summaryrefslogtreecommitdiffstats
path: root/drivers/cpuidle/cpuidle-cps.c
blob: fc7b62720debf3e95cae71973d1f726d1c7ce79d (plain)
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
/*
 * Copyright (C) 2014 Imagination Technologies
 * Author: Paul Burton <paul.burton@imgtec.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/cpu_pm.h>
#include <linux/cpuidle.h>
#include <linux/init.h>

#include <asm/idle.h>
#include <asm/pm-cps.h>

/* Enumeration of the various idle states this driver may enter */
enum cps_idle_state {
	STATE_WAIT = 0,		/* MIPS wait instruction, coherent */
	STATE_NC_WAIT,		/* MIPS wait instruction, non-coherent */
	STATE_CLOCK_GATED,	/* Core clock gated */
	STATE_POWER_GATED,	/* Core power gated */
	STATE_COUNT
};

static int cps_nc_enter(struct cpuidle_device *dev,
			struct cpuidle_driver *drv, int index)
{
	enum cps_pm_state pm_state;
	int err;

	/*
	 * At least one core must remain powered up & clocked in order for the
	 * system to have any hope of functioning.
	 *
	 * TODO: don't treat core 0 specially, just prevent the final core
	 * TODO: remap interrupt affinity temporarily
	 */
	if (!cpu_data[dev->cpu].core && (index > STATE_NC_WAIT))
		index = STATE_NC_WAIT;

	/* Select the appropriate cps_pm_state */
	switch (index) {
	case STATE_NC_WAIT:
		pm_state = CPS_PM_NC_WAIT;
		break;
	case STATE_CLOCK_GATED:
		pm_state = CPS_PM_CLOCK_GATED;
		break;
	case STATE_POWER_GATED:
		pm_state = CPS_PM_POWER_GATED;
		break;
	default:
		BUG();
		return -EINVAL;
	}

	/* Notify listeners the CPU is about to power down */
	if ((pm_state == CPS_PM_POWER_GATED) && cpu_pm_enter())
		return -EINTR;

	/* Enter that state */
	err = cps_pm_enter_state(pm_state);

	/* Notify listeners the CPU is back up */
	if (pm_state == CPS_PM_POWER_GATED)
		cpu_pm_exit();

	return err ?: index;
}

static struct cpuidle_driver cps_driver = {
	.name			= "cpc_cpuidle",
	.owner			= THIS_MODULE,
	.states = {
		[STATE_WAIT] = MIPS_CPUIDLE_WAIT_STATE,
		[STATE_NC_WAIT] = {
			.enter	= cps_nc_enter,
			.exit_latency		= 200,
			.target_residency	= 450,
			.flags	= CPUIDLE_FLAG_TIME_VALID,
			.name	= "nc-wait",
			.desc	= "non-coherent MIPS wait",
		},
		[STATE_CLOCK_GATED] = {
			.enter	= cps_nc_enter,
			.exit_latency		= 300,
			.target_residency	= 700,
			.flags	= CPUIDLE_FLAG_TIME_VALID |
				  CPUIDLE_FLAG_TIMER_STOP,
			.name	= "clock-gated",
			.desc	= "core clock gated",
		},
		[STATE_POWER_GATED] = {
			.enter	= cps_nc_enter,
			.exit_latency		= 600,
			.target_residency	= 1000,
			.flags	= CPUIDLE_FLAG_TIME_VALID |
				  CPUIDLE_FLAG_TIMER_STOP,
			.name	= "power-gated",
			.desc	= "core power gated",
		},
	},
	.state_count		= STATE_COUNT,
	.safe_state_index	= 0,
};

static void __init cps_cpuidle_unregister(void)
{
	int cpu;
	struct cpuidle_device *device;

	for_each_possible_cpu(cpu) {
		device = &per_cpu(cpuidle_dev, cpu);
		cpuidle_unregister_device(device);
	}

	cpuidle_unregister_driver(&cps_driver);
}

static int __init cps_cpuidle_init(void)
{
	int err, cpu, core, i;
	struct cpuidle_device *device;

	/* Detect supported states */
	if (!cps_pm_support_state(CPS_PM_POWER_GATED))
		cps_driver.state_count = STATE_CLOCK_GATED + 1;
	if (!cps_pm_support_state(CPS_PM_CLOCK_GATED))
		cps_driver.state_count = STATE_NC_WAIT + 1;
	if (!cps_pm_support_state(CPS_PM_NC_WAIT))
		cps_driver.state_count = STATE_WAIT + 1;

	/* Inform the user if some states are unavailable */
	if (cps_driver.state_count < STATE_COUNT) {
		pr_info("cpuidle-cps: limited to ");
		switch (cps_driver.state_count - 1) {
		case STATE_WAIT:
			pr_cont("coherent wait\n");
			break;
		case STATE_NC_WAIT:
			pr_cont("non-coherent wait\n");
			break;
		case STATE_CLOCK_GATED:
			pr_cont("clock gating\n");
			break;
		}
	}

	/*
	 * Set the coupled flag on the appropriate states if this system
	 * requires it.
	 */
	if (coupled_coherence)
		for (i = STATE_NC_WAIT; i < cps_driver.state_count; i++)
			cps_driver.states[i].flags |= CPUIDLE_FLAG_COUPLED;

	err = cpuidle_register_driver(&cps_driver);
	if (err) {
		pr_err("Failed to register CPS cpuidle driver\n");
		return err;
	}

	for_each_possible_cpu(cpu) {
		core = cpu_data[cpu].core;
		device = &per_cpu(cpuidle_dev, cpu);
		device->cpu = cpu;
#ifdef CONFIG_MIPS_MT
		cpumask_copy(&device->coupled_cpus, &cpu_sibling_map[cpu]);
#endif

		err = cpuidle_register_device(device);
		if (err) {
			pr_err("Failed to register CPU%d cpuidle device\n",
			       cpu);
			goto err_out;
		}
	}

	return 0;
err_out:
	cps_cpuidle_unregister();
	return err;
}
device_initcall(cps_cpuidle_init);