Add a small serial driver

[netwatch.git] / lib / serial.c

diff --git a/lib/serial.c b/lib/serial.c
new file mode 100644 (file)
index 0000000..5318c95
--- /dev/null
+++ b/lib/serial.c
@@ -0,0 +1,50 @@
+#include <minilib.h>
+#include <io.h>
+
+#define SER_BASE 0x3F8
+#define SER_THR 0x0
+#define SER_RBR 0x0
+#define SER_DLL 0x0
+#define SER_IER 0x1
+#define SER_DLM 0x1
+#define SER_IIR 0x2
+#define SER_FCR 0x2
+#define SER_LCR 0x3
+#define SER_LCR_DLAB 0x80
+#define SER_MCR 0x4
+#define SER_LSR 0x5
+#define SER_LSR_THR_EMPTY 0x20
+#define SER_MSR 0x6
+#define SER_SR 0x7
+
+#define SER_BAUD_BASE 115200
+#define SER_BAUD_REQ 115200
+
+void _outb(unsigned short port, unsigned char d)
+{
+       outb(SER_BASE + port, d);
+}
+
+unsigned char _inb(unsigned short port)
+{
+       return inb(SER_BASE + port);
+}
+
+void serial_init()
+{
+       unsigned short baud = SER_BAUD_REQ / SER_BAUD_BASE;
+       _outb(SER_LCR, inb(SER_LCR) | SER_LCR_DLAB);
+       _outb(SER_DLL, baud & 0xFF);
+       _outb(SER_DLM, baud >> 8);
+       _outb(SER_LCR, inb(SER_LCR) & ~SER_LCR_DLAB);
+       _outb(SER_IER, 0x0);
+       _outb(SER_FCR, 0x0);    /* FIFOs off */
+       _outb(SER_LCR, 0x03);   /* 8 data bits, one stop bit, no parity */
+}
+
+void serial_tx(unsigned char c)
+{
+       while (!(_inb(SER_LSR) & SER_LSR_THR_EMPTY))
+               ;
+       _outb(SER_THR, c);
+}