Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / tty / serial / 8250 / 8250_early.c

diff --git a/kernel/drivers/tty/serial/8250/8250_early.c b/kernel/drivers/tty/serial/8250/8250_early.c
new file mode 100644 (file)
index 0000000..6c0fd8b
--- /dev/null
+++ b/kernel/drivers/tty/serial/8250/8250_early.c
@@ -0,0 +1,154 @@
+/*
+ * Early serial console for 8250/16550 devices
+ *
+ * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
+ *     Bjorn Helgaas <bjorn.helgaas@hp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Based on the 8250.c serial driver, Copyright (C) 2001 Russell King,
+ * and on early_printk.c by Andi Kleen.
+ *
+ * This is for use before the serial driver has initialized, in
+ * particular, before the UARTs have been discovered and named.
+ * Instead of specifying the console device as, e.g., "ttyS0",
+ * we locate the device directly by its MMIO or I/O port address.
+ *
+ * The user can specify the device directly, e.g.,
+ *     earlycon=uart8250,io,0x3f8,9600n8
+ *     earlycon=uart8250,mmio,0xff5e0000,115200n8
+ *     earlycon=uart8250,mmio32,0xff5e0000,115200n8
+ * or
+ *     console=uart8250,io,0x3f8,9600n8
+ *     console=uart8250,mmio,0xff5e0000,115200n8
+ *     console=uart8250,mmio32,0xff5e0000,115200n8
+ */
+
+#include <linux/tty.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/serial_reg.h>
+#include <linux/serial.h>
+#include <linux/serial_8250.h>
+#include <asm/io.h>
+#include <asm/serial.h>
+
+unsigned int __weak __init serial8250_early_in(struct uart_port *port, int offset)
+{
+       switch (port->iotype) {
+       case UPIO_MEM:
+               return readb(port->membase + offset);
+       case UPIO_MEM32:
+               return readl(port->membase + (offset << 2));
+       case UPIO_MEM32BE:
+               return ioread32be(port->membase + (offset << 2));
+       case UPIO_PORT:
+               return inb(port->iobase + offset);
+       default:
+               return 0;
+       }
+}
+
+void __weak __init serial8250_early_out(struct uart_port *port, int offset, int value)
+{
+       switch (port->iotype) {
+       case UPIO_MEM:
+               writeb(value, port->membase + offset);
+               break;
+       case UPIO_MEM32:
+               writel(value, port->membase + (offset << 2));
+               break;
+       case UPIO_MEM32BE:
+               iowrite32be(value, port->membase + (offset << 2));
+               break;
+       case UPIO_PORT:
+               outb(value, port->iobase + offset);
+               break;
+       }
+}
+
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+static void __init wait_for_xmitr(struct uart_port *port)
+{
+       unsigned int status;
+
+       for (;;) {
+               status = serial8250_early_in(port, UART_LSR);
+               if ((status & BOTH_EMPTY) == BOTH_EMPTY)
+                       return;
+               cpu_relax();
+       }
+}
+
+static void __init serial_putc(struct uart_port *port, int c)
+{
+       wait_for_xmitr(port);
+       serial8250_early_out(port, UART_TX, c);
+}
+
+static void __init early_serial8250_write(struct console *console,
+                                       const char *s, unsigned int count)
+{
+       struct earlycon_device *device = console->data;
+       struct uart_port *port = &device->port;
+       unsigned int ier;
+
+       /* Save the IER and disable interrupts preserving the UUE bit */
+       ier = serial8250_early_in(port, UART_IER);
+       if (ier)
+               serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
+
+       uart_console_write(port, s, count, serial_putc);
+
+       /* Wait for transmitter to become empty and restore the IER */
+       wait_for_xmitr(port);
+
+       if (ier)
+               serial8250_early_out(port, UART_IER, ier);
+}
+
+static void __init init_port(struct earlycon_device *device)
+{
+       struct uart_port *port = &device->port;
+       unsigned int divisor;
+       unsigned char c;
+       unsigned int ier;
+
+       serial8250_early_out(port, UART_LCR, 0x3);      /* 8n1 */
+       ier = serial8250_early_in(port, UART_IER);
+       serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */
+       serial8250_early_out(port, UART_FCR, 0);        /* no fifo */
+       serial8250_early_out(port, UART_MCR, 0x3);      /* DTR + RTS */
+
+       divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
+       c = serial8250_early_in(port, UART_LCR);
+       serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB);
+       serial8250_early_out(port, UART_DLL, divisor & 0xff);
+       serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
+       serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB);
+}
+
+static int __init early_serial8250_setup(struct earlycon_device *device,
+                                        const char *options)
+{
+       if (!(device->port.membase || device->port.iobase))
+               return -ENODEV;
+
+       if (!device->baud) {
+               struct uart_port *port = &device->port;
+               unsigned int ier;
+
+               /* assume the device was initialized, only mask interrupts */
+               ier = serial8250_early_in(port, UART_IER);
+               serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
+       } else
+               init_port(device);
+
+       device->con->write = early_serial8250_write;
+       return 0;
+}
+EARLYCON_DECLARE(uart8250, early_serial8250_setup);
+EARLYCON_DECLARE(uart, early_serial8250_setup);