arch/xtensa/include/xtensa_rtos.h

/*
 * Copyright (c) 2016 Cadence Design Systems, Inc.
 * SPDX-License-Identifier: Apache-2.0
 */

/*
 *        RTOS-SPECIFIC INFORMATION FOR XTENSA RTOS ASSEMBLER SOURCES
 *                            (FreeRTOS Port)
 *
 * This header is the primary glue between generic Xtensa RTOS support
 * sources and a specific RTOS port for Xtensa.  It contains definitions
 * and macros for use primarily by Xtensa assembly coded source files.
 *
 * Macros in this header map callouts from generic Xtensa files to specific
 * RTOS functions. It may also be included in C source files.
 *
 * Xtensa RTOS ports support all RTOS-compatible configurations of the Xtensa
 * architecture, using the Xtensa hardware abstraction layer (HAL) to deal
 * with configuration specifics.
 *
 * Should be included by all Xtensa generic and RTOS port-specific sources.
 */

#ifndef XTENSA_RTOS_H
#define XTENSA_RTOS_H

#ifdef __ASSEMBLER__
#include    <xtensa/coreasm.h>
#else
#include    <xtensa/config/core.h>
#endif

#include    <xtensa/corebits.h>
#include    <xtensa/config/system.h>
#include    <xtensa/simcall.h>


/*
 * Convert Zephyr definitions to XTENSA definitions.
 */

#undef XT_SIMULATOR
#undef XT_BOARD
#ifdef CONFIG_SIMULATOR_XTENSA
  #define XT_SIMULATOR 1
#else
  #define XT_BOARD 1
#endif

#ifdef CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC
  #undef XT_CLOCK_FREQ
  #define XT_CLOCK_FREQ CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC
#endif

#ifndef XT_TIMER_INDEX
  #if defined configXT_TIMER_INDEX
    /* Index of hardware timer to be used */
    #define XT_TIMER_INDEX           configXT_TIMER_INDEX
  #endif
#endif

#ifndef XT_INTEXC_HOOKS
  #if configXT_INTEXC_HOOKS
    #define XT_INTEXC_HOOKS          1  /* Enables exception hooks */
  #endif
#endif

#if (!XT_SIMULATOR) && (!XT_BOARD)
  #error Either XT_SIMULATOR or XT_BOARD must be defined.
#endif


/*
 * Name of RTOS (for messages).
 */
#define XT_RTOS_NAME    Zephyr

/*
 * Define for enabling RTOS specific code. Enable only one of below lines.
 */
#define XT_RTOS_IS_ZEPHYR_OS 1
#undef XT_RTOS_IS_FREE_RTOS

/*
 * Check some Xtensa configuration requirements and report error if not met.
 * Error messages can be customize to the RTOS port.
 */

#if !XCHAL_HAVE_XEA2
#error "Zephyr/Xtensa requires XEA2 (exception architecture 2)."
#endif

/*
 * RTOS CALLOUT MACROS MAPPED TO RTOS PORT-SPECIFIC FUNCTIONS.
 *
 * Define callout macros used in generic Xtensa code to interact with the RTOS.
 * The macros are simply the function names for use in calls from assembler
 * code.
 * Some of these functions may call back to generic functions in
 * xtensa_context.h .
 */

/*
 * Inform RTOS of entry into an interrupt handler that will affect it.
 * Allows RTOS to manage switch to any system stack and count nesting level.
 * Called after minimal context has been saved, with interrupts disabled.
 * RTOS port can call0 _xt_context_save to save the rest of the context.
 * May only be called from assembly code by the 'call0' instruction.
 */
#define XT_RTOS_INT_ENTER   _zxt_int_enter

/*
 * Inform RTOS of completion of an interrupt handler, and give control to
 * RTOS to perform thread/task scheduling, switch back from any system stack
 * and restore the context, and return to the exit dispatcher saved in the
 * stack frame at XT_STK_EXIT. RTOS port can call0 _xt_context_restore
 * to save the context saved in XT_RTOS_INT_ENTER via _xt_context_save,
 * leaving only a minimal part of the context to be restored by the exit
 * dispatcher. This function does not return to the place it was called from.
 * May only be called from assembly code by the 'call0' instruction.
 */
#define XT_RTOS_INT_EXIT    _zxt_int_exit

