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
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/cpufreq.h>
17 #include <linux/module.h>
18 #include <linux/err.h>
19 #include <linux/sched.h> /* set_cpus_allowed() */
20 #include <linux/delay.h>
21 #include <linux/platform_device.h>
22
23 #include <asm/idle.h>
24
25 #include <asm/mach-loongson2ef/loongson.h>
26
27 static uint nowait;
28
29 static void (*saved_cpu_wait) (void);
30
31 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
32 unsigned long val, void *data);
33
34 static struct notifier_block loongson2_cpufreq_notifier_block = {
35 .notifier_call = loongson2_cpu_freq_notifier
36 };
37
loongson2_cpu_freq_notifier(struct notifier_block * nb,unsigned long val,void * data)38 static 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
47 /*
48 * Here we notify other drivers of the proposed change and the final change.
49 */
loongson2_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)50 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
51 unsigned int index)
52 {
53 unsigned int freq;
54
55 freq =
56 ((cpu_clock_freq / 1000) *
57 loongson2_clockmod_table[index].driver_data) / 8;
58
59 /* setting the cpu frequency */
60 loongson2_cpu_set_rate(freq);
61
62 return 0;
63 }
64
loongson2_cpufreq_cpu_init(struct cpufreq_policy * policy)65 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
66 {
67 int i;
68 unsigned long rate;
69 int ret;
70
71 rate = cpu_clock_freq / 1000;
72 if (!rate)
73 return -EINVAL;
74
75 /* clock table init */
76 for (i = 2;
77 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
78 i++)
79 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
80
81 ret = loongson2_cpu_set_rate(rate);
82 if (ret)
83 return ret;
84
85 cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
86 return 0;
87 }
88
loongson2_cpufreq_exit(struct cpufreq_policy * policy)89 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
90 {
91 return 0;
92 }
93
94 static struct cpufreq_driver loongson2_cpufreq_driver = {
95 .name = "loongson2",
96 .init = loongson2_cpufreq_cpu_init,
97 .verify = cpufreq_generic_frequency_table_verify,
98 .target_index = loongson2_cpufreq_target,
99 .get = cpufreq_generic_get,
100 .exit = loongson2_cpufreq_exit,
101 .attr = cpufreq_generic_attr,
102 };
103
104 static const struct platform_device_id platform_device_ids[] = {
105 {
106 .name = "loongson2_cpufreq",
107 },
108 {}
109 };
110
111 MODULE_DEVICE_TABLE(platform, platform_device_ids);
112
113 static struct platform_driver platform_driver = {
114 .driver = {
115 .name = "loongson2_cpufreq",
116 },
117 .id_table = platform_device_ids,
118 };
119
120 /*
121 * This is the simple version of Loongson-2 wait, Maybe we need do this in
122 * interrupt disabled context.
123 */
124
125 static DEFINE_SPINLOCK(loongson2_wait_lock);
126
loongson2_cpu_wait(void)127 static void loongson2_cpu_wait(void)
128 {
129 unsigned long flags;
130 u32 cpu_freq;
131
132 spin_lock_irqsave(&loongson2_wait_lock, flags);
133 cpu_freq = readl(LOONGSON_CHIPCFG);
134 /* Put CPU into wait mode */
135 writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
136 /* Restore CPU state */
137 writel(cpu_freq, LOONGSON_CHIPCFG);
138 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
139 local_irq_enable();
140 }
141
cpufreq_init(void)142 static int __init cpufreq_init(void)
143 {
144 int ret;
145
146 /* Register platform stuff */
147 ret = platform_driver_register(&platform_driver);
148 if (ret)
149 return ret;
150
151 pr_info("Loongson-2F CPU frequency driver\n");
152
153 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
154 CPUFREQ_TRANSITION_NOTIFIER);
155
156 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
157
158 if (!ret && !nowait) {
159 saved_cpu_wait = cpu_wait;
160 cpu_wait = loongson2_cpu_wait;
161 }
162
163 return ret;
164 }
165
cpufreq_exit(void)166 static void __exit cpufreq_exit(void)
167 {
168 if (!nowait && saved_cpu_wait)
169 cpu_wait = saved_cpu_wait;
170 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
171 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
172 CPUFREQ_TRANSITION_NOTIFIER);
173
174 platform_driver_unregister(&platform_driver);
175 }
176
177 module_init(cpufreq_init);
178 module_exit(cpufreq_exit);
179
180 module_param(nowait, uint, 0644);
181 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
182
183 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
184 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
185 MODULE_LICENSE("GPL");
186