/*
* arch/sh/kernel/cpufreq.c
*
* cpufreq driver for the SuperH processors.
*
* Copyright (C) 2002, 2003, 2004, 2005 Paul Mundt
* Copyright (C) 2002 M. R. Brown
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/types.h>
#include <linux/cpufreq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
#include <linux/sched.h> /* set_cpus_allowed() */
#include <asm/processor.h>
#include <asm/watchdog.h>
#include <asm/freq.h>
#include <asm/io.h>
/*
* For SuperH, each policy change requires that we change the IFC, BFC, and
* PFC at the same time. Here we define sane values that won't trash the
* system.
*
* Note the max set is computed at runtime, we use the divisors that we booted
* with to setup our maximum operating frequencies.
*/
struct clock_set {
unsigned int ifc;
unsigned int bfc;
unsigned int pfc;
} clock_sets[] = {
#if defined(CONFIG_CPU_SH3) || defined(CONFIG_CPU_SH2)
{ 0, 0, 0 }, /* not implemented yet */
#elif defined(CONFIG_CPU_SH4)
{ 4, 8, 8 }, /* min - IFC: 1/4, BFC: 1/8, PFC: 1/8 */
{ 1, 2, 2 }, /* max - IFC: 1, BFC: 1/2, PFC: 1/2 */
#endif
};
#define MIN_CLOCK_SET 0
#define MAX_CLOCK_SET (ARRAY_SIZE(clock_sets) - 1)
/*
* For the time being, we only support two frequencies, which in turn are
* aimed at the POWERSAVE and PERFORMANCE policies, which in turn are derived
* directly from the respective min/max clock sets. Technically we could
* support a wider range of frequencies, but these vary far too much for each
* CPU subtype (and we'd have to construct a frequency table for each subtype).
*
* Maybe something to implement in the future..
*/
#define SH_FREQ_MAX 0
#define SH_FREQ_MIN 1
static struct cpufreq_frequency_table sh_freqs[] = {
{ SH_FREQ_MAX, 0 },
{ SH_FREQ_MIN, 0 },
{ 0, CPUFREQ_TABLE_END },
};
static void sh_cpufreq_update_clocks(unsigned int set)
{
current_cpu_data.cpu_clock = current_cpu_data.master_clock / clock_sets[set].ifc;
current_cpu_data.bus_clock = current_cpu_data.master_clock / clock_sets[set].bfc;
current_cpu_data.module_clock = current_cpu_data.master_clock / clock_sets[set].pfc;
current_cpu_data.loops_per_jiffy = loops_per_jiffy;
}
/* XXX: This needs to be split out per CPU and CPU subtype. */
/*
* Here we notify other drivers of the proposed change and the final change.
*/
static int sh_cpufreq_setstate(unsigned int cpu, unsigned int set)
{
unsigned short frqcr = ctrl_inw(FRQCR);
cpumask_t cpus_allowed;
struct cpufreq_freqs freqs;
if (!cpu_online(cpu))
return -ENODEV;
cpus_allowed = current->cpus_allowed;
set_cpus_allowed(current, cpumask_of_cpu(cpu));
BUG_ON(smp_processor_id() != cpu);
freqs.cpu = cpu;
freqs.old = current_cpu_data.cpu_clock / 1000;
freqs.new = (current_cpu_data.master_clock / clock_sets[set].ifc) / 1000;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
#if defined(CONFIG_CPU_SH3)
frqcr |= (newstate & 0x4000) << 14;
frqcr |= (newstate & 0x000c) << 2;
#elif defined(CONFIG_CPU_SH4)
/*
* FRQCR.PLL2EN is 1, we need to allow the PLL to stabilize by
* initializing the WDT.
*/
if (frqcr & (1 << 9)) {
__u8 csr;
/*
* Set the overflow period to the highest available,
* in this case a 1/4096 division ratio yields a 5.25ms
* overflow period. See asm-sh/watchdog.h for more
* information and a range of other divisors.
*/
csr = sh_wdt_read_csr();
csr |= WTCSR_CKS_4096;
sh_wdt_write_csr(csr);
sh_wdt_write_cnt(0);
}
frqcr &= 0x0e00; /* Clear ifc, bfc, pfc */
frqcr |= get_ifc_value(clock_sets[set].ifc) << 6;
frqcr |= get_bfc_value(clock_sets[set].bfc) << 3;
frqcr |= get_pfc_value(clock_sets[set].pfc);
#endif
ctrl_outw(frqcr, FRQCR);
sh_cpufreq_update_clocks(set);
set_cpus_allowed(current, cpus_allowed);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return 0;
}
static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
unsigned int min_freq, max_freq;
unsigned int ifc, bfc, pfc;
if (!cpu_online(policy->cpu))
return -ENODEV;
/* Update our maximum clock set */
get_current_frequency_divisors(&ifc, &bfc, &pfc);
clock_sets[MAX_CLOCK_SET].ifc = ifc;
clock_sets[MAX_CLOCK_SET].bfc = bfc;
clock_sets[MAX_CLOCK_SET].pfc = pfc;
/* Convert from Hz to kHz */
max_freq = current_cpu_data.cpu_clock / 1000;
min_freq = (current_cpu_data.master_clock / clock_sets[MIN_CLOCK_SET].ifc) / 1000;
sh_freqs[SH_FREQ_MAX].frequency = max_freq;
sh_freqs[SH_FREQ_MIN].frequency = min_freq;
/* cpuinfo and default policy values */
policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
policy->cur = max_freq;
return cpufreq_frequency_table_cpuinfo(policy, &sh_freqs[0]);
}
static int sh_cpufreq_verify(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, &sh_freqs[0]);
}
static int sh_cpufreq_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
unsigned int set, idx = 0;
if (cpufreq_frequency_table_target(policy, &sh_freqs[0], target_freq, relation, &idx))
return -EINVAL;
set = (idx == SH_FREQ_MIN) ? MIN_CLOCK_SET : MAX_CLOCK_SET;
sh_cpufreq_setstate(policy->cpu, set);
return 0;
}
static struct cpufreq_driver sh_cpufreq_driver = {
.owner = THIS_MODULE,
.name = "SH cpufreq",
.init = sh_cpufreq_cpu_init,
.verify = sh_cpufreq_verify,
.target = sh_cpufreq_target,
};
static int __init sh_cpufreq_init(void)
{
if (!current_cpu_data.cpu_clock)
return -EINVAL;
if (cpufreq_register_driver(&sh_cpufreq_driver))
return -EINVAL;
return 0;
}
static void __exit sh_cpufreq_exit(void)
{
cpufreq_unregister_driver(&sh_cpufreq_driver);
}
module_init(sh_cpufreq_init);
module_exit(sh_cpufreq_exit);
MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("cpufreq driver for SuperH");
MODULE_LICENSE("GPL");
