[PATCH v2 09/10] microblaze: start.S: add support for configurable vector base address

[Ovidiu Panait <ovidiu.panait@windriver.com>]

Current code assumes that the vector base address is always at 0x0.
However, this value is configurable for MicroBlaze, so update the
__setup_exceptions routine to work with any vector base address.

The r4 register is reserved for the vector base address inside
__setup_exceptions and the function prologe/epilogue are also updated to
save and restore r4.

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
---

(no changes since v1)

 arch/microblaze/cpu/start.S | 58 ++++++++++++++++++++-----------------
 1 file changed, 32 insertions(+), 26 deletions(-)

diff --git a/arch/microblaze/cpu/start.S b/arch/microblaze/cpu/start.S
index 68f97f426c..645f7cb038 100644
--- a/arch/microblaze/cpu/start.S
+++ b/arch/microblaze/cpu/start.S
@@ -105,15 +105,17 @@ clear_bss:
  * r10: Stores little/big endian offset for vectors
  * r2: Stores imm opcode
  * r3: Stores brai opcode
+ * r4: Stores the vector base address
  */
 __setup_exceptions:
-	addik	r1, r1, -28
+	addik	r1, r1, -32
 	swi	r2, r1, 4
 	swi	r3, r1, 8
-	swi	r6, r1, 12
-	swi	r7, r1, 16
-	swi	r8, r1, 20
-	swi	r10, r1, 24
+	swi	r4, r1, 12
+	swi	r6, r1, 16
+	swi	r7, r1, 20
+	swi	r8, r1, 24
+	swi	r10, r1, 28
 
 	/* Find-out if u-boot is running on BIG/LITTLE endian platform
 	 * There are some steps which is necessary to keep in mind:
@@ -132,22 +134,25 @@ __setup_exceptions:
 	addi	r2, r0, 0xb0000000	/* hex b000 opcode imm */
 	addi	r3, r0, 0xb8080000	/* hew b808 opcode brai */
 
+	/* Store the vector base address in r4 */
+	addi	r4, r0, CONFIG_XILINX_MICROBLAZE0_VECTOR_BASE_ADDR
+
 	/* reset address */
-	swi	r2, r0, 0x0	/* reset address - imm opcode */
-	swi	r3, r0, 0x4	/* reset address - brai opcode */
+	swi	r2, r4, 0x0	/* reset address - imm opcode */
+	swi	r3, r4, 0x4	/* reset address - brai opcode */
 
 	addik	r6, r0, CONFIG_SYS_TEXT_BASE
 	sw	r6, r1, r0
 	lhu	r7, r1, r10
 	rsubi	r8, r10, 0x2
-	sh	r7, r0, r8
+	sh	r7, r4, r8
 	rsubi	r8, r10, 0x6
-	sh	r6, r0, r8
+	sh	r6, r4, r8
 
 #if CONFIG_IS_ENABLED(XILINX_MICROBLAZE0_USR_EXCEP)
 	/* user_vector_exception */
-	swi	r2, r0, 0x8	/* user vector exception - imm opcode */
-	swi	r3, r0, 0xC	/* user vector exception - brai opcode */
+	swi	r2, r4, 0x8	/* user vector exception - imm opcode */
+	swi	r3, r4, 0xC	/* user vector exception - brai opcode */
 
 	addik	r6, r5, _exception_handler
 	sw	r6, r1, r0
@@ -173,42 +178,43 @@ __setup_exceptions:
 	 */
 	lhu	r7, r1, r10
 	rsubi	r8, r10, 0xa
-	sh	r7, r0, r8
+	sh	r7, r4, r8
 	rsubi	r8, r10, 0xe
-	sh	r6, r0, r8
+	sh	r6, r4, r8
 #endif
 
 	/* interrupt_handler */
-	swi	r2, r0, 0x10	/* interrupt - imm opcode */
-	swi	r3, r0, 0x14	/* interrupt - brai opcode */
+	swi	r2, r4, 0x10	/* interrupt - imm opcode */
+	swi	r3, r4, 0x14	/* interrupt - brai opcode */
 
 	addik	r6, r5, _interrupt_handler
 	sw	r6, r1, r0
 	lhu	r7, r1, r10
 	rsubi	r8, r10, 0x12
-	sh	r7, r0, r8
+	sh	r7, r4, r8
 	rsubi	r8, r10, 0x16
-	sh	r6, r0, r8
+	sh	r6, r4, r8
 
 	/* hardware exception */
-	swi	r2, r0, 0x20	/* hardware exception - imm opcode */
-	swi	r3, r0, 0x24	/* hardware exception - brai opcode */
+	swi	r2, r4, 0x20	/* hardware exception - imm opcode */
+	swi	r3, r4, 0x24	/* hardware exception - brai opcode */
 
 	addik	r6, r5, _hw_exception_handler
 	sw	r6, r1, r0
 	lhu	r7, r1, r10
 	rsubi	r8, r10, 0x22
-	sh	r7, r0, r8
+	sh	r7, r4, r8
 	rsubi	r8, r10, 0x26
-	sh	r6, r0, r8
+	sh	r6, r4, r8
 
-	lwi	r10, r1, 24
-	lwi	r8, r1, 20
-	lwi	r7, r1, 16
-	lwi	r6, r1, 12
+	lwi	r10, r1, 28
+	lwi	r8, r1, 24
+	lwi	r7, r1, 20
+	lwi	r6, r1, 16
+	lwi	r4, r1, 12
 	lwi	r3, r1, 8
 	lwi	r2, r1, 4
-	addik	r1, r1, 28
+	addik	r1, r1, 32
 
 	rtsd	r15, 8
 	or	r0, r0, r0
-- 
2.25.1