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 
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  */
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 
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 
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 
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 
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 
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