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 atomic_t master = ATOMIC_INIT(0);
20 static DEFINE_SPINLOCK(master_lock);
21 
22 static int imx6q_enter_wait(struct cpuidle_device *dev,
23 			    struct cpuidle_driver *drv, int index)
24 {
25 	if (atomic_inc_return(&master) == num_online_cpus()) {
26 		/*
27 		 * With this lock, we prevent other cpu to exit and enter
28 		 * this function again and become the master.
29 		 */
30 		if (!spin_trylock(&master_lock))
31 			goto idle;
32 		imx6_set_lpm(WAIT_UNCLOCKED);
33 		cpu_do_idle();
34 		imx6_set_lpm(WAIT_CLOCKED);
35 		spin_unlock(&master_lock);
36 		goto done;
37 	}
38 
39 idle:
40 	cpu_do_idle();
41 done:
42 	atomic_dec(&master);
43 
44 	return index;
45 }
46 
47 static struct cpuidle_driver imx6q_cpuidle_driver = {
48 	.name = "imx6q_cpuidle",
49 	.owner = THIS_MODULE,
50 	.states = {
51 		/* WFI */
52 		ARM_CPUIDLE_WFI_STATE,
53 		/* WAIT */
54 		{
55 			.exit_latency = 50,
56 			.target_residency = 75,
57 			.flags = 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 /*
68  * i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the
69  * CPUs when they are in wait(unclocked) state. As the hardware workaround isn't
70  * applicable to all boards, disable the deeper idle state when the workaround
71  * isn't present and the FEC is in use.
72  */
73 void imx6q_cpuidle_fec_irqs_used(void)
74 {
75 	imx6q_cpuidle_driver.states[1].disabled = true;
76 }
77 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used);
78 
79 void imx6q_cpuidle_fec_irqs_unused(void)
80 {
81 	imx6q_cpuidle_driver.states[1].disabled = false;
82 }
83 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused);
84 
85 int __init imx6q_cpuidle_init(void)
86 {
87 	/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
88 	imx6q_set_int_mem_clk_lpm(true);
89 
90 	return cpuidle_register(&imx6q_cpuidle_driver, NULL);
91 }
92