| Albin Tonnerre | 1ea60cf | 2009-11-01 18:40:50 +0100 | [diff] [blame] | 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); |