disable();
104
105 return index;
106}
107
108static int nap_loop(struct cpuidle_device *dev,
109 struct cpuidle_driver *drv,
110 int index)
111{
112 power7_idle_type(PNV_THREAD_NAP);
113
114 return index;
115}
116
117/* Register for fastsleep only in oneshot mode of broadcast */
118#ifdef CONFIG_TICK_ONESHOT
119static int fastsleep_loop(struct cpuidle_device *dev,
120 struct cpuidle_driver *drv,
121 int index)
122{
123 unsigned long old_lpcr = mfspr(SPRN_LPCR);
124 unsigned long new_lpcr;
125
126 if (unlikely(system_state < SYSTEM_RUNNING))
127 return index;
128
129 new_lpcr = old_lpcr;
130 /* Do not exit powersave upon decrementer as we've setup the timer
131 * offload.
132 */
133 new_lpcr &= ~LPCR_PECE1;
134
135 mtspr(SPRN_LPCR, new_lpcr);
136
137 power7_idle_type(PNV_THREAD_SLEEP);
138
139 mtspr(SPRN_LPCR, old_lpcr);
140
141 return index;
142}
143#endif
144
145static int stop_loop(struct cpuidle_device *dev,
146 struct cpuidle_driver *drv,
147 int index)
148{
149 arch300_idle_type(stop_psscr_table[index].val,
150 stop_psscr_table[index].mask);
151 return index;
152}
153
154/*
155 * States for dedicated partition case.
156 */
157static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
158 { /* Snooze */
159 .name = "snooze",
160 .desc = "snooze",
161 .exit_latency = 0,
162 .target_residency = 0,
163 .enter = snooze_loop,
164 .flags = CPUIDLE_FLAG_POLLING },
165};
166
167static int powernv_cpuidle_cpu_online(unsigned int cpu)
168{
169 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
170
171 if (dev && cpuidle_get_driver()) {
172 cpuidle_pause_and_lock();
173 cpuidle_enable_device(dev);
174 cpuidle_resume_and_unlock();
175 }
176 return 0;
177}
178
179static int powernv_cpuidle_cpu_dead(unsigned int cpu)
180{
181 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
182
183 if (dev && cpuidle_get_driver()) {
184 cpuidle_pause_and_lock();
185 cpuidle_disable_device(dev);
186 cpuidle_resume_and_unlock();
187 }
188 return 0;
189}
190
191/*
192 * powernv_cpuidle_driver_init()
193 */
194static int powernv_cpuidle_driver_init(void)
195{
196 int idle_state;
197 struct cpuidle_driver *drv = &powernv_idle_driver;
198
199 drv->state_count = 0;
200
201 for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
202 /* Is the state not enabled? */
203 if (cpuidle_state_table[idle_state].enter == NULL)
204 continue;
205
206 drv->states[drv->state_count] = /* structure copy */
207 cpuidle_state_table[idle_state];
208
209 drv->state_count += 1;
210 }
211
212 /*
213 * On the PowerNV platform cpu_present may be less than cpu_possible in
214 * cases when firmware detects the CPU, but it is not available to the
215 * OS. If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
216 * run time and hence cpu_devices are not created for those CPUs by the
217 * generic topology_init().
218 *
219 * drv->cpumask defaults to cpu_possible_mask in
220 * __cpuidle_driver_init(). This breaks cpuidle on PowerNV where
221 * cpu_devices are not created for CPUs in cpu_possible_mask that
222 * cannot be hot-added later at run time.
223 *
224 * Trying cpuidle_register_device() on a CPU without a cpu_device is
225 * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
226 */
227
228 drv->cpumask = (struct cpumask *)cpu_present_mask;
229
230 return 0;
231}
232
233static inline void add_powernv_state(int index, const char *name,
234 unsigned int flags,
235 int (*idle_fn)(struct cpuidle_device *,
236 struct cpuidle_driver *,
237 int),
238 unsigned int target_residency,
239 unsigned int exit_latency,
240 u64 psscr_val, u64 psscr_mask)
241{
242 strscpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
243 strscpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
244 powernv_states[index].flags = flags;
245 powernv_states[index].target_residency = target_residency;
246 powernv_states[index].exit_latency = exit_latency;
247 powernv_states[index].enter = idle_fn;
248 /* For power8 and below psscr_* will be 0 */
249 stop_psscr_table[index].val = psscr_val;
250 stop_psscr_table[index].mask = psscr_mask;
251}
252
253extern u32 pnv_get_supported_cpuidle_states(void);
254static int powernv_add_idle_states(void)
255{
256 int nr_idle_states = 1; /* Snooze */
257 int dt_idle_states;
258 u32 has_stop_states = 0;
259 int i;
260 u32 supported_flags = pnv_get_supported_cpuidle_states();
261
262
263 /* Currently we have snooze statically defined */
264 if (nr_pnv_idle_states <= 0) {
265 pr_warn("cpuidle-powernv : Only Snooze is available\n");
266 goto out;
267 }
268
269 /* TODO: Count only states which are eligible for cpuidle */
270 dt_idle_states = nr_pnv_idle_states;
271
272 /*
273 * Since snooze is used as first idle state, max idle states allowed is
274 * CPUIDLE_STATE_MAX -1
275 */
276 if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
277 pr_warn("cpuidle-powernv: discovered idle states more than allowed");
278 dt_idle_states = CPUIDLE_STATE_MAX - 1;
279 }
280
281 /*
282 * If the idle states use stop instruction, probe for psscr values
283 * and psscr mask which are necessary to specify required stop level.
