Merge branch 'master' of git://git.denx.de/u-boot-arm

[oweals/u-boot.git] / arch / arm / cpu / arm926ejs / mxs / mxs.c

diff --git a/arch/arm/cpu/arm926ejs/mxs/mxs.c b/arch/arm/cpu/arm926ejs/mxs/mxs.c
index a5e388b5add4d6c02beb83ef1e602edf55c61c4e..365542fe0bb29e1a7c2cc4ff4d35c83adb41d37b 100644 (file)
--- a/arch/arm/cpu/arm926ejs/mxs/mxs.c
+++ b/arch/arm/cpu/arm926ejs/mxs/mxs.c
@@ -7,23 +7,7 @@
  * Based on code from LTIB:
  * Copyright (C) 2010 Freescale Semiconductor, Inc.
  *
- * 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
+ * SPDX-License-Identifier:    GPL-2.0+
  */
 
 #include <common.h>
@@ -76,13 +60,32 @@ void enable_caches(void)
 #endif
 }
 
+/*
+ * This function will craft a jumptable at 0x0 which will redirect interrupt
+ * vectoring to proper location of U-Boot in RAM.
+ *
+ * The structure of the jumptable will be as follows:
+ *  ldr pc, [pc, #0x18] ..... for each vector, thus repeated 8 times
+ *  <destination address> ... for each previous ldr, thus also repeated 8 times
+ *
+ * The "ldr pc, [pc, #0x18]" instruction above loads address from memory at
+ * offset 0x18 from current value of PC register. Note that PC is already
+ * incremented by 4 when computing the offset, so the effective offset is
+ * actually 0x20, this the associated <destination address>. Loading the PC
+ * register with an address performs a jump to that address.
+ */
 void mx28_fixup_vt(uint32_t start_addr)
 {
-       uint32_t *vt = (uint32_t *)0x20;
+       /* ldr pc, [pc, #0x18] */
+       const uint32_t ldr_pc = 0xe59ff018;
+       /* Jumptable location is 0x0 */
+       uint32_t *vt = (uint32_t *)0x0;
        int i;
 
-       for (i = 0; i < 8; i++)
-               vt[i] = start_addr + (4 * i);
+       for (i = 0; i < 8; i++) {
+               vt[i] = ldr_pc;
+               vt[i + 8] = start_addr + (4 * i);
+       }
 }
 
 #ifdef CONFIG_ARCH_MISC_INIT