Das U-Boot: Universal Boot Loader

diff --git a/cpu/arm920t/cpu.c b/cpu/arm920t/cpu.c
new file mode 100644 (file)
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