#########################################################################
#                                                                       
#  FILENAME: INIT860.S                                                  
#                                                                       
#  DESCRIPTION: 
#                                                                       
#  This file contains the initialization software that is first executed. 
#  It initializes or defines the operation for the following areas:
#
#   - Defines the vector interrupt table and establishes where it will 
#     reside in the memory map.
#
#   - Dcache (Data Cache) and Icache (Instruction Cache).
#
#   - MMU (Memory Management Unit)
#
#   - SIU (System Interface Unit)
#
#   - Memory Controller and UPM Table
#
#   - Defines Internal Memory Map (IMMR)
#
#   - Clock and Reset Circuitry
#
#   - External Bus Interface
#
#   - User's Program Stack
#
#  This file also contains an interrupt handler template called "handler" for
#  processing PowerPC exceptions.
#
#  NOTES:  
#
#  (1) This startup was assembled using the Diab Data Compiler.
#
#  (2) We are not using simplified mnemonics in this example. When the user 
#      has determined that the assembler chosen supports a simplified 
#      mnemonic set, then the user is free to change mnemonics for clarity's
#      sake. Refer to PowerPC Microprocessor Family: The Programming 
#      Environments for 32-Bit Microprocessors book for details on these 
#      instructions. The simplified mnemonic set for assemblers that support 
#      them are listed in appendix F of this manual.
#
#  (3) R0 is used exclusively as a means for transferring immediate data. It 
#      will always have the value of 0.
#
#  (4) R4 is used exclusively to contain the IMMR base address.
#
#  (5) R1 is used exclusively as the stack pointer.
#
#
#  REFERENCES:
#
#  1. MPC860 PowerQUICC User's Manual
#  2. PowerPC Microprocessor Family: The Programming Environments for 32-Bit
#     Microprocessors
#
#  HISTORY:
#
#  jay 4/22/98    Initial Release
#  jay 6/9/98     Fixed a bug in the flush_cache function. See the function
#                 header for details.
#  jay 9/2/98     There were bugs in the interrupt handling code. LR was
#                 getting wasted and the interrupt couldn't return to the
#                 the place where the interrupt happended. There were also
#                 a couple of other registers that were being hammered. I 
#                 added interrupt vectors for other possible interrupts.
#  
#########################################################################



#----------------------
# Assembler directives
#----------------------

 .text
 .align 2

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#
#   Exception Vector Table. Note: This is the starting point for code
#   mapping. Note that "handler" is called in some of the vectors. This 
#   interrupt function has been created in template form as a starting 
#   point for the user. It is defined further down in this module.
#
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
VectorTable:

   #~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0100: SYSTEM RESET                
   #~~~~~~~~~~~~~~~~~~~~~~

   .skip 0x0100-(.-VectorTable)

Xreset:

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------
 
   addis    r2,0,_start@h    
   ori      r2,r2,_start@l
   mtspr    LR,r2 
   bclr     20,0                 # jump unconditionally to address in Link 
                                 # Register (LR)

   #~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0200: MACHINE CHECK               
   #~~~~~~~~~~~~~~~~~~~~~~                                          

   .skip 0x0200-(.-VectorTable)

__Xmchk:

   #--------------------------------------------
   # save off registers used in vector routine 
   #--------------------------------------------

   mtspr SPRG3,r3    # save r3
   
   mfspr r3,LR
   mtspr SPRG2,r3    # save LR

   #-------------------------------------#
   #   FLUSH AND INVALIDATE THE CACHES   # 
   #-------------------------------------#

   mfspr r3,srr0  # get the faulting instruction address
   icbi  0,r3     # invalidate the cache block
   mfspr r3,19    # get the faulting data from DAR -> r2
   dcbi  0,r3     # invalidate the data cache block

   #---------------------------------------------------
   # Load the vector offset value in SPRG0 for handler
   #--------------------------------------------------- 

   addi  r3,r0,0x0200
   mtspr SPRG0,r3

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------

   addis    r3,0,handler@h    
   ori      r3,r3,handler@l
   mtspr    LR,r3 
   bclr     20,0                 # jump unconditionally to address in Link 
                                 # Register (LR)


   #~~~~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0300: DATA ACCESS ERROR              
   #~~~~~~~~~~~~~~~~~~~~~~~~~                                          

   # never generated by the MPC8xx

   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0400:INSTRUCTION ACCESS ERROR          
   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                                          

