tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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 struct clk *cpuclk;
28
29static void (*saved_cpu_wait) (void);
30
31static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
32 unsigned long val, void *data);
33
34static struct notifier_block loongson2_cpufreq_notifier_block = {
35 .notifier_call = loongson2_cpu_freq_notifier
36};
37
38static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
39 unsigned long val, void *data)
40{
41 if (val == CPUFREQ_POSTCHANGE)
42 current_cpu_data.udelay_val = loops_per_jiffy;
43
44 return 0;
45}
46
47static unsigned int loongson2_cpufreq_get(unsigned int cpu)
48{
49 return clk_get_rate(cpuclk);
50}
51
52/*
53 * Here we notify other drivers of the proposed change and the final change.
54 */
55static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
56 unsigned int target_freq,
57 unsigned int relation)
58{
59 unsigned int cpu = policy->cpu;
60 unsigned int newstate = 0;
61 cpumask_t cpus_allowed;
62 struct cpufreq_freqs freqs;
63 unsigned int freq;
64
65 cpus_allowed = current->cpus_allowed;
66 set_cpus_allowed_ptr(current, cpumask_of(cpu));
67
68 if (cpufreq_frequency_table_target
69 (policy, &loongson2_clockmod_table[0], target_freq, relation,
70 &newstate))
71 return -EINVAL;
72
73 freq =
74 ((cpu_clock_freq / 1000) *
75 loongson2_clockmod_table[newstate].driver_data) / 8;
76 if (freq < policy->min || freq > policy->max)
77 return -EINVAL;
78
79 pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
80
81 freqs.old = loongson2_cpufreq_get(cpu);
82 freqs.new = freq;
83 freqs.flags = 0;
84
85 if (freqs.new == freqs.old)
86 return 0;
87
88 /* notifiers */
89 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
90
91 set_cpus_allowed_ptr(current, &cpus_allowed);
92
93 /* setting the cpu frequency */
94 clk_set_rate(cpuclk, freq);
95
96 /* notifiers */
97 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
98
99 pr_debug("cpufreq: set frequency %u kHz\n", freq);
100
101 return 0;
102}
103
104static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
105{
106 int i;
107 unsigned long rate;
108 int ret;
109
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);
114 }
115
116 rate = cpu_clock_freq / 1000;
117 if (!rate) {
118 clk_put(cpuclk);
119 return -EINVAL;
120 }
121
122 /* clock table init */
123 for (i = 2;
124 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
125 i++)
126 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
127
128 ret = clk_set_rate(cpuclk, rate);
129 if (ret) {
130 clk_put(cpuclk);
131 return ret;
132 }
133
134 policy->cur = loongson2_cpufreq_get(policy->cpu);
135
136 cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
137 policy->cpu);
138
139 return cpufreq_frequency_table_cpuinfo(policy,
140 &loongson2_clockmod_table[0]);
141}
142
143static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
144{
145 return cpufreq_frequency_table_verify(policy,
146 &loongson2_clockmod_table[0]);
147}
148
149static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
150{
151 clk_put(cpuclk);
152 return 0;
153}
154
155static struct freq_attr *loongson2_table_attr[] = {
156 &cpufreq_freq_attr_scaling_available_freqs,
157 NULL,
158};
159
160static struct cpufreq_driver loongson2_cpufreq_driver = {
161 .name = "loongson2",
162 .init = loongson2_cpufreq_cpu_init,
163 .verify = loongson2_cpufreq_verify,
164 .target = loongson2_cpufreq_target,
165 .get = loongson2_cpufreq_get,
166 .exit = loongson2_cpufreq_exit,
167 .attr = loongson2_table_attr,
168};
169
170static struct platform_device_id platform_device_ids[] = {
171 {
172 .name = "loongson2_cpufreq",
173 },
174 {}
175};
176
177MODULE_DEVICE_TABLE(platform, platform_device_ids);
178
179static struct platform_driver platform_driver = {
180 .driver = {
181 .name = "loongson2_cpufreq",
182 .owner = THIS_MODULE,
183 },
184 .id_table = platform_device_ids,
185};
186
187/*
188 * This is the simple version of Loongson-2 wait, Maybe we need do this in
189 * interrupt disabled context.
190 */
191
192static DEFINE_SPINLOCK(loongson2_wait_lock);
193
194static void loongson2_cpu_wait(void)
195{
196 unsigned long flags;
197 u32 cpu_freq;
198
199 spin_lock_irqsave(&loongson2_wait_lock, flags);
200 cpu_freq = LOONGSON_CHIPCFG0;
201 LOONGSON_CHIPCFG0 &= ~0x7; /* Put CPU into wait mode */
202 LOONGSON_CHIPCFG0 = cpu_freq; /* Restore CPU state */
203 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
204 local_irq_enable();
205}
206
207static int __init cpufreq_init(void)
208{
209 int ret;
210
211 /* Register platform stuff */
212 ret = platform_driver_register(&platform_driver);
213 if (ret)
214 return ret;
215
216 pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
217
218 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
219 CPUFREQ_TRANSITION_NOTIFIER);
220
221 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
222
223 if (!ret && !nowait) {
224 saved_cpu_wait = cpu_wait;
225 cpu_wait = loongson2_cpu_wait;
226 }
227
228 return ret;
229}
230
231static void __exit cpufreq_exit(void)
232{
233 if (!nowait && saved_cpu_wait)
234 cpu_wait = saved_cpu_wait;
235 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
236 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
237 CPUFREQ_TRANSITION_NOTIFIER);
238
239 platform_driver_unregister(&platform_driver);
240}
241
242module_init(cpufreq_init);
243module_exit(cpufreq_exit);
244
245module_param(nowait, uint, 0644);
246MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
247
248MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
249MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
250MODULE_LICENSE("GPL");