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. & Institute 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-loongson64/loongson.h>
24
25 static uint nowait;
26
27 static void (*saved_cpu_wait) (void);
28
29 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
30 unsigned long val, void *data);
31
32 static struct notifier_block loongson2_cpufreq_notifier_block = {
33 .notifier_call = loongson2_cpu_freq_notifier
34 };
35
loongson2_cpu_freq_notifier(struct notifier_block * nb,unsigned long val,void * data)36 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
37 unsigned long val, void *data)
38 {
39 if (val == CPUFREQ_POSTCHANGE)
40 current_cpu_data.udelay_val = loops_per_jiffy;
41
42 return 0;
43 }
44
45 /*
46 * Here we notify other drivers of the proposed change and the final change.
47 */
loongson2_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)48 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
49 unsigned int index)
50 {
51 unsigned int cpu = policy->cpu;
52 cpumask_t cpus_allowed;
53 unsigned int freq;
54
55 cpus_allowed = current->cpus_allowed;
56 set_cpus_allowed_ptr(current, cpumask_of(cpu));
57
58 freq =
59 ((cpu_clock_freq / 1000) *
60 loongson2_clockmod_table[index].driver_data) / 8;
61
62 set_cpus_allowed_ptr(current, &cpus_allowed);
63
64 /* setting the cpu frequency */
65 clk_set_rate(policy->clk, freq * 1000);
66
67 return 0;
68 }
69
loongson2_cpufreq_cpu_init(struct cpufreq_policy * policy)70 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
71 {
72 struct clk *cpuclk;
73 int i;
74 unsigned long rate;
75 int ret;
76
77 cpuclk = clk_get(NULL, "cpu_clk");
78 if (IS_ERR(cpuclk)) {
79 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
80 return PTR_ERR(cpuclk);
81 }
82
83 rate = cpu_clock_freq / 1000;
84 if (!rate) {
85 clk_put(cpuclk);
86 return -EINVAL;
87 }
88
89 /* clock table init */
90 for (i = 2;
91 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
92 i++)
93 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
94
95 ret = clk_set_rate(cpuclk, rate * 1000);
96 if (ret) {
97 clk_put(cpuclk);
98 return ret;
99 }
100
101 policy->clk = cpuclk;
102 return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
103 }
104
loongson2_cpufreq_exit(struct cpufreq_policy * policy)105 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
106 {
107 clk_put(policy->clk);
108 return 0;
109 }
110
111 static struct cpufreq_driver loongson2_cpufreq_driver = {
112 .name = "loongson2",
113 .init = loongson2_cpufreq_cpu_init,
114 .verify = cpufreq_generic_frequency_table_verify,
115 .target_index = loongson2_cpufreq_target,
116 .get = cpufreq_generic_get,
117 .exit = loongson2_cpufreq_exit,
118 .attr = cpufreq_generic_attr,
119 };
120
121 static struct platform_device_id platform_device_ids[] = {
122 {
123 .name = "loongson2_cpufreq",
124 },
125 {}
126 };
127
128 MODULE_DEVICE_TABLE(platform, platform_device_ids);
129
130 static struct platform_driver platform_driver = {
131 .driver = {
132 .name = "loongson2_cpufreq",
133 },
134 .id_table = platform_device_ids,
135 };
136
137 /*
138 * This is the simple version of Loongson-2 wait, Maybe we need do this in
139 * interrupt disabled context.
140 */
141
142 static DEFINE_SPINLOCK(loongson2_wait_lock);
143
loongson2_cpu_wait(void)144 static void loongson2_cpu_wait(void)
145 {
146 unsigned long flags;
147 u32 cpu_freq;
148
149 spin_lock_irqsave(&loongson2_wait_lock, flags);
150 cpu_freq = LOONGSON_CHIPCFG(0);
151 LOONGSON_CHIPCFG(0) &= ~0x7; /* Put CPU into wait mode */
152 LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
153 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
154 local_irq_enable();
155 }
156
cpufreq_init(void)157 static int __init cpufreq_init(void)
158 {
159 int ret;
160
161 /* Register platform stuff */
162 ret = platform_driver_register(&platform_driver);
163 if (ret)
164 return ret;
165
166 pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
167
168 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
169 CPUFREQ_TRANSITION_NOTIFIER);
170
171 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
172
173 if (!ret && !nowait) {
174 saved_cpu_wait = cpu_wait;
175 cpu_wait = loongson2_cpu_wait;
176 }
177
178 return ret;
179 }
180
cpufreq_exit(void)181 static void __exit cpufreq_exit(void)
182 {
183 if (!nowait && saved_cpu_wait)
184 cpu_wait = saved_cpu_wait;
185 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
186 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
187 CPUFREQ_TRANSITION_NOTIFIER);
188
189 platform_driver_unregister(&platform_driver);
190 }
191
192 module_init(cpufreq_init);
193 module_exit(cpufreq_exit);
194
195 module_param(nowait, uint, 0644);
196 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
197
198 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
199 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
200 MODULE_LICENSE("GPL");
201