2 * linux/arch/arm/plat-omap/cpu-omap.c
4 * CPU frequency scaling for OMAP
6 * Copyright (C) 2005 Nokia Corporation
7 * Written by Tony Lindgren <tony@atomide.com>
9 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
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.
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>
25 #include <mach/hardware.h>
26 #include <plat/clock.h>
27 #include <asm/system.h>
29 #define VERY_HI_RATE 900000000
31 static struct cpufreq_frequency_table
*freq_table
;
33 #ifdef CONFIG_ARCH_OMAP1
36 #define MPU_CLK "virt_prcm_set"
39 static struct clk
*mpu_clk
;
41 /* TODO: Add support for SDRAM timing changes */
43 int omap_verify_speed(struct cpufreq_policy
*policy
)
46 return cpufreq_frequency_table_verify(policy
, freq_table
);
51 cpufreq_verify_within_limits(policy
, policy
->cpuinfo
.min_freq
,
52 policy
->cpuinfo
.max_freq
);
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
);
61 unsigned int omap_getspeed(unsigned int cpu
)
68 rate
= clk_get_rate(mpu_clk
) / 1000;
72 static int omap_target(struct cpufreq_policy
*policy
,
73 unsigned int target_freq
,
74 unsigned int relation
)
76 struct cpufreq_freqs freqs
;
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
;
86 freqs
.old
= omap_getspeed(0);
87 freqs
.new = clk_round_rate(mpu_clk
, target_freq
* 1000) / 1000;
90 if (freqs
.old
== freqs
.new)
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);
98 ret
= clk_set_rate(mpu_clk
, freqs
.new * 1000);
99 cpufreq_notify_transition(&freqs
, CPUFREQ_POSTCHANGE
);
104 static int __init
omap_cpu_init(struct cpufreq_policy
*policy
)
108 mpu_clk
= clk_get(NULL
, MPU_CLK
);
110 return PTR_ERR(mpu_clk
);
112 if (policy
->cpu
!= 0)
115 policy
->cur
= policy
->min
= policy
->max
= omap_getspeed(0);
117 clk_init_cpufreq_table(&freq_table
);
119 result
= cpufreq_frequency_table_cpuinfo(policy
, freq_table
);
121 cpufreq_frequency_table_get_attr(freq_table
,
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;
129 /* FIXME: what's the actual transition time? */
130 policy
->cpuinfo
.transition_latency
= 300 * 1000;
135 static int omap_cpu_exit(struct cpufreq_policy
*policy
)
141 static struct freq_attr
*omap_cpufreq_attr
[] = {
142 &cpufreq_freq_attr_scaling_available_freqs
,
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
,
154 .attr
= omap_cpufreq_attr
,
157 static int __init
omap_cpufreq_init(void)
159 return cpufreq_register_driver(&omap_driver
);
162 arch_initcall(omap_cpufreq_init
);
165 * if ever we want to remove this, upon cleanup call:
167 * cpufreq_unregister_driver()
168 * cpufreq_frequency_table_put_attr()