LXR linux/arch/powerpc/boot/virtex.c

   1/*
   2 * The platform specific code for virtex devices since a boot loader is not
   3 * always used.
   4 *
   5 * (C) Copyright 2008 Xilinx, Inc.
   6 *
   7 * This program is free software; you can redistribute it and/or modify it
   8 * under the terms of the GNU General Public License version 2 as published
   9 * by the Free Software Foundation.
  10 */
  11
  12#include "ops.h"
  13#include "io.h"
  14#include "stdio.h"
  15
  16#define UART_DLL                0       /* Out: Divisor Latch Low */
  17#define UART_DLM                1       /* Out: Divisor Latch High */
  18#define UART_FCR                2       /* Out: FIFO Control Register */
  19#define UART_FCR_CLEAR_RCVR     0x02    /* Clear the RCVR FIFO */
  20#define UART_FCR_CLEAR_XMIT     0x04    /* Clear the XMIT FIFO */
  21#define UART_LCR                3       /* Out: Line Control Register */
  22#define UART_MCR                4       /* Out: Modem Control Register */
  23#define UART_MCR_RTS            0x02    /* RTS complement */
  24#define UART_MCR_DTR            0x01    /* DTR complement */
  25#define UART_LCR_DLAB           0x80    /* Divisor latch access bit */
  26#define UART_LCR_WLEN8          0x03    /* Wordlength: 8 bits */
  27
  28static int virtex_ns16550_console_init(void *devp)
  29{
  30        unsigned char *reg_base;
  31        u32 reg_shift, reg_offset, clk, spd;
  32        u16 divisor;
  33        int n;
  34
  35        if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1)
  36                return -1;
  37
  38        n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
  39        if (n == sizeof(reg_offset))
  40                reg_base += reg_offset;
  41
  42        n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
  43        if (n != sizeof(reg_shift))
  44                reg_shift = 0;
  45
  46        n = getprop(devp, "current-speed", (void *)&spd, sizeof(spd));
  47        if (n != sizeof(spd))
  48                spd = 9600;
  49
  50        /* should there be a default clock rate?*/
  51        n = getprop(devp, "clock-frequency", (void *)&clk, sizeof(clk));
  52        if (n != sizeof(clk))
  53                return -1;
  54
  55        divisor = clk / (16 * spd);
  56
  57        /* Access baud rate */
  58        out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_DLAB);
  59
  60        /* Baud rate based on input clock */
  61        out_8(reg_base + (UART_DLL << reg_shift), divisor & 0xFF);
  62        out_8(reg_base + (UART_DLM << reg_shift), divisor >> 8);
  63
  64        /* 8 data, 1 stop, no parity */
  65        out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_WLEN8);
  66
  67        /* RTS/DTR */
  68        out_8(reg_base + (UART_MCR << reg_shift), UART_MCR_RTS | UART_MCR_DTR);
  69
  70        /* Clear transmitter and receiver */
  71        out_8(reg_base + (UART_FCR << reg_shift),
  72                                UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
  73        return 0;
  74}
  75
  76/* For virtex, the kernel may be loaded without using a bootloader and if so
  77   some UARTs need more setup than is provided in the normal console init
  78*/
  79int platform_specific_init(void)
  80{
  81        void *devp;
  82        char devtype[MAX_PROP_LEN];
  83        char path[MAX_PATH_LEN];
  84
  85        devp = finddevice("/chosen");
  86        if (devp == NULL)
  87                return -1;
  88
  89        if (getprop(devp, "linux,stdout-path", path, MAX_PATH_LEN) > 0) {
  90                devp = finddevice(path);
  91                if (devp == NULL)
  92                        return -1;
  93
  94                if ((getprop(devp, "device_type", devtype, sizeof(devtype)) > 0)
  95                                && !strcmp(devtype, "serial")
  96                                && (dt_is_compatible(devp, "ns16550")))
  97                                virtex_ns16550_console_init(devp);
  98        }
  99        return 0;
 100}
 101