context.c

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/*
 * Copyright (C) 2001-2005 by egnite Software GmbH. All rights reserved.
 *
 * 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.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH 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 EGNITE
 * SOFTWARE GMBH 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.
 *
 * For additional information see http://www.ethernut.de/
 *
 */

/*
 * $Log$
 * Revision 1.10  2009/01/19 18:55:12  haraldkipp
 * Added stack checking code.
 *
 * Revision 1.9  2009/01/17 11:26:37  haraldkipp
 * Getting rid of two remaining BSD types in favor of stdint.
 * Replaced 'u_int' by 'unsinged int' and 'uptr_t' by 'uintptr_t'.
 *
 * Revision 1.8  2009/01/16 19:45:42  haraldkipp
 * All ARM code is now running in system mode.
 *
 * Revision 1.7  2008/08/11 06:59:14  haraldkipp
 * BSD types replaced by stdint types (feature request #1282721).
 *
 * Revision 1.6  2008/07/07 11:04:27  haraldkipp
 * Configurable ways of handling critical sections for ARM targets.
 *
 * Revision 1.5  2006/03/16 19:06:16  haraldkipp
 * Use link register to jump into thread and use dedicated routine to
 * jump into the idle thread. The way we did start the idle thread
 * before, jumping into the middle of NutThreadSwitch(), doesn't work
 * with optimized code.
 *
 * Revision 1.4  2006/03/16 15:25:00  haraldkipp
 * Changed human readable strings from u_char to char to stop GCC 4 from
 * nagging about signedness.
 *
 * Revision 1.3  2005/10/24 09:09:41  haraldkipp
 * Switch frame reduced.
 * NutThreadEntry included in the execution path.
 * The 'cc' globber had been removed from the context switching asm macro,
 * after Michael Fischer found out that this fixes a problem with optimized
 * compilation. Unfortunately, compiler optimized binaries still seem to
 * run unreliable.
 *
 * Revision 1.2  2005/08/02 17:46:45  haraldkipp
 * Major API documentation update.
 *
 * Revision 1.1  2005/07/26 18:10:48  haraldkipp
 * Moved from os/thread.c
 *
 * Revision 1.1  2005/05/27 17:16:40  drsung
 * Moved the file.
 *
 * Revision 1.4  2005/04/05 17:54:36  haraldkipp
 * Moved from user mode to system mode. Probably breaks the GBA port.
 *
 * Revision 1.3  2004/11/08 19:15:33  haraldkipp
 * Made assembly includes look nicer.
 * Changed mode from supervisory to user supervisory, which seems to work
 * with the GBA.
 * Skipped entry frame, because it simply confuses me. :-)
 *
 * Revision 1.2  2004/09/08 10:19:31  haraldkipp
 * Tyou's support for the ARM7
 *
 * Revision 1.1  2004/03/16 16:48:46  haraldkipp
 * Added Jan Dubiec's H8/300 port.
 *
 * Revision 1.2  2004/02/18 16:32:48  drsung
 * Bugfix in NutThreadCreate. Thanks to Mike Cornelius.
 *
 * Revision 1.1  2004/02/01 18:49:48  haraldkipp
 * Added CPU family support
 *
 */

#include <cfg/os.h>

#include <string.h>

#include <sys/atom.h>
#include <sys/heap.h>
#include <sys/thread.h>



typedef struct {
    uint32_t csf_cpsr;
    uint32_t csf_r4;
    uint32_t csf_r5;
    uint32_t csf_r6;
    uint32_t csf_r7;
    uint32_t csf_r8;
    uint32_t csf_r9;
    uint32_t csf_r10;
    uint32_t csf_r11;             /* AKA fp */
    uint32_t csf_lr;
} SWITCHFRAME;

typedef struct {
    uint32_t cef_r0;
    uint32_t cef_pc;
} ENTERFRAME;

static void NutThreadEntry(void) __attribute__ ((naked));
void NutThreadEntry(void)
{
    /* Load argument in r0 and jump to thread entry. */
    asm volatile ("ldmfd   sp!, {r0, lr}\n\tbx lr":::"r0", "lr");
}

void NutThreadSwitch(void) __attribute__ ((naked));
void NutThreadSwitch(void)
{
    __asm__ __volatile__
        /* Save CPU context. */
     ("@ Save context\n\t"
      /* Save registers. */
      "stmfd   sp!, {r4-r11, lr}\n\t"
      /* Save status. */
      "mrs     r0, cpsr\n\t"
      /* */
      "stmfd   sp!, {r0}\n\t"
      /* Save stack pointer. */
      "str     sp, %[td_sp]"
      /* Output. */
      :
      /* Input. */
      :[td_sp] "o"(runningThread->td_sp)
      /* Clobbers. */
      :"r0", "memory");

    /* Select thread on top of the run queue. */
    runningThread = runQueue;
    runningThread->td_state = TDS_RUNNING;
#if defined(NUT_CRITICAL_NESTING) && !defined(NUT_CRITICAL_NESTING_STACK)
    critical_nesting_level = 0;
#endif

