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. & Insititute 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-loongson/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);
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);
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 		.owner = THIS_MODULE,
134 	},
135 	.id_table = platform_device_ids,
136 };
137 
138 /*
139  * This is the simple version of Loongson-2 wait, Maybe we need do this in
140  * interrupt disabled context.
141  */
142 
143 static DEFINE_SPINLOCK(loongson2_wait_lock);
144 
145 static void loongson2_cpu_wait(void)
146 {
147 	unsigned long flags;
148 	u32 cpu_freq;
149 
150 	spin_lock_irqsave(&loongson2_wait_lock, flags);
151 	cpu_freq = LOONGSON_CHIPCFG0;
152 	LOONGSON_CHIPCFG0 &= ~0x7;	/* Put CPU into wait mode */
153 	LOONGSON_CHIPCFG0 = cpu_freq;	/* Restore CPU state */
154 	spin_unlock_irqrestore(&loongson2_wait_lock, flags);
155 	local_irq_enable();
156 }
157 
158 static int __init cpufreq_init(void)
159 {
160 	int ret;
161 
162 	/* Register platform stuff */
163 	ret = platform_driver_register(&platform_driver);
164 	if (ret)
165 		return ret;
166 
167 	pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
168 
169 	cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
170 				  CPUFREQ_TRANSITION_NOTIFIER);
171 
172 	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
173 
174 	if (!ret && !nowait) {
175 		saved_cpu_wait = cpu_wait;
176 		cpu_wait = loongson2_cpu_wait;
177 	}
178 
179 	return ret;
180 }
181 
182 static void __exit cpufreq_exit(void)
183 {
184 	if (!nowait && saved_cpu_wait)
185 		cpu_wait = saved_cpu_wait;
186 	cpufreq_unregister_driver(&loongson2_cpufreq_driver);
187 	cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
188 				    CPUFREQ_TRANSITION_NOTIFIER);
189 
190 	platform_driver_unregister(&platform_driver);
191 }
192 
193 module_init(cpufreq_init);
194 module_exit(cpufreq_exit);
195 
196 module_param(nowait, uint, 0644);
197 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
198 
199 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
200 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
201 MODULE_LICENSE("GPL");
202