init.s

Uboot源码,非常通用的bootloader.适用于各种平台的Linux系统引导.

/*
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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
*/

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

/* General */
#define TLB_VALID   0x00000200

/* Supported page sizes */

#define SZ_1K	    0x00000000
#define SZ_4K	    0x00000010
#define SZ_16K	    0x00000020
#define SZ_64K	    0x00000030
#define SZ_256K	    0x00000040
#define SZ_1M	    0x00000050
#define SZ_8M       0x00000060
#define SZ_16M	    0x00000070
#define SZ_256M	    0x00000090

/* Storage attributes */
#define SA_W	    0x00000800	    /* Write-through */
#define SA_I	    0x00000400	    /* Caching inhibited */
#define SA_M	    0x00000200	    /* Memory coherence */
#define SA_G	    0x00000100	    /* Guarded */
#define SA_E	    0x00000080	    /* Endian */

/* Access control */
#define AC_X	    0x00000024	    /* Execute */
#define AC_W	    0x00000012	    /* Write */
#define AC_R	    0x00000009	    /* Read */

/* Some handy macros */

#define EPN(e)		((e) & 0xfffffc00)
#define TLB0(epn,sz)	( (EPN((epn)) | (sz) | TLB_VALID ) )
#define TLB1(rpn,erpn)	( ((rpn)&0xfffffc00) | (erpn) )
#define TLB2(a)		( (a)&0x00000fbf )

#define tlbtab_start\
	mflr    r1  ;\
	bl 0f	    ;

#define tlbtab_end\
	.long 0, 0, 0	;   \
0:	mflr    r0	;   \
	mtlr    r1	;   \
	blr		;

#define tlbentry(epn,sz,rpn,erpn,attr)\
	.long TLB0(epn,sz),TLB1(rpn,erpn),TLB2(attr)


/**************************************************************************
 * TLB TABLE
 *
 * This table is used by the cpu boot code to setup the initial tlb
 * entries. Rather than make broad assumptions in the cpu source tree,
 * this table lets each board set things up however they like.
 *
 *  Pointer to the table is returned in r1
 *
 *************************************************************************/

    .section .bootpg,"ax"
    .globl tlbtab

tlbtab:
    tlbtab_start

    /*
     * BOOT_CS (FLASH) must be first. Before relocation SA_I can be off to use the
     * speed up boot process. It is patched after relocation to enable SA_I
     */
    tlbentry( CFG_BOOT_BASE_ADDR, SZ_256M, CFG_BOOT_BASE_ADDR, 0, AC_R|AC_W|AC_X|SA_G/*|SA_I*/)

    /* TLB-entry for init-ram in dcache (SA_I must be turned off!) */
    tlbentry( CFG_INIT_RAM_ADDR, SZ_64K, CFG_INIT_RAM_ADDR, 0, AC_R|AC_W|AC_X|SA_G )

    tlbentry( CFG_SDRAM_BASE, SZ_256M, CFG_SDRAM_BASE, 0, AC_R|AC_W|AC_X|SA_G|SA_I )
    tlbentry( CFG_PCI_BASE, SZ_256M, CFG_PCI_BASE, 0, AC_R|AC_W|SA_G|SA_I )
    tlbentry( CFG_NVRAM_BASE_ADDR, SZ_256M, CFG_NVRAM_BASE_ADDR, 0, AC_R|AC_W|AC_X|SA_W|SA_I )

    /* PCI */
    tlbentry( CFG_PCI_MEMBASE, SZ_256M, CFG_PCI_MEMBASE, 0, AC_R|AC_W|SA_G|SA_I )
    tlbentry( CFG_PCI_MEMBASE1, SZ_256M, CFG_PCI_MEMBASE1, 0, AC_R|AC_W|SA_G|SA_I )
    tlbentry( CFG_PCI_MEMBASE2, SZ_256M, CFG_PCI_MEMBASE2, 0, AC_R|AC_W|SA_G|SA_I )
    tlbentry( CFG_PCI_MEMBASE3, SZ_256M, CFG_PCI_MEMBASE3, 0, AC_R|AC_W|SA_G|SA_I )

    /* USB 2.0 Device */
    tlbentry( CFG_USB_DEVICE, SZ_1K, 0x50000000, 0, AC_R|AC_W|SA_G|SA_I )

    tlbtab_end