1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * CPU idle Marvell Kirkwood SoCs
4  *
5  * The cpu idle uses wait-for-interrupt and DDR self refresh in order
6  * to implement two idle states -
7  * #1 wait-for-interrupt
8  * #2 wait-for-interrupt and DDR self refresh
9  *
10  * Maintainer: Jason Cooper <jason@lakedaemon.net>
11  * Maintainer: Andrew Lunn <andrew@lunn.ch>
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/platform_device.h>
18 #include <linux/cpuidle.h>
19 #include <linux/io.h>
20 #include <linux/export.h>
21 #include <asm/cpuidle.h>
22 
23 #define KIRKWOOD_MAX_STATES	2
24 
25 static void __iomem *ddr_operation_base;
26 
27 /* Actual code that puts the SoC in different idle states */
28 static int kirkwood_enter_idle(struct cpuidle_device *dev,
29 			       struct cpuidle_driver *drv,
30 			       int index)
31 {
32 	writel(0x7, ddr_operation_base);
33 	cpu_do_idle();
34 
35 	return index;
36 }
37 
38 static struct cpuidle_driver kirkwood_idle_driver = {
39 	.name			= "kirkwood_idle",
40 	.owner			= THIS_MODULE,
41 	.states[0]		= ARM_CPUIDLE_WFI_STATE,
42 	.states[1]		= {
43 		.enter			= kirkwood_enter_idle,
44 		.exit_latency		= 10,
45 		.target_residency	= 100000,
46 		.name			= "DDR SR",
47 		.desc			= "WFI and DDR Self Refresh",
48 	},
49 	.state_count = KIRKWOOD_MAX_STATES,
50 };
51 
52 /* Initialize CPU idle by registering the idle states */
53 static int kirkwood_cpuidle_probe(struct platform_device *pdev)
54 {
55 	ddr_operation_base = devm_platform_ioremap_resource(pdev, 0);
56 	if (IS_ERR(ddr_operation_base))
57 		return PTR_ERR(ddr_operation_base);
58 
59 	return cpuidle_register(&kirkwood_idle_driver, NULL);
60 }
61 
62 static int kirkwood_cpuidle_remove(struct platform_device *pdev)
63 {
64 	cpuidle_unregister(&kirkwood_idle_driver);
65 	return 0;
66 }
67 
68 static struct platform_driver kirkwood_cpuidle_driver = {
69 	.probe = kirkwood_cpuidle_probe,
70 	.remove = kirkwood_cpuidle_remove,
71 	.driver = {
72 		   .name = "kirkwood_cpuidle",
73 		   },
74 };
75 
76 module_platform_driver(kirkwood_cpuidle_driver);
77 
78 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
79 MODULE_DESCRIPTION("Kirkwood cpu idle driver");
80 MODULE_LICENSE("GPL v2");
81 MODULE_ALIAS("platform:kirkwood-cpuidle");
82