cpu.h

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/* SPDX-License-Identifier: BSD-2-Clause */

 
/*
 *  This include file contains macros pertaining to the Opencores
 *  or1k processor family.
 *
 *  COPYRIGHT (c) 2014 Hesham ALMatary <heshamelmatary@gmail.com>
 *  COPYRIGHT (c) 1989-1999.
 *  On-Line Applications Research Corporation (OAR).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 *  This file adapted from no_cpu example of the RTEMS distribution.
 *  The body has been modified for the Opencores OR1k implementation by
 *  Chris Ziomkowski. <chris@asics.ws>
 *
 */
 
#ifndef _OR1K_CPU_H
#define _OR1K_CPU_H
 
#ifdef __cplusplus
extern "C" {
#endif
 
 
#include <rtems/score/or1k.h>            /* pick up machine definitions */
#include <rtems/score/or1k-utility.h>
#include <rtems/score/basedefs.h>
 
/* conditional compilation parameters */
 
/*
 *  Does the RTEMS invoke the user's ISR with the vector number and
 *  a pointer to the saved interrupt frame (1) or just the vector
 *  number (0)?
 *
 */
 
#define CPU_ISR_PASSES_FRAME_POINTER TRUE
 
#define CPU_HARDWARE_FP FALSE
 
#define CPU_SOFTWARE_FP FALSE
 
#define CPU_ALL_TASKS_ARE_FP FALSE
 
#define CPU_IDLE_TASK_IS_FP FALSE
 
#define CPU_USE_DEFERRED_FP_SWITCH TRUE
 
#define CPU_ENABLE_ROBUST_THREAD_DISPATCH FALSE
 
/*
 *  Does the stack grow up (toward higher addresses) or down
 *  (toward lower addresses)?
 *
 *  If TRUE, then the grows upward.
 *  If FALSE, then the grows toward smaller addresses.
 *
 */
 
#define CPU_STACK_GROWS_UP               FALSE
 
/* FIXME: Is this the right value? */
#define CPU_CACHE_LINE_BYTES 32
 
#define CPU_STRUCTURE_ALIGNMENT RTEMS_ALIGNED( CPU_CACHE_LINE_BYTES )
 
/*
 *  The following defines the number of bits actually used in the
 *  interrupt field of the task mode.  How those bits map to the
 *  CPU interrupt levels is defined by the routine _CPU_ISR_Set_level().
 *
 */
 
#define CPU_MODES_INTERRUPT_MASK   0x00000001
 
/*
 *  Processor defined structures required for cpukit/score.
 */
 
 
/*
 * Contexts
 *
 *  Generally there are 2 types of context to save.
 *     1. Interrupt registers to save
 *     2. Task level registers to save
 *
 *  This means we have the following 3 context items:
 *     1. task level context stuff::  Context_Control
 *     2. floating point task stuff:: Context_Control_fp
 *     3. special interrupt level context :: Context_Control_interrupt
 *
 *  On some processors, it is cost-effective to save only the callee
 *  preserved registers during a task context switch.  This means
 *  that the ISR code needs to save those registers which do not
 *  persist across function calls.  It is not mandatory to make this
 *  distinctions between the caller/callee saves registers for the
 *  purpose of minimizing context saved during task switch and on interrupts.
 *  If the cost of saving extra registers is minimal, simplicity is the
 *  choice.  Save the same context on interrupt entry as for tasks in
 *  this case.
 *
 *  Additionally, if gdb is to be made aware of RTEMS tasks for this CPU, then
 *  care should be used in designing the context area.
 *
 *  On some CPUs with hardware floating point support, the Context_Control_fp
 *  structure will not be used or it simply consist of an array of a
 *  fixed number of bytes.   This is done when the floating point context
 *  is dumped by a "FP save context" type instruction and the format
 *  is not really defined by the CPU.  In this case, there is no need
 *  to figure out the exact format -- only the size.  Of course, although
 *  this is enough information for RTEMS, it is probably not enough for
 *  a debugger such as gdb.  But that is another problem.
 *
 *
 */
#ifndef ASM
#ifdef OR1K_64BIT_ARCH
#define or1kreg uint64_t
#else
#define or1kreg uint32_t
#endif
 
