rockbox/firmware/thread.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2002 by Ulf Ralberg
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "config.h"
#include <stdbool.h>
#include "thread.h"
#include "panic.h"
#include "system.h"
#include "kernel.h"
#include "cpu.h"
#include "string.h"

#define DEADBEEF ((unsigned int)0xdeadbeef)
/* Cast to the the machine int type, whose size could be < 4. */

struct core_entry cores[NUM_CORES] IBSS_ATTR;
#ifdef HAVE_PRIORITY_SCHEDULING
static unsigned short highest_priority IBSS_ATTR;
#endif

/* Define to enable additional checks for blocking violations etc. */
// #define THREAD_EXTRA_CHECKS

static const char main_thread_name[] = "main";

extern int stackbegin[];
extern int stackend[];

#ifdef CPU_PP
#ifndef BOOTLOADER
extern int cop_stackbegin[];
extern int cop_stackend[];
#else
/* The coprocessor stack is not set up in the bootloader code, but the
   threading is.  No threads are run on the coprocessor, so set up some dummy
   stack */
int *cop_stackbegin = stackbegin;
int *cop_stackend = stackend;
#endif
#endif

/* Conserve IRAM
static void add_to_list(struct thread_entry **list,
                        struct thread_entry *thread) ICODE_ATTR;
static void remove_from_list(struct thread_entry **list,
                             struct thread_entry *thread) ICODE_ATTR;
*/

void switch_thread(bool save_context, struct thread_entry **blocked_list)
    ICODE_ATTR;

static inline void store_context(void* addr) __attribute__ ((always_inline));
static inline void load_context(const void* addr) __attribute__ ((always_inline));

#ifdef RB_PROFILE
#include <profile.h>
void profile_thread(void) {
    profstart(cores[CURRENT_CORE].current_thread);
}
#endif

#if defined(CPU_ARM)
/*---------------------------------------------------------------------------
 * Store non-volatile context.
 *---------------------------------------------------------------------------
 */
static inline void store_context(void* addr)
{
    asm volatile(
        "stmia  %0, { r4-r11, sp, lr }\n"
        : : "r" (addr)
    );
}

/*---------------------------------------------------------------------------
 * Load non-volatile context.
 *---------------------------------------------------------------------------
 */
static inline void load_context(const void* addr)
{
    asm volatile(
        "ldmia  %0, { r4-r11, sp, lr }\n" /* load regs r4 to r14 from context */
        "ldr    r0, [%0, #40]    \n" /* load start pointer */
        "mov    r1, #0           \n"
        "cmp    r0, r1           \n" /* check for NULL */
        "strne  r1, [%0, #40]    \n" /* if it's NULL, we're already running */
        "movne  pc, r0           \n" /* not already running, so jump to start */
        : : "r" (addr) : "r0", "r1"
    );
}

#elif defined(CPU_COLDFIRE)
/*---------------------------------------------------------------------------
 * Store non-volatile context.
 *---------------------------------------------------------------------------
 */
static inline void store_context(void* addr)
{
    asm volatile (
        "move.l  %%macsr,%%d0    \n"
        "movem.l %%d0/%%d2-%%d7/%%a2-%%a7,(%0)   \n"
        : : "a" (addr) : "d0" /* only! */
    );
}

/*---------------------------------------------------------------------------
 * Load non-volatile context.
 *---------------------------------------------------------------------------
 */
static inline void load_context(const void* addr)
{
    asm volatile (
        "movem.l (%0),%%d0/%%d2-%%d7/%%a2-%%a7   \n"  /* Load context */
        "move.l  %%d0,%%macsr    \n"
        "move.l  (52,%0),%%d0    \n"  /* Get start address */
        "beq.b   .running        \n"  /* NULL -> already running */
        "clr.l   (52,%0)         \n"  /* Clear start address.. */
        "move.l  %%d0,%0         \n"
        "jmp     (%0)            \n"  /* ..and start the thread */
    ".running:                   \n"
        : : "a" (addr) : "d0" /* only! */
    );
}

#elif CONFIG_CPU == SH7034
/*---------------------------------------------------------------------------
 * Store non-volatile context.
 *---------------------------------------------------------------------------
 */
static inline void store_context(void* addr)
{
    asm volatile (
        "add     #36,%0    \n"
        "sts.l   pr, @-%0  \n"
        "mov.l   r15,@-%0  \n"
        "mov.l   r14,@-%0  \n"
        "mov.l   r13,@-%0  \n"
        "mov.l   r12,@-%0  \n"
        "mov.l   r11,@-%0  \n"
        "mov.l   r10,@-%0  \n"
        "mov.l   r9, @-%0  \n"
        "mov.l   r8, @-%0  \n"
        : : "r" (addr)
    );
}

