1/*
2 *  cpuidle-powernv - idle state cpuidle driver.
3 *  Adapted from drivers/cpuidle/cpuidle-pseries
4 *
5 */
6
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/moduleparam.h>
11#include <linux/cpuidle.h>
12#include <linux/cpu.h>
13#include <linux/notifier.h>
14#include <linux/clockchips.h>
15#include <linux/of.h>
16
17#include <asm/machdep.h>
18#include <asm/firmware.h>
19#include <asm/runlatch.h>
20
21/* Flags and constants used in PowerNV platform */
22
23#define MAX_POWERNV_IDLE_STATES	8
24#define IDLE_USE_INST_NAP	0x00010000 /* Use nap instruction */
25#define IDLE_USE_INST_SLEEP	0x00020000 /* Use sleep instruction */
26
27struct cpuidle_driver powernv_idle_driver = {
28	.name             = "powernv_idle",
29	.owner            = THIS_MODULE,
30};
31
32static int max_idle_state;
33static struct cpuidle_state *cpuidle_state_table;
34
35static int snooze_loop(struct cpuidle_device *dev,
36			struct cpuidle_driver *drv,
37			int index)
38{
39	local_irq_enable();
40	set_thread_flag(TIF_POLLING_NRFLAG);
41
42	ppc64_runlatch_off();
43	while (!need_resched()) {
44		HMT_low();
45		HMT_very_low();
46	}
47
48	HMT_medium();
49	ppc64_runlatch_on();
50	clear_thread_flag(TIF_POLLING_NRFLAG);
51	smp_mb();
52	return index;
53}
54
55static int nap_loop(struct cpuidle_device *dev,
56			struct cpuidle_driver *drv,
57			int index)
58{
59	ppc64_runlatch_off();
60	power7_idle();
61	ppc64_runlatch_on();
62	return index;
63}
64
65static int fastsleep_loop(struct cpuidle_device *dev,
66				struct cpuidle_driver *drv,
67				int index)
68{
69	unsigned long old_lpcr = mfspr(SPRN_LPCR);
70	unsigned long new_lpcr;
71
72	if (unlikely(system_state < SYSTEM_RUNNING))
73		return index;
74
75	new_lpcr = old_lpcr;
76	/* Do not exit powersave upon decrementer as we've setup the timer
77	 * offload.
78	 */
79	new_lpcr &= ~LPCR_PECE1;
80
81	mtspr(SPRN_LPCR, new_lpcr);
82	power7_sleep();
83
84	mtspr(SPRN_LPCR, old_lpcr);
85
86	return index;
87}
88
89/*
90 * States for dedicated partition case.
91 */
92static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
93	{ /* Snooze */
94		.name = "snooze",
95		.desc = "snooze",
96		.flags = CPUIDLE_FLAG_TIME_VALID,
97		.exit_latency = 0,
98		.target_residency = 0,
99		.enter = &snooze_loop },
100};
101
102static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
103			unsigned long action, void *hcpu)
104{
105	int hotcpu = (unsigned long)hcpu;
106	struct cpuidle_device *dev =
107				per_cpu(cpuidle_devices, hotcpu);
108
109	if (dev && cpuidle_get_driver()) {
110		switch (action) {
111		case CPU_ONLINE:
112		case CPU_ONLINE_FROZEN:
113			cpuidle_pause_and_lock();
114			cpuidle_enable_device(dev);
115			cpuidle_resume_and_unlock();
116			break;
117
118		case CPU_DEAD:
119		case CPU_DEAD_FROZEN:
120			cpuidle_pause_and_lock();
121			cpuidle_disable_device(dev);
122			cpuidle_resume_and_unlock();
123			break;
124
125		default:
126			return NOTIFY_DONE;
127		}
128	}
129	return NOTIFY_OK;
130}
131
132static struct notifier_block setup_hotplug_notifier = {
133	.notifier_call = powernv_cpuidle_add_cpu_notifier,
134};
135
136/*
137 * powernv_cpuidle_driver_init()
138 */
139static int powernv_cpuidle_driver_init(void)
140{
141	int idle_state;
142	struct cpuidle_driver *drv = &powernv_idle_driver;
143
144	drv->state_count = 0;
145
146	for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
147		/* Is the state not enabled? */
148		if (cpuidle_state_table[idle_state].enter == NULL)
149			continue;
150
151		drv->states[drv->state_count] =	/* structure copy */
