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 
31 static struct cpuidle_driver powernv_idle_driver = {
32 	.name             = "powernv_idle",
33 	.owner            = THIS_MODULE,
34 };
35 
36 static int max_idle_state __read_mostly;
37 static struct cpuidle_state *cpuidle_state_table __read_mostly;
38 
39 struct stop_psscr_table {
40 	u64 val;
41 	u64 mask;
42 };
43 
44 static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;
45 
46 static u64 default_snooze_timeout __read_mostly;
47 static bool snooze_timeout_en __read_mostly;
48 
get_snooze_timeout(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)49 static 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 
snooze_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)68 static 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 
nap_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)105 static 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
fastsleep_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)116 static 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 
stop_loop(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)142 static 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  */
154 static 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 
powernv_cpuidle_cpu_online(unsigned int cpu)164 static 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 
powernv_cpuidle_cpu_dead(unsigned int cpu)176 static 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  */
powernv_cpuidle_driver_init(void)191 static 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 
add_powernv_state(int index,const char * name,unsigned int flags,int (* idle_fn)(struct cpuidle_device *,struct cpuidle_driver *,int),unsigned int target_residency,unsigned int exit_latency,u64 psscr_val,u64 psscr_mask)230 static 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(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
240 	strscpy(powernv_states[index].desc, 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 
250 extern u32 pnv_get_supported_cpuidle_states(void);
powernv_add_idle_states(void)251 static 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(nr_idle_states, "Nap",
319 					  CPUIDLE_FLAG_NONE, nap_loop,
320 					  target_residency, exit_latency, 0, 0);
321 		} else if (has_stop_states && !stops_timebase) {
322 			add_powernv_state(nr_idle_states, state->name,
323 					  CPUIDLE_FLAG_NONE, stop_loop,
324 					  target_residency, exit_latency,
325 					  state->psscr_val,
326 					  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(nr_idle_states, "FastSleep",
338 					  CPUIDLE_FLAG_TIMER_STOP,
339 					  fastsleep_loop,
340 					  target_residency, exit_latency, 0, 0);
341 		} else if (has_stop_states && stops_timebase) {
342 			add_powernv_state(nr_idle_states, state->name,
343 					  CPUIDLE_FLAG_TIMER_STOP, stop_loop,
344 					  target_residency, exit_latency,
345 					  state->psscr_val,
346 					  state->psscr_mask);
347 		}
348 #endif
349 		else
350 			continue;
351 		nr_idle_states++;
352 	}
353 out:
354 	return nr_idle_states;
355 }
356 
357 /*
358  * powernv_idle_probe()
359  * Choose state table for shared versus dedicated partition
360  */
powernv_idle_probe(void)361 static 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 
powernv_processor_idle_init(void)379 static 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(&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(CPUHP_AP_ONLINE_DYN,
395 					   "cpuidle/powernv:online",
396 					   powernv_cpuidle_cpu_online, NULL);
397 	WARN_ON(retval < 0);
398 	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
399 					   "cpuidle/powernv:dead", NULL,
400 					   powernv_cpuidle_cpu_dead);
401 	WARN_ON(retval < 0);
402 	printk(KERN_DEBUG "powernv_idle_driver registered\n");
403 	return 0;
404 }
405 
406 device_initcall(powernv_processor_idle_init);
407