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 <asm/system.h>
27
28 #define VERY_HI_RATE 900000000
29
30 #ifdef CONFIG_ARCH_OMAP1
31 #define MPU_CLK "mpu"
32 #else
33 #define MPU_CLK "virt_prcm_set"
34 #endif
35
36 static struct clk *mpu_clk;
37
38 /* TODO: Add support for SDRAM timing changes */
39
omap_verify_speed(struct cpufreq_policy * policy)40 int omap_verify_speed(struct cpufreq_policy *policy)
41 {
42 if (policy->cpu)
43 return -EINVAL;
44
45 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
46 policy->cpuinfo.max_freq);
47
48 policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
49 policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
50 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
51 policy->cpuinfo.max_freq);
52 return 0;
53 }
54
omap_getspeed(unsigned int cpu)55 unsigned int omap_getspeed(unsigned int cpu)
56 {
57 unsigned long rate;
58
59 if (cpu)
60 return 0;
61
62 rate = clk_get_rate(mpu_clk) / 1000;
63 return rate;
64 }
65
omap_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)66 static int omap_target(struct cpufreq_policy *policy,
67 unsigned int target_freq,
68 unsigned int relation)
69 {
70 struct cpufreq_freqs freqs;
71 int ret = 0;
72
73 freqs.old = omap_getspeed(0);
74 freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
75 freqs.cpu = 0;
76
77 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
78 ret = clk_set_rate(mpu_clk, target_freq * 1000);
79 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
80
81 return ret;
82 }
83
omap_cpu_init(struct cpufreq_policy * policy)84 static int __init omap_cpu_init(struct cpufreq_policy *policy)
85 {
86 mpu_clk = clk_get(NULL, MPU_CLK);
87 if (IS_ERR(mpu_clk))
88 return PTR_ERR(mpu_clk);
89
90 if (policy->cpu != 0)
91 return -EINVAL;
92 policy->cur = policy->min = policy->max = omap_getspeed(0);
93 policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
94 policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, VERY_HI_RATE) / 1000;
95 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
96
97 return 0;
98 }
99
omap_cpu_exit(struct cpufreq_policy * policy)100 static int omap_cpu_exit(struct cpufreq_policy *policy)
101 {
102 clk_put(mpu_clk);
103 return 0;
104 }
105
106 static struct cpufreq_driver omap_driver = {
107 .flags = CPUFREQ_STICKY,
108 .verify = omap_verify_speed,
109 .target = omap_target,
110 .get = omap_getspeed,
111 .init = omap_cpu_init,
112 .exit = omap_cpu_exit,
113 .name = "omap",
114 };
115
omap_cpufreq_init(void)116 static int __init omap_cpufreq_init(void)
117 {
118 return cpufreq_register_driver(&omap_driver);
119 }
120
121 arch_initcall(omap_cpufreq_init);
122