284 */
285 has_stop_states = (pnv_idle_states[0].flags &
286 (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
287
288 for (i = 0; i < dt_idle_states; i++) {
289 unsigned int exit_latency, target_residency;
290 bool stops_timebase = false;
291 struct pnv_idle_states_t *state = &pnv_idle_states[i];
292
293 /*
294 * Skip the platform idle state whose flag isn't in
295 * the supported_cpuidle_states flag mask.
296 */
297 if ((state->flags & supported_flags) != state->flags)
298 continue;
299 /*
300 * If an idle state has exit latency beyond
301 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
302 * in cpu-idle.
303 */
304 if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
305 continue;
306 /*
307 * Firmware passes residency and latency values in ns.
308 * cpuidle expects it in us.
309 */
310 exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
311 target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
312
313 if (has_stop_states && !(state->valid))
314 continue;
315
316 if (state->flags & OPAL_PM_TIMEBASE_STOP)
317 stops_timebase = true;
318
319 if (state->flags & OPAL_PM_NAP_ENABLED) {
320 /* Add NAP state */
321 add_powernv_state(nr_idle_states, "Nap",
322 CPUIDLE_FLAG_NONE, nap_loop,
323 target_residency, exit_latency, 0, 0);
324 } else if (has_stop_states && !stops_timebase) {
325 add_powernv_state(nr_idle_states, state->name,
326 CPUIDLE_FLAG_NONE, stop_loop,
327 target_residency, exit_latency,
328 state->psscr_val,
329 state->psscr_mask);
330 }
331
332 /*
333 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
334 * within this config dependency check.
335 */
336#ifdef CONFIG_TICK_ONESHOT
337 else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
338 state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
339 /* Add FASTSLEEP state */
340 add_powernv_state(nr_idle_states, "FastSleep",
341 CPUIDLE_FLAG_TIMER_STOP,
342 fastsleep_loop,
343 target_residency, exit_latency, 0, 0);
344 } else if (has_stop_states && stops_timebase) {
345 add_powernv_state(nr_idle_states, state->name,
346 CPUIDLE_FLAG_TIMER_STOP, stop_loop,
347 target_residency, exit_latency,
348 state->psscr_val,
349 state->psscr_mask);
350 }
351#endif
352 else
353 continue;
354 nr_idle_states++;
355 }
356out:
357 return nr_idle_states;
358}
359
360/*
361 * powernv_idle_probe()
362 * Choose state table for shared versus dedicated partition
363 */
364static int powernv_idle_probe(void)
365{
366 if (cpuidle_disable != IDLE_NO_OVERRIDE)
367 return -ENODEV;
368
369 if (firmware_has_feature(FW_FEATURE_OPAL)) {
370 cpuidle_state_table = powernv_states;
371 /* Device tree can indicate more idle states */
372 max_idle_state = powernv_add_idle_states();
373 default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
374 if (max_idle_state > 1)
375 snooze_timeout_en = true;
376 } else
377 return -ENODEV;
378
379 return 0;
380}
381
382static int __init powernv_processor_idle_init(void)
383{
384 int retval;
385
386 retval = powernv_idle_probe();
387 if (retval)
388 return retval;
389
390 powernv_cpuidle_driver_init();
391 retval = cpuidle_register(&powernv_idle_driver, NULL);
392 if (retval) {
393 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
394 return retval;
395 }
396
397 retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
398 "cpuidle/powernv:online",
399 powernv_cpuidle_cpu_online, NULL);
400 WARN_ON(retval < 0);
401 retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
402 "cpuidle/powernv:dead", NULL,
403 powernv_cpuidle_cpu_dead);
404 WARN_ON(retval < 0);
405 printk(KERN_DEBUG "powernv_idle_driver registered\n");
406 return 0;
407}
408
409device_initcall(powernv_processor_idle_init);