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linux/arch/arm/mach-imx/cpufreq.c

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/*
* cpu.c: clock scaling for the iMX
*
* Copyright (C) 2000 2001, The Delft University of Technology
* Copyright (c) 2004 Sascha Hauer <sascha@saschahauer.de>
* Copyright (C) 2006 Inky Lung <ilung@cwlinux.com>
* Copyright (C) 2006 Pavel Pisa, PiKRON <ppisa@pikron.com>
*
* Based on SA1100 version written by:
* - Johan Pouwelse (J.A.Pouwelse@its.tudelft.nl): initial version
* - Erik Mouw (J.A.K.Mouw@its.tudelft.nl):
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/*#define DEBUG*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include "generic.h"
#ifndef __val2mfld
#define __val2mfld(mask,val) (((mask)&~((mask)<<1))*(val)&(mask))
#endif
#ifndef __mfld2val
#define __mfld2val(mask,val) (((val)&(mask))/((mask)&~((mask)<<1)))
#endif
#define CR_920T_CLOCK_MODE 0xC0000000
#define CR_920T_FASTBUS_MODE 0x00000000
#define CR_920T_ASYNC_MODE 0xC0000000
static u32 mpctl0_at_boot;
static u32 bclk_div_at_boot;
static void imx_set_async_mode(void)
{
adjust_cr(CR_920T_CLOCK_MODE, CR_920T_ASYNC_MODE);
}
static void imx_set_fastbus_mode(void)
{
adjust_cr(CR_920T_CLOCK_MODE, CR_920T_FASTBUS_MODE);
}
static void imx_set_mpctl0(u32 mpctl0)
{
unsigned long flags;
if (mpctl0 == 0) {
local_irq_save(flags);
CSCR &= ~CSCR_MPEN;
local_irq_restore(flags);
return;
}
local_irq_save(flags);
MPCTL0 = mpctl0;
CSCR |= CSCR_MPEN;
local_irq_restore(flags);
}
/**
* imx_compute_mpctl - compute new PLL parameters
* @new_mpctl: pointer to location assigned by new PLL control register value
* @cur_mpctl: current PLL control register parameters
* @f_ref: reference source frequency Hz
* @freq: required frequency in Hz
* @relation: is one of %CPUFREQ_RELATION_L (supremum)
* and %CPUFREQ_RELATION_H (infimum)
*/
long imx_compute_mpctl(u32 *new_mpctl, u32 cur_mpctl, u32 f_ref, unsigned long freq, int relation)
{
u32 mfi;
u32 mfn;
u32 mfd;
u32 pd;
unsigned long long ll;
long l;
long quot;
/* Fdppl=2*Fref*(MFI+MFN/(MFD+1))/(PD+1) */
/* PD=<0,15>, MFD=<1,1023>, MFI=<5,15> MFN=<0,1022> */
if (cur_mpctl) {
mfd = ((cur_mpctl >> 16) & 0x3ff) + 1;
pd = ((cur_mpctl >> 26) & 0xf) + 1;
} else {
pd=2; mfd=313;
}
/* pd=2; mfd=313; mfi=8; mfn=183; */
/* (MFI+MFN/(MFD)) = Fdppl / (2*Fref) * (PD); */
quot = (f_ref + (1 << 9)) >> 10;
l = (freq * pd + quot) / (2 * quot);
mfi = l >> 10;
mfn = ((l & ((1 << 10) - 1)) * mfd + (1 << 9)) >> 10;
mfd -= 1;
pd -= 1;
*new_mpctl = ((mfi & 0xf) << 10) | (mfn & 0x3ff) | ((mfd & 0x3ff) << 16)
| ((pd & 0xf) << 26);
ll = 2 * (unsigned long long)f_ref * ( (mfi<<16) + (mfn<<16) / (mfd+1) );
quot = (pd+1) * (1<<16);
ll += quot / 2;
do_div(ll, quot);
freq = ll;
pr_debug(KERN_DEBUG "imx: new PLL parameters pd=%d mfd=%d mfi=%d mfn=%d, freq=%ld\n",
pd, mfd, mfi, mfn, freq);
return freq;
}
static int imx_verify_speed(struct cpufreq_policy *policy)
{
if (policy->cpu != 0)
return -EINVAL;
cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
return 0;
}
static unsigned int imx_get_speed(unsigned int cpu)
{
unsigned int freq;
unsigned int cr;
unsigned int cscr;
unsigned int bclk_div;
if (cpu)
return 0;
cscr = CSCR;
bclk_div = __mfld2val(CSCR_BCLK_DIV, cscr) + 1;
cr = get_cr();
if((cr & CR_920T_CLOCK_MODE) == CR_920T_FASTBUS_MODE) {
freq = imx_get_system_clk();
freq = (freq + bclk_div/2) / bclk_div;
} else {
freq = imx_get_mcu_clk();
if (cscr & CSCR_MPU_PRESC)
freq /= 2;
}
freq = (freq + 500) / 1000;
return freq;
}
static int imx_set_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
struct cpufreq_freqs freqs;
u32 mpctl0 = 0;
u32 cscr;
unsigned long flags;
long freq;
long sysclk;
unsigned int bclk_div = bclk_div_at_boot;
/*
* Some governors do not respects CPU and policy lower limits
* which leads to bad things (division by zero etc), ensure
* that such things do not happen.
