blob: 38e03a18359156077e17d8f5b35671de47bf6d8e [file] [log] [blame]
Michal Simekbd2a3372013-06-04 07:17:39 +00001/*
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/of.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 */
38static 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
53static 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 */
73static int __init zynq_cpuidle_init(void)
74{
75 if (!of_machine_is_compatible("xlnx,zynq-7000"))
76 return -ENODEV;
77
78 pr_info("Xilinx Zynq CpuIdle Driver started\n");
79
80 return cpuidle_register(&zynq_idle_driver, NULL);
81}
82
83device_initcall(zynq_cpuidle_init);