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>
22 #include <asm/mach-loongson/loongson.h>
26 static struct clk *cpuclk;
28 static void (*saved_cpu_wait) (void);
30 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
31 unsigned long val, void *data);
33 static struct notifier_block loongson2_cpufreq_notifier_block = {
34 .notifier_call = loongson2_cpu_freq_notifier
37 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
38 unsigned long val, void *data)
40 if (val == CPUFREQ_POSTCHANGE)
41 current_cpu_data.udelay_val = loops_per_jiffy;
46 static unsigned int loongson2_cpufreq_get(unsigned int cpu)
48 return clk_get_rate(cpuclk);
52 * Here we notify other drivers of the proposed change and the final change.
54 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
55 unsigned int target_freq,
56 unsigned int relation)
58 unsigned int cpu = policy->cpu;
59 unsigned int newstate = 0;
60 cpumask_t cpus_allowed;
61 struct cpufreq_freqs freqs;
64 cpus_allowed = current->cpus_allowed;
65 set_cpus_allowed_ptr(current, cpumask_of(cpu));
67 if (cpufreq_frequency_table_target
68 (policy, &loongson2_clockmod_table[0], target_freq, relation,
73 ((cpu_clock_freq / 1000) *
74 loongson2_clockmod_table[newstate].index) / 8;
75 if (freq < policy->min || freq > policy->max)
78 pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
80 freqs.old = loongson2_cpufreq_get(cpu);
84 if (freqs.new == freqs.old)
88 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
90 set_cpus_allowed_ptr(current, &cpus_allowed);
92 /* setting the cpu frequency */
93 clk_set_rate(cpuclk, freq);
96 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
98 pr_debug("cpufreq: set frequency %u kHz\n", freq);
103 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
109 cpuclk = clk_get(NULL, "cpu_clk");
110 if (IS_ERR(cpuclk)) {
111 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
112 return PTR_ERR(cpuclk);
115 rate = cpu_clock_freq / 1000;
120 ret = clk_set_rate(cpuclk, rate);
126 /* clock table init */
128 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
130 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
132 policy->cur = loongson2_cpufreq_get(policy->cpu);
134 cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
137 return cpufreq_frequency_table_cpuinfo(policy,
138 &loongson2_clockmod_table[0]);
141 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
143 return cpufreq_frequency_table_verify(policy,
144 &loongson2_clockmod_table[0]);
147 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
153 static struct freq_attr *loongson2_table_attr[] = {
154 &cpufreq_freq_attr_scaling_available_freqs,
158 static struct cpufreq_driver loongson2_cpufreq_driver = {
159 .owner = THIS_MODULE,
161 .init = loongson2_cpufreq_cpu_init,
162 .verify = loongson2_cpufreq_verify,
163 .target = loongson2_cpufreq_target,
164 .get = loongson2_cpufreq_get,
165 .exit = loongson2_cpufreq_exit,
166 .attr = loongson2_table_attr,
169 static struct platform_device_id platform_device_ids[] = {
171 .name = "loongson2_cpufreq",
176 MODULE_DEVICE_TABLE(platform, platform_device_ids);
178 static struct platform_driver platform_driver = {
180 .name = "loongson2_cpufreq",
181 .owner = THIS_MODULE,
183 .id_table = platform_device_ids,
187 * This is the simple version of Loongson-2 wait, Maybe we need do this in
188 * interrupt disabled context.
191 static DEFINE_SPINLOCK(loongson2_wait_lock);
193 static void loongson2_cpu_wait(void)
198 spin_lock_irqsave(&loongson2_wait_lock, flags);
199 cpu_freq = LOONGSON_CHIPCFG0;
200 LOONGSON_CHIPCFG0 &= ~0x7; /* Put CPU into wait mode */
201 LOONGSON_CHIPCFG0 = cpu_freq; /* Restore CPU state */
202 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
205 static int __init cpufreq_init(void)
209 /* Register platform stuff */
210 ret = platform_driver_register(&platform_driver);
214 pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
216 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
217 CPUFREQ_TRANSITION_NOTIFIER);
219 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
221 if (!ret && !nowait) {
222 saved_cpu_wait = cpu_wait;
223 cpu_wait = loongson2_cpu_wait;
229 static void __exit cpufreq_exit(void)
231 if (!nowait && saved_cpu_wait)
232 cpu_wait = saved_cpu_wait;
233 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
234 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
235 CPUFREQ_TRANSITION_NOTIFIER);
237 platform_driver_unregister(&platform_driver);
240 module_init(cpufreq_init);
241 module_exit(cpufreq_exit);
243 module_param(nowait, uint, 0644);
244 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
246 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
247 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
248 MODULE_LICENSE("GPL");