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/delay.h>
20 #include <linux/platform_device.h>
21
22 #include <asm/idle.h>
23
24 #include <asm/mach-loongson2ef/loongson.h>
25
26 static uint nowait;
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
46 /*
47 * Here we notify other drivers of the proposed change and the final change.
48 */
loongson2_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)49 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
50 unsigned int index)
51 {
52 unsigned int freq;
53
54 freq =
55 ((cpu_clock_freq / 1000) *
56 loongson2_clockmod_table[index].driver_data) / 8;
57
58 /* setting the cpu frequency */
59 loongson2_cpu_set_rate(freq);
60
61 return 0;
62 }
63
loongson2_cpufreq_cpu_init(struct cpufreq_policy * policy)64 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
65 {
66 int i;
67 unsigned long rate;
68 int ret;
69
70 rate = cpu_clock_freq / 1000;
71 if (!rate)
72 return -EINVAL;
73
74 /* clock table init */
75 for (i = 2;
76 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
77 i++)
78 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
79
80 ret = loongson2_cpu_set_rate(rate);
81 if (ret)
82 return ret;
83
84 cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
85 return 0;
86 }
87
88 static struct cpufreq_driver loongson2_cpufreq_driver = {
89 .name = "loongson2",
90 .init = loongson2_cpufreq_cpu_init,
91 .verify = cpufreq_generic_frequency_table_verify,
92 .target_index = loongson2_cpufreq_target,
93 .get = cpufreq_generic_get,
94 .attr = cpufreq_generic_attr,
95 };
96
97 static const struct platform_device_id platform_device_ids[] = {
98 {
99 .name = "loongson2_cpufreq",
100 },
101 {}
102 };
103
104 MODULE_DEVICE_TABLE(platform, platform_device_ids);
105
106 static struct platform_driver platform_driver = {
107 .driver = {
108 .name = "loongson2_cpufreq",
109 },
110 .id_table = platform_device_ids,
111 };
112
113 /*
114 * This is the simple version of Loongson-2 wait, Maybe we need do this in
115 * interrupt disabled context.
116 */
117
118 static DEFINE_SPINLOCK(loongson2_wait_lock);
119
loongson2_cpu_wait(void)120 static void loongson2_cpu_wait(void)
121 {
122 unsigned long flags;
123 u32 cpu_freq;
124
125 spin_lock_irqsave(&loongson2_wait_lock, flags);
126 cpu_freq = readl(LOONGSON_CHIPCFG);
127 /* Put CPU into wait mode */
128 writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
129 /* Restore CPU state */
130 writel(cpu_freq, LOONGSON_CHIPCFG);
131 spin_unlock_irqrestore(&loongson2_wait_lock, flags);
132 local_irq_enable();
133 }
134
cpufreq_init(void)135 static int __init cpufreq_init(void)
136 {
137 int ret;
138
139 /* Register platform stuff */
140 ret = platform_driver_register(&platform_driver);
141 if (ret)
142 return ret;
143
144 pr_info("Loongson-2F CPU frequency driver\n");
145
146 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
147 CPUFREQ_TRANSITION_NOTIFIER);
148
149 ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
150
151 if (!ret && !nowait) {
152 saved_cpu_wait = cpu_wait;
153 cpu_wait = loongson2_cpu_wait;
154 }
155
156 return ret;
157 }
158
cpufreq_exit(void)159 static void __exit cpufreq_exit(void)
160 {
161 if (!nowait && saved_cpu_wait)
162 cpu_wait = saved_cpu_wait;
163 cpufreq_unregister_driver(&loongson2_cpufreq_driver);
164 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
165 CPUFREQ_TRANSITION_NOTIFIER);
166
167 platform_driver_unregister(&platform_driver);
168 }
169
170 module_init(cpufreq_init);
171 module_exit(cpufreq_exit);
172
173 module_param(nowait, uint, 0644);
174 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
175
176 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
177 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
178 MODULE_LICENSE("GPL");
179