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cpu/arm920t/cpu.c
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185
cpu/arm920t/cpu.c
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/*
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* (C) Copyright 2002
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* Sysgo Real-Time Solutions, GmbH <www.elinos.com>
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* Marius Groeger <mgroeger@sysgo.de>
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*
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* (C) Copyright 2002
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* Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/*
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* CPU specific code
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*/
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#include <common.h>
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#include <command.h>
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#include <arm920t.h>
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/* read co-processor 15, register #1 (control register) */
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static unsigned long read_p15_c1 (void)
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{
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unsigned long value;
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__asm__ __volatile__(
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"mrc p15, 0, %0, c1, c0, 0 @ read control reg\n"
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: "=r" (value)
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:
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: "memory");
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#ifdef MMU_DEBUG
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printf ("p15/c1 is = %08lx\n", value);
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#endif
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return value;
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}
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/* write to co-processor 15, register #1 (control register) */
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static void write_p15_c1 (unsigned long value)
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{
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#ifdef MMU_DEBUG
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printf ("write %08lx to p15/c1\n", value);
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#endif
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__asm__ __volatile__(
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"mcr p15, 0, %0, c1, c0, 0 @ write it back\n"
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:
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: "r" (value)
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: "memory");
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read_p15_c1 ();
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}
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static void cp_delay (void)
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{
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volatile int i;
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/* copro seems to need some delay between reading and writing */
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for (i = 0; i < 100; i++);
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}
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/* See also ARM Ref. Man. */
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#define C1_MMU (1<<0) /* mmu off/on */
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#define C1_ALIGN (1<<1) /* alignment faults off/on */
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#define C1_DC (1<<2) /* dcache off/on */
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#define C1_BIG_ENDIAN (1<<7) /* big endian off/on */
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#define C1_SYS_PROT (1<<8) /* system protection */
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#define C1_ROM_PROT (1<<9) /* ROM protection */
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#define C1_IC (1<<12) /* icache off/on */
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#define C1_HIGH_VECTORS (1<<13) /* location of vectors: low/high addresses */
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#define RESERVED_1 (0xf << 3) /* must be 111b for R/W */
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int cpu_init (void)
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{
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/*
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* setup up stack if necessary
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*/
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#ifdef CONFIG_USE_IRQ
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IRQ_STACK_START = _armboot_end +
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CONFIG_STACKSIZE + CONFIG_STACKSIZE_IRQ - 4;
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FIQ_STACK_START = IRQ_STACK_START + CONFIG_STACKSIZE_FIQ;
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_armboot_real_end = FIQ_STACK_START + 4;
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#else
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_armboot_real_end = _armboot_end + CONFIG_STACKSIZE;
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#endif /* CONFIG_USE_IRQ */
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return (0);
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}
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int cleanup_before_linux (void)
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{
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/*
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* this function is called just before we call linux
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* it prepares the processor for linux
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*
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* we turn off caches etc ...
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*/
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unsigned long i;
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disable_interrupts ();
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/* turn off I/D-cache */
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asm ("mrc p15, 0, %0, c1, c0, 0":"=r" (i));
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i &= ~(C1_DC | C1_IC);
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asm ("mcr p15, 0, %0, c1, c0, 0": :"r" (i));
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/* flush I/D-cache */
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i = 0;
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asm ("mcr p15, 0, %0, c7, c7, 0": :"r" (i));
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return (0);
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}
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int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
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{
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extern void reset_cpu (ulong addr);
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disable_interrupts ();
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reset_cpu (0);
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/*NOTREACHED*/
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return (0);
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}
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void icache_enable (void)
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{
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ulong reg;
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reg = read_p15_c1 ();
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cp_delay ();
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write_p15_c1 (reg | C1_IC);
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}
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void icache_disable (void)
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{
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ulong reg;
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reg = read_p15_c1 ();
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cp_delay ();
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write_p15_c1 (reg & ~C1_IC);
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}
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int icache_status (void)
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{
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return (read_p15_c1 () & C1_IC) != 0;
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}
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#ifdef USE_920T_MMU
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/* It makes no sense to use the dcache if the MMU is not enabled */
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void dcache_enable (void)
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{
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ulong reg;
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reg = read_p15_c1 ();
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cp_delay ();
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write_p15_c1 (reg | C1_DC);
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}
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void dcache_disable (void)
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{
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ulong reg;
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reg = read_p15_c1 ();
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cp_delay ();
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reg &= ~C1_DC;
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write_p15_c1 (reg);
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}
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int dcache_status (void)
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{
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return (read_p15_c1 () & C1_DC) != 0;
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}
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#endif
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