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 
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  */
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 
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 
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 
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 
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 
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