arm64: Add apple,s5l UART driver

This is the debug UART found in Apple SoCs. Tested on M1 MacBook Air.

Registers definitions were taken from:
  - https://github.com/AsahiLinux/m1n1/blob/18eb02fa92789dfcdab8e00e8b1cace7ab002718/src/uart_regs.h
  - https://www.sistemasorp.es/blog/S3C2410%20-%20datasheet.pdf

Change-Id: I2e4c8b7927fc823cedca421e1a2623b91f5ef112
Reviewed-on: https://review.haiku-os.org/c/haiku/+/10480
Reviewed-by: waddlesplash <[email protected]>

headers/private/kernel/arch/arm64/arch_uart_samsung.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2026 Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Sam Roberts, [email protected]
+ */
+#ifndef __DEV_UART_SAMSUNG_H
+#define __DEV_UART_SAMSUNG_H
+
+
+#include <arch/generic/debug_uart.h>
+
+
+#define UART_KIND_SAMSUNG "samsung"
+
+
+class ArchUARTSamsung : public DebugUART {
+public:
+						ArchUARTSamsung(addr_t base, int64 clock);
+						~ArchUARTSamsung();
+
+
+			void		InitPort(uint32 baud);
+
+			void		Enable();
+			void		Disable();
+
+			int			PutChar(char c);
+			int			GetChar(bool wait);
+
+			void		FlushTx();
+			void		FlushRx();
+
+private:
+			void		Out32(int reg, uint32 data);
+			uint32		In32(int reg);
+};
+
+
+#endif

src/system/boot/arch/arm64/Jamfile

@@ -5,6 +5,7 @@ local platform ;
 local kernelArchSources =
 	arch_elf.cpp
 	arch_uart_linflex.cpp
+	arch_uart_samsung.cpp
 ;
 
 local kernelArchReusableSources =

src/system/boot/platform/efi/dtb.cpp

@@ -20,6 +20,7 @@
 #elif defined(__aarch64__)
 #	include <arch/arm/arch_uart_pl011.h>
 #	include <arch/arm64/arch_uart_linflex.h>
+#	include <arch/arm64/arch_uart_samsung.h>
 #endif
 
 
@@ -83,6 +84,7 @@ const struct supported_uarts {
 	{ "arm,pl011", UART_KIND_PL011, &get_uart<ArchUARTPL011> },
 	{ "fsl,s32-linflexuart", UART_KIND_LINFLEX, &get_uart<ArchUARTlinflex> },
 	{ "brcm,bcm2835-aux-uart", UART_KIND_8250, &get_uart<DebugUART8250> },
+	{ "apple,s5l-uart", UART_KIND_SAMSUNG, &get_uart<ArchUARTSamsung> },
 #endif
 };
 

src/system/kernel/arch/arm64/arch_uart_samsung.cpp

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2026 Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Sam Roberts, [email protected]
+ */
+
+#include <arch/generic/debug_uart.h>
+#include <arch/arm64/arch_uart_samsung.h>
+
+
+#define ULCON    0x00 // Line control
+#define UCON     0x04 // Control
+#define UFCON    0x08 // FIFO control
+#define UTRSTAT  0x10 // Transmit status
+#define UFSTAT   0x18 // FIFO status
+#define UTXH     0x20 // Transmit holding
+#define URXH     0x24 // Receive holding
+#define UBRDIV   0x28 // Baud rate divider
+
+#define UCON_TXTHRESH_ENA (1 << 13) // Transmit threshold enable
+#define UCON_RXTHRESH_ENA (1 << 12) // Receive threshold enable
+#define UCON_RXTO_ENA     (1 << 9)  // Receive timeout enable
+#define UCON_TXMODE       (3 << 2)  // Transmit mode
+#define UCON_RXMODE       (3 << 0)  // Receive mode
+
+#define UCON_MODE_OFF 0
+#define UCON_MODE_IRQ 1
+
+#define UTRSTAT_RXTO     (1 << 9) // Receive timeout status
+#define UTRSTAT_TXTHRESH (1 << 5) // Transmit threshold status
+#define UTRSTAT_RXTHRESH (1 << 4) // Receive threshold status
+#define UTRSTAT_TXE      (1 << 2) // Transmit empty status
+#define UTRSTAT_TXBE     (1 << 1) // Transmit buffer empty status
+#define UTRSTAT_RXD      (1 << 0) // Receive data status
+
+#define UFSTAT_TXFULL (1 << 9) // Transmit FIFO full status
+#define UFSTAT_RXFULL (1 << 8) // Receive FIFO full status
+#define UFSTAT_TXCNT  (15 << 4) // Transmit FIFO count
+#define UFSTAT_RXCNT  (15 << 0) // Receive FIFO count
+
+
+ArchUARTSamsung::ArchUARTSamsung(addr_t base, int64 clock)
+	:
+	DebugUART(base, clock)
+{
+}
+
+
+ArchUARTSamsung::~ArchUARTSamsung()
+{
+}
+
+
+void
+ArchUARTSamsung::Out32(int reg, uint32 data)
+{
+	*(volatile uint32*)(Base() + reg) = data;
+}
+
+
+uint32
+ArchUARTSamsung::In32(int reg)
+{
+	return *(volatile uint32*)(Base() + reg);
+}
+
+
+void
+ArchUARTSamsung::InitPort(uint32 baud)
+{
+	uint32 ucon = In32(UCON);
+	// Disable TX and RX IRQ
+	Out32(UCON, ucon & !(UCON_RXMODE | UCON_TXMODE));
+}
+
+
+void
+ArchUARTSamsung::Enable()
+{
+	DebugUART::Enable();
+}
+
+void
+ArchUARTSamsung::Disable()
+{
+	DebugUART::Disable();
+}
+
+
+int
+ArchUARTSamsung::PutChar(char c)
+{
+	if (Enabled()) {
+		while ((In32(UFSTAT) & UFSTAT_TXFULL) != 0)
+			;
+
+		Out32(UTXH, c);
+		return 0;
+	}
+
+	return -1;
+}
+
+
+int
+ArchUARTSamsung::GetChar(bool wait)
+{
+	if (Enabled()) {
+		while (wait && ((In32(UFSTAT) & UFSTAT_RXCNT) == 0))
+			;
+
+		if ((In32(UFSTAT) & UFSTAT_RXCNT) == 0)
+			return -1;
+
+		return In32(URXH);
+	}
+
+	return -1;
+}
+
+
+void
+ArchUARTSamsung::FlushTx()
+{
+}
+
+
+void
+ArchUARTSamsung::FlushRx()
+{
+}