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kunit / linux / 353f6dd2dec992ddd34620a94b051b0f76227379 / . / arch / arm / mach-kirkwood / cpuidle.c
blob: f68d33f1f396c5a72b62629e736f3a7265bbc442 [file] [log] [blame]
Rabeeh Khourye50b6be2009-03-24 16:10:15 +0200[diff] [blame]1/*
2 * arch/arm/mach-kirkwood/cpuidle.c
3 *
4 * CPU idle Marvell Kirkwood SoCs
5 *
6 * This file is licensed under the terms of the GNU General Public
7 * License version 2. This program is licensed "as is" without any
8 * warranty of any kind, whether express or implied.
9 *
10 * The cpu idle uses wait-for-interrupt and DDR self refresh in order
11 * to implement two idle states -
12 * #1 wait-for-interrupt
13 * #2 wait-for-interrupt and DDR self refresh
14 */
15
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/platform_device.h>
19#include <linux/cpuidle.h>
20#include <linux/io.h>
21#include <asm/proc-fns.h>
22#include <mach/kirkwood.h>
23
24#define KIRKWOOD_MAX_STATES 2
25
26static struct cpuidle_driver kirkwood_idle_driver = {
27 .name = "kirkwood_idle",
28 .owner = THIS_MODULE,
29};
30
31static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device);
32
33/* Actual code that puts the SoC in different idle states */
34static int kirkwood_enter_idle(struct cpuidle_device *dev,
35 struct cpuidle_state *state)
36{
37 struct timeval before, after;
38 int idle_time;
39
40 local_irq_disable();
41 do_gettimeofday(&before);
42 if (state == &dev->states[0])
43 /* Wait for interrupt state */
44 cpu_do_idle();
45 else if (state == &dev->states[1]) {
46 /*
47 * Following write will put DDR in self refresh.
48 * Note that we have 256 cycles before DDR puts it
49 * self in self-refresh, so the wait-for-interrupt
50 * call afterwards won't get the DDR from self refresh
51 * mode.
52 */
53 writel(0x7, DDR_OPERATION_BASE);
54 cpu_do_idle();
55 }
56 do_gettimeofday(&after);
57 local_irq_enable();
58 idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
59 (after.tv_usec - before.tv_usec);
60 return idle_time;
61}
62
63/* Initialize CPU idle by registering the idle states */
64static int kirkwood_init_cpuidle(void)
65{
66 struct cpuidle_device *device;
67
68 cpuidle_register_driver(&kirkwood_idle_driver);
69
70 device = &per_cpu(kirkwood_cpuidle_device, smp_processor_id());
71 device->state_count = KIRKWOOD_MAX_STATES;
72
73 /* Wait for interrupt state */
74 device->states[0].enter = kirkwood_enter_idle;
75 device->states[0].exit_latency = 1;
76 device->states[0].target_residency = 10000;
77 device->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
78 strcpy(device->states[0].name, "WFI");
79 strcpy(device->states[0].desc, "Wait for interrupt");
80
81 /* Wait for interrupt and DDR self refresh state */
82 device->states[1].enter = kirkwood_enter_idle;
83 device->states[1].exit_latency = 10;
84 device->states[1].target_residency = 10000;
85 device->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
86 strcpy(device->states[1].name, "DDR SR");
87 strcpy(device->states[1].desc, "WFI and DDR Self Refresh");
88
89 if (cpuidle_register_device(device)) {
90 printk(KERN_ERR "kirkwood_init_cpuidle: Failed registering\n");
91 return -EIO;
92 }
93 return 0;
94}
95
96device_initcall(kirkwood_init_cpuidle);