1 /*
2  * Copyright (C) 2012 Freescale Semiconductor, Inc.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8 
9 #include <linux/cpuidle.h>
10 #include <linux/module.h>
11 #include <asm/cpuidle.h>
12 #include <asm/proc-fns.h>
13 
14 #include "common.h"
15 #include "cpuidle.h"
16 #include "hardware.h"
17 
18 static atomic_t master = ATOMIC_INIT(0);
19 static DEFINE_SPINLOCK(master_lock);
20 
21 static int imx6q_enter_wait(struct cpuidle_device *dev,
22 			    struct cpuidle_driver *drv, int index)
23 {
24 	if (atomic_inc_return(&master) == num_online_cpus()) {
25 		/*
26 		 * With this lock, we prevent other cpu to exit and enter
27 		 * this function again and become the master.
28 		 */
29 		if (!spin_trylock(&master_lock))
30 			goto idle;
31 		imx6q_set_lpm(WAIT_UNCLOCKED);
32 		cpu_do_idle();
33 		imx6q_set_lpm(WAIT_CLOCKED);
34 		spin_unlock(&master_lock);
35 		goto done;
36 	}
37 
38 idle:
39 	cpu_do_idle();
40 done:
41 	atomic_dec(&master);
42 
43 	return index;
44 }
45 
46 static struct cpuidle_driver imx6q_cpuidle_driver = {
47 	.name = "imx6q_cpuidle",
48 	.owner = THIS_MODULE,
49 	.states = {
50 		/* WFI */
51 		ARM_CPUIDLE_WFI_STATE,
52 		/* WAIT */
53 		{
54 			.exit_latency = 50,
55 			.target_residency = 75,
56 			.flags = CPUIDLE_FLAG_TIME_VALID |
57 			         CPUIDLE_FLAG_TIMER_STOP,
58 			.enter = imx6q_enter_wait,
59 			.name = "WAIT",
60 			.desc = "Clock off",
61 		},
62 	},
63 	.state_count = 2,
64 	.safe_state_index = 0,
65 };
66 
67 int __init imx6q_cpuidle_init(void)
68 {
69 	/* Need to enable SCU standby for entering WAIT modes */
70 	if (!cpu_is_imx6sx())
71 		imx_scu_standby_enable();
72 
73 	/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
74 	imx6q_set_int_mem_clk_lpm(true);
75 
76 	return cpuidle_register(&imx6q_cpuidle_driver, NULL);
77 }
78