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 /*
248  * Returns 0 if prop1_len == prop2_len. Else returns -1
249  */
250 static inline int validate_dt_prop_sizes(const char *prop1, int prop1_len,
251 					 const char *prop2, int prop2_len)
252 {
253 	if (prop1_len == prop2_len)
254 		return 0;
255 
256 	pr_warn("cpuidle-powernv: array sizes don't match for %s and %s\n",
257 		prop1, prop2);
258 	return -1;
259 }
260 
261 extern u32 pnv_get_supported_cpuidle_states(void);
262 static int powernv_add_idle_states(void)
263 {
264 	int nr_idle_states = 1; /* Snooze */
265 	int dt_idle_states;
266 	u32 has_stop_states = 0;
267 	int i;
268 	u32 supported_flags = pnv_get_supported_cpuidle_states();
269 
270 
271 	/* Currently we have snooze statically defined */
272 	if (nr_pnv_idle_states <= 0) {
273 		pr_warn("cpuidle-powernv : Only Snooze is available\n");
274 		goto out;
275 	}
276 
277 	/* TODO: Count only states which are eligible for cpuidle */
278 	dt_idle_states = nr_pnv_idle_states;
279 
280 	/*
281 	 * Since snooze is used as first idle state, max idle states allowed is
282 	 * CPUIDLE_STATE_MAX -1
283 	 */
284 	if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
285 		pr_warn("cpuidle-powernv: discovered idle states more than allowed");
286 		dt_idle_states = CPUIDLE_STATE_MAX - 1;
287 	}
288 
289 	/*
290 	 * If the idle states use stop instruction, probe for psscr values
291 	 * and psscr mask which are necessary to specify required stop level.
292 	 */
293 	has_stop_states = (pnv_idle_states[0].flags &
294 			   (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
295 
296 	for (i = 0; i < dt_idle_states; i++) {
297 		unsigned int exit_latency, target_residency;
298 		bool stops_timebase = false;
299 		struct pnv_idle_states_t *state = &pnv_idle_states[i];
300 
301 		/*
302 		 * Skip the platform idle state whose flag isn't in
303 		 * the supported_cpuidle_states flag mask.
304 		 */
305 		if ((state->flags & supported_flags) != state->flags)
306 			continue;
307 		/*
308 		 * If an idle state has exit latency beyond
309 		 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
310 		 * in cpu-idle.
311 		 */
312 		if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
313 			continue;
314 		/*
315 		 * Firmware passes residency and latency values in ns.
316 		 * cpuidle expects it in us.
317 		 */
318 		exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
319 		target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
320 
321 		if (has_stop_states && !(state->valid))
322 				continue;
323 
324 		if (state->flags & OPAL_PM_TIMEBASE_STOP)
325 			stops_timebase = true;
326 
327 		if (state->flags & OPAL_PM_NAP_ENABLED) {
328 			/* Add NAP state */
329 			add_powernv_state(nr_idle_states, "Nap",
330 					  CPUIDLE_FLAG_NONE, nap_loop,
331 					  target_residency, exit_latency, 0, 0);
332 		} else if (has_stop_states && !stops_timebase) {
333 			add_powernv_state(nr_idle_states, state->name,
334 					  CPUIDLE_FLAG_NONE, stop_loop,
335 					  target_residency, exit_latency,
336 					  state->psscr_val,
337 					  state->psscr_mask);
338 		}
339 
340 		/*
341 		 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
342 		 * within this config dependency check.
343 		 */
344 #ifdef CONFIG_TICK_ONESHOT
345 		else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
346 			 state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
347 			/* Add FASTSLEEP state */
348 			add_powernv_state(nr_idle_states, "FastSleep",
349 					  CPUIDLE_FLAG_TIMER_STOP,
350 					  fastsleep_loop,
351 					  target_residency, exit_latency, 0, 0);
352 		} else if (has_stop_states && stops_timebase) {
353 			add_powernv_state(nr_idle_states, state->name,
354 					  CPUIDLE_FLAG_TIMER_STOP, stop_loop,
355 					  target_residency, exit_latency,
356 					  state->psscr_val,
357 					  state->psscr_mask);
358 		}
359 #endif
360 		else
361 			continue;
362 		nr_idle_states++;
363 	}
364 out:
365 	return nr_idle_states;
366 }
367 
368 /*
369  * powernv_idle_probe()
370  * Choose state table for shared versus dedicated partition
371  */
372 static int powernv_idle_probe(void)
373 {
374 	if (cpuidle_disable != IDLE_NO_OVERRIDE)
375 		return -ENODEV;
376 
377 	if (firmware_has_feature(FW_FEATURE_OPAL)) {
378 		cpuidle_state_table = powernv_states;
379 		/* Device tree can indicate more idle states */
380 		max_idle_state = powernv_add_idle_states();
381 		default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
382 		if (max_idle_state > 1)
383 			snooze_timeout_en = true;
384  	} else
385  		return -ENODEV;
386 
387 	return 0;
388 }
389 
390 static int __init powernv_processor_idle_init(void)
391 {
392 	int retval;
393 
394 	retval = powernv_idle_probe();
395 	if (retval)
396 		return retval;
397 
398 	powernv_cpuidle_driver_init();
399 	retval = cpuidle_register(&powernv_idle_driver, NULL);
400 	if (retval) {
401 		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
402 		return retval;
403 	}
404 
405 	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
406 					   "cpuidle/powernv:online",
407 					   powernv_cpuidle_cpu_online, NULL);
408 	WARN_ON(retval < 0);
409 	retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
410 					   "cpuidle/powernv:dead", NULL,
411 					   powernv_cpuidle_cpu_dead);
412 	WARN_ON(retval < 0);
413 	printk(KERN_DEBUG "powernv_idle_driver registered\n");
414 	return 0;
415 }
416 
417 device_initcall(powernv_processor_idle_init);
418