typedef struct {
  uint32_t  r1;     /* Stack pointer */
  uint32_t  r2;     /* Frame pointer */
  uint32_t  r3;
  uint32_t  r4;
  uint32_t  r5;
  uint32_t  r6;
  uint32_t  r7;
  uint32_t  r8;
  uint32_t  r9;
  uint32_t  r10;
  uint32_t  r11;
  uint32_t  r12;
  uint32_t  r13;
  uint32_t  r14;
  uint32_t  r15;
  uint32_t  r16;
  uint32_t  r17;
  uint32_t  r18;
  uint32_t  r19;
  uint32_t  r20;
  uint32_t  r21;
  uint32_t  r22;
  uint32_t  r23;
  uint32_t  r24;
  uint32_t  r25;
  uint32_t  r26;
  uint32_t  r27;
  uint32_t  r28;
  uint32_t  r29;
  uint32_t  r30;
  uint32_t  r31;
 
  uint32_t  sr;  /* Current supervision register non persistent values */
  uint32_t  epcr;
  uint32_t  eear;
  uint32_t  esr;
} Context_Control;
 
#define _CPU_Context_Get_SP( _context ) \
  (_context)->r1
 
typedef Context_Control CPU_Interrupt_frame;
 
/*
 *  Amount of extra stack (above minimum stack size) required by
 *  MPCI receive server thread.  Remember that in a multiprocessor
 *  system this thread must exist and be able to process all directives.
 *
 */
 
#define CPU_MPCI_RECEIVE_SERVER_EXTRA_STACK 0
 
/*
 *  Should be large enough to run all RTEMS tests.  This insures
 *  that a "reasonable" small application should not have any problems.
 *
 */
 
#define CPU_STACK_MINIMUM_SIZE  4096
 
/*
 *  CPU's worst alignment requirement for data types on a byte boundary.  This
 *  alignment does not take into account the requirements for the stack.
 *
 */
 
#define CPU_ALIGNMENT  8
 
/*
 *  This is defined if the port has a special way to report the ISR nesting
 *  level.  Most ports maintain the variable _ISR_Nest_level.
 */
#define CPU_PROVIDES_ISR_IS_IN_PROGRESS FALSE

#define CPU_SIZEOF_POINTER         4
 
/*
 *  This number corresponds to the byte alignment requirement for the
 *  heap handler.  This alignment requirement may be stricter than that
 *  for the data types alignment specified by CPU_ALIGNMENT.  It is
 *  common for the heap to follow the same alignment requirement as
 *  CPU_ALIGNMENT.  If the CPU_ALIGNMENT is strict enough for the heap,
 *  then this should be set to CPU_ALIGNMENT.
 *
 *  NOTE:  This does not have to be a power of 2 although it should be
 *         a multiple of 2 greater than or equal to 2.  The requirement
 *         to be a multiple of 2 is because the heap uses the least
 *         significant field of the front and back flags to indicate
 *         that a block is in use or free.  So you do not want any odd
 *         length blocks really putting length data in that bit.
 *
 *         On byte oriented architectures, CPU_HEAP_ALIGNMENT normally will
 *         have to be greater or equal to than CPU_ALIGNMENT to ensure that
 *         elements allocated from the heap meet all restrictions.
 *
 */
 
#define CPU_HEAP_ALIGNMENT         CPU_ALIGNMENT
 
#define CPU_STACK_ALIGNMENT        CPU_ALIGNMENT
 
#define CPU_INTERRUPT_STACK_ALIGNMENT CPU_CACHE_LINE_BYTES
 
/* ISR handler macros */
 
/*
 *  Disable all interrupts for an RTEMS critical section.  The previous
 *  level is returned in _level.
 *
 */
 
static inline uint32_t or1k_interrupt_disable( void )
{
  uint32_t sr;
  sr = _OR1K_mfspr(CPU_OR1K_SPR_SR);
 
  _OR1K_mtspr(CPU_OR1K_SPR_SR, (sr & ~CPU_OR1K_SPR_SR_IEE));
 
  return sr;
}
 
static inline void or1k_interrupt_enable(uint32_t level)
{
  uint32_t sr;
 
