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 */
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 */
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