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. & Insititute 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
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>
20 #include <asm/clock.h>
23 #include <asm/mach-loongson/loongson.h>
27 static struct clk *cpuclk;
29 static void (*saved_cpu_wait) (void);
31 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
32 unsigned long val, void *data);
34 static struct notifier_block loongson2_cpufreq_notifier_block = {
35 .notifier_call = loongson2_cpu_freq_notifier
38 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
39 unsigned long val, void *data)
41 if (val == CPUFREQ_POSTCHANGE)
42 current_cpu_data.udelay_val = loops_per_jiffy;
47 static unsigned int loongson2_cpufreq_get(unsigned int cpu)
49 return clk_get_rate(cpuclk);
53 * Here we notify other drivers of the proposed change and the final change.
55 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
56 unsigned int target_freq,
57 unsigned int relation)
59 unsigned int cpu = policy->cpu;
60 unsigned int newstate = 0;
61 cpumask_t cpus_allowed;
62 struct cpufreq_freqs freqs;
65 cpus_allowed = current->cpus_allowed;
66 set_cpus_allowed_ptr(current, cpumask_of(cpu));
68 if (cpufreq_frequency_table_target
69 (policy, &loongson2_clockmod_table[0], target_freq, relation,
74 ((cpu_clock_freq / 1000) *
75 loongson2_clockmod_table[newstate].driver_data) / 8;
76 if (freq < policy->min || freq > policy->max)
79 pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
81 freqs.old = loongson2_cpufreq_get(cpu);
85 if (freqs.new == freqs.old)
89 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
91 set_cpus_allowed_ptr(current, &cpus_allowed);
93 /* setting the cpu frequency */
94 clk_set_rate(cpuclk, freq);
97 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
99 pr_debug("cpufreq: set frequency %u kHz\n", freq);
104 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
110 cpuclk = clk_get(NULL, "cpu_clk");
111 if (IS_ERR(cpuclk)) {
112 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
113 return PTR_ERR(cpuclk);
116 rate = cpu_clock_freq / 1000;
122 /* clock table init */
124 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
126 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
128 ret = clk_set_rate(cpuclk, rate);
134 return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
137 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
139 cpufreq_frequency_table_put_attr(policy->cpu);
144 static struct cpufreq_driver loongson2_cpufreq_driver = {
146 .init = loongson2_cpufreq_cpu_init,
147 .verify = cpufreq_generic_frequency_table_verify,
148 .target = loongson2_cpufreq_target,
149 .get = loongson2_cpufreq_get,
150 .exit = loongson2_cpufreq_exit,
151 .attr = cpufreq_generic_attr,
154 static struct platform_device_id platform_device_ids[] = {
156 .name = "loongson2_cpufreq",
161 MODULE_DEVICE_TABLE(platform, platform_device_ids);
163 static struct platform_driver platform_driver = {
165 .name = "loongson2_cpufreq",
166 .owner = THIS_MODULE,
168 .id_table = platform_device_ids,
172 * This is the simple version of Loongson-2 wait, Maybe we need do this in
173 * interrupt disabled context.
176 static DEFINE_SPINLOCK(loongson2_wait_lock);
178 static void loongson2_cpu_wait(void)
183 spin_lock_irqsave(&loongson2_wait_lock, flags);
184 cpu_freq = LOONGSON_CHIPCFG0;
185 LOONGSON_CHIPCFG0 &= ~0x7; /* Put CPU into wait mode */
186 LOONGSON_CHIPCFG0 = cpu_freq; /* Restore CPU state */
187 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
191 static int __init cpufreq_init(void)
195 /* Register platform stuff */
196 ret = platform_driver_register(&platform_driver);
200 pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
202 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
203 CPUFREQ_TRANSITION_NOTIFIER);
205 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
207 if (!ret && !nowait) {
208 saved_cpu_wait = cpu_wait;
209 cpu_wait = loongson2_cpu_wait;
215 static void __exit cpufreq_exit(void)
217 if (!nowait && saved_cpu_wait)
218 cpu_wait = saved_cpu_wait;
219 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
220 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
221 CPUFREQ_TRANSITION_NOTIFIER);
223 platform_driver_unregister(&platform_driver);
226 module_init(cpufreq_init);
227 module_exit(cpufreq_exit);
229 module_param(nowait, uint, 0644);
230 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
232 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
233 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
234 MODULE_LICENSE("GPL");