From f27de46472e55a54aceae042f2b3a9ced68491a2 Mon Sep 17 00:00:00 2001
From: Solomon Peachy <pizza@shaftnet.org>
Date: Fri, 25 Jul 2025 07:56:06 -0400
Subject: [PATCH] PP502x:  Hacky technique to switch UARTs based on which IRQ
 was triggered

This lets us have multiple serial ports enabled, which will help with
4th-gen ipods that have a serial port in the HP jack as well in the dock.

Change-Id: I6a00a776020848a6908413e05a6f27bad65b2d8e
---
 firmware/target/arm/pp/system-pp502x.c |  9 ++++++---
 firmware/target/arm/pp/uart-pp.c       | 16 +++++++++++++++-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/firmware/target/arm/pp/system-pp502x.c b/firmware/target/arm/pp/system-pp502x.c
index fb6fe28d91..860e17957c 100644
--- a/firmware/target/arm/pp/system-pp502x.c
+++ b/firmware/target/arm/pp/system-pp502x.c
@@ -47,7 +47,7 @@
 #if !defined(BOOTLOADER) || defined(HAVE_BOOTLOADER_USB_MODE)
 extern void TIMER1(void);
 extern void TIMER2(void);
-extern void SERIAL_ISR(void);
+extern void SERIAL_ISR(int port);
 
 #if defined(HAVE_ADJUSTABLE_CPU_FREQ) && (NUM_CORES > 1)
 static struct corelock cpufreq_cl SHAREDBSS_ATTR;
@@ -187,8 +187,11 @@ void __attribute__((interrupt("IRQ"))) irq_handler(void)
 /* end PBELL_VIBE500 */
 #endif
 #ifdef IPOD_ACCESSORY_PROTOCOL
-        else if (CPU_HI_INT_STAT & (SER0_MASK | SER1_MASK)) {
-            SERIAL_ISR();
+        else if (CPU_HI_INT_STAT & SER0_MASK) {
+            SERIAL_ISR(0);
+        }
+        else if (CPU_HI_INT_STAT & SER1_MASK) {
+            SERIAL_ISR(1);
         }
 #endif
     } else {
diff --git a/firmware/target/arm/pp/uart-pp.c b/firmware/target/arm/pp/uart-pp.c
index 2820db0e88..9eadc81bd6 100644
--- a/firmware/target/arm/pp/uart-pp.c
+++ b/firmware/target/arm/pp/uart-pp.c
@@ -188,12 +188,26 @@ static unsigned char rx_readc(void)
     return (*base_RBR & 0xFF);
 }
 
-void SERIAL_ISR(void)
+void SERIAL_ISR(int port)
 {
     static int badbaud = 0;
     static bool newpkt = true;
     char temp;
 
+    if (port && base_RBR != &SER1_RBR) {
+        base_RBR = &SER1_RBR;
+        base_THR = &SER1_THR;
+        base_LCR = &SER1_LCR;
+        base_LSR = &SER1_LSR;
+        base_DLL = &SER1_DLL;
+    } else if (!port && base_RBR != &SER0_RBR) {
+        base_RBR = &SER0_RBR;
+        base_THR = &SER0_THR;
+        base_LCR = &SER0_LCR;
+        base_LSR = &SER0_LSR;
+        base_DLL = &SER0_DLL;
+    }
+
     while(rx_rdy())
     {
         temp = rx_readc();