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/*
* File: arch/blackfin/mach-common/cpufreq.c
* Based on:
* Author:
*
* Created:
* Description: Blackfin core clock scaling
*
* Modified:
* Copyright 2004-2008 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see the file COPYING, or write
* to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/fs.h>
#include <asm/blackfin.h>
#include <asm/time.h>
/* this is the table of CCLK frequencies, in Hz */
/* .index is the entry in the auxillary dpm_state_table[] */
static struct cpufreq_frequency_table bfin_freq_table[] = {
{
.frequency = CPUFREQ_TABLE_END,
.index = 0,
},
{
.frequency = CPUFREQ_TABLE_END,
.index = 1,
},
{
.frequency = CPUFREQ_TABLE_END,
.index = 2,
},
{
.frequency = CPUFREQ_TABLE_END,
.index = 0,
},
};
static struct bfin_dpm_state {
unsigned int csel; /* system clock divider */
unsigned int tscale; /* change the divider on the core timer interrupt */
} dpm_state_table[3];
/**************************************************************************/
static unsigned int bfin_getfreq(unsigned int cpu)
{
/* The driver only support single cpu */
if (cpu != 0)
return -1;
return get_cclk();
}
static int bfin_target(struct cpufreq_policy *policy,
unsigned int target_freq, unsigned int relation)
{
unsigned int index, plldiv, tscale;
unsigned long flags, cclk_hz;
struct cpufreq_freqs freqs;
if (cpufreq_frequency_table_target(policy, bfin_freq_table,
target_freq, relation, &index))
return -EINVAL;
cclk_hz = bfin_freq_table[index].frequency;
freqs.old = bfin_getfreq(0);
freqs.new = cclk_hz;
freqs.cpu = 0;
pr_debug("cpufreq: changing cclk to %lu; target = %u, oldfreq = %u\n",
cclk_hz, target_freq, freqs.old);
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
local_irq_save(flags);
plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel;
tscale = dpm_state_table[index].tscale;
bfin_write_PLL_DIV(plldiv);
/* we have to adjust the core timer, because it is using cclk */
bfin_write_TSCALE(tscale);
SSYNC();
local_irq_restore(flags);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return 0;
}
static int bfin_verify_speed(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, bfin_freq_table);
}
static int __init __bfin_cpu_init(struct cpufreq_policy *policy)
{
unsigned long cclk, sclk, csel, min_cclk;
int index;
#ifdef CONFIG_CYCLES_CLOCKSOURCE
/*
* Clocksource CYCLES is still CONTINUOUS but not longer MONOTONIC in case we enable
* CPU frequency scaling, since CYCLES runs off Core Clock.
*/
printk(KERN_WARNING "CPU frequency scaling not supported: Clocksource not suitable\n"
return -ENODEV;
#endif
if (policy->cpu != 0)
return -EINVAL;
cclk = get_cclk();
sclk = get_sclk();
#if ANOMALY_05000273
min_cclk = sclk * 2;
#else
min_cclk = sclk;
#endif
csel = ((bfin_read_PLL_DIV() & CSEL) >> 4);
for (index = 0; (cclk >> index) >= min_cclk && csel <= 3; index++, csel++) {
bfin_freq_table[index].frequency = cclk >> index;
dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */
dpm_state_table[index].tscale = (TIME_SCALE / (1 << csel)) - 1;
pr_debug("cpufreq: freq:%d csel:%d tscale:%d\n",
bfin_freq_table[index].frequency,
dpm_state_table[index].csel,
dpm_state_table[index].tscale);
}
policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
policy->cpuinfo.transition_latency = (bfin_read_PLL_LOCKCNT() / (sclk / 1000000)) * 1000;
/*Now ,only support one cpu */
policy->cur = cclk;
cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu);
return cpufreq_frequency_table_cpuinfo(policy, bfin_freq_table);
}
static struct freq_attr *bfin_freq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver bfin_driver = {
.verify = bfin_verify_speed,
.target = bfin_target,
.get = bfin_getfreq,
.init = __bfin_cpu_init,
.name = "bfin cpufreq",
.owner = THIS_MODULE,
.attr = bfin_freq_attr,
};
static int __init bfin_cpu_init(void)
{
return cpufreq_register_driver(&bfin_driver);
}
static void __exit bfin_cpu_exit(void)
{
cpufreq_unregister_driver(&bfin_driver);
}
MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("cpufreq driver for Blackfin");
MODULE_LICENSE("GPL");
module_init(bfin_cpu_init);
module_exit(bfin_cpu_exit);
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