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-rw-r--r--cpu/arm920t/cpu.c185
1 files changed, 185 insertions, 0 deletions
diff --git a/cpu/arm920t/cpu.c b/cpu/arm920t/cpu.c
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+++ b/cpu/arm920t/cpu.c
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+/*
+ * (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