/*
 * krane payload entry shim — runs at 0x40000040 right after the
 * depthcharge handoff (MMU off, caches off; position-independent:
 * immediate-encoded addresses only).
 *
 * depthcharge's display_cleanup() stops the overlay engines and drops
 * the backlight before jumping to the payload; this shim undoes those
 * writes so the screen stays alive until U-Boot's scanout driver
 * probes (the driver repeats the revival itself). The shim cannot be
 * removed: depthcharge jumps to payload+0x40, while U-Boot's PIE
 * fixup needs its runtime _start 4K-aligned — so U-Boot sits at image
 * offset 0x1000 and this shim branches there (branch imm26 patched at
 * build time by build-uboot-payload.sh).
 *
 * Register sources (all verified on device, RESEARCH.md rounds 4/10):
 *   OVL0 base 0x14008000: OVL_EN @ +0x000c, OVL0_2L_EN @ +0x100c
 *   (device-era depthcharge mtk_ddp.c offsets).
 *   GPIO controller 0x10005000, dout block +0x100, 16 B per 32-pin
 *   group, set @ +4 (mt8183.h GpioRegs):
 *   DISP_PWM  = pin 43  (bit 11, set 0x10005114),
 *   EN_LCD_BL = pin 176 (bit 16, set 0x10005154).
 */

	.text
	.globl _start
_start:
	/* OVL_EN = 1 */
	mov	w2, #1
	mov	w3, #0x800c
	movk	w3, #0x1400, lsl #16
	str	w2, [x3]
	/* OVL0_2L_EN = 1 */
	mov	w3, #0x900c
	movk	w3, #0x1400, lsl #16
	str	w2, [x3]
	/* backlight on: pin 43 (DISP_PWM), dout set 0x10005114, bit 11 */
	mov	w2, #0x800
	mov	w3, #0x5114
	movk	w3, #0x1000, lsl #16
	str	w2, [x3]
	/* backlight on: pin 176 (EN_LCD_BL), dout set 0x10005154, bit 16 */
	mov	w2, #0x10000
	mov	w3, #0x5154
	movk	w3, #0x1000, lsl #16
	str	w2, [x3]
1:	b	.			/* PATCHED: branch to U-Boot entry */