  /* Enable interrupts and restore rs */
  sr = level | CPU_OR1K_SPR_SR_IEE | CPU_OR1K_SPR_SR_TEE;
  _OR1K_mtspr(CPU_OR1K_SPR_SR, sr);
 
}
 
#define _CPU_ISR_Disable( _level ) \
    _level = or1k_interrupt_disable()
 
 
/*
 *  Enable interrupts to the previous level (returned by _CPU_ISR_Disable).
 *  This indicates the end of an RTEMS critical section.  The parameter
 *  _level is not modified.
 *
 */
 
#define _CPU_ISR_Enable( _level )  \
  or1k_interrupt_enable( _level )
 
/*
 *  This temporarily restores the interrupt to _level before immediately
 *  disabling them again.  This is used to divide long RTEMS critical
 *  sections into two or more parts.  The parameter _level is not
 *  modified.
 *
 */
 
#define _CPU_ISR_Flash( _level ) \
  do{ \
      _CPU_ISR_Enable( _level ); \
      _OR1K_mtspr(CPU_OR1K_SPR_SR, (_level & ~CPU_OR1K_SPR_SR_IEE)); \
    } while(0)
 
static inline bool _CPU_ISR_Is_enabled( uint32_t level )
{
  return ( level & CPU_OR1K_SPR_SR ) != 0;
}
 
/*
 *  Map interrupt level in task mode onto the hardware that the CPU
 *  actually provides.  Currently, interrupt levels which do not
 *  map onto the CPU in a generic fashion are undefined.  Someday,
 *  it would be nice if these were "mapped" by the application
 *  via a callout.  For example, m68k has 8 levels 0 - 7, levels
 *  8 - 255 would be available for bsp/application specific meaning.
 *  This could be used to manage a programmable interrupt controller
 *  via the rtems_task_mode directive.
 *
 *  The get routine usually must be implemented as a subroutine.
 *
 */
 
void _CPU_ISR_Set_level( uint32_t level );
 
uint32_t _CPU_ISR_Get_level( void );
 
/* end of ISR handler macros */
 
/* Context handler macros */
 
#define OR1K_FAST_CONTEXT_SWITCH_ENABLED FALSE
/*
 *  Initialize the context to a state suitable for starting a
 *  task after a context restore operation.  Generally, this
 *  involves:
 *
 *     - setting a starting address
 *     - preparing the stack
 *     - preparing the stack and frame pointers
 *     - setting the proper interrupt level in the context
 *     - initializing the floating point context
 *
 *  This routine generally does not set any unnecessary register
 *  in the context.  The state of the "general data" registers is
 *  undefined at task start time.
 *
 *  NOTE: This is_fp parameter is TRUE if the thread is to be a floating
 *        point thread.  This is typically only used on CPUs where the
 *        FPU may be easily disabled by software such as on the SPARC
 *        where the PSR contains an enable FPU bit.
 *
 */

void _CPU_Context_Initialize(
  Context_Control *context,
  void *stack_area_begin,
  size_t stack_area_size,
  uint32_t new_level,
  void (*entry_point)( void ),
  bool is_fp,
  void *tls_area
);
 
/*
 *  This routine is responsible for somehow restarting the currently
 *  executing task.  If you are lucky, then all that is necessary
 *  is restoring the context.  Otherwise, there will need to be
 *  a special assembly routine which does something special in this
 *  case.  Context_Restore should work most of the time.  It will
 *  not work if restarting self conflicts with the stack frame
 *  assumptions of restoring a context.
 *
 */
 
#define _CPU_Context_Restart_self( _the_context ) \
   _CPU_Context_restore( (_the_context) );
 
/* end of Context handler macros */
 
#define CPU_USE_GENERIC_BITFIELD_CODE TRUE
 
#define CPU_USE_LIBC_INIT_FINI_ARRAY TRUE
 
#endif /* ASM */
 
#define CPU_SIZEOF_POINTER 4
 
#define CPU_MAXIMUM_PROCESSORS 32
 
#ifndef ASM
typedef struct {
  uint32_t r[32];
 
  /* The following registers must be saved if we have
  fast context switch disabled and nested interrupt
  levels are enabled.
  */
#if !OR1K_FAST_CONTEXT_SWITCH_ENABLED
  uint32_t epcr; /* exception PC register */
  uint32_t eear; /* exception effective address register */
  uint32_t esr; /* exception supervision register */
#endif
 
