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 
13 #include <soc/imx/cpuidle.h>
14 
15 #include "common.h"
16 #include "cpuidle.h"
17 #include "hardware.h"
18 
19 static int num_idle_cpus = 0;
20 static DEFINE_SPINLOCK(cpuidle_lock);
21 
22 static int imx6q_enter_wait(struct cpuidle_device *dev,
23 			    struct cpuidle_driver *drv, int index)
24 {
25 	spin_lock(&cpuidle_lock);
26 	if (++num_idle_cpus == num_online_cpus())
27 		imx6_set_lpm(WAIT_UNCLOCKED);
28 	spin_unlock(&cpuidle_lock);
29 
30 	cpu_do_idle();
31 
32 	spin_lock(&cpuidle_lock);
33 	if (num_idle_cpus-- == num_online_cpus())
34 		imx6_set_lpm(WAIT_CLOCKED);
35 	spin_unlock(&cpuidle_lock);
36 
37 	return index;
38 }
39 
40 static struct cpuidle_driver imx6q_cpuidle_driver = {
41 	.name = "imx6q_cpuidle",
42 	.owner = THIS_MODULE,
43 	.states = {
44 		/* WFI */
45 		ARM_CPUIDLE_WFI_STATE,
46 		/* WAIT */
47 		{
48 			.exit_latency = 50,
49 			.target_residency = 75,
50 			.flags = CPUIDLE_FLAG_TIMER_STOP,
51 			.enter = imx6q_enter_wait,
52 			.name = "WAIT",
53 			.desc = "Clock off",
54 		},
55 	},
56 	.state_count = 2,
57 	.safe_state_index = 0,
58 };
59 
60 /*
61  * i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the
62  * CPUs when they are in wait(unclocked) state. As the hardware workaround isn't
63  * applicable to all boards, disable the deeper idle state when the workaround
64  * isn't present and the FEC is in use.
65  */
66 void imx6q_cpuidle_fec_irqs_used(void)
67 {
68 	imx6q_cpuidle_driver.states[1].disabled = true;
69 }
70 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used);
71 
72 void imx6q_cpuidle_fec_irqs_unused(void)
73 {
74 	imx6q_cpuidle_driver.states[1].disabled = false;
75 }
76 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused);
77 
78 int __init imx6q_cpuidle_init(void)
79 {
80 	/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
81 	imx6_set_int_mem_clk_lpm(true);
82 
83 	return cpuidle_register(&imx6q_cpuidle_driver, NULL);
84 }
85