virtex.c

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/*
 * The platform specific code for virtex devices since a boot loader is not
 * always used.
 *
 * (C) Copyright 2008 Xilinx, Inc.
 *
 * 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.
 */

#include "ops.h"
#include "io.h"
#include "stdio.h"

#define UART_DLL        0   /* Out: Divisor Latch Low */
#define UART_DLM        1   /* Out: Divisor Latch High */
#define UART_FCR        2   /* Out: FIFO Control Register */
#define UART_FCR_CLEAR_RCVR     0x02    /* Clear the RCVR FIFO */
#define UART_FCR_CLEAR_XMIT 0x04    /* Clear the XMIT FIFO */
#define UART_LCR        3   /* Out: Line Control Register */
#define UART_MCR        4   /* Out: Modem Control Register */
#define UART_MCR_RTS        0x02    /* RTS complement */
#define UART_MCR_DTR        0x01    /* DTR complement */
#define UART_LCR_DLAB       0x80    /* Divisor latch access bit */
#define UART_LCR_WLEN8      0x03    /* Wordlength: 8 bits */

static int virtex_ns16550_console_init(void *devp)
{
    unsigned char *reg_base;
    u32 reg_shift, reg_offset, clk, spd;
    u16 divisor;
    int n;

    if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1)
        return -1;

    n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
    if (n == sizeof(reg_offset))
        reg_base += reg_offset;

    n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
    if (n != sizeof(reg_shift))
        reg_shift = 0;

    n = getprop(devp, "current-speed", (void *)&spd, sizeof(spd));
    if (n != sizeof(spd))
        spd = 9600;

    /* should there be a default clock rate?*/
    n = getprop(devp, "clock-frequency", (void *)&clk, sizeof(clk));
    if (n != sizeof(clk))
        return -1;

    divisor = clk / (16 * spd);

    /* Access baud rate */
    out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_DLAB);

    /* Baud rate based on input clock */
    out_8(reg_base + (UART_DLL << reg_shift), divisor & 0xFF);
    out_8(reg_base + (UART_DLM << reg_shift), divisor >> 8);

    /* 8 data, 1 stop, no parity */
    out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_WLEN8);

    /* RTS/DTR */
    out_8(reg_base + (UART_MCR << reg_shift), UART_MCR_RTS | UART_MCR_DTR);

    /* Clear transmitter and receiver */
    out_8(reg_base + (UART_FCR << reg_shift),
                UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
    return 0;
}

/* For virtex, the kernel may be loaded without using a bootloader and if so
   some UARTs need more setup than is provided in the normal console init
*/
int platform_specific_init(void)
{
    void *devp;
    char devtype[MAX_PROP_LEN];
    char path[MAX_PATH_LEN];

    devp = finddevice("/chosen");
    if (devp == NULL)
        return -1;

    if (getprop(devp, "linux,stdout-path", path, MAX_PATH_LEN) > 0) {
        devp = finddevice(path);
        if (devp == NULL)
            return -1;

        if ((getprop(devp, "device_type", devtype, sizeof(devtype)) > 0)
                && !strcmp(devtype, "serial")
                && (dt_is_compatible(devp, "ns16550")))
                virtex_ns16550_console_init(devp);
    }
    return 0;
}