1 /*
2  * Copyright (C) 2012-2013 Xilinx
3  *
4  * CPU idle support for Xilinx Zynq
5  *
6  * based on arch/arm/mach-at91/cpuidle.c
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms and conditions of the GNU General Public License,
10  * version 2, as published by the Free Software Foundation.
11  *
12  * This program is distributed in the hope it will be useful, but WITHOUT
13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
15  * more details.
16  *
17  * You should have received a copy of the GNU General Public License along with
18  * this program.  If not, see <http://www.gnu.org/licenses/>.
19  *
20  * The cpu idle uses wait-for-interrupt and RAM self refresh in order
21  * to implement two idle states -
22  * #1 wait-for-interrupt
23  * #2 wait-for-interrupt and RAM self refresh
24  *
25  * Maintainer: Michal Simek <michal.simek@xilinx.com>
26  */
27 
28 #include <linux/init.h>
29 #include <linux/cpu_pm.h>
30 #include <linux/cpuidle.h>
31 #include <linux/platform_device.h>
32 #include <asm/proc-fns.h>
33 #include <asm/cpuidle.h>
34 
35 #define ZYNQ_MAX_STATES		2
36 
37 /* Actual code that puts the SoC in different idle states */
38 static int zynq_enter_idle(struct cpuidle_device *dev,
39 			   struct cpuidle_driver *drv, int index)
40 {
41 	/* Devices must be stopped here */
42 	cpu_pm_enter();
43 
44 	/* Add code for DDR self refresh start */
45 	cpu_do_idle();
46 
47 	/* Add code for DDR self refresh stop */
48 	cpu_pm_exit();
49 
50 	return index;
51 }
52 
53 static struct cpuidle_driver zynq_idle_driver = {
54 	.name = "zynq_idle",
55 	.owner = THIS_MODULE,
56 	.states = {
57 		ARM_CPUIDLE_WFI_STATE,
58 		{
59 			.enter			= zynq_enter_idle,
60 			.exit_latency		= 10,
61 			.target_residency	= 10000,
62 			.flags			= CPUIDLE_FLAG_TIME_VALID |
63 						  CPUIDLE_FLAG_TIMER_STOP,
64 			.name			= "RAM_SR",
65 			.desc			= "WFI and RAM Self Refresh",
66 		},
67 	},
68 	.safe_state_index = 0,
69 	.state_count = ZYNQ_MAX_STATES,
70 };
71 
72 /* Initialize CPU idle by registering the idle states */
73 static int zynq_cpuidle_probe(struct platform_device *pdev)
74 {
75 	pr_info("Xilinx Zynq CpuIdle Driver started\n");
76 
77 	return cpuidle_register(&zynq_idle_driver, NULL);
78 }
79 
80 static struct platform_driver zynq_cpuidle_driver = {
81 	.driver = {
82 		.name = "cpuidle-zynq",
83 		.owner = THIS_MODULE,
84 	},
85 	.probe = zynq_cpuidle_probe,
86 };
87 
88 module_platform_driver(zynq_cpuidle_driver);
89