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@@ -0,0 +1,139 @@
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+#include "boot.h"
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+
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+#define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
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+
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+#define XMTRDY 0x20
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+
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+#define DLAB 0x80
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+
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+#define TXR 0 /* Transmit register (WRITE) */
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+#define RXR 0 /* Receive register (READ) */
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+#define IER 1 /* Interrupt Enable */
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+#define IIR 2 /* Interrupt ID */
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+#define FCR 2 /* FIFO control */
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+#define LCR 3 /* Line control */
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+#define MCR 4 /* Modem control */
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+#define LSR 5 /* Line Status */
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+#define MSR 6 /* Modem Status */
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+#define DLL 0 /* Divisor Latch Low */
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+#define DLH 1 /* Divisor latch High */
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+
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+#define DEFAULT_BAUD 9600
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+
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+static void early_serial_init(int port, int baud)
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+{
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+ unsigned char c;
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+ unsigned divisor;
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+
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+ outb(0x3, port + LCR); /* 8n1 */
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+ outb(0, port + IER); /* no interrupt */
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+ outb(0, port + FCR); /* no fifo */
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+ outb(0x3, port + MCR); /* DTR + RTS */
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+
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+ divisor = 115200 / baud;
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+ c = inb(port + LCR);
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+ outb(c | DLAB, port + LCR);
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+ outb(divisor & 0xff, port + DLL);
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+ outb((divisor >> 8) & 0xff, port + DLH);
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+ outb(c & ~DLAB, port + LCR);
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+
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+ early_serial_base = port;
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+}
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+
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+static void parse_earlyprintk(void)
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+{
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+ int baud = DEFAULT_BAUD;
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+ char arg[32];
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+ int pos = 0;
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+ int port = 0;
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+
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+ if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) {
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+ char *e;
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+
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+ if (!strncmp(arg, "serial", 6)) {
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+ port = DEFAULT_SERIAL_PORT;
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+ pos += 6;
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+ }
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+
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+ if (arg[pos] == ',')
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+ pos++;
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+
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+ if (!strncmp(arg, "ttyS", 4)) {
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+ static const int bases[] = { 0x3f8, 0x2f8 };
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+ int idx = 0;
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+
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+ if (!strncmp(arg + pos, "ttyS", 4))
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+ pos += 4;
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+
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+ if (arg[pos++] == '1')
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+ idx = 1;
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+
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+ port = bases[idx];
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+ }
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+
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+ if (arg[pos] == ',')
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+ pos++;
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+
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+ baud = simple_strtoull(arg + pos, &e, 0);
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+ if (baud == 0 || arg + pos == e)
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+ baud = DEFAULT_BAUD;
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+ }
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+
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+ if (port)
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+ early_serial_init(port, baud);
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+}
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+
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+#define BASE_BAUD (1843200/16)
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+static unsigned int probe_baud(int port)
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+{
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+ unsigned char lcr, dll, dlh;
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+ unsigned int quot;
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+
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+ lcr = inb(port + LCR);
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+ outb(lcr | DLAB, port + LCR);
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+ dll = inb(port + DLL);
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+ dlh = inb(port + DLH);
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+ outb(lcr, port + LCR);
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+ quot = (dlh << 8) | dll;
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+
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+ return BASE_BAUD / quot;
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+}
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+
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+static void parse_console_uart8250(void)
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+{
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+ char optstr[64], *options;
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+ int baud = DEFAULT_BAUD;
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+ int port = 0;
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+
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+ /*
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+ * console=uart8250,io,0x3f8,115200n8
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+ * need to make sure it is last one console !
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+ */
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+ if (cmdline_find_option("console", optstr, sizeof optstr) <= 0)
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+ return;
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+
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+ options = optstr;
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+
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+ if (!strncmp(options, "uart8250,io,", 12))
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+ port = simple_strtoull(options + 12, &options, 0);
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+ else if (!strncmp(options, "uart,io,", 8))
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+ port = simple_strtoull(options + 8, &options, 0);
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+ else
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+ return;
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+
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+ if (options && (options[0] == ','))
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+ baud = simple_strtoull(options + 1, &options, 0);
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+ else
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+ baud = probe_baud(port);
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+
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+ if (port)
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+ early_serial_init(port, baud);
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+}
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+
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+void console_init(void)
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+{
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+ parse_earlyprintk();
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+
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+ if (!early_serial_base)
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+ parse_console_uart8250();
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+}
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