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 <linux/io.h>
21 #include <linux/export.h>
22 #include <asm/cpuidle.h>
23
24 #define AT91_MAX_STATES 2
25
26 static void (*at91_standby)(void);
27
28 /* Actual code that puts the SoC in different idle states */
at91_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)29 static int at91_enter_idle(struct cpuidle_device *dev,
30 struct cpuidle_driver *drv,
31 int index)
32 {
33 at91_standby();
34 return index;
35 }
36
37 static struct cpuidle_driver at91_idle_driver = {
38 .name = "at91_idle",
39 .owner = THIS_MODULE,
40 .states[0] = ARM_CPUIDLE_WFI_STATE,
41 .states[1] = {
42 .enter = at91_enter_idle,
43 .exit_latency = 10,
44 .target_residency = 10000,
45 .name = "RAM_SR",
46 .desc = "WFI and DDR Self Refresh",
47 },
48 .state_count = AT91_MAX_STATES,
49 };
50
51 /* Initialize CPU idle by registering the idle states */
at91_cpuidle_probe(struct platform_device * dev)52 static int at91_cpuidle_probe(struct platform_device *dev)
53 {
54 at91_standby = (void *)(dev->dev.platform_data);
55
56 return cpuidle_register(&at91_idle_driver, NULL);
57 }
58
59 static struct platform_driver at91_cpuidle_driver = {
60 .driver = {
61 .name = "cpuidle-at91",
62 },
63 .probe = at91_cpuidle_probe,
64 };
65 builtin_platform_driver(at91_cpuidle_driver);
66