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-rw-r--r--com32/sysdump/serial.c82
1 files changed, 82 insertions, 0 deletions
diff --git a/com32/sysdump/serial.c b/com32/sysdump/serial.c
new file mode 100644
index 00000000..75bbd481
--- /dev/null
+++ b/com32/sysdump/serial.c
@@ -0,0 +1,82 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <sys/io.h>
+
+#include "file.h"
+
+enum {
+ THR = 0,
+ RBR = 0,
+ DLL = 0,
+ DLM = 1,
+ IER = 1,
+ IIR = 2,
+ FCR = 2,
+ LCR = 3,
+ MCR = 4,
+ LSR = 5,
+ MSR = 6,
+ SCR = 7,
+};
+
+int serial_init(struct serial_if *sif)
+{
+ uint16_t port = sif->port;
+ uint8_t dll, dlm, lcr;
+
+ /* Set 115200n81 */
+ outb(0x83, port + LCR);
+ outb(0x01, port + DLL);
+ outb(0x00, port + DLM);
+ (void)inb(port + IER); /* Synchronize */
+ dll = inb(port + DLL);
+ dlm = inb(port + DLM);
+ lcr = inb(port + LCR);
+ outb(0x03, port + LCR);
+ (void)inb(port + IER); /* Synchronize */
+
+ if (dll != 0x01 || dlm != 0x00 || lcr != 0x83)
+ return -1; /* This doesn't look like a serial port */
+
+ /* Disable interrupts */
+ outb(port + IER, 0);
+
+ /* Enable 16550A FIFOs if available */
+ outb(port + FCR, 0x01); /* Enable FIFO */
+ (void)inb(port + IER); /* Synchronize */
+ if (inb(port + IIR) < 0xc0)
+ outb(port + FCR, 0x00); /* Disable FIFOs if non-functional */
+ (void)inb(port + IER); /* Synchronize */
+
+ return 0;
+}
+
+void serial_write(struct serial_if *sif, const void *data, size_t n)
+{
+ uint16_t port = sif->port;
+ const char *p = data;
+ uint8_t lsr;
+
+ while (n--) {
+ do {
+ lsr = inb(port + LSR);
+ } while (!(lsr & 0x20));
+
+ outb(*p++, port + THR);
+ }
+}
+
+void serial_read(struct serial_if *sif, void *data, size_t n)
+{
+ uint16_t port = sif->port;
+ char *p = data;
+ uint8_t lsr;
+
+ while (n--) {
+ do {
+ lsr = inb(port + LSR);
+ } while (!(lsr & 0x01));
+
+ *p++ = inb(port + RBR);
+ }
+}