1 /*
2 * linux/arch/arm/plat-omap/cpu-omap.c
3 *
4 * CPU frequency scaling for OMAP
5 *
6 * Copyright (C) 2005 Nokia Corporation
7 * Written by Tony Lindgren <tony@atomide.com>
8 *
9 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/sched.h>
18 #include <linux/cpufreq.h>
19 #include <linux/delay.h>
20 #include <linux/init.h>
21 #include <linux/err.h>
22 #include <linux/clk.h>
23 #include <linux/io.h>
24
25 #include <mach/hardware.h>
26 #include <mach/clock.h>
27 #include <asm/system.h>
28
29 #define VERY_HI_RATE 900000000
30
31 static struct cpufreq_frequency_table *freq_table;
32
33 #ifdef CONFIG_ARCH_OMAP1
34 #define MPU_CLK "mpu"
35 #else
36 #define MPU_CLK "virt_prcm_set"
37 #endif
38
39 static struct clk *mpu_clk;
40
41 /* TODO: Add support for SDRAM timing changes */
42
43 int omap_verify_speed(struct cpufreq_policy *policy)
44 {
45 if (freq_table)
46 return cpufreq_frequency_table_verify(policy, freq_table);
47
48 if (policy->cpu)
49 return -EINVAL;
50
51 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
52 policy->cpuinfo.max_freq);
53
54 policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
55 policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
56 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
57 policy->cpuinfo.max_freq);
58 return 0;
59 }
60
61 unsigned int omap_getspeed(unsigned int cpu)
62 {
63 unsigned long rate;
64
65 if (cpu)
66 return 0;
67
68 rate = clk_get_rate(mpu_clk) / 1000;
69 return rate;
70 }
71
72 static int omap_target(struct cpufreq_policy *policy,
73 unsigned int target_freq,
74 unsigned int relation)
75 {
76 struct cpufreq_freqs freqs;
77 int ret = 0;
78
79 /* Ensure desired rate is within allowed range. Some govenors
80 * (ondemand) will just pass target_freq=0 to get the minimum. */
81 if (target_freq < policy->min)
82 target_freq = policy->min;
83 if (target_freq > policy->max)
84 target_freq = policy->max;
85
86 freqs.old = omap_getspeed(0);
87 freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
88 freqs.cpu = 0;
89
90 if (freqs.old == freqs.new)
91 return ret;
92
93 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
94 #ifdef CONFIG_CPU_FREQ_DEBUG
95 printk(KERN_DEBUG "cpufreq-omap: transition: %u --> %u\n",
96 freqs.old, freqs.new);
97 #endif
98 ret = clk_set_rate(mpu_clk, freqs.new * 1000);
99 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
100
101 return ret;
102 }
103
104 static int __init omap_cpu_init(struct cpufreq_policy *policy)
105 {
106 int result = 0;
107
108 mpu_clk = clk_get(NULL, MPU_CLK);
109 if (IS_ERR(mpu_clk))
110 return PTR_ERR(mpu_clk);
111
112 if (policy->cpu != 0)
113 return -EINVAL;
114
115 policy->cur = policy->min = policy->max = omap_getspeed(0);
116
117 clk_init_cpufreq_table(&freq_table);
118 if (freq_table) {
119 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
120 if (!result)
121 cpufreq_frequency_table_get_attr(freq_table,
122 policy->cpu);
123 } else {
124 policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
125 policy->cpuinfo.max_freq = clk_round_rate(mpu_clk,
126 VERY_HI_RATE) / 1000;
127 }
128
129 /* FIXME: what's the actual transition time? */
130 policy->cpuinfo.transition_latency = 10 * 1000 * 1000;
131
132 return 0;
133 }
134
135 static int omap_cpu_exit(struct cpufreq_policy *policy)
136 {
137 clk_put(mpu_clk);
138 return 0;
139 }
140
141 static struct freq_attr *omap_cpufreq_attr[] = {
142 &cpufreq_freq_attr_scaling_available_freqs,
143 NULL,
144 };
145
146 static struct cpufreq_driver omap_driver = {
147 .flags = CPUFREQ_STICKY,
148 .verify = omap_verify_speed,
149 .target = omap_target,
150 .get = omap_getspeed,
151 .init = omap_cpu_init,
152 .exit = omap_cpu_exit,
153 .name = "omap",
154 .attr = omap_cpufreq_attr,
155 };
156
157 static int __init omap_cpufreq_init(void)
158 {
159 return cpufreq_register_driver(&omap_driver);
160 }
161
162 arch_initcall(omap_cpufreq_init);
163
164 /*
165 * if ever we want to remove this, upon cleanup call:
166 *
167 * cpufreq_unregister_driver()
168 * cpufreq_frequency_table_put_attr()
169 */
170
171
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