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1ea60cf7 AT |
1 | /* |
2 | * based on arch/arm/mach-kirkwood/cpuidle.c | |
3 | * | |
4 | * CPU idle support for AT91 SoC | |
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 RAM self refresh in order | |
11 | * to implement two idle states - | |
12 | * #1 wait-for-interrupt | |
13 | * #2 wait-for-interrupt and RAM 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 <asm/proc-fns.h> | |
21 | #include <linux/io.h> | |
22 | ||
23 | #include "pm.h" | |
24 | ||
25 | #define AT91_MAX_STATES 2 | |
26 | ||
27 | static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device); | |
28 | ||
29 | static struct cpuidle_driver at91_idle_driver = { | |
30 | .name = "at91_idle", | |
31 | .owner = THIS_MODULE, | |
32 | }; | |
33 | ||
34 | /* Actual code that puts the SoC in different idle states */ | |
35 | static int at91_enter_idle(struct cpuidle_device *dev, | |
36 | struct cpuidle_state *state) | |
37 | { | |
38 | struct timeval before, after; | |
39 | int idle_time; | |
40 | u32 saved_lpr; | |
41 | ||
42 | local_irq_disable(); | |
43 | do_gettimeofday(&before); | |
44 | if (state == &dev->states[0]) | |
45 | /* Wait for interrupt state */ | |
46 | cpu_do_idle(); | |
47 | else if (state == &dev->states[1]) { | |
48 | asm("b 1f; .align 5; 1:"); | |
49 | asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */ | |
50 | saved_lpr = sdram_selfrefresh_enable(); | |
51 | cpu_do_idle(); | |
52 | sdram_selfrefresh_disable(saved_lpr); | |
53 | } | |
54 | do_gettimeofday(&after); | |
55 | local_irq_enable(); | |
56 | idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC + | |
57 | (after.tv_usec - before.tv_usec); | |
58 | return idle_time; | |
59 | } | |
60 | ||
61 | /* Initialize CPU idle by registering the idle states */ | |
62 | static int at91_init_cpuidle(void) | |
63 | { | |
64 | struct cpuidle_device *device; | |
65 | ||
66 | cpuidle_register_driver(&at91_idle_driver); | |
67 | ||
68 | device = &per_cpu(at91_cpuidle_device, smp_processor_id()); | |
69 | device->state_count = AT91_MAX_STATES; | |
70 | ||
71 | /* Wait for interrupt state */ | |
72 | device->states[0].enter = at91_enter_idle; | |
73 | device->states[0].exit_latency = 1; | |
74 | device->states[0].target_residency = 10000; | |
75 | device->states[0].flags = CPUIDLE_FLAG_TIME_VALID; | |
76 | strcpy(device->states[0].name, "WFI"); | |
77 | strcpy(device->states[0].desc, "Wait for interrupt"); | |
78 | ||
79 | /* Wait for interrupt and RAM self refresh state */ | |
80 | device->states[1].enter = at91_enter_idle; | |
81 | device->states[1].exit_latency = 10; | |
82 | device->states[1].target_residency = 10000; | |
83 | device->states[1].flags = CPUIDLE_FLAG_TIME_VALID; | |
84 | strcpy(device->states[1].name, "RAM_SR"); | |
85 | strcpy(device->states[1].desc, "WFI and RAM Self Refresh"); | |
86 | ||
87 | if (cpuidle_register_device(device)) { | |
88 | printk(KERN_ERR "at91_init_cpuidle: Failed registering\n"); | |
89 | return -EIO; | |
90 | } | |
91 | return 0; | |
92 | } | |
93 | ||
94 | device_initcall(at91_init_cpuidle); |