152			cpuidle_state_table[idle_state];
153
154		drv->state_count += 1;
155	}
156
157	return 0;
158}
159
160static int powernv_add_idle_states(void)
161{
162	struct device_node *power_mgt;
163	int nr_idle_states = 1; /* Snooze */
164	int dt_idle_states;
165	const __be32 *idle_state_flags;
166	const __be32 *idle_state_latency;
167	u32 len_flags, flags, latency_ns;
168	int i;
169
170	/* Currently we have snooze statically defined */
171
172	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
173	if (!power_mgt) {
174		pr_warn("opal: PowerMgmt Node not found\n");
175		return nr_idle_states;
176	}
177
178	idle_state_flags = of_get_property(power_mgt, "ibm,cpu-idle-state-flags", &len_flags);
179	if (!idle_state_flags) {
180		pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
181		return nr_idle_states;
182	}
183
184	idle_state_latency = of_get_property(power_mgt,
185			"ibm,cpu-idle-state-latencies-ns", NULL);
186	if (!idle_state_latency) {
187		pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
188		return nr_idle_states;
189	}
190
191	dt_idle_states = len_flags / sizeof(u32);
192
193	for (i = 0; i < dt_idle_states; i++) {
194
195		flags = be32_to_cpu(idle_state_flags[i]);
196
197		/* Cpuidle accepts exit_latency in us and we estimate
198		 * target residency to be 10x exit_latency
199		 */
200		latency_ns = be32_to_cpu(idle_state_latency[i]);
201		if (flags & IDLE_USE_INST_NAP) {
202			/* Add NAP state */
203			strcpy(powernv_states[nr_idle_states].name, "Nap");
204			strcpy(powernv_states[nr_idle_states].desc, "Nap");
205			powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
206			powernv_states[nr_idle_states].exit_latency =
207					((unsigned int)latency_ns) / 1000;
208			powernv_states[nr_idle_states].target_residency =
209					((unsigned int)latency_ns / 100);
210			powernv_states[nr_idle_states].enter = &nap_loop;
211			nr_idle_states++;
212		}
213
214		if (flags & IDLE_USE_INST_SLEEP) {
215			/* Add FASTSLEEP state */
216			strcpy(powernv_states[nr_idle_states].name, "FastSleep");
217			strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
218			powernv_states[nr_idle_states].flags =
219				CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
220			powernv_states[nr_idle_states].exit_latency =
221					((unsigned int)latency_ns) / 1000;
222			powernv_states[nr_idle_states].target_residency =
223					((unsigned int)latency_ns / 100);
224			powernv_states[nr_idle_states].enter = &fastsleep_loop;
225			nr_idle_states++;
226		}
227	}
228
229	return nr_idle_states;
230}
231
232/*
233 * powernv_idle_probe()
234 * Choose state table for shared versus dedicated partition
235 */
236static int powernv_idle_probe(void)
237{
238	if (cpuidle_disable != IDLE_NO_OVERRIDE)
239		return -ENODEV;
240
241	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
242		cpuidle_state_table = powernv_states;
243		/* Device tree can indicate more idle states */
244		max_idle_state = powernv_add_idle_states();
245 	} else
246 		return -ENODEV;
247
248	return 0;
249}
250
251static int __init powernv_processor_idle_init(void)
252{
253	int retval;
254
255	retval = powernv_idle_probe();
256	if (retval)
257		return retval;
258
259	powernv_cpuidle_driver_init();
260	retval = cpuidle_register(&powernv_idle_driver, NULL);
261	if (retval) {
262		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
263		return retval;
264	}
265
266	register_cpu_notifier(&setup_hotplug_notifier);
267	printk(KERN_DEBUG "powernv_idle_driver registered\n");
268	return 0;
269}
270
271device_initcall(powernv_processor_idle_init);
272