2 * arch/arm/mach-kirkwood/cpuidle.c
4 * CPU idle Marvell Kirkwood SoCs
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.
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
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <linux/platform_device.h>
19 #include <linux/cpuidle.h>
21 #include <asm/proc-fns.h>
22 #include <mach/kirkwood.h>
24 #define KIRKWOOD_MAX_STATES 2
26 static struct cpuidle_driver kirkwood_idle_driver = {
27 .name = "kirkwood_idle",
31 static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device);
33 /* Actual code that puts the SoC in different idle states */
34 static int kirkwood_enter_idle(struct cpuidle_device *dev,
35 struct cpuidle_driver *drv,
38 struct timeval before, after;
42 do_gettimeofday(&before);
44 /* Wait for interrupt state */
46 else if (index == 1) {
48 * Following write will put DDR in self refresh.
49 * Note that we have 256 cycles before DDR puts it
50 * self in self-refresh, so the wait-for-interrupt
51 * call afterwards won't get the DDR from self refresh
54 writel(0x7, DDR_OPERATION_BASE);
57 do_gettimeofday(&after);
59 idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
60 (after.tv_usec - before.tv_usec);
62 /* Update last residency */
63 dev->last_residency = idle_time;
68 /* Initialize CPU idle by registering the idle states */
69 static int kirkwood_init_cpuidle(void)
71 struct cpuidle_device *device;
72 struct cpuidle_driver *driver = &kirkwood_idle_driver;
74 device = &per_cpu(kirkwood_cpuidle_device, smp_processor_id());
75 device->state_count = KIRKWOOD_MAX_STATES;
76 driver->state_count = KIRKWOOD_MAX_STATES;
78 /* Wait for interrupt state */
79 driver->states[0].enter = kirkwood_enter_idle;
80 driver->states[0].exit_latency = 1;
81 driver->states[0].target_residency = 10000;
82 driver->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
83 strcpy(driver->states[0].name, "WFI");
84 strcpy(driver->states[0].desc, "Wait for interrupt");
86 /* Wait for interrupt and DDR self refresh state */
87 driver->states[1].enter = kirkwood_enter_idle;
88 driver->states[1].exit_latency = 10;
89 driver->states[1].target_residency = 10000;
90 driver->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
91 strcpy(driver->states[1].name, "DDR SR");
92 strcpy(driver->states[1].desc, "WFI and DDR Self Refresh");
94 cpuidle_register_driver(&kirkwood_idle_driver);
95 if (cpuidle_register_device(device)) {
96 printk(KERN_ERR "kirkwood_init_cpuidle: Failed registering\n");
102 device_initcall(kirkwood_init_cpuidle);