boardcfg.c

Ibmstb02500 miniboot 源码

/* openbios/arch/vesta/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 Vesta 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 bus speed is the same as the processor 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;
   }
   HSMC_speed = PROC_CLOCK * Mult * RangeA / RangeB ;
   HSMC_speed = HSMC_speed / 4;
   board_cfg.processor_speed = HSMC_speed / 2;
   Ticks_per_sec = board_cfg.bus_speed = board_cfg.processor_speed;
}