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
24#include <asm/hardware.h>
25#include <asm/io.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/* TODO: Add support for SDRAM timing changes */
37
38int omap_verify_speed(struct cpufreq_policy *policy)
39{
40	struct clk * mpu_clk;
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	mpu_clk = clk_get(NULL, MPU_CLK);
48	if (IS_ERR(mpu_clk))
49		return PTR_ERR(mpu_clk);
50	policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
51	policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
52	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
53				     policy->cpuinfo.max_freq);
54	clk_put(mpu_clk);
55
56	return 0;
57}
58
59unsigned int omap_getspeed(unsigned int cpu)
60{
61	struct clk * mpu_clk;
62	unsigned long rate;
63
64	if (cpu)
65		return 0;
66
67	mpu_clk = clk_get(NULL, MPU_CLK);
68	if (IS_ERR(mpu_clk))
69		return 0;
70	rate = clk_get_rate(mpu_clk) / 1000;
71	clk_put(mpu_clk);
72
73	return rate;
74}
75
76static int omap_target(struct cpufreq_policy *policy,
77		       unsigned int target_freq,
78		       unsigned int relation)
79{
80	struct clk * mpu_clk;
81	struct cpufreq_freqs freqs;
82	int ret = 0;
83
84	mpu_clk = clk_get(NULL, MPU_CLK);
85	if (IS_ERR(mpu_clk))
86		return PTR_ERR(mpu_clk);
87
88	freqs.old = omap_getspeed(0);
89	freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
90	freqs.cpu = 0;
91
92	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
93	ret = clk_set_rate(mpu_clk, target_freq * 1000);
94	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
95	clk_put(mpu_clk);
96
97	return ret;
98}
99
100static int __init omap_cpu_init(struct cpufreq_policy *policy)
101{
102	struct clk * mpu_clk;
103
104	mpu_clk = clk_get(NULL, MPU_CLK);
105	if (IS_ERR(mpu_clk))
106		return PTR_ERR(mpu_clk);
107
108	if (policy->cpu != 0)
109		return -EINVAL;
110	policy->cur = policy->min = policy->max = omap_getspeed(0);
111	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
112	policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
113	policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, VERY_HI_RATE) / 1000;
114	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
115	clk_put(mpu_clk);
116
117	return 0;
118}
119
120static struct cpufreq_driver omap_driver = {
121	.flags		= CPUFREQ_STICKY,
122	.verify		= omap_verify_speed,
123	.target		= omap_target,
124	.get		= omap_getspeed,
125	.init		= omap_cpu_init,
126	.name		= "omap",
127};
128
129static int __init omap_cpufreq_init(void)
130{
131	return cpufreq_register_driver(&omap_driver);
132}
133
134arch_initcall(omap_cpufreq_init);
135