From 71b76c153db7ea57ef046890a874f8621decd852 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Thu, 22 Feb 2018 19:27:01 +0000
Subject: [PATCH 1/2] Add uart

---
 exosphere/uart.c | 33 +++++++++++++++++++++++++++++++++
 exosphere/uart.h | 20 ++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 exosphere/uart.c
 create mode 100644 exosphere/uart.h

diff --git a/exosphere/uart.c b/exosphere/uart.c
new file mode 100644
index 000000000..265931789
--- /dev/null
+++ b/exosphere/uart.c
@@ -0,0 +1,33 @@
+#include "uart.h"
+
+volatile void *g_uart_registers = NULL;
+
+void set_uart_address(void *uart_base) {
+    g_uart_registers = uart_base;
+}
+
+inline void *get_uart_address(void) {
+    return g_uart_registers;
+}
+
+void uart_initialize(uint16_t divider) {
+    /* Setup UART in 16450 mode. We assume the relevant UART clock has been enabled. */
+
+    /* Disable FIFO */
+    UART_IIR_FCR_0 = 0x00;
+
+    /* Set DLAB */
+    UART_LCR_0 = 0x80;
+    UART_THR_DLAB_0_0 = (uint8_t)divider;
+    UART_IER_DLAB_0_0 = (uint8_t)(divider >> 8);
+
+    /* 8N1 mode */
+    UART_LCR_0 = 0x03;
+}
+
+void uart_transmit_char(char ch) {
+    /* Wait for THR to be empty */
+    while (!(UART_LSR_0 & 0x20)) {}
+
+    UART_THR_DLAB_0_0 = ch;
+}
\ No newline at end of file
diff --git a/exosphere/uart.h b/exosphere/uart.h
new file mode 100644
index 000000000..cb7010774
--- /dev/null
+++ b/exosphere/uart.h
@@ -0,0 +1,20 @@
+#ifndef EXOSPHERE_UART_H
+#define EXOSPHERE_UART_H
+
+#include <stdint.h>
+
+/* Exosphere driver for the Tegra X1 UARTs. */
+
+void set_uart_address(void *uart_base);
+void *get_uart_address(void); /* This is inlined in uart.c */
+
+#define UART_THR_DLAB_0_0 (*((volatile uint32_t *)(get_uart_address() + 0x0)))
+#define UART_IER_DLAB_0_0 (*((volatile uint32_t *)(get_uart_address() + 0x4)))
+#define UART_IIR_FCR_0 (*((volatile uint32_t *)(get_uart_address() + 0x8)))
+#define UART_LCR_0 (*((volatile uint32_t *)(get_uart_address() + 0xC)))
+#define UART_LSR_0 (*((volatile uint32_t *)(get_uart_address() + 0x14)))
+
+void uart_initialize(uint16_t divider);
+void uart_transmit_char(char ch);
+
+#endif
\ No newline at end of file

From a2909320348f36b6201894e0bf3ea307dc38a8b3 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Thu, 22 Feb 2018 19:27:22 +0000
Subject: [PATCH 2/2] uart: transmit string and hex

---
 exosphere/uart.c | 13 +++++++++++++
 exosphere/uart.h |  2 ++
 2 files changed, 15 insertions(+)

diff --git a/exosphere/uart.c b/exosphere/uart.c
index 265931789..86b10d6e4 100644
--- a/exosphere/uart.c
+++ b/exosphere/uart.c
@@ -30,4 +30,17 @@ void uart_transmit_char(char ch) {
     while (!(UART_LSR_0 & 0x20)) {}
 
     UART_THR_DLAB_0_0 = ch;
+}
+
+void uart_transmit_str(const char *str) {
+    while (*str) {
+        uart_transmit_char(*str++);
+    }
+}
+
+void uart_transmit_hex(uint32_t value) {
+    for (unsigned int i = 0; i < 8; i++) {
+        uint32_t nibble = (value >> (28 - i * 4)) & 0xF;
+        uart_transmit_char("0123456789ABCDEF"[nibble]);
+    }
 }
\ No newline at end of file
diff --git a/exosphere/uart.h b/exosphere/uart.h
index cb7010774..3da1219bf 100644
--- a/exosphere/uart.h
+++ b/exosphere/uart.h
@@ -16,5 +16,7 @@ void *get_uart_address(void); /* This is inlined in uart.c */
 
 void uart_initialize(uint16_t divider);
 void uart_transmit_char(char ch);
+void uart_transmit_str(const char *str);
+void uart_transmit_hex(uint32_t value);
 
 #endif
\ No newline at end of file