   # never generated by the MPC8xx

   #~~~~~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0500: EXTERNAL INTERRUPT             
   #~~~~~~~~~~~~~~~~~~~~~~~~~~                                          

   #-------------------------------------------#
   # save off registers used in vector routine #
   #-------------------------------------------#

   mtspr SPRG3,r3    # save r3
   
   mfspr r3,LR
   mtspr SPRG2,r3    # save LR

   #---------------------------------------------------
   # Load the vector offset value in SPRG0 for handler
   #--------------------------------------------------- 

   addi  r3,r0,0x0500
   mtspr SPRG0,r3

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------

   addis    r3,0,handler@h    
   ori      r3,r3,handler@l
   mtspr    LR,r3 
   bclr     20,0                 # jump unconditionally to address in Link 
                                 # Register (LR)


   #~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0600: ALIGNMENT ERROR             
   #~~~~~~~~~~~~~~~~~~~~~~                                          

   .skip 0x0600-(.-VectorTable)

__Xalgn:

   #-------------------------------------------#
   # save off registers used in vector routine #
   #-------------------------------------------#

   mtspr SPRG3,r3    # save r3
   
   mfspr r3,LR
   mtspr SPRG2,r3    # save LR

   #---------------------------------------------------
   # Load the vector offset value in SPRG0 for handler
   #--------------------------------------------------- 

   addi  r3,r0,0x0600
   mtspr SPRG0,r3

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------

   addis    r3,0,handler@h    
   ori      r3,r3,handler@l
   mtspr    LR,r3 
   bclr     20,0                 # jump unconditionally to address in Link 
 
   #~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0700: PROGRAM ERROR               
   #~~~~~~~~~~~~~~~~~~~~~~                                          

    .skip 0x0700-(.-VectorTable)

__Xprog:

   #-------------------------------------------#
   # save off registers used in vector routine #
   #-------------------------------------------#

   mtspr SPRG3,r3    # save r3
   
   mfspr r3,LR
   mtspr SPRG2,r3    # save LR

   #---------------------------------------------------
   # Load the vector offset value in SPRG0 for handler
   #--------------------------------------------------- 

   addi  r3,r0,0x0700
   mtspr SPRG0,r3

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------

   addis    r3,0,handler@h    
   ori      r3,r3,handler@l
   mtspr    LR,r3 
   bclr     20,0                 # jump unconditionally to address in Link 
                                 # Register (LR)


   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0800: FLOATING-POINT UNAVAILABLE           
   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                                          

   # never generated by the MPC8xx

   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                                          
   # 0900: DECREMENTER INTERRUPT          
   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                                          

   .skip 0x0900-(.-VectorTable)

__Xdec:

   #-------------------------------------------#
   # save off registers used in vector routine #
   #-------------------------------------------#

   mtspr SPRG3,r3    # save r3
   
   mfspr r3,LR
   mtspr SPRG2,r3    # save LR

   #---------------------------------------------------
   # Load the vector offset value in SPRG0 for handler
   #--------------------------------------------------- 

   addi  r3,r0,0x0900
   mtspr SPRG0,r3

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------

   addis    r3,0,handler@h    
   ori      r3,r3,handler@l
   mtspr    LR,r3 
   bclr     20,0                 # jump unconditionally to address in Link 
                                 # Register (LR)


   #~~~~~~~~~~~~~~~                                          
   # 0A00: RESERVED              
   #~~~~~~~~~~~~~~~                                          
   

   #~~~~~~~~~~~~~~~                                          
   # 0B00: RESERVED              
   #~~~~~~~~~~~~~~~                                          
   

   #~~~~~~~~~~~~~~~~~~~                                          
   # 0C00: SYSTEM CALL                 
   #~~~~~~~~~~~~~~~~~~~                                          

   .skip 0x0C00-(.-VectorTable)

__Xsysc:

   #-------------------------------------------#
   # save off registers used in vector routine #
   #-------------------------------------------#

   mtspr SPRG3,r3    # save r3
   
   mfspr r3,LR
   mtspr SPRG2,r3    # save LR

   #---------------------------------------------------
   # Load the vector offset value in SPRG0 for handler
   #--------------------------------------------------- 

   addi  r3,r0,0x0C00
   mtspr SPRG0,r3

   #---------------------------------------------------------
   # load link register in order to jump to physical address
   #---------------------------------------------------------

   addis    r3,0,handler@h    
   ori      r3,r3,handler@l
   mtspr    LR,r3 
   bclr     20,0                 # jump unconditionally to address in Link 
                                 # Register (LR)