*/
if(target_freq < policy->cpuinfo.min_freq)
target_freq = policy->cpuinfo.min_freq;
if(target_freq < policy->min)
target_freq = policy->min;
freq = target_freq * 1000;
pr_debug(KERN_DEBUG "imx: requested frequency %ld Hz, mpctl0 at boot 0x%08x\n",
freq, mpctl0_at_boot);
sysclk = imx_get_system_clk();
if (freq > sysclk / bclk_div_at_boot + 1000000) {
freq = imx_compute_mpctl(&mpctl0, mpctl0_at_boot, CLK32 * 512, freq, relation);
if (freq < 0) {
printk(KERN_WARNING "imx: target frequency %ld Hz cannot be set\n", freq);
return -EINVAL;
}
} else {
if(freq + 1000 < sysclk) {
if (relation == CPUFREQ_RELATION_L)
bclk_div = (sysclk - 1000) / freq;
else
bclk_div = (sysclk + freq + 1000) / freq;
if(bclk_div > 16)
bclk_div = 16;
if(bclk_div < bclk_div_at_boot)
bclk_div = bclk_div_at_boot;
}
freq = (sysclk + bclk_div / 2) / bclk_div;
}
freqs.old = imx_get_speed(0);
freqs.new = (freq + 500) / 1000;
freqs.cpu = 0;
freqs.flags = 0;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
local_irq_save(flags);
imx_set_fastbus_mode();
imx_set_mpctl0(mpctl0);
cscr = CSCR;
cscr &= ~CSCR_BCLK_DIV;
cscr |= __val2mfld(CSCR_BCLK_DIV, bclk_div - 1);
CSCR = cscr;
if(mpctl0) {
CSCR |= CSCR_MPLL_RESTART;
/* Wait until MPLL is stabilized */
while( CSCR & CSCR_MPLL_RESTART );
imx_set_async_mode();
}
local_irq_restore(flags);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
pr_debug(KERN_INFO "imx: set frequency %ld Hz, running from %s\n",
freq, mpctl0? "MPLL": "SPLL");
return 0;
}
static int __init imx_cpufreq_driver_init(struct cpufreq_policy *policy)
{
printk(KERN_INFO "i.MX cpu freq change driver v1.0\n");
if (policy->cpu != 0)
return -EINVAL;
policy->cur = policy->min = policy->max = imx_get_speed(0);
policy->cpuinfo.min_freq = 8000;
policy->cpuinfo.max_freq = 200000;
/* Manual states, that PLL stabilizes in two CLK32 periods */
policy->cpuinfo.transition_latency = 4 * 1000000000LL / CLK32;
return 0;
}
static struct cpufreq_driver imx_driver = {
.flags = CPUFREQ_STICKY,
.verify = imx_verify_speed,
.target = imx_set_target,
.get = imx_get_speed,
.init = imx_cpufreq_driver_init,
.name = "imx",
};
static int __init imx_cpufreq_init(void)
{
bclk_div_at_boot = __mfld2val(CSCR_BCLK_DIV, CSCR) + 1;
mpctl0_at_boot = 0;
if((CSCR & CSCR_MPEN) &&
((get_cr() & CR_920T_CLOCK_MODE) != CR_920T_FASTBUS_MODE))
mpctl0_at_boot = MPCTL0;
return cpufreq_register_driver(&imx_driver);
}
arch_initcall(imx_cpufreq_init);
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