summaryrefslogtreecommitdiffstats
path: root/drivers/cpufreq/loongson2_cpufreq.c
blob: d05e761d95721ee8bc892313b034b2110e0fa95f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
/*
 * Cpufreq driver for the loongson-2 processors
 *
 * The 2E revision of loongson processor not support this feature.
 *
 * Copyright (C) 2006 - 2008 Lemote Inc. & Institute of Computing Technology
 * Author: Yanhua, yanh@lemote.com
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/sched.h>	/* set_cpus_allowed() */
#include <linux/delay.h>
#include <linux/platform_device.h>

#include <asm/idle.h>

#include <asm/mach-loongson2ef/loongson.h>

static uint nowait;

static void (*saved_cpu_wait) (void);

static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
					unsigned long val, void *data);

static struct notifier_block loongson2_cpufreq_notifier_block = {
	.notifier_call = loongson2_cpu_freq_notifier
};

static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
					unsigned long val, void *data)
{
	if (val == CPUFREQ_POSTCHANGE)
		current_cpu_data.udelay_val = loops_per_jiffy;

	return 0;
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
				     unsigned int index)
{
	unsigned int freq;

	freq =
	    ((cpu_clock_freq / 1000) *
	     loongson2_clockmod_table[index].driver_data) / 8;

	/* setting the cpu frequency */
	loongson2_cpu_set_rate(freq);

	return 0;
}

static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
	int i;
	unsigned long rate;
	int ret;

	rate = cpu_clock_freq / 1000;
	if (!rate)
		return -EINVAL;

	/* clock table init */
	for (i = 2;
	     (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
	     i++)
		loongson2_clockmod_table[i].frequency = (rate * i) / 8;

	ret = loongson2_cpu_set_rate(rate);
	if (ret)
		return ret;

	cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
	return 0;
}

static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
{
	return 0;
}

static struct cpufreq_driver loongson2_cpufreq_driver = {
	.name = "loongson2",
	.init = loongson2_cpufreq_cpu_init,
	.verify = cpufreq_generic_frequency_table_verify,
	.target_index = loongson2_cpufreq_target,
	.get = cpufreq_generic_get,
	.exit = loongson2_cpufreq_exit,
	.attr = cpufreq_generic_attr,
};

static const struct platform_device_id platform_device_ids[] = {
	{
		.name = "loongson2_cpufreq",
	},
	{}
};

MODULE_DEVICE_TABLE(platform, platform_device_ids);

static struct platform_driver platform_driver = {
	.driver = {
		.name = "loongson2_cpufreq",
	},
	.id_table = platform_device_ids,
};

/*
 * This is the simple version of Loongson-2 wait, Maybe we need do this in
 * interrupt disabled context.
 */

static DEFINE_SPINLOCK(loongson2_wait_lock);

static void loongson2_cpu_wait(void)
{
	unsigned long flags;
	u32 cpu_freq;

	spin_lock_irqsave(&loongson2_wait_lock, flags);
	cpu_freq = readl(LOONGSON_CHIPCFG);
	/* Put CPU into wait mode */
	writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
	/* Restore CPU state */
	writel(cpu_freq, LOONGSON_CHIPCFG);
	spin_unlock_irqrestore(&loongson2_wait_lock, flags);
	local_irq_enable();
}

static int __init cpufreq_init(void)
{
	int ret;

	/* Register platform stuff */
	ret = platform_driver_register(&platform_driver);
	if (ret)
		return ret;

	pr_info("Loongson-2F CPU frequency driver\n");

	cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
				  CPUFREQ_TRANSITION_NOTIFIER);

	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);

	if (!ret && !nowait) {
		saved_cpu_wait = cpu_wait;
		cpu_wait = loongson2_cpu_wait;
	}

	return ret;
}

static void __exit cpufreq_exit(void)
{
	if (!nowait && saved_cpu_wait)
		cpu_wait = saved_cpu_wait;
	cpufreq_unregister_driver(&loongson2_cpufreq_driver);
	cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
				    CPUFREQ_TRANSITION_NOTIFIER);

	platform_driver_unregister(&platform_driver);
}

module_init(cpufreq_init);
module_exit(cpufreq_exit);

module_param(nowait, uint, 0644);
MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");

MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
MODULE_LICENSE("GPL");