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 | |
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 | */ |
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 | |
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 int loongson2_cpufreq_exit(struct cpufreq_policy *policy) |
89 | { |
90 | return 0; |
91 | } |
92 | |
93 | static struct cpufreq_driver loongson2_cpufreq_driver = { |
94 | .name = "loongson2" , |
95 | .init = loongson2_cpufreq_cpu_init, |
96 | .verify = cpufreq_generic_frequency_table_verify, |
97 | .target_index = loongson2_cpufreq_target, |
98 | .get = cpufreq_generic_get, |
99 | .exit = loongson2_cpufreq_exit, |
100 | .attr = cpufreq_generic_attr, |
101 | }; |
102 | |
103 | static const struct platform_device_id platform_device_ids[] = { |
104 | { |
105 | .name = "loongson2_cpufreq" , |
106 | }, |
107 | {} |
108 | }; |
109 | |
110 | MODULE_DEVICE_TABLE(platform, platform_device_ids); |
111 | |
112 | static struct platform_driver platform_driver = { |
113 | .driver = { |
114 | .name = "loongson2_cpufreq" , |
115 | }, |
116 | .id_table = platform_device_ids, |
117 | }; |
118 | |
119 | /* |
120 | * This is the simple version of Loongson-2 wait, Maybe we need do this in |
121 | * interrupt disabled context. |
122 | */ |
123 | |
124 | static DEFINE_SPINLOCK(loongson2_wait_lock); |
125 | |
126 | static void loongson2_cpu_wait(void) |
127 | { |
128 | unsigned long flags; |
129 | u32 cpu_freq; |
130 | |
131 | spin_lock_irqsave(&loongson2_wait_lock, flags); |
132 | cpu_freq = readl(LOONGSON_CHIPCFG); |
133 | /* Put CPU into wait mode */ |
134 | writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG); |
135 | /* Restore CPU state */ |
136 | writel(cpu_freq, LOONGSON_CHIPCFG); |
137 | spin_unlock_irqrestore(lock: &loongson2_wait_lock, flags); |
138 | local_irq_enable(); |
139 | } |
140 | |
141 | static int __init cpufreq_init(void) |
142 | { |
143 | int ret; |
144 | |
145 | /* Register platform stuff */ |
146 | ret = platform_driver_register(&platform_driver); |
147 | if (ret) |
148 | return ret; |
149 | |
150 | pr_info("Loongson-2F CPU frequency driver\n" ); |
151 | |
152 | cpufreq_register_notifier(nb: &loongson2_cpufreq_notifier_block, |
153 | CPUFREQ_TRANSITION_NOTIFIER); |
154 | |
155 | ret = cpufreq_register_driver(driver_data: &loongson2_cpufreq_driver); |
156 | |
157 | if (!ret && !nowait) { |
158 | saved_cpu_wait = cpu_wait; |
159 | cpu_wait = loongson2_cpu_wait; |
160 | } |
161 | |
162 | return ret; |
163 | } |
164 | |
165 | static void __exit cpufreq_exit(void) |
166 | { |
167 | if (!nowait && saved_cpu_wait) |
168 | cpu_wait = saved_cpu_wait; |
169 | cpufreq_unregister_driver(driver_data: &loongson2_cpufreq_driver); |
170 | cpufreq_unregister_notifier(nb: &loongson2_cpufreq_notifier_block, |
171 | CPUFREQ_TRANSITION_NOTIFIER); |
172 | |
173 | platform_driver_unregister(&platform_driver); |
174 | } |
175 | |
176 | module_init(cpufreq_init); |
177 | module_exit(cpufreq_exit); |
178 | |
179 | module_param(nowait, uint, 0644); |
180 | MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait" ); |
181 | |
182 | MODULE_AUTHOR("Yanhua <yanh@lemote.com>" ); |
183 | MODULE_DESCRIPTION("cpufreq driver for Loongson2F" ); |
184 | MODULE_LICENSE("GPL" ); |
185 | |