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
  28 static 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 */
  79 int 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 }