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Diffstat (limited to 'cpu/arm920t/cpu.c')
| -rw-r--r-- | cpu/arm920t/cpu.c | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/cpu/arm920t/cpu.c b/cpu/arm920t/cpu.c new file mode 100644 index 0000000..41cebdf --- /dev/null +++ b/cpu/arm920t/cpu.c @@ -0,0 +1,185 @@ +/* + * (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> + +/* 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 ARM Ref. Man. */ +#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 */ +#define RESERVED_1 (0xf << 3) /* must be 111b for R/W */ + +int cpu_init (void) +{ + /* + * setup up stack if necessary + */ +#ifdef CONFIG_USE_IRQ + IRQ_STACK_START = _armboot_end + + CONFIG_STACKSIZE + CONFIG_STACKSIZE_IRQ - 4; + FIQ_STACK_START = IRQ_STACK_START + CONFIG_STACKSIZE_FIQ; + _armboot_real_end = FIQ_STACK_START + 4; +#else + _armboot_real_end = _armboot_end + CONFIG_STACKSIZE; +#endif /* CONFIG_USE_IRQ */ + 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[]) +{ + extern void reset_cpu (ulong addr); + + disable_interrupts (); + reset_cpu (0); + /*NOTREACHED*/ + return (0); +} + +void icache_enable (void) +{ + ulong reg; + + reg = read_p15_c1 (); + 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 |