From c5be5f6f54893bce9b5f3e8e4b35e38c923fc069 Mon Sep 17 00:00:00 2001
From: Pali Rohár
Date: Thu, 11 Aug 2022 22:27:22 +0200
Subject: Nokia RX-51: Use U-Boot generic position independent code

Switch from custom board specific fixup/copy code to U-Boot generic
position independent code provided by config option POSITION_INDEPENDENT.

This also slightly decrease size of u-boot.bin binary (by 52 bytes). Note
that option POSITION_INDEPENDENT increase size but not more than custom
board fixup/copy code which is being deleted (as it is not needed anymore).

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 board/nokia/rx51/lowlevel_init.S | 127 +++++----------------------------------
 1 file changed, 15 insertions(+), 112 deletions(-)

(limited to 'board/nokia/rx51')

diff --git a/board/nokia/rx51/lowlevel_init.S b/board/nokia/rx51/lowlevel_init.S
index 632595f8378..dd3c830cc2e 100644
--- a/board/nokia/rx51/lowlevel_init.S
+++ b/board/nokia/rx51/lowlevel_init.S
@@ -33,16 +33,24 @@ z_magic:		/* LINUX_ARM_ZIMAGE_MAGIC */
 /*
  * Routine: save_boot_params (called after reset from start.S)
  * Description: Copy attached kernel to address KERNEL_ADDRESS
- *              Copy u-boot to address CONFIG_SYS_TEXT_BASE
- *              Return to copied u-boot address
  */
 
 .global save_boot_params
 save_boot_params:
-	/* Get return address */
-	ldr	lr, =save_boot_params_ret
 
-/* Copy valid attached kernel to address KERNEL_ADDRESS */
+/*
+ * Copy valid attached kernel to absolute address KERNEL_ADDRESS
+ *
+ * Nokia X-Loader is loading secondary image to address 0x80400000.
+ * NOLO is loading boot image to random place, so it doesn't really
+ * matter what is set in CONFIG_SYS_TEXT_BASE. We have to detect
+ * KERNEL_OFFSET from the current execution address and copy it to
+ * absolute address KERNEL_ADDRESS.
+ *
+ * Note that U-Boot has to be compiled with CONFIG_POSITION_INDEPENDENT
+ * because it is loaded at random address and not to the fixed address
+ * (CONFIG_SYS_TEXT_BASE).
+ */
 
 copy_kernel_start:
 	adr	r0, relocaddr	/* r0 - address of section relocaddr */
@@ -100,110 +108,5 @@ copy_kernel_end:
 	str	r5, [r0]	/* remove 4 bytes header of kernel uImage */
 	str	r5, [r0, #36]	/* remove 4 bytes header of kernel zImage */
 
-
-/* Fix u-boot code */
-
-fix_start:
-	adr	r0, relocaddr	/* r0 - address of section relocaddr */
-	ldr	r1, relocaddr	/* r1 - address of relocaddr after relocation */
-	cmp	r0, r1
-
-	beq	copy_uboot_end	/* skip if u-boot is on correct address */
-
-	/* r5 - calculated offset */
-	subhi	r5, r0, r1
-	sublo	r5, r1, r0
-
-	/* r6 - maximal u-boot size */
-	ldr	r6, imagesize
-
-	/* r1 - start of u-boot after */
-	ldr	r1, startaddr
-
-	/* r0 - start of u-boot before */
-	addhi	r0, r1, r5
-	sublo	r0, r1, r5
-
-	/* check if we need to move uboot copy code before calling it */
-	cmp	r5, r6
-	bhi	copy_uboot_start /* now coping u-boot code directly is safe */
-
-
-copy_code_start:
-	/* r0 - start of u-boot before */
-	/* r1 - start of u-boot after */
-	/* r6 - maximal u-boot size */
-
-	/* r7 - maximal kernel size */
-	ldr	r7, kernsize
-
-	/* r4 - end of kernel before */
-	add	r4, r0, r6
-	add	r4, r4, r7
-
-	/* r5 - end of u-boot after */
-	ldr	r5, startaddr
-	add	r5, r5, r6
-
-	/* r2 - start of loop code after */
-	cmp	r4, r5		/* higher address (r4 or r5) */
-	movhs	r2, r4
-	movlo	r2, r5
-
-	/* r3 - end of loop code before */
-	adr	r3, end
-
-	/* r4 - end of loop code after */
-	adr	r4, copy_uboot_start
-	sub	r4, r3, r4
-	add	r4, r2, r4
-
-copy_code_loop:
-	ldmdb	r3!, {r7 - r10}
-	stmdb	r4!, {r7 - r10}
-	cmp	r4, r2
-	bhi	copy_code_loop
-
-copy_code_end:
-	mov	pc, r2
-
-
-/*
- * Copy u-boot to address CONFIG_SYS_TEXT_BASE
- *
- * Nokia X-Loader loading secondary image to address 0x80400000
- * NOLO loading boot image to random place, so it doesn't really
- * matter what is set in CONFIG_SYS_TEXT_BASE. We have to copy
- * u-boot to CONFIG_SYS_TEXT_BASE address.
- */
-
-copy_uboot_start:
-	/* r0 - start of u-boot before */
-	/* r1 - start of u-boot after */
-	/* r6 - maximal u-boot size */
-
-	/* r2 - end of u-boot after */
-	add	r2, r1, r6
-
-	/* condition for copying from left to right */
-	cmp	r0, r1
-	addlo	r1, r0, r6	/* r1 - end of u-boot before */
-	blo	copy_uboot_loop_right
-
-copy_uboot_loop_left:
-	ldmia	r0!, {r3 - r10}
-	stmia	r1!, {r3 - r10}
-	cmp	r1, r2
-	blo	copy_uboot_loop_left
-	b	copy_uboot_end
-
-copy_uboot_loop_right:
-	ldmdb	r1!, {r3 - r10}
-	stmdb	r2!, {r3 - r10}
-	cmp	r1, r0
-	bhi	copy_uboot_loop_right
-
-copy_uboot_end:
-	bx	lr
-
-end:
+	/* Returns */
+	b	save_boot_params_ret
-- 
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