Rabeeh Khoury | e50b6be | 2009-03-24 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 | |
| 26 | static struct cpuidle_driver kirkwood_idle_driver = { |
| 27 | .name = "kirkwood_idle", |
| 28 | .owner = THIS_MODULE, |
| 29 | }; |
| 30 | |
| 31 | static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device); |
| 32 | |
| 33 | /* Actual code that puts the SoC in different idle states */ |
| 34 | static 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 */ |
| 64 | static 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 | |
| 96 | device_initcall(kirkwood_init_cpuidle); |