aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/cpuidle/cpuidle-powernv.c
blob: 719f6fb5b1c35d00108c47a61918741200eae75d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
/*
 *  cpuidle-powernv - idle state cpuidle driver.
 *  Adapted from drivers/cpuidle/cpuidle-pseries
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/cpuidle.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/clockchips.h>
#include <linux/of.h>

#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/runlatch.h>

/* Flags and constants used in PowerNV platform */

#define MAX_POWERNV_IDLE_STATES	8
#define IDLE_USE_INST_NAP	0x00010000 /* Use nap instruction */
#define IDLE_USE_INST_SLEEP	0x00020000 /* Use sleep instruction */

struct cpuidle_driver powernv_idle_driver = {
	.name             = "powernv_idle",
	.owner            = THIS_MODULE,
};

static int max_idle_state;
static struct cpuidle_state *cpuidle_state_table;

static int snooze_loop(struct cpuidle_device *dev,
			struct cpuidle_driver *drv,
			int index)
{
	local_irq_enable();
	set_thread_flag(TIF_POLLING_NRFLAG);

	ppc64_runlatch_off();
	while (!need_resched()) {
		HMT_low();
		HMT_very_low();
	}

	HMT_medium();
	ppc64_runlatch_on();
	clear_thread_flag(TIF_POLLING_NRFLAG);
	smp_mb();
	return index;
}

static int nap_loop(struct cpuidle_device *dev,
			struct cpuidle_driver *drv,
			int index)
{
	ppc64_runlatch_off();
	power7_idle();
	ppc64_runlatch_on();
	return index;
}

static int fastsleep_loop(struct cpuidle_device *dev,
				struct cpuidle_driver *drv,
				int index)
{
	unsigned long old_lpcr = mfspr(SPRN_LPCR);
	unsigned long new_lpcr;

	if (unlikely(system_state < SYSTEM_RUNNING))
		return index;

	new_lpcr = old_lpcr;
	new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */

	/* exit powersave upon external interrupt, but not decrementer
	 * interrupt.
	 */
	new_lpcr |= LPCR_PECE0;

	mtspr(SPRN_LPCR, new_lpcr);
	power7_sleep();

	mtspr(SPRN_LPCR, old_lpcr);

	return index;
}

/*
 * States for dedicated partition case.
 */
static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
	{ /* Snooze */
		.name = "snooze",
		.desc = "snooze",
		.flags = CPUIDLE_FLAG_TIME_VALID,
		.exit_latency = 0,
		.target_residency = 0,
		.enter = &snooze_loop },
};

static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
			unsigned long action, void *hcpu)
{
	int hotcpu = (unsigned long)hcpu;
	struct cpuidle_device *dev =
				per_cpu(cpuidle_devices, hotcpu);

	if (dev && cpuidle_get_driver()) {
		switch (action) {
		case CPU_ONLINE:
		case CPU_ONLINE_FROZEN:
			cpuidle_pause_and_lock();
			cpuidle_enable_device(dev);
			cpuidle_resume_and_unlock();
			break;

		case CPU_DEAD:
		case CPU_DEAD_FROZEN:
			cpuidle_pause_and_lock();
			cpuidle_disable_device(dev);
			cpuidle_resume_and_unlock();
			break;

		default:
			return NOTIFY_DONE;
		}
	}
	return NOTIFY_OK;
}

static struct notifier_block setup_hotplug_notifier = {
	.notifier_call = powernv_cpuidle_add_cpu_notifier,
};

/*
 * powernv_cpuidle_driver_init()
 */
static int powernv_cpuidle_driver_init(void)
{
	int idle_state;
	struct cpuidle_driver *drv = &powernv_idle_driver;

	drv->state_count = 0;

	for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
		/* Is the state not enabled? */
		if (cpuidle_state_table[idle_state].enter == NULL)
			continue;

		drv->states[drv->state_count] =	/* structure copy */
			cpuidle_state_table[idle_state];

		drv->state_count += 1;
	}

	return 0;
}

static int powernv_add_idle_states(void)
{
	struct device_node *power_mgt;
	struct property *prop;
	int nr_idle_states = 1; /* Snooze */
	int dt_idle_states;
	u32 *flags;
	int i;

	/* Currently we have snooze statically defined */

	power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
	if (!power_mgt) {
		pr_warn("opal: PowerMgmt Node not found\n");
		return nr_idle_states;
	}

	prop = of_find_property(power_mgt, "ibm,cpu-idle-state-flags", NULL);
	if (!prop) {
		pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
		return nr_idle_states;
	}

	dt_idle_states = prop->length / sizeof(u32);
	flags = (u32 *) prop->value;

	for (i = 0; i < dt_idle_states; i++) {

		if (flags[i] & IDLE_USE_INST_NAP) {
			/* Add NAP state */
			strcpy(powernv_states[nr_idle_states].name, "Nap");
			strcpy(powernv_states[nr_idle_states].desc, "Nap");
			powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
			powernv_states[nr_idle_states].exit_latency = 10;
			powernv_states[nr_idle_states].target_residency = 100;
			powernv_states[nr_idle_states].enter = &nap_loop;
			nr_idle_states++;
		}

		if (flags[i] & IDLE_USE_INST_SLEEP) {
			/* Add FASTSLEEP state */
			strcpy(powernv_states[nr_idle_states].name, "FastSleep");
			strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
			powernv_states[nr_idle_states].flags =
				CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
			powernv_states[nr_idle_states].exit_latency = 300;
			powernv_states[nr_idle_states].target_residency = 1000000;
			powernv_states[nr_idle_states].enter = &fastsleep_loop;
			nr_idle_states++;
		}
	}

	return nr_idle_states;
}

/*
 * powernv_idle_probe()
 * Choose state table for shared versus dedicated partition
 */
static int powernv_idle_probe(void)
{
	if (cpuidle_disable != IDLE_NO_OVERRIDE)
		return -ENODEV;

	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
		cpuidle_state_table = powernv_states;
		/* Device tree can indicate more idle states */
		max_idle_state = powernv_add_idle_states();
 	} else
 		return -ENODEV;

	return 0;
}

static int __init powernv_processor_idle_init(void)
{
	int retval;

	retval = powernv_idle_probe();
	if (retval)
		return retval;

	powernv_cpuidle_driver_init();
	retval = cpuidle_register(&powernv_idle_driver, NULL);
	if (retval) {
		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
		return retval;
	}

	register_cpu_notifier(&setup_hotplug_notifier);
	printk(KERN_DEBUG "powernv_idle_driver registered\n");
	return 0;
}

device_initcall(powernv_processor_idle_init);