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 clear_thread_flag(TIF_POLLING_NRFLAG);
99
100 local_irq_disable();
101
102 return index;
103}
104
105static int nap_loop(struct cpuidle_device *dev,
106 struct cpuidle_driver *drv,
107 int index)
108{
109 power7_idle_type(PNV_THREAD_NAP);
110
111 return index;
112}
113
114/* Register for fastsleep only in oneshot mode of broadcast */
115#ifdef CONFIG_TICK_ONESHOT
116static int fastsleep_loop(struct cpuidle_device *dev,
117 struct cpuidle_driver *drv,
118 int index)
119{
120 unsigned long old_lpcr = mfspr(SPRN_LPCR);
121 unsigned long new_lpcr;
122
123 if (unlikely(system_state < SYSTEM_RUNNING))
124 return index;
125
126 new_lpcr = old_lpcr;
127 /* Do not exit powersave upon decrementer as we've setup the timer
128 * offload.
129 */
130 new_lpcr &= ~LPCR_PECE1;
131
132 mtspr(SPRN_LPCR, new_lpcr);
133
134 power7_idle_type(PNV_THREAD_SLEEP);
135
136 mtspr(SPRN_LPCR, old_lpcr);
137
138 return index;
139}
140#endif
141
142static int stop_loop(struct cpuidle_device *dev,
143 struct cpuidle_driver *drv,
144 int index)
145{
146 arch300_idle_type(stop_psscr_table[index].val,
147 stop_psscr_table[index].mask);
148 return index;
149}
150
151/*
152 * States for dedicated partition case.
153 */
154static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
155 { /* Snooze */
156 .name = "snooze",
157 .desc = "snooze",
158 .exit_latency = 0,
159 .target_residency = 0,
160 .enter = snooze_loop,
161 .flags = CPUIDLE_FLAG_POLLING },
162};
163
164static int powernv_cpuidle_cpu_online(unsigned int cpu)
165{
166 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
167
168 if (dev && cpuidle_get_driver()) {
169 cpuidle_pause_and_lock();
170 cpuidle_enable_device(dev);
171 cpuidle_resume_and_unlock();
172 }
173 return 0;
174}
175
176static int powernv_cpuidle_cpu_dead(unsigned int cpu)
177{
178 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
179
180 if (dev && cpuidle_get_driver()) {
181 cpuidle_pause_and_lock();
182 cpuidle_disable_device(dev);
183 cpuidle_resume_and_unlock();
184 }
185 return 0;
186}
187
188/*
189 * powernv_cpuidle_driver_init()
190 */
191static int powernv_cpuidle_driver_init(void)
192{
193 int idle_state;
194 struct cpuidle_driver *drv = &powernv_idle_driver;
195
196 drv->state_count = 0;
197
198 for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
199 /* Is the state not enabled? */
200 if (cpuidle_state_table[idle_state].enter == NULL)
201 continue;
202
203 drv->states[drv->state_count] = /* structure copy */
204 cpuidle_state_table[idle_state];
205
206 drv->state_count += 1;
207 }
208
209 /*
210 * On the PowerNV platform cpu_present may be less than cpu_possible in
211 * cases when firmware detects the CPU, but it is not available to the
212 * OS. If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
213 * run time and hence cpu_devices are not created for those CPUs by the
214 * generic topology_init().
215 *
216 * drv->cpumask defaults to cpu_possible_mask in
217 * __cpuidle_driver_init(). This breaks cpuidle on PowerNV where
218 * cpu_devices are not created for CPUs in cpu_possible_mask that
219 * cannot be hot-added later at run time.
220 *
221 * Trying cpuidle_register_device() on a CPU without a cpu_device is
222 * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
223 */
224
225 drv->cpumask = (struct cpumask *)cpu_present_mask;
226
227 return 0;
228}
229
230static inline void add_powernv_state(int index, const char *name,
231 unsigned int flags,
232 int (*idle_fn)(struct cpuidle_device *,
233 struct cpuidle_driver *,
234 int),
235 unsigned int target_residency,
236 unsigned int exit_latency,
237 u64 psscr_val, u64 psscr_mask)
238{
239 strscpy(p: powernv_states[index].name, q: name, CPUIDLE_NAME_LEN);
240 strscpy(p: powernv_states[index].desc, q: name, CPUIDLE_NAME_LEN);
241 powernv_states[index].flags = flags;
242 powernv_states[index].target_residency = target_residency;
243 powernv_states[index].exit_latency = exit_latency;
244 powernv_states[index].enter = idle_fn;
245 /* For power8 and below psscr_* will be 0 */
246 stop_psscr_table[index].val = psscr_val;
247 stop_psscr_table[index].mask = psscr_mask;
248}
249
250extern u32 pnv_get_supported_cpuidle_states(void);
251static int powernv_add_idle_states(void)
252{
253 int nr_idle_states = 1; /* Snooze */
254 int dt_idle_states;
255 u32 has_stop_states = 0;
256 int i;
257 u32 supported_flags = pnv_get_supported_cpuidle_states();
258
259
260 /* Currently we have snooze statically defined */
261 if (nr_pnv_idle_states <= 0) {
262 pr_warn("cpuidle-powernv : Only Snooze is available\n");
263 goto out;
264 }
265
266 /* TODO: Count only states which are eligible for cpuidle */
267 dt_idle_states = nr_pnv_idle_states;
268
269 /*
270 * Since snooze is used as first idle state, max idle states allowed is
271 * CPUIDLE_STATE_MAX -1
272 */
273 if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
274 pr_warn("cpuidle-powernv: discovered idle states more than allowed");
275 dt_idle_states = CPUIDLE_STATE_MAX - 1;
276 }
277
278 /*
279 * If the idle states use stop instruction, probe for psscr values
280 * and psscr mask which are necessary to specify required stop level.
