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(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
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(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	}
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(&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
406device_initcall(powernv_processor_idle_init);
407