1/*
  2 * arch/sh/kernel/cpufreq.c
  3 *
  4 * cpufreq driver for the SuperH processors.
  5 *
  6 * Copyright (C) 2002 - 2007 Paul Mundt
  7 * Copyright (C) 2002 M. R. Brown
  8 *
  9 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
 10 *
 11 *   Copyright (C) 2004-2007 Atmel Corporation
 12 *
 13 * This file is subject to the terms and conditions of the GNU General Public
 14 * License.  See the file "COPYING" in the main directory of this archive
 15 * for more details.
 16 */
 17#include <linux/types.h>
 18#include <linux/cpufreq.h>
 19#include <linux/kernel.h>
 20#include <linux/module.h>
 21#include <linux/init.h>
 22#include <linux/err.h>
 23#include <linux/cpumask.h>
 24#include <linux/smp.h>
 25#include <linux/sched.h>	/* set_cpus_allowed() */
 26#include <linux/clk.h>
 27
 28static struct clk *cpuclk;
 29
 30static unsigned int sh_cpufreq_get(unsigned int cpu)
 31{
 32	return (clk_get_rate(cpuclk) + 500) / 1000;
 33}
 34
 35/*
 36 * Here we notify other drivers of the proposed change and the final change.
 37 */
 38static int sh_cpufreq_target(struct cpufreq_policy *policy,
 39			     unsigned int target_freq,
 40			     unsigned int relation)
 41{
 42	unsigned int cpu = policy->cpu;
 43	cpumask_t cpus_allowed;
 44	struct cpufreq_freqs freqs;
 45	long freq;
 46
 47	if (!cpu_online(cpu))
 48		return -ENODEV;
 49
 50	cpus_allowed = current->cpus_allowed;
 51	set_cpus_allowed_ptr(current, cpumask_of(cpu));
 52
 53	BUG_ON(smp_processor_id() != cpu);
 54
 55	/* Convert target_freq from kHz to Hz */
 56	freq = clk_round_rate(cpuclk, target_freq * 1000);
 57
 58	if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
 59		return -EINVAL;
 60
 61	pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
 62
 63	freqs.cpu	= cpu;
 64	freqs.old	= sh_cpufreq_get(cpu);
 65	freqs.new	= (freq + 500) / 1000;
 66	freqs.flags	= 0;
 67
 68	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 69	set_cpus_allowed_ptr(current, &cpus_allowed);
 70	clk_set_rate(cpuclk, freq);
 71	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 72
 73	pr_debug("cpufreq: set frequency %lu Hz\n", freq);
 74
 75	return 0;
 76}
 77
 78static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
 79{
 80	if (!cpu_online(policy->cpu))
 81		return -ENODEV;
 82
 83	cpuclk = clk_get(NULL, "cpu_clk");
 84	if (IS_ERR(cpuclk)) {
 85		printk(KERN_ERR "cpufreq: couldn't get CPU#%d clk\n",
 86		       policy->cpu);
 87		return PTR_ERR(cpuclk);
 88	}
 89
 90	/* cpuinfo and default policy values */
 91	policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
 92	policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 93	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 94
 95	policy->cur		= sh_cpufreq_get(policy->cpu);
 96	policy->min		= policy->cpuinfo.min_freq;
 97	policy->max		= policy->cpuinfo.max_freq;
 98
 99	/*
100	 * Catch the cases where the clock framework hasn't been wired up
101	 * properly to support scaling.
102	 */
103	if (unlikely(policy->min == policy->max)) {
104		printk(KERN_ERR "cpufreq: clock framework rate rounding "
105		       "not supported on CPU#%d.\n", policy->cpu);
106
107		clk_put(cpuclk);
108		return -EINVAL;
109	}
110
111	printk(KERN_INFO "cpufreq: CPU#%d Frequencies - Minimum %u.%03u MHz, "
112	       "Maximum %u.%03u MHz.\n",
113	       policy->cpu, policy->min / 1000, policy->min % 1000,
114	       policy->max / 1000, policy->max % 1000);
115
116	return 0;
117}
118
119static int sh_cpufreq_verify(struct cpufreq_policy *policy)
120{
121	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
122				     policy->cpuinfo.max_freq);
123	return 0;
124}
125
126static int sh_cpufreq_exit(struct cpufreq_policy *policy)
127{
128	clk_put(cpuclk);
129	return 0;
130}
131
132static struct cpufreq_driver sh_cpufreq_driver = {
133	.owner		= THIS_MODULE,
134	.name		= "sh",
135	.init		= sh_cpufreq_cpu_init,
136	.verify		= sh_cpufreq_verify,
137	.target		= sh_cpufreq_target,
138	.get		= sh_cpufreq_get,
139	.exit		= sh_cpufreq_exit,
140};
141
142static int __init sh_cpufreq_module_init(void)
143{
144	printk(KERN_INFO "cpufreq: SuperH CPU frequency driver.\n");
145	return cpufreq_register_driver(&sh_cpufreq_driver);
146}
147
148static void __exit sh_cpufreq_module_exit(void)
149{
150	cpufreq_unregister_driver(&sh_cpufreq_driver);
151}
152
153module_init(sh_cpufreq_module_init);
154module_exit(sh_cpufreq_module_exit);
155
156MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
157MODULE_DESCRIPTION("cpufreq driver for SuperH");
158MODULE_LICENSE("GPL");