boardcfg.c

来自「Ibmstb02500 miniboot 源码」· C语言 代码 · 共 64 行

/* openbios/arch/pallas/boardcfg.c */
/*-----------------------------------------------------------------------------+
|
|       This source code has been made available to you by IBM on an AS-IS
|       basis.  Anyone receiving this source is licensed under IBM
|       copyrights to use it in any way he or she deems fit, including
|       copying it, modifying it, compiling it, and redistributing it either
|       with or without modifications.  No license under IBM patents or
|       patent applications is to be implied by the copyright license.
|
|       Any user of this software should understand that IBM cannot provide
|       technical support for this software and will not be responsible for
|       any consequences resulting from the use of this software.
|
|       Any person who transfers this source code or any derivative work
|       must include the IBM copyright notice, this paragraph, and the
|       preceding two paragraphs in the transferred software.
|
|       COPYRIGHT   I B M   CORPORATION 1995
|       LICENSED MATERIAL  -  PROGRAM PROPERTY OF I B M
+-----------------------------------------------------------------------------*/
/*-----------------------------------------------------------------------------+
|
|  File Name:  boardcfg.c
|
|  Function:   Defines Pallas specific board config related routines.
|
|  Author:     Yudong Yang
|
|  Change Activity-
|
|  Date        Description of Change                                       BY
|  ---------   ---------------------                                       ---
|  15-Jan-02   Splitted architecture specific parts from miscLib/boardcfg  YYD
|
+-----------------------------------------------------------------------------*/

static void init_sysclock_ratio()
{
       unsigned long                temp_value;
       unsigned long                Mult, RangeA, RangeB;
       unsigned long                HSMC_speed;

       /*--------------------------------------------------------------------------+
       | Calculate the HSMC and processor speeds from clock registers.  Note that
       | the processor speed is 4x as the bus speed.
       | Set the processor_speed and bus_speed fields in the board_cfg structure.
       +--------------------------------------------------------------------------*/
       temp_value = ppcMfclkgpcr();
       RangeB = 8 - ((temp_value >> 8) & 0x7);
       RangeA = 8 - ((temp_value >> 4) & 0x7);
       Mult = temp_value & 0xf;
       if (!Mult)
       {
          Mult = 16;
       }
       temp_value = PROC_CLOCK * Mult * RangeA / RangeB ;

       board_cfg.processor_speed = temp_value / 2;
       HSMC_speed                = temp_value / 4;
       board_cfg.bus_speed       = temp_value / 8;
       Ticks_per_sec = BOARD_CLOCK;  // board_cfg.bus_speed;
}