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/sched.h>	/* set_cpus_allowed() */
20#include <linux/delay.h>
21#include <linux/platform_device.h>
22
23#include <asm/idle.h>
24
25#include <asm/mach-loongson2ef/loongson.h>
26
27static uint nowait;
28
29static void (*saved_cpu_wait) (void);
30
31static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
32					unsigned long val, void *data);
33
34static struct notifier_block loongson2_cpufreq_notifier_block = {
35	.notifier_call = loongson2_cpu_freq_notifier
36};
37
38static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
39					unsigned long val, void *data)
40{
41	if (val == CPUFREQ_POSTCHANGE)
42		current_cpu_data.udelay_val = loops_per_jiffy;
43
44	return 0;
45}
46
47/*
48 * Here we notify other drivers of the proposed change and the final change.
49 */
50static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
51				     unsigned int index)
52{
53	unsigned int freq;
54
55	freq =
56	    ((cpu_clock_freq / 1000) *
57	     loongson2_clockmod_table[index].driver_data) / 8;
58
59	/* setting the cpu frequency */
60	loongson2_cpu_set_rate(freq);
61
62	return 0;
63}
64
65static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
66{
67	int i;
68	unsigned long rate;
69	int ret;
70
71	rate = cpu_clock_freq / 1000;
72	if (!rate)
73		return -EINVAL;
74
75	/* clock table init */
76	for (i = 2;
77	     (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
78	     i++)
79		loongson2_clockmod_table[i].frequency = (rate * i) / 8;
80
81	ret = loongson2_cpu_set_rate(rate);
82	if (ret)
83		return ret;
84
85	cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
86	return 0;
87}
88
89static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
90{
91	return 0;
92}
93
94static struct cpufreq_driver loongson2_cpufreq_driver = {
95	.name = "loongson2",
96	.init = loongson2_cpufreq_cpu_init,
97	.verify = cpufreq_generic_frequency_table_verify,
98	.target_index = loongson2_cpufreq_target,
99	.get = cpufreq_generic_get,
100	.exit = loongson2_cpufreq_exit,
101	.attr = cpufreq_generic_attr,
102};
103
104static const struct platform_device_id platform_device_ids[] = {
105	{
106		.name = "loongson2_cpufreq",
107	},
108	{}
109};
110
111MODULE_DEVICE_TABLE(platform, platform_device_ids);
112
113static struct platform_driver platform_driver = {
114	.driver = {
115		.name = "loongson2_cpufreq",
116	},
117	.id_table = platform_device_ids,
118};
119
120/*
121 * This is the simple version of Loongson-2 wait, Maybe we need do this in
122 * interrupt disabled context.
123 */
124
125static DEFINE_SPINLOCK(loongson2_wait_lock);
126
127static void loongson2_cpu_wait(void)
128{
129	unsigned long flags;
130	u32 cpu_freq;
131
132	spin_lock_irqsave(&loongson2_wait_lock, flags);
133	cpu_freq = readl(LOONGSON_CHIPCFG);
134	/* Put CPU into wait mode */
135	writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
136	/* Restore CPU state */
137	writel(cpu_freq, LOONGSON_CHIPCFG);
138	spin_unlock_irqrestore(&loongson2_wait_lock, flags);
139	local_irq_enable();
140}
141
142static int __init cpufreq_init(void)
143{
144	int ret;
145
146	/* Register platform stuff */
147	ret = platform_driver_register(&platform_driver);
148	if (ret)
149		return ret;
150
151	pr_info("Loongson-2F CPU frequency driver\n");
152
153	cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
154				  CPUFREQ_TRANSITION_NOTIFIER);
155
156	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
157
158	if (!ret && !nowait) {
159		saved_cpu_wait = cpu_wait;
160		cpu_wait = loongson2_cpu_wait;
161	}
162
163	return ret;
164}
165
166static void __exit cpufreq_exit(void)
167{
168	if (!nowait && saved_cpu_wait)
169		cpu_wait = saved_cpu_wait;
170	cpufreq_unregister_driver(&loongson2_cpufreq_driver);
171	cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
172				    CPUFREQ_TRANSITION_NOTIFIER);
173
174	platform_driver_unregister(&platform_driver);
175}
176
177module_init(cpufreq_init);
178module_exit(cpufreq_exit);
179
180module_param(nowait, uint, 0644);
181MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
182
183MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
184MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
185MODULE_LICENSE("GPL");
186