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virtex.c

/*
 * 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;
}

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