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/*
* Blackfin core clock scaling
*
* Copyright 2008-2009 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#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>
#include <asm/dpmc.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];
/*
normalized to maximum frequncy offset for CYCLES,
used in time-ts cycles clock source, but could be used
somewhere also.
*/
unsigned long long __bfin_cycles_off;
unsigned int __bfin_cycles_mod;
/**************************************************************************/
static unsigned int bfin_getfreq_khz(unsigned int cpu)
{
/* The driver only support single cpu */
if (cpu != 0)
return -1;
return get_cclk() / 1000;
}
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;
cycles_t cycles;
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_khz(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_hw(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);
cycles = get_cycles();
SSYNC();
cycles += 10; /* ~10 cycles we lose after get_cycles() */
__bfin_cycles_off += (cycles << __bfin_cycles_mod) - (cycles << index);
__bfin_cycles_mod = index;
local_irq_restore_hw(flags);
/* TODO: just test case for cycles clock source, remove later */
pr_debug("cpufreq: done\n");
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;
if (policy->cpu != 0)
return -EINVAL;
cclk = get_cclk() / 1000;
sclk = get_sclk() / 1000;
#if ANOMALY_05000273 || ANOMALY_05000274 || \
(!defined(CONFIG_BF54x) && defined(CONFIG_BFIN_EXTMEM_DCACHEABLE))
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:0x%x tscale:%d\n",
bfin_freq_table[index].frequency,
dpm_state_table[index].csel,
dpm_state_table[index].tscale);
}
policy->cpuinfo.transition_latency = 50000; /* 50us assumed */
/*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_khz,
.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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