    __asm__ __volatile__
        /* Restore context. */
     ("@ Reload context\n\t"
      /* Restore stack pointer. */
      "ldr     sp, %[td_sp]\n\t"
      /* Get saved status... */
      "ldmfd   sp!, {r0}\n\t"
      /* ...enable interrupts */
      "bic     r0, r0, #0xC0\n\t"
      /* ...and save in spsr. */
      "msr     spsr, r0\n\t"
      /* Restore registers. */
      "ldmfd   sp!, {r4-r11, lr}\n\t"
      /* Restore status and return. */
      "movs    pc, lr"
      /* Output. */
      :
      /* Input. */
      :[td_sp] "m"(runningThread->td_sp)
      /* Clobbers. */
      :"r0", "memory");
}

HANDLE NutThreadCreate(char * name, void (*fn) (void *), void *arg, size_t stackSize)
{
    uint8_t *threadMem;
    SWITCHFRAME *sf;
    ENTERFRAME *ef;
    NUTTHREADINFO *td;

    /*
     * Allocate stack and thread info structure in one block.
     * We sill setup the following layout:
     *
     * Upper memory addresses.
     *
     *              +--------------------+
     *              I                    I
     *              I   NUTTHREADINFO    I
     *              I                    I
     * td ->        +-----+--------------+ <- Stack top
     *              I     I              I
     *              I  T  I   ENTERFRAME I
     *              I  H  I              I
     * ef ->        I  R  +--------------+
     *              I  E  I              I    ^
     *              I  A  I  SWITCHFRAME I    I
     *              I  D  I              I    I  pop moves up
     * sf ->        I     +--------------+ <- Initial stack pointer
     *              I  S  I              I    I  push moves down
     *              I  T  I Application  I    I
     *              I  A  I Stack        I    V
     *              I  C  I              I
     *              I  K  I              I
     * threadMem -> +-----+--------------+ <- Stack bottom
     *
     * Lower memory addresses.
     */
    if ((threadMem = NutHeapAlloc(stackSize + sizeof(NUTTHREADINFO))) == 0) {
        return 0;
    }
    td = (NUTTHREADINFO *) (threadMem + stackSize);
    ef = (ENTERFRAME *) ((uintptr_t) td - sizeof(ENTERFRAME));
    sf = (SWITCHFRAME *) ((uintptr_t) ef - sizeof(SWITCHFRAME));

    /* 
     * Set predefined values at the stack bottom. May be used to detect
     * stack overflows.
     */
#if defined(NUTDEBUG_CHECK_STACKMIN) || defined(NUTDEBUG_CHECK_STACK)
    {
        uint32_t *fip = (uint32_t *)threadMem;
        while (fip < (uint32_t *)sf) {
            *fip++ = DEADBEEF;
        }
    }
#else
    *((uint32_t *) threadMem) = DEADBEEF;
    *((uint32_t *) (threadMem + 4)) = DEADBEEF;
    *((uint32_t *) (threadMem + 8)) = DEADBEEF;
    *((uint32_t *) (threadMem + 12)) = DEADBEEF;
#endif

    /*
     * Setup the entry frame to simulate C function entry.
     */
    ef->cef_pc = (uintptr_t) fn;
    ef->cef_r0 = (uintptr_t) arg;

    /*
     * Setup the switch frame.
     */
    sf->csf_lr = (uintptr_t) NutThreadEntry;
    sf->csf_cpsr = ARM_CPSR_I_BIT | ARM_CPSR_F_BIT | ARM_MODE_SYS;

    /*
     * Initialize the thread info structure and insert it into the 
     * thread list and the run queue.
     */
    memcpy(td->td_name, name, sizeof(td->td_name) - 1);
    td->td_name[sizeof(td->td_name) - 1] = 0;
    td->td_state = TDS_READY;
    td->td_sp = (uintptr_t) sf;
    td->td_priority = 64;
    td->td_memory = threadMem;
    td->td_timer = 0;
    td->td_queue = 0;

    NutEnterCritical();
    td->td_next = nutThreadList;
    nutThreadList = td;
    NutThreadAddPriQueue(td, (NUTTHREADINFO **) & runQueue);

    /*
     * If no thread is running, then this is the first thread ever 
     * created. In Nut/OS, the idle thread is created first.
     */
    if (runningThread == 0) {
        /* This will never return. */
        runningThread = runQueue;
        runningThread->td_state = TDS_RUNNING;

        __asm__ __volatile__
            /* Load initial idle thread context. */
         ("@ Load context\n\t"
          /* Restore stack pointer. */
          "ldr     sp, %[td_sp]\n\t"
          /* Get saved status... */
          "ldmfd   sp!, {r0}\n\t"
          /* ...enable interrupts */
          "bic     r0, r0, #0xC0\n\t"
          /* ...and save in spsr. */
          "msr     spsr, r0\n\t"
          /* Restore registers. */
          "ldmfd   sp!, {r4-r11, lr}\n\t"
          /* Restore status and return. */
          "movs    pc, lr"
          /* Input. */
          :
          /* Output. */
          :[td_sp] "m" (runningThread->td_sp)
          /* Clobbers. */
          :"r0", "memory");
    }

    /*
     * If current context is not in front of the run queue (highest 
     * priority), then switch to the thread in front.
     */
    if (runningThread != runQueue) {
        runningThread->td_state = TDS_READY;
        NutThreadSwitch();
    }
    NutExitCritical();

    return td;
}