1 /*
2  * CPU idle Marvell Kirkwood SoCs
3  *
4  * This file is licensed under the terms of the GNU General Public
5  * License version 2.  This program is licensed "as is" without any
6  * warranty of any kind, whether express or implied.
7  *
8  * The cpu idle uses wait-for-interrupt and DDR self refresh in order
9  * to implement two idle states -
10  * #1 wait-for-interrupt
11  * #2 wait-for-interrupt and DDR self refresh
12  *
13  * Maintainer: Jason Cooper <jason@lakedaemon.net>
14  * Maintainer: Andrew Lunn <andrew@lunn.ch>
15  */
16 
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/init.h>
20 #include <linux/platform_device.h>
21 #include <linux/cpuidle.h>
22 #include <linux/io.h>
23 #include <linux/export.h>
24 #include <asm/cpuidle.h>
25 
26 #define KIRKWOOD_MAX_STATES	2
27 
28 static void __iomem *ddr_operation_base;
29 
30 /* Actual code that puts the SoC in different idle states */
31 static int kirkwood_enter_idle(struct cpuidle_device *dev,
32 			       struct cpuidle_driver *drv,
33 			       int index)
34 {
35 	writel(0x7, ddr_operation_base);
36 	cpu_do_idle();
37 
38 	return index;
39 }
40 
41 static struct cpuidle_driver kirkwood_idle_driver = {
42 	.name			= "kirkwood_idle",
43 	.owner			= THIS_MODULE,
44 	.states[0]		= ARM_CPUIDLE_WFI_STATE,
45 	.states[1]		= {
46 		.enter			= kirkwood_enter_idle,
47 		.exit_latency		= 10,
48 		.target_residency	= 100000,
49 		.name			= "DDR SR",
50 		.desc			= "WFI and DDR Self Refresh",
51 	},
52 	.state_count = KIRKWOOD_MAX_STATES,
53 };
54 
55 /* Initialize CPU idle by registering the idle states */
56 static int kirkwood_cpuidle_probe(struct platform_device *pdev)
57 {
58 	ddr_operation_base = devm_platform_ioremap_resource(pdev, 0);
59 	if (IS_ERR(ddr_operation_base))
60 		return PTR_ERR(ddr_operation_base);
61 
62 	return cpuidle_register(&kirkwood_idle_driver, NULL);
63 }
64 
65 static int kirkwood_cpuidle_remove(struct platform_device *pdev)
66 {
67 	cpuidle_unregister(&kirkwood_idle_driver);
68 	return 0;
69 }
70 
71 static struct platform_driver kirkwood_cpuidle_driver = {
72 	.probe = kirkwood_cpuidle_probe,
73 	.remove = kirkwood_cpuidle_remove,
74 	.driver = {
75 		   .name = "kirkwood_cpuidle",
76 		   },
77 };
78 
79 module_platform_driver(kirkwood_cpuidle_driver);
80 
81 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
82 MODULE_DESCRIPTION("Kirkwood cpu idle driver");
83 MODULE_LICENSE("GPL v2");
84 MODULE_ALIAS("platform:kirkwood-cpuidle");
85