2 * Cpufreq driver for the loongson-2 processors
4 * The 2E revision of loongson processor not support this feature.
6 * Copyright (C) 2006 - 2008 Lemote Inc. & Institute of Computing Technology
7 * Author: Yanhua, yanh@lemote.com
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
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
23 #include <asm/clock.h>
26 #include <asm/mach-loongson64/loongson.h>
30 static void (*saved_cpu_wait) (void);
32 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
33 unsigned long val, void *data);
35 static struct notifier_block loongson2_cpufreq_notifier_block = {
36 .notifier_call = loongson2_cpu_freq_notifier
39 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
40 unsigned long val, void *data)
42 if (val == CPUFREQ_POSTCHANGE)
43 current_cpu_data.udelay_val = loops_per_jiffy;
49 * Here we notify other drivers of the proposed change and the final change.
51 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
57 ((cpu_clock_freq / 1000) *
58 loongson2_clockmod_table[index].driver_data) / 8;
60 /* setting the cpu frequency */
61 clk_set_rate(policy->clk, freq * 1000);
66 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
73 cpuclk = clk_get(NULL, "cpu_clk");
75 pr_err("couldn't get CPU clk\n");
76 return PTR_ERR(cpuclk);
79 rate = cpu_clock_freq / 1000;
85 /* clock table init */
87 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
89 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
91 ret = clk_set_rate(cpuclk, rate * 1000);
98 cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
102 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
104 clk_put(policy->clk);
108 static struct cpufreq_driver loongson2_cpufreq_driver = {
110 .init = loongson2_cpufreq_cpu_init,
111 .verify = cpufreq_generic_frequency_table_verify,
112 .target_index = loongson2_cpufreq_target,
113 .get = cpufreq_generic_get,
114 .exit = loongson2_cpufreq_exit,
115 .attr = cpufreq_generic_attr,
118 static const struct platform_device_id platform_device_ids[] = {
120 .name = "loongson2_cpufreq",
125 MODULE_DEVICE_TABLE(platform, platform_device_ids);
127 static struct platform_driver platform_driver = {
129 .name = "loongson2_cpufreq",
131 .id_table = platform_device_ids,
135 * This is the simple version of Loongson-2 wait, Maybe we need do this in
136 * interrupt disabled context.
139 static DEFINE_SPINLOCK(loongson2_wait_lock);
141 static void loongson2_cpu_wait(void)
146 spin_lock_irqsave(&loongson2_wait_lock, flags);
147 cpu_freq = LOONGSON_CHIPCFG(0);
148 LOONGSON_CHIPCFG(0) &= ~0x7; /* Put CPU into wait mode */
149 LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
150 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
154 static int __init cpufreq_init(void)
158 /* Register platform stuff */
159 ret = platform_driver_register(&platform_driver);
163 pr_info("Loongson-2F CPU frequency driver\n");
165 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
166 CPUFREQ_TRANSITION_NOTIFIER);
168 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
170 if (!ret && !nowait) {
171 saved_cpu_wait = cpu_wait;
172 cpu_wait = loongson2_cpu_wait;
178 static void __exit cpufreq_exit(void)
180 if (!nowait && saved_cpu_wait)
181 cpu_wait = saved_cpu_wait;
182 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
183 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
184 CPUFREQ_TRANSITION_NOTIFIER);
186 platform_driver_unregister(&platform_driver);
189 module_init(cpufreq_init);
190 module_exit(cpufreq_exit);
192 module_param(nowait, uint, 0644);
193 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
195 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
196 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
197 MODULE_LICENSE("GPL");