1/*
2 * Cpufreq driver for the loongson-2 processors
3 *
4 * The 2E revision of loongson processor not support this feature.
5 *
6 * Copyright (C) 2006 - 2008 Lemote Inc. & Institute of Computing Technology
7 * Author: Yanhua, yanh@lemote.com
8 *
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License.  See the file "COPYING" in the main directory of this archive
11 * for more details.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/cpufreq.h>
17#include <linux/module.h>
18#include <linux/err.h>
19#include <linux/delay.h>
20#include <linux/platform_device.h>
21
22#include <asm/idle.h>
23
24#include <asm/mach-loongson2ef/loongson.h>
25
26static uint nowait;
27
28static void (*saved_cpu_wait) (void);
29
30static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
31					unsigned long val, void *data);
32
33static struct notifier_block loongson2_cpufreq_notifier_block = {
34	.notifier_call = loongson2_cpu_freq_notifier
35};
36
37static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
38					unsigned long val, void *data)
39{
40	if (val == CPUFREQ_POSTCHANGE)
41		current_cpu_data.udelay_val = loops_per_jiffy;
42
43	return 0;
44}
45
46/*
47 * Here we notify other drivers of the proposed change and the final change.
48 */
49static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
50				     unsigned int index)
51{
52	unsigned int freq;
53
54	freq =
55	    ((cpu_clock_freq / 1000) *
56	     loongson2_clockmod_table[index].driver_data) / 8;
57
58	/* setting the cpu frequency */
59	loongson2_cpu_set_rate(freq);
60
61	return 0;
62}
63
64static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
65{
66	int i;
67	unsigned long rate;
68	int ret;
69
70	rate = cpu_clock_freq / 1000;
71	if (!rate)
72		return -EINVAL;
73
74	/* clock table init */
75	for (i = 2;
76	     (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
77	     i++)
78		loongson2_clockmod_table[i].frequency = (rate * i) / 8;
79
80	ret = loongson2_cpu_set_rate(rate);
81	if (ret)
82		return ret;
83
84	cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
85	return 0;
86}
87
88static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
89{
90	return 0;
91}
92
93static struct cpufreq_driver loongson2_cpufreq_driver = {
94	.name = "loongson2",
95	.init = loongson2_cpufreq_cpu_init,
96	.verify = cpufreq_generic_frequency_table_verify,
97	.target_index = loongson2_cpufreq_target,
98	.get = cpufreq_generic_get,
99	.exit = loongson2_cpufreq_exit,
100	.attr = cpufreq_generic_attr,
101};
102
103static const struct platform_device_id platform_device_ids[] = {
104	{
105		.name = "loongson2_cpufreq",
106	},
107	{}
108};
109
110MODULE_DEVICE_TABLE(platform, platform_device_ids);
111
112static struct platform_driver platform_driver = {
113	.driver = {
114		.name = "loongson2_cpufreq",
115	},
116	.id_table = platform_device_ids,
117};
118
119/*
120 * This is the simple version of Loongson-2 wait, Maybe we need do this in
121 * interrupt disabled context.
122 */
123
124static DEFINE_SPINLOCK(loongson2_wait_lock);
125
126static void loongson2_cpu_wait(void)
127{
128	unsigned long flags;
129	u32 cpu_freq;
130
131	spin_lock_irqsave(&loongson2_wait_lock, flags);
132	cpu_freq = readl(LOONGSON_CHIPCFG);
133	/* Put CPU into wait mode */
134	writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
135	/* Restore CPU state */
136	writel(cpu_freq, LOONGSON_CHIPCFG);
137	spin_unlock_irqrestore(&loongson2_wait_lock, flags);
138	local_irq_enable();
139}
140
141static int __init cpufreq_init(void)
142{
143	int ret;
144
145	/* Register platform stuff */
146	ret = platform_driver_register(&platform_driver);
147	if (ret)
148		return ret;
149
150	pr_info("Loongson-2F CPU frequency driver\n");
151
152	cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
153				  CPUFREQ_TRANSITION_NOTIFIER);
154
155	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
156
157	if (!ret && !nowait) {
158		saved_cpu_wait = cpu_wait;
159		cpu_wait = loongson2_cpu_wait;
160	}
161
162	return ret;
163}
164
165static void __exit cpufreq_exit(void)
166{
167	if (!nowait && saved_cpu_wait)
168		cpu_wait = saved_cpu_wait;
169	cpufreq_unregister_driver(&loongson2_cpufreq_driver);
170	cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
171				    CPUFREQ_TRANSITION_NOTIFIER);
172
173	platform_driver_unregister(&platform_driver);
174}
175
176module_init(cpufreq_init);
177module_exit(cpufreq_exit);
178
179module_param(nowait, uint, 0644);
180MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
181
182MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
183MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
184MODULE_LICENSE("GPL");
185