1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * based on arch/arm/mach-kirkwood/cpuidle.c
4  *
5  * CPU idle support for AT91 SoC
6  *
7  * The cpu idle uses wait-for-interrupt and RAM self refresh in order
8  * to implement two idle states -
9  * #1 wait-for-interrupt
10  * #2 wait-for-interrupt and RAM self refresh
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/platform_device.h>
16 #include <linux/cpuidle.h>
17 #include <linux/io.h>
18 #include <linux/export.h>
19 #include <asm/cpuidle.h>
20 
21 #define AT91_MAX_STATES	2
22 
23 static void (*at91_standby)(void);
24 
25 /* Actual code that puts the SoC in different idle states */
at91_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)26 static int at91_enter_idle(struct cpuidle_device *dev,
27 			struct cpuidle_driver *drv,
28 			       int index)
29 {
30 	at91_standby();
31 	return index;
32 }
33 
34 static struct cpuidle_driver at91_idle_driver = {
35 	.name			= "at91_idle",
36 	.owner			= THIS_MODULE,
37 	.states[0]		= ARM_CPUIDLE_WFI_STATE,
38 	.states[1]		= {
39 		.enter			= at91_enter_idle,
40 		.exit_latency		= 10,
41 		.target_residency	= 10000,
42 		.name			= "RAM_SR",
43 		.desc			= "WFI and DDR Self Refresh",
44 	},
45 	.state_count = AT91_MAX_STATES,
46 };
47 
48 /* Initialize CPU idle by registering the idle states */
at91_cpuidle_probe(struct platform_device * dev)49 static int at91_cpuidle_probe(struct platform_device *dev)
50 {
51 	at91_standby = (void *)(dev->dev.platform_data);
52 
53 	return cpuidle_register(&at91_idle_driver, NULL);
54 }
55 
56 static struct platform_driver at91_cpuidle_driver = {
57 	.driver = {
58 		.name = "cpuidle-at91",
59 	},
60 	.probe = at91_cpuidle_probe,
61 };
62 builtin_platform_driver(at91_cpuidle_driver);
63