rtl/gfx/firmware: implement bootloader

1 files changed, 76 insertions, 0 deletions

diff --git a/rtl/gfx/firmware/gfx_bootrom.S b/rtl/gfx/firmware/gfx_bootrom.S
new file mode 100644
index 0000000..bf7bd7d
--- /dev/null
+++ b/rtl/gfx/firmware/gfx_bootrom.S
@@ -0,0 +1,76 @@
+#include "custom_ops.S"
+
+.text
+
+.global _start
+_start:
+
+	li   a0, 0x00300000       # HOST_CTRL_BASE
+	li   a1, 1 << 1 | 1 << 0  # ARINT | AWINT
+	li   a2, 1 << 0           # B.VALID = 1
+	li   a3, 0x8              # Firmware handover word
+	la   a4, .read_data
+	li   a5, 1 << 11 | 1 << 9 # CTRL.WVALID | CTRL.AWVALID
+	li   a6, 1 << 12          # CTRL.BDONE, doesn't fit in andi
+
+	sw   a1, 0(a0)
+
+.wait_axi:
+	picorv32_waitirq_insn(zero)
+
+	lw   t0, 0(a0)
+	andi t1, t0, 1 << 8 # ARVALID
+	bne  t1, zero, .read
+	and  t0, t0, a5
+	beq  t0, a5, .write
+	j    .wait_axi
+
+.read:
+	lw   t0, 4(a0)
+	andi t1, t0, 1 << 0 # AW.VALID
+	beq  t1, zero, .wait_axi
+	andi t0, t0, 0b11 << 2
+	add  t0, a4, t0
+	lw   t0, 0(t0)
+	sw   t0, 12(a0) # R.DATA
+
+.read_done:
+	lw   t0, 0(a0)
+	andi t0, t0, 1 << 10 # CTRL.RDONE
+	beq  t0, zero, .read_done
+	j    .wait_axi
+
+.write:
+	lw   t0, 8(a0)
+	andi t1, t0, 1 << 0 # AW.VALID
+	beq  t1, zero, .wait_axi
+	lw   t1, 16(a0)
+	sw   a2, 20(a0)
+
+.write_done:
+	lw   t2, 0(a0)
+	and  t2, t2, a6
+	beq  t2, zero, .write_done
+
+	andi t0, t0, ~0b11
+	bne  t0, a3, .wait_axi
+	sw   zero, 0(a0)
+	# Pass magic & hardware version
+	lw   a0, 0(a4)
+	lw   a1, 4(a4)
+	jalr t1
+	j    .
+
+.balign 4
+
+.read_data:
+	# Magic
+	.word 0x4a7a7b0c
+	# Hardware major.minor.patch
+	.word 1 << 16 | 0 << 8 | 0 << 0
+	# Firmware yyyy.mm.dd.build
+	.word 2024 << 18 | 5 << 15 | 12 << 10 | 1 << 0
+	# Register map version, rev 0 means this is the bootrom firmware
+	.word 0
+
+.balign 4