usermode capable kernel with logging syscall

1 files changed, 62 insertions, 0 deletions

diff --git a/arch/x86_64/serial.c b/arch/x86_64/serial.c
new file mode 100644
index 0000000..1b49e3f
--- /dev/null
+++ b/arch/x86_64/serial.c
@@ -0,0 +1,62 @@
+#include "serial.h"
+#include "uart.h"
+#include "io/log.h"
+
+static struct LogDevice s_serial_logdev =
+    { .out = serial_out, .chain = NULL };
+
+bool serial_supported = true;
+
+void
+serial_setup(void)
+{
+    /* Disable interrupts. */
+    poutb(SERIAL_UART_COM_IER(SERIAL_UART_COM1), 0x0);
+    /* Enable DLAB. */
+    poutb(SERIAL_UART_COM_LCR(SERIAL_UART_COM1), 0x80);
+    /* Set divisor to 3 (38400 baud)*/
+    poutb(SERIAL_UART_COM_DLAB_DLL(SERIAL_UART_COM1), 3);
+    poutb(SERIAL_UART_COM_DLAB_DLH(SERIAL_UART_COM1), 0);
+    /* Set flags for LCR (8 bits, no parity, one stop)*/
+    poutb(SERIAL_UART_COM_LCR(SERIAL_UART_COM1), 1 | 2);
+    /* Enable & clear FIFO, 14-byte threshold */
+    poutb(SERIAL_UART_COM_FCR(SERIAL_UART_COM1), 1 | 2 | 4 | 0xC0);
+    /* Enable interrupts, set RTS/DSR. */
+    poutb(SERIAL_UART_COM_MCR(SERIAL_UART_COM1), 1 | 2 | 8);
+    /* Set loopback mode for testing. */
+    poutb(SERIAL_UART_COM_MCR(SERIAL_UART_COM1), 2 | 4 | 8 | 0x10);
+    /* Test serial output. */
+    poutb(SERIAL_UART_COM1, 0xAE);
+    if(pinb(SERIAL_UART_COM1) != 0xAE) {
+        serial_supported = false;
+        return;
+    }
+
+    /* Serial is not faulty.
+     * No loopback, enable output 1 & 2.*/
+    poutb(SERIAL_UART_COM_MCR(SERIAL_UART_COM1), 1 | 2 | 4 | 8);
+
+    klog_newdev(&s_serial_logdev);
+}
+
+static ALWAYS_INLINE bool
+serial_transmit_empty(uint16_t com)
+{
+    return pinb(SERIAL_UART_COM_LSR(com) & 0x20);
+}
+
+static inline void
+serial_outb(uint16_t com, uint8_t b)
+{
+    if(b == '\n') serial_outb(com, '\r');
+    while(!serial_transmit_empty(SERIAL_UART_COM1));
+    poutb(com, b);
+}
+
+void
+serial_out(const char *s, size_t len)
+{
+    if(!serial_supported) return;
+    for(; len > 0; len--)
+        serial_outb(SERIAL_UART_COM1, *(s++));
+}