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/cpuidle.h>
30 #include <linux/platform_device.h>
31 #include <asm/cpuidle.h>
32 
33 #define ZYNQ_MAX_STATES		2
34 
35 /* Actual code that puts the SoC in different idle states */
zynq_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)36 static int zynq_enter_idle(struct cpuidle_device *dev,
37 			   struct cpuidle_driver *drv, int index)
38 {
39 	/* Add code for DDR self refresh start */
40 	cpu_do_idle();
41 
42 	return index;
43 }
44 
45 static struct cpuidle_driver zynq_idle_driver = {
46 	.name = "zynq_idle",
47 	.owner = THIS_MODULE,
48 	.states = {
49 		ARM_CPUIDLE_WFI_STATE,
50 		{
51 			.enter			= zynq_enter_idle,
52 			.exit_latency		= 10,
53 			.target_residency	= 10000,
54 			.name			= "RAM_SR",
55 			.desc			= "WFI and RAM Self Refresh",
56 		},
57 	},
58 	.safe_state_index = 0,
59 	.state_count = ZYNQ_MAX_STATES,
60 };
61 
62 /* Initialize CPU idle by registering the idle states */
zynq_cpuidle_probe(struct platform_device * pdev)63 static int zynq_cpuidle_probe(struct platform_device *pdev)
64 {
65 	pr_info("Xilinx Zynq CpuIdle Driver started\n");
66 
67 	return cpuidle_register(&zynq_idle_driver, NULL);
68 }
69 
70 static struct platform_driver zynq_cpuidle_driver = {
71 	.driver = {
72 		.name = "cpuidle-zynq",
73 	},
74 	.probe = zynq_cpuidle_probe,
75 };
76 builtin_platform_driver(zynq_cpuidle_driver);
77