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 <linux/export.h>
22 #include <asm/proc-fns.h>
23 #include <mach/kirkwood.h>
24
25 #define KIRKWOOD_MAX_STATES 2
26
27 static struct cpuidle_driver kirkwood_idle_driver = {
28 .name = "kirkwood_idle",
29 .owner = THIS_MODULE,
30 };
31
32 static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device);
33
34 /* Actual code that puts the SoC in different idle states */
kirkwood_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)35 static int kirkwood_enter_idle(struct cpuidle_device *dev,
36 struct cpuidle_driver *drv,
37 int index)
38 {
39 struct timeval before, after;
40 int idle_time;
41
42 local_irq_disable();
43 do_gettimeofday(&before);
44 if (index == 0)
45 /* Wait for interrupt state */
46 cpu_do_idle();
47 else if (index == 1) {
48 /*
49 * Following write will put DDR in self refresh.
50 * Note that we have 256 cycles before DDR puts it
51 * self in self-refresh, so the wait-for-interrupt
52 * call afterwards won't get the DDR from self refresh
53 * mode.
54 */
55 writel(0x7, DDR_OPERATION_BASE);
56 cpu_do_idle();
57 }
58 do_gettimeofday(&after);
59 local_irq_enable();
60 idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
61 (after.tv_usec - before.tv_usec);
62
63 /* Update last residency */
64 dev->last_residency = idle_time;
65
66 return index;
67 }
68
69 /* Initialize CPU idle by registering the idle states */
kirkwood_init_cpuidle(void)70 static int kirkwood_init_cpuidle(void)
71 {
72 struct cpuidle_device *device;
73 struct cpuidle_driver *driver = &kirkwood_idle_driver;
74
75 device = &per_cpu(kirkwood_cpuidle_device, smp_processor_id());
76 device->state_count = KIRKWOOD_MAX_STATES;
77 driver->state_count = KIRKWOOD_MAX_STATES;
78
79 /* Wait for interrupt state */
80 driver->states[0].enter = kirkwood_enter_idle;
81 driver->states[0].exit_latency = 1;
82 driver->states[0].target_residency = 10000;
83 driver->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
84 strcpy(driver->states[0].name, "WFI");
85 strcpy(driver->states[0].desc, "Wait for interrupt");
86
87 /* Wait for interrupt and DDR self refresh state */
88 driver->states[1].enter = kirkwood_enter_idle;
89 driver->states[1].exit_latency = 10;
90 driver->states[1].target_residency = 10000;
91 driver->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
92 strcpy(driver->states[1].name, "DDR SR");
93 strcpy(driver->states[1].desc, "WFI and DDR Self Refresh");
94
95 cpuidle_register_driver(&kirkwood_idle_driver);
96 if (cpuidle_register_device(device)) {
97 printk(KERN_ERR "kirkwood_init_cpuidle: Failed registering\n");
98 return -EIO;
99 }
100 return 0;
101 }
102
103 device_initcall(kirkwood_init_cpuidle);
104