/*
 * Inform RTOS of the occurrence of a tick timer interrupt.
 * If RTOS has no tick timer, leave XT_RTOS_TIMER_INT undefined.
 * May be coded in or called from C or assembly, per ABI conventions.
 * RTOS may optionally define XT_TICK_PER_SEC in its own way (eg. macro).
 */
#define XT_RTOS_TIMER_INT   _zxt_timer_int
#define XT_TICK_PER_SEC     CONFIG_SYS_CLOCK_TICKS_PER_SEC

/*
 * Return in a15 the base address of the co-processor state save area for the
 * thread that triggered a co-processor exception, or 0 if no thread was
 * running.  The state save area is structured as defined in xtensa_context.h
 * and has size XT_CP_SIZE. Co-processor instructions should only be used in
 * thread code, never in interrupt handlers or the RTOS kernel. May only be
 * called from assembly code and by the 'call0' instruction. A result of 0
 * indicates an unrecoverable error.
 *
 * The implementation may use only a2-4, a15 (all other regs must be
 * preserved).
 */
#define XT_RTOS_CP_STATE    _zxt_task_coproc_state


/*
 * HOOKS TO DYNAMICALLY INSTALL INTERRUPT AND EXCEPTION HANDLERS PER LEVEL.
 *
 * This Xtensa RTOS port provides hooks for dynamically installing exception
 * and interrupt handlers to facilitate automated testing where each test case
 * can install its own handler for user exceptions and each interrupt priority
 * (level). This consists of an array of function pointers indexed by interrupt
 * priority, with index 0 being the user exception handler hook.  Each entry in
 * the array is initially 0, and may be replaced by a function pointer of type
 * XT_INTEXC_HOOK. A handler may be uninstalled by installing 0.
 *
 * The handler for low and medium priority obeys ABI conventions so may be
 * coded in C. For the exception handler, the cause is the contents of the
 * EXCCAUSE reg, and the result is -1 if handled, else the cause (still needs
 * handling).  For interrupt handlers, the cause is a mask of pending enabled
 * interrupts at that level, and the result is the same mask with the bits for
 * the handled interrupts cleared (those not cleared still need handling). This
 * allows a test case to either pre-handle or override the default handling for
 * the exception or interrupt level (see xtensa_vectors.S).
 *
 * High priority handlers (including NMI) must be coded in assembly, are always
 * called by 'call0' regardless of ABI, must preserve all registers except a0,
 * and must not use or modify the interrupted stack. The hook argument 'cause'
 * is not passed and the result is ignored, so as not to burden the caller
 * with saving and restoring a2 (it assumes only one interrupt per level - see
 * the discussion in high priority interrupts in xtensa_vectors.S). The handler
 * therefore should be coded to prototype 'void h(void)' even though it plugs
 * into an array of handlers of prototype 'unsigned h(unsigned)'.
 *
 * To enable interrupt/exception hooks, compile the RTOS with
 * '-DXT_INTEXC_HOOKS'.
 */
#define XT_INTEXC_HOOK_NUM  (1 + XCHAL_NUM_INTLEVELS + XCHAL_HAVE_NMI)

#ifndef __ASSEMBLER__
typedef unsigned int (*XT_INTEXC_HOOK)(unsigned int cause);
extern  volatile XT_INTEXC_HOOK _xt_intexc_hooks[XT_INTEXC_HOOK_NUM];
#endif


/*
 * CONVENIENCE INCLUSIONS.
 *
 * Ensures RTOS specific files need only include this one Xtensa-generic
 * header.  These headers are included last so they can use the RTOS
 * definitions above.
 */

#include    "xtensa_context.h"

#ifdef XT_RTOS_TIMER_INT
#include    "xtensa_timer.h"
#endif

#endif /* XTENSA_RTOS_H */