init.s

Linux2.4.27在AT91RM9200下的U-BOOT代码。可以在Redhat9等版本下使用。适合ARM学习者使用。

/*------------------------------------------------------------------------------+ */
/* */
/*       This source code has been made available to you by IBM on an AS-IS */
/*       basis.  Anyone receiving this source is licensed under IBM */
/*       copyrights to use it in any way he or she deems fit, including */
/*       copying it, modifying it, compiling it, and redistributing it either */
/*       with or without modifications.  No license under IBM patents or */
/*       patent applications is to be implied by the copyright license. */
/* */
/*       Any user of this software should understand that IBM cannot provide */
/*       technical support for this software and will not be responsible for */
/*       any consequences resulting from the use of this software. */
/* */
/*       Any person who transfers this source code or any derivative work */
/*       must include the IBM copyright notice, this paragraph, and the */
/*       preceding two paragraphs in the transferred software. */
/* */
/*       COPYRIGHT   I B M   CORPORATION 1995 */
/*       LICENSED MATERIAL  -  PROGRAM PROPERTY OF I B M */
/*------------------------------------------------------------------------------- */

/*----------------------------------------------------------------------------- */
/* Function:     ext_bus_cntlr_init */
/* Description:  Initializes the External Bus Controller for the external */
/*		peripherals. IMPORTANT: For pass1 this code must run from */
/*		cache since you can not reliably change a peripheral banks */
/*		timing register (pbxap) while running code from that bank. */
/*		For ex., since we are running from ROM on bank 0, we can NOT */
/*		execute the code that modifies bank 0 timings from ROM, so */
/*		we run it from cache. */
/*	Bank 0 - Flash and SRAM */
/*	Bank 1 - NVRAM/RTC */
/*	Bank 2 - Keyboard/Mouse controller */
/*	Bank 3 - IR controller */
/*	Bank 4 - not used */
/*	Bank 5 - not used */
/*	Bank 6 - not used */
/*	Bank 7 - FPGA registers */
/*----------------------------------------------------------------------------- */
#include <ppc4xx.h>

#include <ppc_asm.tmpl>
#include <ppc_defs.h>

#include <asm/cache.h>
#include <asm/mmu.h>


	.globl	ext_bus_cntlr_init
ext_bus_cntlr_init:
	mflr    r4                      /* save link register */
	bl      ..getAddr
..getAddr:
	mflr    r3                      /* get address of ..getAddr */
	mtlr    r4                      /* restore link register */
	addi    r4,0,14                 /* set ctr to 10; used to prefetch */
	mtctr   r4                      /* 10 cache lines to fit this function */
					/* in cache (gives us 8x10=80 instrctns) */
..ebcloop:
	icbt    r0,r3                   /* prefetch cache line for addr in r3 */
	addi    r3,r3,32		/* move to next cache line */
	bdnz    ..ebcloop               /* continue for 10 cache lines */

	/*------------------------------------------------------------------- */
	/* Delay to ensure all accesses to ROM are complete before changing */
	/* bank 0 timings. 200usec should be enough. */
	/*   200,000,000 (cycles/sec) X .000200 (sec) = 0x9C40 cycles */
	/*------------------------------------------------------------------- */
	addis	r3,0,0x0
	ori     r3,r3,0xA000          /* ensure 200usec have passed since reset */
	mtctr   r3
..spinlp:
	bdnz    ..spinlp                /* spin loop */

	/*----------------------------------------------------------------------- */
	/* Memory Bank 0 (Flash and SRAM) initialization */
	/*----------------------------------------------------------------------- */
	addi    r4,0,pb0ap
	mtdcr   ebccfga,r4
	addis   r4,0,0x9B01
	ori     r4,r4,0x5480
	mtdcr   ebccfgd,r4

	addi    r4,0,pb0cr
	mtdcr   ebccfga,r4
	addis   r4,0,0xFFF1           /* BAS=0xFFF,BS=0x0(1MB),BU=0x3(R/W), */
	ori     r4,r4,0x8000          /* BW=0x0( 8 bits) */
	mtdcr   ebccfgd,r4

	blr


/*----------------------------------------------------------------------------- */
/* Function:     sdram_init */
/* Description:  Dummy implementation here - done in C later */
/*----------------------------------------------------------------------------- */
	.globl  sdram_init
sdram_init:
	blr