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
22 #include <loongson.h>
23
24 static uint nowait;
25
26 static struct clk *cpuclk;
27
28 static void (*saved_cpu_wait) (void);
29
30 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
31 unsigned long val, void *data);
32
33 static struct notifier_block loongson2_cpufreq_notifier_block = {
34 .notifier_call = loongson2_cpu_freq_notifier
35 };
36
loongson2_cpu_freq_notifier(struct notifier_block * nb,unsigned long val,void * data)37 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
38 unsigned long val, void *data)
39 {
40 if (val == CPUFREQ_POSTCHANGE)
41 current_cpu_data.udelay_val = loops_per_jiffy;
42
43 return 0;
44 }
45
loongson2_cpufreq_get(unsigned int cpu)46 static unsigned int loongson2_cpufreq_get(unsigned int cpu)
47 {
48 return clk_get_rate(cpuclk);
49 }
50
51 /*
52 * Here we notify other drivers of the proposed change and the final change.
53 */
loongson2_cpufreq_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)54 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
55 unsigned int target_freq,
56 unsigned int relation)
57 {
58 unsigned int cpu = policy->cpu;
59 unsigned int newstate = 0;
60 cpumask_t cpus_allowed;
61 struct cpufreq_freqs freqs;
62 unsigned int freq;
63
64 if (!cpu_online(cpu))
65 return -ENODEV;
66
67 cpus_allowed = current->cpus_allowed;
68 set_cpus_allowed_ptr(current, cpumask_of(cpu));
69
70 if (cpufreq_frequency_table_target
71 (policy, &loongson2_clockmod_table[0], target_freq, relation,
72 &newstate))
73 return -EINVAL;
74
75 freq =
76 ((cpu_clock_freq / 1000) *
77 loongson2_clockmod_table[newstate].index) / 8;
78 if (freq < policy->min || freq > policy->max)
79 return -EINVAL;
80
81 pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
82
83 freqs.cpu = cpu;
84 freqs.old = loongson2_cpufreq_get(cpu);
85 freqs.new = freq;
86 freqs.flags = 0;
87
88 if (freqs.new == freqs.old)
89 return 0;
90
91 /* notifiers */
92 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
93
94 set_cpus_allowed_ptr(current, &cpus_allowed);
95
96 /* setting the cpu frequency */
97 clk_set_rate(cpuclk, freq);
98
99 /* notifiers */
100 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
101
102 pr_debug("cpufreq: set frequency %u kHz\n", freq);
103
104 return 0;
105 }
106
loongson2_cpufreq_cpu_init(struct cpufreq_policy * policy)107 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
108 {
109 int i;
110
111 if (!cpu_online(policy->cpu))
112 return -ENODEV;
113
114 cpuclk = clk_get(NULL, "cpu_clk");
115 if (IS_ERR(cpuclk)) {
116 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
117 return PTR_ERR(cpuclk);
118 }
119
120 cpuclk->rate = cpu_clock_freq / 1000;
121 if (!cpuclk->rate)
122 return -EINVAL;
123
124 /* clock table init */
125 for (i = 2;
126 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
127 i++)
128 loongson2_clockmod_table[i].frequency = (cpuclk->rate * i) / 8;
129
130 policy->cur = loongson2_cpufreq_get(policy->cpu);
131
132 cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
133 policy->cpu);
134
135 return cpufreq_frequency_table_cpuinfo(policy,
136 &loongson2_clockmod_table[0]);
137 }
138
loongson2_cpufreq_verify(struct cpufreq_policy * policy)139 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
140 {
141 return cpufreq_frequency_table_verify(policy,
142 &loongson2_clockmod_table[0]);
143 }
144
loongson2_cpufreq_exit(struct cpufreq_policy * policy)145 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
146 {
147 clk_put(cpuclk);
148 return 0;
149 }
150
151 static struct freq_attr *loongson2_table_attr[] = {
152 &cpufreq_freq_attr_scaling_available_freqs,
153 NULL,
154 };
155
156 static struct cpufreq_driver loongson2_cpufreq_driver = {
157 .owner = THIS_MODULE,
158 .name = "loongson2",
159 .init = loongson2_cpufreq_cpu_init,
160 .verify = loongson2_cpufreq_verify,
161 .target = loongson2_cpufreq_target,
162 .get = loongson2_cpufreq_get,
163 .exit = loongson2_cpufreq_exit,
164 .attr = loongson2_table_attr,
165 };
166
167 static struct platform_device_id platform_device_ids[] = {
168 {
169 .name = "loongson2_cpufreq",
170 },
171 {}
172 };
173
174 MODULE_DEVICE_TABLE(platform, platform_device_ids);
175
176 static struct platform_driver platform_driver = {
177 .driver = {
178 .name = "loongson2_cpufreq",
179 .owner = THIS_MODULE,
180 },
181 .id_table = platform_device_ids,
182 };
183
cpufreq_init(void)184 static int __init cpufreq_init(void)
185 {
186 int ret;
187
188 /* Register platform stuff */
189 ret = platform_driver_register(&platform_driver);
190 if (ret)
191 return ret;
192
193 pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
194
195 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
196 CPUFREQ_TRANSITION_NOTIFIER);
197
198 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
199
200 if (!ret && !nowait) {
201 saved_cpu_wait = cpu_wait;
202 cpu_wait = loongson2_cpu_wait;
203 }
204
205 return ret;
206 }
207
cpufreq_exit(void)208 static void __exit cpufreq_exit(void)
209 {
210 if (!nowait && saved_cpu_wait)
211 cpu_wait = saved_cpu_wait;
212 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
213 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
214 CPUFREQ_TRANSITION_NOTIFIER);
215
216 platform_driver_unregister(&platform_driver);
217 }
218
219 module_init(cpufreq_init);
220 module_exit(cpufreq_exit);
221
222 module_param(nowait, uint, 0644);
223 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
224
225 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
226 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
227 MODULE_LICENSE("GPL");
228