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 
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 
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 	ppc64_runlatch_off();
80 	HMT_very_low();
81 	while (!need_resched()) {
82 		if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
83 			/*
84 			 * Task has not woken up but we are exiting the polling
85 			 * loop anyway. Require a barrier after polling is
86 			 * cleared to order subsequent test of need_resched().
87 			 */
88 			clear_thread_flag(TIF_POLLING_NRFLAG);
89 			smp_mb();
90 			break;
91 		}
92 	}
93 
94 	HMT_medium();
95 	ppc64_runlatch_on();
96 	clear_thread_flag(TIF_POLLING_NRFLAG);
97 
98 	local_irq_disable();
99 
100 	return index;
101 }
102 
103 static int nap_loop(struct cpuidle_device *dev,
104 			struct cpuidle_driver *drv,
105 			int index)
106 {
107 	power7_idle_type(PNV_THREAD_NAP);
108 
109 	return index;
110 }
111 
112 /* Register for fastsleep only in oneshot mode of broadcast */
113 #ifdef CONFIG_TICK_ONESHOT
114 static int fastsleep_loop(struct cpuidle_device *dev,
115 				struct cpuidle_driver *drv,
116 				int index)
117 {
118 	unsigned long old_lpcr = mfspr(SPRN_LPCR);
119 	unsigned long new_lpcr;
120 
121 	if (unlikely(system_state < SYSTEM_RUNNING))
122 		return index;
123 
124 	new_lpcr = old_lpcr;
125 	/* Do not exit powersave upon decrementer as we've setup the timer
126 	 * offload.
127 	 */
128 	new_lpcr &= ~LPCR_PECE1;
129 
130 	mtspr(SPRN_LPCR, new_lpcr);
131 
132 	power7_idle_type(PNV_THREAD_SLEEP);
133 
134 	mtspr(SPRN_LPCR, old_lpcr);
135 
136 	return index;
137 }
138 #endif
139 
140 static int stop_loop(struct cpuidle_device *dev,
141 		     struct cpuidle_driver *drv,
142 		     int index)
143 {
144 	power9_idle_type(stop_psscr_table[index].val,
145 			 stop_psscr_table[index].mask);
146 	return index;
147 }
148 
149 /*
150  * States for dedicated partition case.
151  */
152 static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
153 	{ /* Snooze */
154 		.name = "snooze",
155 		.desc = "snooze",
156 		.exit_latency = 0,
157 		.target_residency = 0,
158 		.enter = snooze_loop },
159 };
160 
161 static int powernv_cpuidle_cpu_online(unsigned int cpu)
162 {
163 	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
164 
165 	if (dev && cpuidle_get_driver()) {
166 		cpuidle_pause_and_lock();
167 		cpuidle_enable_device(dev);
168 		cpuidle_resume_and_unlock();
169 	}
170 	return 0;
171 }
172 
173 static int powernv_cpuidle_cpu_dead(unsigned int cpu)
174 {
175 	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
176 
177 	if (dev && cpuidle_get_driver()) {
178 		cpuidle_pause_and_lock();
179 		cpuidle_disable_device(dev);
180 		cpuidle_resume_and_unlock();
181 	}
182 	return 0;
183 }
184 
185 /*
186  * powernv_cpuidle_driver_init()
187  */
188 static int powernv_cpuidle_driver_init(void)
189 {
190 	int idle_state;
191 	struct cpuidle_driver *drv = &powernv_idle_driver;
192 
193 	drv->state_count = 0;
194 
195 	for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
196 		/* Is the state not enabled? */
197 		if (cpuidle_state_table[idle_state].enter == NULL)
198 			continue;
199 
200 		drv->states[drv->state_count] =	/* structure copy */
201 			cpuidle_state_table[idle_state];
202 
203 		drv->state_count += 1;
204 	}
205 
206 	/*
207 	 * On the PowerNV platform cpu_present may be less than cpu_possible in
208 	 * cases when firmware detects the CPU, but it is not available to the
209 	 * OS.  If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
210 	 * run time and hence cpu_devices are not created for those CPUs by the
211 	 * generic topology_init().
212 	 *
213 	 * drv->cpumask defaults to cpu_possible_mask in
214 	 * __cpuidle_driver_init().  This breaks cpuidle on PowerNV where
215 	 * cpu_devices are not created for CPUs in cpu_possible_mask that
216 	 * cannot be hot-added later at run time.
