Kirkwood: Add support for 6282 based QNAP devices
[linux-3.10.git] / arch / arm / mach-kirkwood / cpuidle.c
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);