source: rtems/c/src/lib/libbsp/m68k/gen68340/timer/timer.c @ 1d22b03

/*
 * Timer_init()
 *
 * ATTENTION: AS MC68349 has no built-in Timer, the following code doesn't work
 *            in a MC68349. You can't use FIFO full mode for the moment, but
 *            it should be easy to fix this by using an external timer
 *
 * Use TIMER 1 for TIMEOUT when using FIFO FULL mode in UART driver
 * Use TIMER 2 for timing test suites
 *
 * Geoffroy Montel
 * France Telecom - CNET/DSM/TAM/CAT
 * 4, rue du Clos Courtel
 * 35512 CESSON-SEVIGNE
 * FRANCE
 * 
 * e-mail: g_montel@yahoo.com
 *
 *  $Id$
 */

/*
 *
 *  Input parameters:  NONE
 *
 *  Output parameters:  NONE
 *
 *  NOTE: It is important that the timer start/stop overhead be 
 *        determined when porting or modifying this code.
 *
 *  COPYRIGHT (c) 1989-1998.
 *  On-Line Applications Research Corporation (OAR).
 *  Copyright assigned to U.S. Government, 1994.
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.OARcorp.com/rtems/license.html.
 */

#include <rtems.h>
#include <bsp.h>
#include <m340uart.h>
#include <m340timer.h>
#include <m68340.h>

#define TIMER1_VECTOR 122
#define TIMER1_IRQ_LEVEL 5
#define TIMER1_INTERRUPT_ARBITRATION 5

#define TIMER2_VECTOR 123
#define TIMER2_IRQ_LEVEL 4
#define TIMER2_INTERRUPT_ARBITRATION 4

#define CLOCK_SPEED 25          /* in Mhz */

#define max(a,b) (((a)>(b)) ? (a) : (b))

void (*Restart_Fifo_Full_A_Timer)();
void (*Restart_Check_A_Timer)();
void (*Restart_Fifo_Full_B_Timer)();
void (*Restart_Check_B_Timer)();

int preload = 0;

/******************************************************
  Name: __Restart_Fifo_Full_Timer
  Input parameters: -
  Output parameters: -
  Description: when a character is received, sets
               the TIMER to raise an interrupt at 
               TIMEOUT.
               It's necessary to prevent from not
               getting n-1 characters (with n the
               Uart Fifo size)
 *****************************************************/
void __Restart_Fifo_Full_Timer (void)
{
 TSR1 |= m340_TO;
 TCR1 &= ~m340_CPE;
 WPREL11 = preload;
 TCR1 |= m340_CPE;
}

/******************************************************
  Name: __Restart_Fifo_Full_Timer
  Input parameters: -
  Output parameters: -
  Description: when no character has been received
               recently, check now and then if whether
               a there's a character in the FIFO
 *****************************************************/
void __Restart_Check_Timer (void)
{
 TSR1 |= m340_TO;
 TCR1 &= ~m340_CPE;
 WPREL11 = 0xFFFF;
 TCR1 |= m340_CPE;
}

/******************************************************
  Name: __do_nothing
  Input parameters: -
  Output parameters: -
  Description: we always restart the fifo full timer
               with a call to Restart_*_Timer
               if we do not use FIFO full, Restart_*_Timer
               are set to do __do_nothing
 *****************************************************/
void __do_nothing (void)
{
}

#define Fifo_Full_on_A (m340_uart_config[UART_CHANNEL_A].rx_mode==UART_FIFO_FULL && m340_uart_config[UART_CHANNEL_A].enable && m340_uart_config[UART_CHANNEL_A].mode==UART_INTERRUPTS)
#define Fifo_Full_on_B (m340_uart_config[UART_CHANNEL_B].rx_mode==UART_FIFO_FULL && m340_uart_config[UART_CHANNEL_B].enable && m340_uart_config[UART_CHANNEL_B].mode==UART_INTERRUPTS)

/******************************************************
  Name: Fifo_Full_Timer_initialize
  Input parameters: -
  Output parameters: -
  Description: initialize Timer 1 for FIFO full mode
 *****************************************************/
void Fifo_Full_Timer_initialize (void)
{
   float max_baud_rate;
   int prescaler_output_tap = -1;
   int nb_of_clock_ticks = 0;

   /*
    *  USE TIMER 1 for UART FIFO FULL mode
    */

   if ( Fifo_Full_on_A || Fifo_Full_on_B )      
      {
        /* Disable the timer */
        TCR1 &= ~m340_SWR;

        /* Reset the interrupts */
        TSR1 &= ~(m340_TO | m340_TG | m340_TC);

        /* Init the stop bit for normal operation, ignore FREEZE, user privileges,
           set interrupt arbitration */
        TMCR1 = TIMER1_INTERRUPT_ARBITRATION;

        /* interrupt priority level and interrupt vector */
        TIR1 = TIMER1_VECTOR | (TIMER1_IRQ_LEVEL << 8);

        /* compute prescaler */
        if ( Fifo_Full_on_A && Fifo_Full_on_B)
                max_baud_rate = max(m340_uart_config[UART_CHANNEL_A].rx_baudrate, m340_uart_config[UART_CHANNEL_B].rx_baudrate);        
        else if ( Fifo_Full_on_A )      
                max_baud_rate = m340_uart_config[UART_CHANNEL_A].rx_baudrate;
             else max_baud_rate = m340_uart_config[UART_CHANNEL_B].rx_baudrate;

