/* * (C) Copyright 2002 * Sysgo Real-Time Solutions, GmbH <www.elinos.com> * Marius Groeger <mgroeger@sysgo.de> * * (C) Copyright 2002 * Gary Jennejohn, DENX Software Engineering, <gj@denx.de> * * 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 */ /* * CPU specific code */ #include <common.h> #include <command.h> #include <arm920t.h> #ifdef CONFIG_USE_IRQ DECLARE_GLOBAL_DATA_PTR; #endif /* read co-processor 15, register #1 (control register) */ static unsigned long read_p15_c1 (void) { unsigned long value; __asm__ __volatile__( "mrc p15, 0, %0, c1, c0, 0 @ read control reg\n" : "=r" (value) : : "memory"); #ifdef MMU_DEBUG printf ("p15/c1 is = %08lx\n", value); #endif return value; } /* write to co-processor 15, register #1 (control register) */ static void write_p15_c1 (unsigned long value) { #ifdef MMU_DEBUG printf ("write %08lx to p15/c1\n", value); #endif __asm__ __volatile__( "mcr p15, 0, %0, c1, c0, 0 @ write it back\n" : : "r" (value) : "memory"); read_p15_c1 (); } static void cp_delay (void) { volatile int i; /* copro seems to need some delay between reading and writing */ for (i = 0; i < 100; i++); } /* See also ARM920T Technical reference Manual */ #define C1_MMU (1<<0) /* mmu off/on */ #define C1_ALIGN (1<<1) /* alignment faults off/on */ #define C1_DC (1<<2) /* dcache off/on */ #define C1_BIG_ENDIAN (1<<7) /* big endian off/on */ #define C1_SYS_PROT (1<<8) /* system protection */ #define C1_ROM_PROT (1<<9) /* ROM protection */ #define C1_IC (1<<12) /* icache off/on */ #define C1_HIGH_VECTORS (1<<13) /* location of vectors: low/high addresses */ int cpu_init (void) { /* * setup up stacks if necessary */ #ifdef CONFIG_USE_IRQ IRQ_STACK_START = _armboot_start - CONFIG_SYS_MALLOC_LEN - CONFIG_SYS_GBL_DATA_SIZE - 4; FIQ_STACK_START = IRQ_STACK_START - CONFIG_STACKSIZE_IRQ; #endif return 0; } int cleanup_before_linux (void) { /* * this function is called just before we call linux * it prepares the processor for linux * * we turn off caches etc ... */ unsigned long i; disable_interrupts (); /* turn off I/D-cache */ asm ("mrc p15, 0, %0, c1, c0, 0":"=r" (i)); i &= ~(C1_DC | C1_IC); asm ("mcr p15, 0, %0, c1, c0, 0": :"r" (i)); /* flush I/D-cache */ i = 0; asm ("mcr p15, 0, %0, c7, c7, 0": :"r" (i)); return (0); } int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) { disable_interrupts (); reset_cpu (0); /*NOTREACHED*/ return (0); } void icache_enable (void) { ulong reg; reg = read_p15_c1 (); /* get control reg. */ cp_delay (); write_p15_c1 (reg | C1_IC); } void icache_disable (void) { ulong reg; reg = read_p15_c1 (); cp_delay (); write_p15_c1 (reg & ~C1_IC); } int icache_status (void) { return (read_p15_c1 () & C1_IC) != 0; } #ifdef USE_920T_MMU /* It makes no sense to use the dcache if the MMU is not enabled */ void dcache_enable (void) { ulong reg; reg = read_p15_c1 (); cp_delay (); write_p15_c1 (reg | C1_DC); } void dcache_disable (void) { ulong reg; reg = read_p15_c1 (); cp_delay (); reg &= ~C1_DC; write_p15_c1 (reg); } int dcache_status (void) { return (read_p15_c1 () & C1_DC) != 0; } #endif