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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2008 Rafaël Carré
*
* 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#ifndef SYSTEM_TARGET_H
#define SYSTEM_TARGET_H
#include "system-arm.h"
#include "mmu-arm.h"
#include "panic.h"
#include "clock-target.h" /* CPUFREQ_* are defined here */
#ifdef HAVE_SCROLLWHEEL
/* let the timer interrupt twice as often for the scrollwheel polling */
#define KERNEL_TIMER_FREQ (TIMER_FREQ/2)
#else
#define KERNEL_TIMER_FREQ TIMER_FREQ
#endif
#ifdef BOOTLOADER
#define UNCACHED_ADDR(a) (a)
#else
#define UNCACHED_ADDR(a) ((typeof(a)) ((uintptr_t)(a) + 0x10000000))
#endif
#ifdef SANSA_C200V2
/* 0: Backlight on A5, 1: Backlight on A7 */
extern int c200v2_variant;
/* c200v2 changes the timer interval often due to software pwm */
#define TIMER_PERIOD TIMER2_BGLOAD
#else
#define TIMER_PERIOD (KERNEL_TIMER_FREQ/HZ)
#endif
/*
* This function is not overly accurate, so rather call it with an usec more
* than less (see below comment)
*
* if inlined it expands to a really small and fast function if it's called
* with compile time constants */
static inline void udelay(unsigned usecs) __attribute__((always_inline));
static inline void udelay(unsigned usecs)
{
int now, end;
/**
* we're limited to 1.5us multiplies due to the odd timer frequency (1.5MHz),
* to avoid calculating which is safer (need to round up for small values)
* and saves spending time in the divider we have a lut for
* small us values, it should be roughly us*2/3
**/
static const unsigned char udelay_lut[] =
{
0, 1, 2, 2, 3, 4, 4, 5, 6, 6,
7, 8, 8, 9, 10, 10, 11, 12, 12, 13,
};
now = TIMER2_VALUE;
/* we don't want to handle multiple overflows, so limit the numbers
* (if you want to wait more than a tick just poll current_tick, or
* call sleep()) */
if (UNLIKELY(usecs >= TIMER_PERIOD))
panicf("%s(): %d too high!", __func__, usecs);
if (UNLIKELY(usecs <= 0))
return;
if (usecs < ARRAYLEN(udelay_lut))
{ /* the timer decrements */
end = now - udelay_lut[usecs];
}
else
{ /* to usecs */
int delay = usecs * 2 / 3; /* us * 1.5 = us*timer_period */
end = now - delay;
}
/* underrun ? */
if (end < 0)
end += TIMER_PERIOD;
while(TIMER2_VALUE != (unsigned)end);
}
#endif /* SYSTEM_TARGET_H */
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