217 	 *
218 	 * Trying cpuidle_register_device() on a CPU without a cpu_device is
219 	 * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
220 	 */
221 
222 	drv->cpumask = (struct cpumask *)cpu_present_mask;
223 
224 	return 0;
225 }
226 
227 static inline void add_powernv_state(int index, const char *name,
228 				     unsigned int flags,
229 				     int (*idle_fn)(struct cpuidle_device *,
230 						    struct cpuidle_driver *,
231 						    int),
232 				     unsigned int target_residency,
233 				     unsigned int exit_latency,
234 				     u64 psscr_val, u64 psscr_mask)
235 {
236 	strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
237 	strlcpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
238 	powernv_states[index].flags = flags;
239 	powernv_states[index].target_residency = target_residency;
240 	powernv_states[index].exit_latency = exit_latency;
241 	powernv_states[index].enter = idle_fn;
242 	/* For power8 and below psscr_* will be 0 */
243 	stop_psscr_table[index].val = psscr_val;
244 	stop_psscr_table[index].mask = psscr_mask;
245 }
246 
247 extern u32 pnv_get_supported_cpuidle_states(void);
248 static int powernv_add_idle_states(void)
249 {
250 	int nr_idle_states = 1; /* Snooze */
251 	int dt_idle_states;
252 	u32 has_stop_states = 0;
253 	int i;
254 	u32 supported_flags = pnv_get_supported_cpuidle_states();
255 
256 
257 	/* Currently we have snooze statically defined */
258 	if (nr_pnv_idle_states <= 0) {
259 		pr_warn("cpuidle-powernv : Only Snooze is available\n");
260 		goto out;
261 	}
262 
263 	/* TODO: Count only states which are eligible for cpuidle */
264 	dt_idle_states = nr_pnv_idle_states;
265 
266 	/*
267 	 * Since snooze is used as first idle state, max idle states allowed is
268 	 * CPUIDLE_STATE_MAX -1
269 	 */
270 	if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
271 		pr_warn("cpuidle-powernv: discovered idle states more than allowed");
272 		dt_idle_states = CPUIDLE_STATE_MAX - 1;
273 	}
274 
275 	/*
276 	 * If the idle states use stop instruction, probe for psscr values
277 	 * and psscr mask which are necessary to specify required stop level.
278 	 */
279 	has_stop_states = (pnv_idle_states[0].flags &
280 			   (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
281 
282 	for (i = 0; i < dt_idle_states; i++) {
283 		unsigned int exit_latency, target_residency;
284 		bool stops_timebase = false;
285 		struct pnv_idle_states_t *state = &pnv_idle_states[i];
286 
287 		/*
288 		 * Skip the platform idle state whose flag isn't in
289 		 * the supported_cpuidle_states flag mask.
290 		 */
291 		if ((state->flags & supported_flags) != state->flags)
292 			continue;
293 		/*
294 		 * If an idle state has exit latency beyond
295 		 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
296 		 * in cpu-idle.
297 		 */
298 		if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
299 			continue;
300 		/*
301 		 * Firmware passes residency and latency values in ns.
302 		 * cpuidle expects it in us.
303 		 */
304 		exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
305 		target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
306 
307 		if (has_stop_states && !(state->valid))
308 				continue;
309 
310 		if (state->flags & OPAL_PM_TIMEBASE_STOP)
311 			stops_timebase = true;
312 
313 		if (state->flags & OPAL_PM_NAP_ENABLED) {
314 			/* Add NAP state */
315 			add_powernv_state(nr_idle_states, "Nap",
316 					  CPUIDLE_FLAG_NONE, nap_loop,
317 					  target_residency, exit_latency, 0, 0);
318 		} else if (has_stop_states && !stops_timebase) {
319 			add_powernv_state(nr_idle_states, state->name,
320 					  CPUIDLE_FLAG_NONE, stop_loop,
321 					  target_residency, exit_latency,
322 					  state->psscr_val,
323 					  state->psscr_mask);
324 		}
325 
326 		/*
327 		 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
328 		 * within this config dependency check.
329 		 */
330 #ifdef CONFIG_TICK_ONESHOT
331 		else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
332 			 state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
333 			/* Add FASTSLEEP state */
334 			add_powernv_state(nr_idle_states, "FastSleep",
335 					  CPUIDLE_FLAG_TIMER_STOP,
336 					  fastsleep_loop,
337 					  target_residency, exit_latency, 0, 0);
338 		} else if (has_stop_states && stops_timebase) {
339 			add_powernv_state(nr_idle_states, state->name,
340 					  CPUIDLE_FLAG_TIMER_STOP, stop_loop,
341 					  target_residency, exit_latency,
342 					  state->psscr_val,
343 					  state->psscr_mask);
344 		}
345 #endif
346 		else
347 			continue;
348 		nr_idle_states++;
349 	}
350 out:
351 	return nr_idle_states;
352 }
353 
354 /*
355  * powernv_idle_probe()
356  * Choose state table for shared versus dedicated partition
357  */
358 static int powernv_idle_probe(void)
359 {
360 	if (cpuidle_disable != IDLE_NO_OVERRIDE)
361 		return -ENODEV;
362 
363 	if (firmware_has_feature(FW_FEATURE_OPAL)) {
364 		cpuidle_state_table = powernv_states;
365 		/* Device tree can indicate more idle states */
366 		max_idle_state = powernv_add_idle_states();
367 		default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
368 		if (max_idle_state > 1)
369 			snooze_timeout_en = true;
370  	} else
371  		return -ENODEV;
372 
373 	return 0;
374 }
375 
376 static int __init powernv_processor_idle_init(void)
377 {
378 	int retval;
379 
380 	retval = powernv_idle_probe();
381 	if (retval)
382 		return retval;
383 
384 	powernv_cpuidle_driver_init();
385 	retval = cpuidle_register(&powernv_idle_driver, NULL);
386 	if (retval) {
387 		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
388 		return retval;
389 	}
390 
391 	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
392 					   "cpuidle/powernv:online",
393 					   powernv_cpuidle_cpu_online, NULL);
394 	WARN_ON(retval < 0);
395 	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
396 					   "cpuidle/powernv:dead", NULL,
397 					   powernv_cpuidle_cpu_dead);
398 	WARN_ON(retval < 0);
399 	printk(KERN_DEBUG "powernv_idle_driver registered\n");
400 	return 0;
401 }
402 
403 device_initcall(powernv_processor_idle_init);
404