xref: /openbmc/linux/arch/arm/mach-davinci/cpuidle.c (revision c819e2cf)
1 /*
2  * CPU idle for DaVinci SoCs
3  *
4  * Copyright (C) 2009 Texas Instruments Incorporated. http://www.ti.com/
5  *
6  * Derived from Marvell Kirkwood CPU idle code
7  * (arch/arm/mach-kirkwood/cpuidle.c)
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/platform_device.h>
17 #include <linux/cpuidle.h>
18 #include <linux/io.h>
19 #include <linux/export.h>
20 #include <asm/proc-fns.h>
21 #include <asm/cpuidle.h>
22 
23 #include <mach/cpuidle.h>
24 #include <mach/ddr2.h>
25 
26 #define DAVINCI_CPUIDLE_MAX_STATES	2
27 
28 static void __iomem *ddr2_reg_base;
29 static bool ddr2_pdown;
30 
31 static void davinci_save_ddr_power(int enter, bool pdown)
32 {
33 	u32 val;
34 
35 	val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
36 
37 	if (enter) {
38 		if (pdown)
39 			val |= DDR2_SRPD_BIT;
40 		else
41 			val &= ~DDR2_SRPD_BIT;
42 		val |= DDR2_LPMODEN_BIT;
43 	} else {
44 		val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
45 	}
46 
47 	__raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
48 }
49 
50 /* Actual code that puts the SoC in different idle states */
51 static int davinci_enter_idle(struct cpuidle_device *dev,
52 			      struct cpuidle_driver *drv, int index)
53 {
54 	davinci_save_ddr_power(1, ddr2_pdown);
55 	cpu_do_idle();
56 	davinci_save_ddr_power(0, ddr2_pdown);
57 
58 	return index;
59 }
60 
61 static struct cpuidle_driver davinci_idle_driver = {
62 	.name			= "cpuidle-davinci",
63 	.owner			= THIS_MODULE,
64 	.states[0]		= ARM_CPUIDLE_WFI_STATE,
65 	.states[1]		= {
66 		.enter			= davinci_enter_idle,
67 		.exit_latency		= 10,
68 		.target_residency	= 10000,
69 		.name			= "DDR SR",
70 		.desc			= "WFI and DDR Self Refresh",
71 	},
72 	.state_count = DAVINCI_CPUIDLE_MAX_STATES,
73 };
74 
75 static int __init davinci_cpuidle_probe(struct platform_device *pdev)
76 {
77 	struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
78 
79 	if (!pdata) {
80 		dev_err(&pdev->dev, "cannot get platform data\n");
81 		return -ENOENT;
82 	}
83 
84 	ddr2_reg_base = pdata->ddr2_ctlr_base;
85 
86 	ddr2_pdown = pdata->ddr2_pdown;
87 
88 	return cpuidle_register(&davinci_idle_driver, NULL);
89 }
90 
91 static struct platform_driver davinci_cpuidle_driver = {
92 	.driver = {
93 		.name	= "cpuidle-davinci",
94 	},
95 };
96 
97 static int __init davinci_cpuidle_init(void)
98 {
99 	return platform_driver_probe(&davinci_cpuidle_driver,
100 						davinci_cpuidle_probe);
101 }
102 device_initcall(davinci_cpuidle_init);
103 
104