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/proc-fns.h>
25 #include <asm/cpuidle.h>
26 
27 #define KIRKWOOD_MAX_STATES	2
28 
29 static void __iomem *ddr_operation_base;
30 
31 /* Actual code that puts the SoC in different idle states */
32 static int kirkwood_enter_idle(struct cpuidle_device *dev,
33 			       struct cpuidle_driver *drv,
34 			       int index)
35 {
36 	writel(0x7, ddr_operation_base);
37 	cpu_do_idle();
38 
39 	return index;
40 }
41 
42 static struct cpuidle_driver kirkwood_idle_driver = {
43 	.name			= "kirkwood_idle",
44 	.owner			= THIS_MODULE,
45 	.states[0]		= ARM_CPUIDLE_WFI_STATE,
46 	.states[1]		= {
47 		.enter			= kirkwood_enter_idle,
48 		.exit_latency		= 10,
49 		.target_residency	= 100000,
50 		.flags			= CPUIDLE_FLAG_TIME_VALID,
51 		.name			= "DDR SR",
52 		.desc			= "WFI and DDR Self Refresh",
53 	},
54 	.state_count = KIRKWOOD_MAX_STATES,
55 };
56 
57 /* Initialize CPU idle by registering the idle states */
58 static int kirkwood_cpuidle_probe(struct platform_device *pdev)
59 {
60 	struct resource *res;
61 
62 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
63 	if (res == NULL)
64 		return -EINVAL;
65 
66 	ddr_operation_base = devm_ioremap_resource(&pdev->dev, res);
67 	if (IS_ERR(ddr_operation_base))
68 		return PTR_ERR(ddr_operation_base);
69 
70 	return cpuidle_register(&kirkwood_idle_driver, NULL);
71 }
72 
73 int kirkwood_cpuidle_remove(struct platform_device *pdev)
74 {
75 	cpuidle_unregister(&kirkwood_idle_driver);
76 	return 0;
77 }
78 
79 static struct platform_driver kirkwood_cpuidle_driver = {
80 	.probe = kirkwood_cpuidle_probe,
81 	.remove = kirkwood_cpuidle_remove,
82 	.driver = {
83 		   .name = "kirkwood_cpuidle",
84 		   .owner = THIS_MODULE,
85 		   },
86 };
87 
88 module_platform_driver(kirkwood_cpuidle_driver);
89 
90 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
91 MODULE_DESCRIPTION("Kirkwood cpu idle driver");
92 MODULE_LICENSE("GPL v2");
93 MODULE_ALIAS("platform:kirkwood-cpuidle");
94