        /* find out config */
        nb_of_clock_ticks = (10/max_baud_rate)*(CLOCK_SPEED*1000000)*1.2;
        if (nb_of_clock_ticks < 0xFFFF) {
           preload = nb_of_clock_ticks;
           prescaler_output_tap = -1;   
        } else if (nb_of_clock_ticks/2 < 0xFFFF) {
           preload = nb_of_clock_ticks/2;
           prescaler_output_tap = m340_Divide_by_2;
        } else if (nb_of_clock_ticks/4 < 0xFFFF) {
           preload = nb_of_clock_ticks/4;
           prescaler_output_tap = m340_Divide_by_4;
        } else if (nb_of_clock_ticks/8 < 0xFFFF) {
           preload = nb_of_clock_ticks/8;
           prescaler_output_tap = m340_Divide_by_16;
        } else if (nb_of_clock_ticks/16 < 0xFFFF) {
           preload = nb_of_clock_ticks/16;
           prescaler_output_tap = m340_Divide_by_16;
        } else if (nb_of_clock_ticks/32 < 0xFFFF) {
           preload = nb_of_clock_ticks/32;
           prescaler_output_tap = m340_Divide_by_32;
        } else if (nb_of_clock_ticks/64 < 0xFFFF) {
           preload = nb_of_clock_ticks/64;
           prescaler_output_tap = m340_Divide_by_64;
        } else if (nb_of_clock_ticks/128 < 0xFFFF) {
           preload = nb_of_clock_ticks/128;
           prescaler_output_tap = m340_Divide_by_128;
        } else if (nb_of_clock_ticks/256 < 0xFFFF) {
           preload = nb_of_clock_ticks/256;
           prescaler_output_tap = m340_Divide_by_256;
        } 

        /* Input Capture/Output Compare (ICOC) */
        TCR1 = m340_SWR | m340_TO_Enabled | m340_ICOC;
        if (prescaler_output_tap!=-1) TCR1 |= prescaler_output_tap | m340_PSE;

        /* install interrupt vector */
        {
         rtems_isr_entry old_handler;
         rtems_status_code sc;

         proc_ptr ignored;
         extern void _Debug_ISR_Handler_Console(void);

         sc = rtems_interrupt_catch (InterruptHandler,
                                     TIMER1_VECTOR,
                                     &old_handler);

         /* uncomment this if you want to pass control to your own ISR handler
            it may be usefull to do so to check for performances with an oscilloscope */
         /*
         _CPU_ISR_install_raw_handler( TIMER1_VECTOR, _Debug_ISR_Handler_Console, &ignored );
         */
        }
       } /* fifo full mode on a uart */

       /* install routines */
       Restart_Check_A_Timer = Fifo_Full_on_A ? __Restart_Check_Timer : __do_nothing;
       Restart_Fifo_Full_A_Timer = Fifo_Full_on_A ? __Restart_Fifo_Full_Timer : __do_nothing;
       Restart_Check_B_Timer = Fifo_Full_on_B ? __Restart_Check_Timer : __do_nothing;
       Restart_Fifo_Full_B_Timer = Fifo_Full_on_B ? __Restart_Fifo_Full_Timer : __do_nothing;
       /* start checking timer */
       Restart_Check_A_Timer();
       Restart_Check_B_Timer();
}

/******************************************************
  Name: Timer_initialize
  Input parameters: -
  Output parameters: -
  Description: init Timer for timing test suites
 *****************************************************/
void Timer_initialize (void)
{
        /* Disable the timer */
        TCR2 &= ~m340_SWR;

        /* Reset the interrupts */
        TSR2 &= ~(m340_TO | m340_TG | m340_TC);

        /* Init the stop bit for normal operation, ignore FREEZE, user privileges,
           set interrupt arbitration */
        TMCR1 = TIMER2_INTERRUPT_ARBITRATION;

        /* interrupt priority level and interrupt vector */
        TIR1 = TIMER2_VECTOR | (TIMER2_IRQ_LEVEL << 8);

        /* Init the stop bit for normal operation, ignore FREEZE, user privileges,
           set interrupt arbitration */
        TMCR2 = TIMER2_INTERRUPT_ARBITRATION;

        /* Preload register 1 */
        WPREL21 = 0xFFFF;

        /* Input Capture/Output Compare (ICOC) */
        TCR2 = m340_SWR | m340_ICOC | m340_PSE | m340_Divide_by_16 | m340_CPE;
}

/******************************************************
  Name: Read_timer 
  Input parameters: -
  Output parameters: -
  Description: Return timer value in microsecond units
 *****************************************************/
int
Read_timer (void)
{
 /* there's CLOCK_SPEED / 16 micro seconds between two timer register decrement */
 return (((0xFFFF - TCNTR2) * CLOCK_SPEED) / 16);
}

/******************************************************
  Name: Empty_function 
  Input parameters: -
  Output parameters: -
  Description: Empty function call used in loops to 
               measure basic cost of looping
               in Timing Test Suite.
 *****************************************************/
rtems_status_code
Empty_function (void)
{
        return RTEMS_SUCCESSFUL;
}

/******************************************************
  Name: Set_find_average_overhead
  Input parameters: -
  Output parameters: -
  Description: -
 *****************************************************/
void
Set_find_average_overhead(rtems_boolean find_flag)
{
}