* ----------------------------------------------------------------------- */
/*
- * Very simple screen I/O
- * XXX: Probably should add very simple serial I/O?
+ * Very simple screen and serial I/O
*/
#include "boot.h"
+#define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
+
+static int early_serial_base;
+
+#define XMTRDY 0x20
+
+#define DLAB 0x80
+
+#define TXR 0 /* Transmit register (WRITE) */
+#define RXR 0 /* Receive register (READ) */
+#define IER 1 /* Interrupt Enable */
+#define IIR 2 /* Interrupt ID */
+#define FCR 2 /* FIFO control */
+#define LCR 3 /* Line control */
+#define MCR 4 /* Modem control */
+#define LSR 5 /* Line Status */
+#define MSR 6 /* Modem Status */
+#define DLL 0 /* Divisor Latch Low */
+#define DLH 1 /* Divisor latch High */
+
+#define DEFAULT_BAUD 9600
+
/*
* These functions are in .inittext so they can be used to signal
* error during initialization.
*/
-void __attribute__((section(".inittext"))) putchar(int ch)
+static void __attribute__((section(".inittext"))) serial_putchar(int ch)
{
- struct biosregs ireg;
+ unsigned timeout = 0xffff;
- if (ch == '\n')
- putchar('\r'); /* \n -> \r\n */
+ while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
+ cpu_relax();
+
+ outb(ch, early_serial_base + TXR);
+}
+
+static void __attribute__((section(".inittext"))) bios_putchar(int ch)
+{
+ struct biosregs ireg;
initregs(&ireg);
ireg.bx = 0x0007;
intcall(0x10, &ireg, NULL);
}
+void __attribute__((section(".inittext"))) putchar(int ch)
+{
+ if (ch == '\n')
+ putchar('\r'); /* \n -> \r\n */
+
+ bios_putchar(ch);
+
+ if (early_serial_base != 0)
+ serial_putchar(ch);
+}
+
void __attribute__((section(".inittext"))) puts(const char *str)
{
while (*str)
return 0; /* Timeout! */
}
+
+static void early_serial_init(int port, int baud)
+{
+ unsigned char c;
+ unsigned divisor;
+
+ outb(0x3, port + LCR); /* 8n1 */
+ outb(0, port + IER); /* no interrupt */
+ outb(0, port + FCR); /* no fifo */
+ outb(0x3, port + MCR); /* DTR + RTS */
+
+ divisor = 115200 / baud;
+ c = inb(port + LCR);
+ outb(c | DLAB, port + LCR);
+ outb(divisor & 0xff, port + DLL);
+ outb((divisor >> 8) & 0xff, port + DLH);
+ outb(c & ~DLAB, port + LCR);
+
+ early_serial_base = port;
+
+ printf("Early serial console at I/O port 0x%x baud: %d\n", port, baud);
+}
+
+static void parse_earlyprintk(void)
+{
+ int baud = DEFAULT_BAUD;
+ char arg[32];
+ int pos = 0;
+ int port = 0;
+
+ if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) {
+ char *e;
+
+ if (!strncmp(arg, "serial", 6)) {
+ port = DEFAULT_SERIAL_PORT;
+ pos += 6;
+ }
+
+ if (arg[pos] == ',')
+ pos++;
+
+ if (!strncmp(arg, "ttyS", 4)) {
+ static const int bases[] = { 0x3f8, 0x2f8 };
+ int idx = 0;
+
+ if (!strncmp(arg + pos, "ttyS", 4))
+ pos += 4;
+
+ if (arg[pos++] == '1')
+ idx = 1;
+
+ port = bases[idx];
+ }
+
+ if (arg[pos] == ',')
+ pos++;
+
+ baud = simple_strtoull(arg + pos, &e, 0);
+ if (baud == 0 || arg + pos == e)
+ baud = DEFAULT_BAUD;
+ }
+
+ if (port)
+ early_serial_init(port, baud);
+}
+
+#define BASE_BAUD (1843200/16)
+static unsigned int probe_baud(int port)
+{
+ unsigned char lcr, dll, dlh;
+ unsigned int quot;
+
+ lcr = inb(port + LCR);
+ outb(lcr | DLAB, port + LCR);
+ dll = inb(port + DLL);
+ dlh = inb(port + DLH);
+ outb(lcr, port + LCR);
+ quot = (dlh << 8) | dll;
+
+ return BASE_BAUD / quot;
+}
+
+static void parse_console_uart8250(void)
+{
+ char optstr[64], *options;
+ int baud = DEFAULT_BAUD;
+ int port = 0;
+
+ /*
+ * console=uart8250,io,0x3f8,115200n8
+ * need to make sure it is last one console !
+ */
+ if (cmdline_find_option("console", optstr, sizeof optstr) <= 0)
+ return;
+
+ options = optstr;
+
+ if (!strncmp(options, "uart8250,io,", 12))
+ port = simple_strtoull(options + 12, &options, 0);
+ else if (!strncmp(options, "uart,io,", 8))
+ port = simple_strtoull(options + 8, &options, 0);
+ else
+ return;
+
+ if (options && (options[0] == ','))
+ baud = simple_strtoull(options + 1, &options, 0);
+ else
+ baud = probe_baud(port);
+
+ if (port)
+ early_serial_init(port, baud);
+}
+
+void console_init(void)
+{
+ parse_earlyprintk();
+
+ if (!early_serial_base)
+ parse_console_uart8250();
+}