281 */
282 has_stop_states = (pnv_idle_states[0].flags &
283 (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
284
285 for (i = 0; i < dt_idle_states; i++) {
286 unsigned int exit_latency, target_residency;
287 bool stops_timebase = false;
288 struct pnv_idle_states_t *state = &pnv_idle_states[i];
289
290 /*
291 * Skip the platform idle state whose flag isn't in
292 * the supported_cpuidle_states flag mask.
293 */
294 if ((state->flags & supported_flags) != state->flags)
295 continue;
296 /*
297 * If an idle state has exit latency beyond
298 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
299 * in cpu-idle.
300 */
301 if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
302 continue;
303 /*
304 * Firmware passes residency and latency values in ns.
305 * cpuidle expects it in us.
306 */
307 exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
308 target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
309
310 if (has_stop_states && !(state->valid))
311 continue;
312
313 if (state->flags & OPAL_PM_TIMEBASE_STOP)
314 stops_timebase = true;
315
316 if (state->flags & OPAL_PM_NAP_ENABLED) {
317 /* Add NAP state */
318 add_powernv_state(index: nr_idle_states, name: "Nap",
319 CPUIDLE_FLAG_NONE, idle_fn: nap_loop,
320 target_residency, exit_latency, psscr_val: 0, psscr_mask: 0);
321 } else if (has_stop_states && !stops_timebase) {
322 add_powernv_state(index: nr_idle_states, name: state->name,
323 CPUIDLE_FLAG_NONE, idle_fn: stop_loop,
324 target_residency, exit_latency,
325 psscr_val: state->psscr_val,
326 psscr_mask: state->psscr_mask);
327 }
328
329 /*
330 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
331 * within this config dependency check.
332 */
333#ifdef CONFIG_TICK_ONESHOT
334 else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
335 state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
336 /* Add FASTSLEEP state */
337 add_powernv_state(index: nr_idle_states, name: "FastSleep",
338 CPUIDLE_FLAG_TIMER_STOP,
339 idle_fn: fastsleep_loop,
340 target_residency, exit_latency, psscr_val: 0, psscr_mask: 0);
341 } else if (has_stop_states && stops_timebase) {
342 add_powernv_state(index: nr_idle_states, name: state->name,
343 CPUIDLE_FLAG_TIMER_STOP, idle_fn: stop_loop,
344 target_residency, exit_latency,
345 psscr_val: state->psscr_val,
346 psscr_mask: state->psscr_mask);
347 }
348#endif
349 else
350 continue;
351 nr_idle_states++;
352 }
353out:
354 return nr_idle_states;
355}
356
357/*
358 * powernv_idle_probe()
359 * Choose state table for shared versus dedicated partition
360 */
361static int powernv_idle_probe(void)
362{
363 if (cpuidle_disable != IDLE_NO_OVERRIDE)
364 return -ENODEV;
365
366 if (firmware_has_feature(FW_FEATURE_OPAL)) {
367 cpuidle_state_table = powernv_states;
368 /* Device tree can indicate more idle states */
369 max_idle_state = powernv_add_idle_states();
370 default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
371 if (max_idle_state > 1)
372 snooze_timeout_en = true;
373 } else
374 return -ENODEV;
375
376 return 0;
377}
378
379static int __init powernv_processor_idle_init(void)
380{
381 int retval;
382
383 retval = powernv_idle_probe();
384 if (retval)
385 return retval;
386
387 powernv_cpuidle_driver_init();
388 retval = cpuidle_register(drv: &powernv_idle_driver, NULL);
389 if (retval) {
390 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
391 return retval;
392 }
393
394 retval = cpuhp_setup_state_nocalls(state: CPUHP_AP_ONLINE_DYN,
395 name: "cpuidle/powernv:online",
396 startup: powernv_cpuidle_cpu_online, NULL);
397 WARN_ON(retval < 0);
398 retval = cpuhp_setup_state_nocalls(state: CPUHP_CPUIDLE_DEAD,
399 name: "cpuidle/powernv:dead", NULL,
400 teardown: powernv_cpuidle_cpu_dead);
401 WARN_ON(retval < 0);
402 printk(KERN_DEBUG "powernv_idle_driver registered\n");
403 return 0;
404}
405
406device_initcall(powernv_processor_idle_init);
407

source code of linux/drivers/cpuidle/cpuidle-powernv.c