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*
*       XTENSA INFORMATION FOR RTOS TICK TIMER AND CLOCK FREQUENCY
*
*  This header contains definitions and macros for use primarily by Xtensa
*  RTOS assembly coded source files. It includes and uses the Xtensa hardware
*  abstraction layer (HAL) to deal with config specifics. It may also be
*  included in C source files.
*
*  User may edit to modify timer selection and to specify clock frequency and
*  tick duration to match timer interrupt to the real-time tick duration.
*
*  If the RTOS has no timer interrupt, then there is no tick timer and the
*  clock frequency is irrelevant, so all of these macros are left undefined
*  and the Xtensa core configuration need not have a timer.
*
*******************************************************************************/

#ifndef XTENSA_TIMER_H
#define XTENSA_TIMER_H

#ifdef __ASSEMBLER__
    #include    <xtensa/coreasm.h>
#endif

#include    <xtensa/corebits.h>
#include    <xtensa/config/system.h>

#include    "xtensa_rtos.h" /* in case this wasn't included directly */

#include    "FreeRTOSConfig.h"

/*
 * Select timer to use for periodic tick, and determine its interrupt number
 * and priority. User may specify a timer by defining XT_TIMER_INDEX with -D,
 * in which case its validity is checked (it must exist in this core and must
 * not be on a high priority interrupt - an error will be reported in invalid).
 * Otherwise select the first low or medium priority interrupt timer available.
 */
#if XCHAL_NUM_TIMERS == 0

    #error "This Xtensa configuration is unsupported, it has no timers."

#else

    #ifndef XT_TIMER_INDEX
        #if XCHAL_TIMER3_INTERRUPT != XTHAL_TIMER_UNCONFIGURED
            #if XCHAL_INT_LEVEL( XCHAL_TIMER3_INTERRUPT ) <= XCHAL_EXCM_LEVEL
                #undef  XT_TIMER_INDEX
                #define XT_TIMER_INDEX    3
            #endif
        #endif
        #if XCHAL_TIMER2_INTERRUPT != XTHAL_TIMER_UNCONFIGURED
            #if XCHAL_INT_LEVEL( XCHAL_TIMER2_INTERRUPT ) <= XCHAL_EXCM_LEVEL
                #undef  XT_TIMER_INDEX
                #define XT_TIMER_INDEX    2
            #endif
        #endif
        #if XCHAL_TIMER1_INTERRUPT != XTHAL_TIMER_UNCONFIGURED
            #if XCHAL_INT_LEVEL( XCHAL_TIMER1_INTERRUPT ) <= XCHAL_EXCM_LEVEL
                #undef  XT_TIMER_INDEX
                #define XT_TIMER_INDEX    1
            #endif
        #endif
        #if XCHAL_TIMER0_INTERRUPT != XTHAL_TIMER_UNCONFIGURED
            #if XCHAL_INT_LEVEL( XCHAL_TIMER0_INTERRUPT ) <= XCHAL_EXCM_LEVEL
                #undef  XT_TIMER_INDEX
                #define XT_TIMER_INDEX    0
            #endif
        #endif
    #endif /* ifndef XT_TIMER_INDEX */
    #ifndef XT_TIMER_INDEX
        #error "There is no suitable timer in this Xtensa configuration."
    #endif

    #define XT_CCOMPARE        ( CCOMPARE + XT_TIMER_INDEX )
    #define XT_TIMER_INTNUM    XCHAL_TIMER_INTERRUPT( XT_TIMER_INDEX )
    #define XT_TIMER_INTPRI    XCHAL_INT_LEVEL( XT_TIMER_INTNUM )
    #define XT_TIMER_INTEN     ( 1 << XT_TIMER_INTNUM )

    #if XT_TIMER_INTNUM == XTHAL_TIMER_UNCONFIGURED
        #error "The timer selected by XT_TIMER_INDEX does not exist in this core."
    #elif XT_TIMER_INTPRI > XCHAL_EXCM_LEVEL
        #error "The timer interrupt cannot be high priority (use medium or low)."
    #endif

#endif /* XCHAL_NUM_TIMERS */

/*
 * Set processor clock frequency, used to determine clock divisor for timer tick.
 * User should BE SURE TO ADJUST THIS for the Xtensa platform being used.
 * If using a supported board via the board-independent API defined in xtbsp.h,
 * this may be left undefined and frequency and tick divisor will be computed
 * and cached during run-time initialization.
 *
 * NOTE ON SIMULATOR:
 * Under the Xtensa instruction set simulator, the frequency can only be estimated
 * because it depends on the speed of the host and the version of the simulator.
 * Also because it runs much slower than hardware, it is not possible to achieve
 * real-time performance for most applications under the simulator. A frequency
 * too low does not allow enough time between timer interrupts, starving threads.
 * To obtain a more convenient but non-real-time tick duration on the simulator,
 * compile with xt-xcc option "-DXT_SIMULATOR".
 * Adjust this frequency to taste (it's not real-time anyway!).
 */
#if defined( XT_SIMULATOR ) && !defined( XT_CLOCK_FREQ )
    #define XT_CLOCK_FREQ    configCPU_CLOCK_HZ
#endif

#if !defined( XT_CLOCK_FREQ ) && !defined( XT_BOARD )
    #error "XT_CLOCK_FREQ must be defined for the target platform."
#endif

/*
 * Default number of timer "ticks" per second (default 100 for 10ms tick).
 * RTOS may define this in its own way (if applicable) in xtensa_rtos.h.
 * User may redefine this to an optimal value for the application, either by
 * editing this here or in xtensa_rtos.h, or compiling with xt-xcc option
 * "-DXT_TICK_PER_SEC=<value>" where <value> is a suitable number.
 */
#ifndef XT_TICK_PER_SEC
    #define XT_TICK_PER_SEC    configTICK_RATE_HZ    /* 10 ms tick = 100 ticks per second */
#endif

/*
 * Derivation of clock divisor for timer tick and interrupt (one per tick).
 */
#ifdef XT_CLOCK_FREQ
    #define XT_TICK_DIVISOR    ( XT_CLOCK_FREQ / XT_TICK_PER_SEC )
#endif

#ifndef __ASSEMBLER__
    extern unsigned _xt_tick_divisor;
    extern void _xt_tick_divisor_init( void );
#endif

#endif /* XTENSA_TIMER_H */