From aae8818fbc80281699f085d0fffbab659f184387 Mon Sep 17 00:00:00 2001
From: Jacques Comeaux <jacquesrcomeaux@protonmail.com>
Date: Sat, 23 Dec 2023 22:50:04 -0600
Subject: Select UART function for GPIO 0 and 1

---
 uart.s | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/uart.s b/uart.s
index 5b03024..39e631b 100644
--- a/uart.s
+++ b/uart.s
@@ -19,6 +19,10 @@
 .equ UARTLCR_H_OFST, 0x2c
 .equ UARTCR_OFST, 0x30
 
+.equ IO_BANK0_BASE, 0x40014000
+.equ GPIO0_CTRL_OFST, 0x04
+.equ GPIO1_CTRL_OFST, 0x0c
+
 .equ ATOMIC_CLEAR,    0x3000
 
 .type setup_uart, %function
@@ -26,6 +30,12 @@
 
 setup_uart:
 
+  // Configure GPIO 0 and 1 as UART0
+  ldr r1, =IO_BANK0_BASE
+  movs r0, 2 // UART function = 2
+  str r0, [r1, GPIO0_CTRL_OFST]
+  str r0, [r1, GPIO1_CTRL_OFST]
+
   // Deassert the reset
   ldr r1, =(RESETS_BASE + ATOMIC_CLEAR)
   movs r0, 1
-- 
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