} CPU_Exception_frame;

void _CPU_Exception_frame_print( const CPU_Exception_frame *frame );
 
 
/* end of Priority handler macros */
 
/* functions */
 
/*
 *  _CPU_Initialize
 *
 *  This routine performs CPU dependent initialization.
 *
 */
 
void _CPU_Initialize(
  void
);
 
typedef void ( *CPU_ISR_raw_handler )( uint32_t, CPU_Exception_frame * );
 
void _CPU_ISR_install_raw_handler(
  uint32_t             vector,
  CPU_ISR_raw_handler  new_handler,
  CPU_ISR_raw_handler *old_handler
);
 
typedef void ( *CPU_ISR_handler )( uint32_t );
 
static inline void _CPU_ISR_install_vector(
  uint32_t         vector,
  CPU_ISR_handler  new_handler,
  CPU_ISR_handler *old_handler
)
{
  _CPU_ISR_install_raw_handler(
    vector,
    (CPU_ISR_raw_handler) new_handler,
    (CPU_ISR_raw_handler *) old_handler
  );
}
 
RTEMS_NO_RETURN void *_CPU_Thread_Idle_body( uintptr_t ignored );
 
/*
 *  _CPU_Context_switch
 *
 *  This routine switches from the run context to the heir context.
 *
 *  Or1k Specific Information:
 *
 *  Please see the comments in the .c file for a description of how
 *  this function works. There are several things to be aware of.
 */
 
void _CPU_Context_switch(
  Context_Control  *run,
  Context_Control  *heir
);
 
/*
 *  _CPU_Context_restore
 *
 *  This routine is generally used only to restart self in an
 *  efficient manner.  It may simply be a label in _CPU_Context_switch.
 *
 *  NOTE: May be unnecessary to reload some registers.
 *
 */
 
RTEMS_NO_RETURN void _CPU_Context_restore( Context_Control *new_context );
 
/*
 *  _CPU_Context_save_fp
 *
 *  This routine saves the floating point context passed to it.
 *
 */
 
void _CPU_Context_save_fp(
  void **fp_context_ptr
);
 
/*
 *  _CPU_Context_restore_fp
 *
 *  This routine restores the floating point context passed to it.
 *
 */
 
void _CPU_Context_restore_fp(
  void **fp_context_ptr
);
 
/*  The following routine swaps the endian format of an unsigned int.
 *  It must be static because it is referenced indirectly.
 *
 *  This version will work on any processor, but if there is a better
 *  way for your CPU PLEASE use it.  The most common way to do this is to:
 *
 *     swap least significant two bytes with 16-bit rotate
 *     swap upper and lower 16-bits
 *     swap most significant two bytes with 16-bit rotate
 *
 *  Some CPUs have special instructions which swap a 32-bit quantity in
 *  a single instruction (e.g. i486).  It is probably best to avoid
 *  an "endian swapping control bit" in the CPU.  One good reason is
 *  that interrupts would probably have to be disabled to insure that
 *  an interrupt does not try to access the same "chunk" with the wrong
 *  endian.  Another good reason is that on some CPUs, the endian bit
 *  endianness for ALL fetches -- both code and data -- so the code
 *  will be fetched incorrectly.
 *
 */
 
static inline unsigned int CPU_swap_u32(
  unsigned int value
)
{
  uint32_t   byte1, byte2, byte3, byte4, swapped;
 
  byte4 = (value >> 24) & 0xff;
  byte3 = (value >> 16) & 0xff;
  byte2 = (value >> 8)  & 0xff;
  byte1 =  value        & 0xff;
 
  swapped = (byte1 << 24) | (byte2 << 16) | (byte3 << 8) | byte4;
  return( swapped );
}
 
#define CPU_swap_u16( value ) \
  (((value&0xff) << 8) | ((value >> 8)&0xff))
 
typedef uint32_t CPU_Counter_ticks;
 
uint32_t _CPU_Counter_frequency( void );
 
CPU_Counter_ticks _CPU_Counter_read( void );

typedef uintptr_t CPU_Uint32ptr;
 
#endif /* ASM */
 
#ifdef __cplusplus
}
#endif
 
#endif