Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * 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

 * or

 *      console=uart8250,io,0x3f8,9600n8

 *      console=uart8250,mmio,0xff5e0000,115200n8

 */

#include <linux/tty.h>

#include <linux/init.h>

#include <linux/console.h>

#include <linux/serial_core.h>

#include <linux/serial_reg.h>

#include <linux/serial.h>

#include <linux/serial_8250.h>

#include <asm/io.h>

#include <asm/serial.h>

#ifdef CONFIG_FIX_EARLYCON_MEM

#include <asm/pgtable.h>

#include <asm/fixmap.h>

#endif

struct early_serial8250_device {

        struct uart_port port;

        char options[16];               /* e.g., 115200n8 */

        unsigned int baud;

};

static struct early_serial8250_device early_device;

static unsigned int __init serial_in(struct uart_port *port, int offset)

{

        if (port->iotype == UPIO_MEM)

                return readb(port->membase + offset);

        else

                return inb(port->iobase + offset);

}

static void __init serial_out(struct uart_port *port, int offset, int value)

{

        if (port->iotype == UPIO_MEM)

                writeb(value, port->membase + offset);

        else

                outb(value, port->iobase + offset);

}

#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)

static void __init wait_for_xmitr(struct uart_port *port)

{

        unsigned int status;

        for (;;) {

                status = serial_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);

        serial_out(port, UART_TX, c);

}

static void __init early_serial8250_write(struct console *console, const char *s, unsigned int count)

{

        struct uart_port *port = &early_device.port;

        unsigned int ier;

        /* Save the IER and disable interrupts */

        ier = serial_in(port, UART_IER);

        serial_out(port, UART_IER, 0);

        uart_console_write(port, s, count, serial_putc);

        /* Wait for transmitter to become empty and restore the IER */

        wait_for_xmitr(port);

        serial_out(port, UART_IER, ier);

}

static unsigned int __init probe_baud(struct uart_port *port)

{

        unsigned char lcr, dll, dlm;

        unsigned int quot;

        lcr = serial_in(port, UART_LCR);

        serial_out(port, UART_LCR, lcr | UART_LCR_DLAB);

        dll = serial_in(port, UART_DLL);

        dlm = serial_in(port, UART_DLM);

        serial_out(port, UART_LCR, lcr);

        quot = (dlm << 8) | dll;

        return (port->uartclk / 16) / quot;

}

static void __init init_port(struct early_serial8250_device *device)

{

        struct uart_port *port = &device->port;

        unsigned int divisor;

        unsigned char c;

        serial_out(port, UART_LCR, 0x3);        /* 8n1 */

        serial_out(port, UART_IER, 0);           /* no interrupt */

        serial_out(port, UART_FCR, 0);           /* no fifo */

        serial_out(port, UART_MCR, 0x3);        /* DTR + RTS */

        divisor = port->uartclk / (16 * device->baud);

        c = serial_in(port, UART_LCR);

        serial_out(port, UART_LCR, c | UART_LCR_DLAB);

        serial_out(port, UART_DLL, divisor & 0xff);

        serial_out(port, UART_DLM, (divisor >> 8) & 0xff);

        serial_out(port, UART_LCR, c & ~UART_LCR_DLAB);

}

static int __init parse_options(struct early_serial8250_device *device, char *options)

{

        struct uart_port *port = &device->port;

        int mmio, length;

        if (!options)

                return -ENODEV;

        /* port->uartclk = BASE_BAUD * 16; */

        port->uartclk = SYS_CLK; /* changed */

        if (!strncmp(options, "mmio,", 5)) {

                port->iotype = UPIO_MEM;

                port->mapbase = simple_strtoul(options + 5, &options, 0);

#ifdef CONFIG_FIX_EARLYCON_MEM

                set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, port->mapbase & PAGE_MASK);

                port->membase = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);

                port->membase += port->mapbase & ~PAGE_MASK;

#else

                port->membase = ioremap(port->mapbase, 64);

                if (!port->membase) {

                        printk(KERN_ERR "%s: Couldn't ioremap 0x%llx\n",

                                __FUNCTION__,

                               (unsigned long long)port->mapbase);

                        return -ENOMEM;

                }

#endif

                mmio = 1;

        } else if (!strncmp(options, "io,", 3)) {

                port->iotype = UPIO_PORT;

                port->iobase = simple_strtoul(options + 3, &options, 0);

                mmio = 0;

        } else

                return -EINVAL;

        if ((options = strchr(options, ','))) {

                options++;

                device->baud = simple_strtoul(options, NULL, 0);

                length = min(strcspn(options, " "), sizeof(device->options));

                strncpy(device->options, options, length);

        } else {

                device->baud = probe_baud(port);

                snprintf(device->options, sizeof(device->options), "%u",

                        device->baud);

        }

        printk(KERN_INFO "Early serial console at %s 0x%llx (options '%s')\n",

                mmio ? "MMIO" : "I/O port",

                mmio ? (unsigned long long) port->mapbase

                     : (unsigned long long) port->iobase,

                device->options);

        return 0;

}

static struct console early_serial8250_console __initdata = {

        .name   = "uart",

        .write  = early_serial8250_write,

        .flags  = CON_PRINTBUFFER | CON_BOOT,

        .index  = -1,

};

static int __init early_serial8250_setup(char *options)

{

        struct early_serial8250_device *device = &early_device;

        int err;

        if (device->port.membase || device->port.iobase)

                return 0;

        if ((err = parse_options(device, options)) < 0)

                return err;

        init_port(device);

        return 0;

}

int __init setup_early_serial8250_console(char *cmdline)

{

        char *options;

        int err;

        options = strstr(cmdline, "uart8250,");

        if (!options) {

                options = strstr(cmdline, "uart,");

                if (!options)

                        return 0;

        }

        options = strchr(cmdline, ',') + 1;

        if ((err = early_serial8250_setup(options)) < 0)

                return err;

        register_console(&early_serial8250_console);

        return 0;

}

int serial8250_find_port_for_earlycon(void)

{

        struct early_serial8250_device *device = &early_device;

        struct uart_port *port = &device->port;

        int line;

        int ret;

        if (!device->port.membase && !device->port.iobase)

                return -ENODEV;

        line = serial8250_find_port(port);

        if (line < 0)

                return -ENODEV;

        ret = update_console_cmdline("uart", 8250,

                             "ttyS", line, device->options);

        if (ret < 0)

                ret = update_console_cmdline("uart", 0,

                                     "ttyS", line, device->options);

        return ret;

}

early_param("earlycon", setup_early_serial8250_console);