Subversion Repositories openrisc_2011-10-31

/* or1k-support - OR1K CPU support functions

   Copyright (C) 2011, ORSoC AB

   Contributor Julius Baxter  <julius.baxter@orsoc.se>

   This file is part of Newlib.

   This program is free software; you can redistribute it and/or modify it

   under the terms of the GNU General Public License as published by the Free

   Software Foundation; either version 3 of the License, or (at your option)

   any later version.

   This program is distributed in the hope that it will be useful, but WITHOUT

   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

   more details.

   You should have received a copy of the GNU General Public License along

   with this program.  If not, see <http://www.gnu.org/licenses/>.            */

#include "or1k-support.h"

#include "spr-defs.h"

/* Board-specific CPU clk HZ value */

extern unsigned long _board_clk_freq;

/* Tick timer variable */

volatile unsigned long or1k_timer_ticks;

/* Tick rate storage */

unsigned long or1k_timer_period;

/* --------------------------------------------------------------------------*/

/*!Report a 32-bit value

   Uses the built-in simulator functionality.

   @param[in] value  Value to report.                                        */

/* --------------------------------------------------------------------------*/

void

or1k_report (unsigned long int  value)

{

  __asm__ __volatile__ ("l.addi\tr3,%0,0\n\t"

                        "l.nop %1": : "r" (value), "K" (NOP_REPORT));

}       /* report () */

/* --------------------------------------------------------------------------*/

/*!Write a SPR

   @todo Surely the SPR should be a short int, since it is only 16-bits. Left

         as is for now due to large amount of user code that might need

         changing.

   @param[in] spr    The SPR to write

   @param[in] value  The value to write to the SPR                           */

/* --------------------------------------------------------------------------*/

void

or1k_mtspr (unsigned long int  spr,

       unsigned long int  value)

{

  __asm__ __volatile__ ("l.mtspr\t\t%0,%1,0": : "r" (spr), "r" (value));

}       /* mtspr () */

/* --------------------------------------------------------------------------*/

/*!Read a SPR

   @todo Surely the SPR should be a short int, since it is only 16-bits. Left

         as is for now due to large amount of user code that might need

         changing.

   @param[in] spr    The SPR to write

   @return  The value read from the SPR                                      */

/* --------------------------------------------------------------------------*/

unsigned long int

or1k_mfspr (unsigned long spr)

{

  unsigned long value;

  __asm__ __volatile__ ("l.mfspr\t\t%0,%1,0" : "=r" (value) : "r" (spr));

  return value;

}       /* mfspr () */

/* --------------------------------------------------------------------------*/

/*!Pseudo-random number generator

   This should return pseudo-random numbers, based on a Galois LFSR

   @return The next pseudo-random number                                     */

/* --------------------------------------------------------------------------*/

unsigned long int

or1k_rand ()

{

  static unsigned long int lfsr = 1;

  static int period = 0;

  /* taps: 32 31 29 1; characteristic polynomial: x^32 + x^31 + x^29 + x + 1 */

  lfsr = (lfsr >> 1) ^ (unsigned long int)((0 - (lfsr & 1u)) & 0xd0000001u);

  ++period;

  return lfsr;

}

/* --------------------------------------------------------------------------*/

/*!Tick timer interrupt handler

   Increment timer ticks counter, reload TTMR

                                                                             */

/* --------------------------------------------------------------------------*/

void

or1k_timer_interrupt_handler(void)

{

  or1k_timer_ticks++;

  or1k_mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT |

        (or1k_timer_period & SPR_TTMR_PERIOD));

}

/* --------------------------------------------------------------------------*/

/*!Enable tick timer

   Install handler, calculate TTMR period, reset tick counter

   @param[in] hz     Rate at which to trigger timer ticks                    */

/* --------------------------------------------------------------------------*/

void

or1k_timer_init(unsigned int hz)

{

  /* Set this, for easy access when reloading */

  or1k_timer_period = _board_clk_freq/hz;

  /* Reset timer tick counter */

  or1k_timer_ticks = 0;

  /* Install handler */

  or1k_exception_handler_add(0x5,or1k_timer_interrupt_handler);

}

/* --------------------------------------------------------------------------*/

/*!Enable tick timer

   Enable timer interrupt, install handler, load TTMR

                                                                             */

/* --------------------------------------------------------------------------*/

void

or1k_timer_enable(void)

{

  or1k_mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT |

        (or1k_timer_period & SPR_TTMR_PERIOD));

  or1k_mtspr(SPR_SR, SPR_SR_TEE | or1k_mfspr(SPR_SR));

}

/* --------------------------------------------------------------------------*/

/*!Disable tick timer

   Disable timer interrupt in SR

                                                                             */

/* --------------------------------------------------------------------------*/

void

or1k_timer_disable(void)

{

   or1k_mtspr(SPR_SR, ~SPR_SR_TEE & or1k_mfspr(SPR_SR));

}

/* --------------------------------------------------------------------------*/

/*!Get tick timer

   Return value of tick timer

                                                                             */

/* --------------------------------------------------------------------------*/

unsigned long

or1k_timer_get_ticks(void)

{

  return or1k_timer_ticks;

}

/* --------------------------------------------------------------------------*/

/*!Reset tick timer

   Clear value of tick timer

                                                                             */

/* --------------------------------------------------------------------------*/

void

or1k_timer_reset_ticks(void)

{

  or1k_timer_ticks = 0;

}