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. & Insititute 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#include <linux/cpufreq.h>
14#include <linux/module.h>
15#include <linux/err.h>
16#include <linux/sched.h>	/* set_cpus_allowed() */
17#include <linux/delay.h>
18#include <linux/platform_device.h>
19
20#include <asm/clock.h>
21#include <asm/idle.h>
22
23#include <asm/mach-loongson/loongson.h>
24
25static uint nowait;
26
27static void (*saved_cpu_wait) (void);
28
29static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
30					unsigned long val, void *data);
31
32static struct notifier_block loongson2_cpufreq_notifier_block = {
33	.notifier_call = loongson2_cpu_freq_notifier
34};
35
36static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
37					unsigned long val, void *data)
38{
39	if (val == CPUFREQ_POSTCHANGE)
40		current_cpu_data.udelay_val = loops_per_jiffy;
41
42	return 0;
43}
44
45/*
46 * Here we notify other drivers of the proposed change and the final change.
47 */
48static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
49				     unsigned int index)
50{
51	unsigned int cpu = policy->cpu;
52	cpumask_t cpus_allowed;
53	unsigned int freq;
54
55	cpus_allowed = current->cpus_allowed;
56	set_cpus_allowed_ptr(current, cpumask_of(cpu));
57
58	freq =
59	    ((cpu_clock_freq / 1000) *
60	     loongson2_clockmod_table[index].driver_data) / 8;
61
62	set_cpus_allowed_ptr(current, &cpus_allowed);
63
64	/* setting the cpu frequency */
65	clk_set_rate(policy->clk, freq * 1000);
66
67	return 0;
68}
69
70static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
71{
72	struct clk *cpuclk;
73	int i;
74	unsigned long rate;
75	int ret;
76
77	cpuclk = clk_get(NULL, "cpu_clk");
78	if (IS_ERR(cpuclk)) {
79		printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
80		return PTR_ERR(cpuclk);
81	}
82
83	rate = cpu_clock_freq / 1000;
84	if (!rate) {
85		clk_put(cpuclk);
86		return -EINVAL;
87	}
88
89	/* clock table init */
90	for (i = 2;
91	     (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
92	     i++)
93		loongson2_clockmod_table[i].frequency = (rate * i) / 8;
94
95	ret = clk_set_rate(cpuclk, rate * 1000);
96	if (ret) {
97		clk_put(cpuclk);
98		return ret;
99	}
100
101	policy->clk = cpuclk;
102	return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
103}
104
105static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
106{
107	clk_put(policy->clk);
108	return 0;
109}
110
111static struct cpufreq_driver loongson2_cpufreq_driver = {
112	.name = "loongson2",
113	.init = loongson2_cpufreq_cpu_init,
114	.verify = cpufreq_generic_frequency_table_verify,
115	.target_index = loongson2_cpufreq_target,
116	.get = cpufreq_generic_get,
117	.exit = loongson2_cpufreq_exit,
118	.attr = cpufreq_generic_attr,
119};
120
121static struct platform_device_id platform_device_ids[] = {
122	{
123		.name = "loongson2_cpufreq",
124	},
125	{}
126};
127
128MODULE_DEVICE_TABLE(platform, platform_device_ids);
129
130static struct platform_driver platform_driver = {
131	.driver = {
132		.name = "loongson2_cpufreq",
133	},
134	.id_table = platform_device_ids,
135};
136
137/*
138 * This is the simple version of Loongson-2 wait, Maybe we need do this in
139 * interrupt disabled context.
140 */
141
142static DEFINE_SPINLOCK(loongson2_wait_lock);
143
144static void loongson2_cpu_wait(void)
145{
146	unsigned long flags;
147	u32 cpu_freq;
148
149	spin_lock_irqsave(&loongson2_wait_lock, flags);
150	cpu_freq = LOONGSON_CHIPCFG(0);
151	LOONGSON_CHIPCFG(0) &= ~0x7;	/* Put CPU into wait mode */
152	LOONGSON_CHIPCFG(0) = cpu_freq;	/* Restore CPU state */
153	spin_unlock_irqrestore(&loongson2_wait_lock, flags);
154	local_irq_enable();
155}
156
157static int __init cpufreq_init(void)
158{
159	int ret;
160
161	/* Register platform stuff */
162	ret = platform_driver_register(&platform_driver);
163	if (ret)
164		return ret;
165
166	pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
167
168	cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
169				  CPUFREQ_TRANSITION_NOTIFIER);
170
171	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
172
173	if (!ret && !nowait) {
174		saved_cpu_wait = cpu_wait;
175		cpu_wait = loongson2_cpu_wait;
176	}
177
178	return ret;
179}
180
181static void __exit cpufreq_exit(void)
182{
183	if (!nowait && saved_cpu_wait)
184		cpu_wait = saved_cpu_wait;
185	cpufreq_unregister_driver(&loongson2_cpufreq_driver);
186	cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
187				    CPUFREQ_TRANSITION_NOTIFIER);
188
189	platform_driver_unregister(&platform_driver);
190}
191
192module_init(cpufreq_init);
193module_exit(cpufreq_exit);
194
195module_param(nowait, uint, 0644);
196MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
197
198MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
199MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
200MODULE_LICENSE("GPL");
201