/*---------------------------------------------------------------------------
 * Load non-volatile context.
 *---------------------------------------------------------------------------
 */
static inline void load_context(const void* addr)
{
    asm volatile (
        "mov.l   @%0+,r8   \n"
        "mov.l   @%0+,r9   \n"
        "mov.l   @%0+,r10  \n"
        "mov.l   @%0+,r11  \n"
        "mov.l   @%0+,r12  \n"
        "mov.l   @%0+,r13  \n"
        "mov.l   @%0+,r14  \n"
        "mov.l   @%0+,r15  \n"
        "lds.l   @%0+,pr   \n"
        "mov.l   @%0,r0    \n"  /* Get start address */
        "tst     r0,r0     \n"
        "bt      .running  \n"  /* NULL -> already running */
        "lds     r0,pr     \n"
        "mov     #0,r0     \n"
        "rts               \n"  /* Start the thread */
        "mov.l   r0,@%0    \n"  /* Clear start address */
    ".running:             \n"
        : : "r" (addr) : "r0" /* only! */
    );
}

#elif CONFIG_CPU == TCC730
/*---------------------------------------------------------------------------
 * Store non-volatile context.
 *---------------------------------------------------------------------------
 */
#define store_context(addr)				\
    __asm__ volatile (                                  \
        "push r0,r1\n\t"				\
        "push r2,r3\n\t"				\
        "push r4,r5\n\t"				\
        "push r6,r7\n\t"				\
        "push a8,a9\n\t"				\
        "push a10,a11\n\t"				\
        "push a12,a13\n\t"				\
        "push a14\n\t"                                  \
        "ldw @[%0+0], a15\n\t" : : "a" (addr) );

/*---------------------------------------------------------------------------
 * Load non-volatile context.
 *---------------------------------------------------------------------------
 */
#define load_context(addr)                      \
    {                                           \
        if (!(addr)->started) {                 \
            (addr)->started = 1;                \
            __asm__ volatile (                  \
                "ldw a15, @[%0+0]\n\t"          \
                "ldw a14, @[%0+4]\n\t"		\
                "jmp a14\n\t" : : "a" (addr)	\
                );				\
        } else                                  \
            __asm__ volatile (                  \
                "ldw a15, @[%0+0]\n\t"		\
                "pop a14\n\t"			\
                "pop a13,a12\n\t"               \
                "pop a11,a10\n\t"               \
                "pop a9,a8\n\t"			\
                "pop r7,r6\n\t"			\
                "pop r5,r4\n\t"			\
                "pop r3,r2\n\t"			\
                "pop r1,r0\n\t" : : "a" (addr)	\
                );                              \
                                                \
    }

#endif

static void add_to_list(struct thread_entry **list,
                        struct thread_entry *thread)
{
    if (*list == NULL)
    {
        thread->next = thread;
        thread->prev = thread;
        *list = thread;
    }
    else
    {
        /* Insert last */
        thread->next = *list;
        thread->prev = (*list)->prev;
        thread->prev->next = thread;
        (*list)->prev = thread;
        
        /* Insert next
         thread->next = (*list)->next;
         thread->prev = *list;
         thread->next->prev = thread;
         (*list)->next = thread;
         */
    }
}

static void remove_from_list(struct thread_entry **list,
                      struct thread_entry *thread)
{
    if (list != NULL)
    {
        if (thread == thread->next)
        {
            *list = NULL;
            return;
        }
        
        if (thread == *list)
            *list = thread->next;
    }
    
    /* Fix links to jump over the removed entry. */
    thread->prev->next = thread->next;
    thread->next->prev = thread->prev;
}

/* Compiler trick: Don't declare as static to prevent putting 
 * function in IRAM. */
void check_sleepers(void)
{
    struct thread_entry *current, *next;
    
    /* Check sleeping threads. */
    current = cores[CURRENT_CORE].sleeping;
    if (current == NULL)
        return ;
    
    for (;;)
    {
        next = current->next;
        
        if ((unsigned)current_tick >= GET_STATE_ARG(current->statearg))
        {
            /* Sleep timeout has been reached so bring the thread
             * back to life again. */
            remove_from_list(&cores[CURRENT_CORE].sleeping, current);
            add_to_list(&cores[CURRENT_CORE].running, current);
            
            /* If there is no more processes in the list, break the loop. */
            if (cores[CURRENT_CORE].sleeping == NULL)
                break;
            
            current = next;
            continue;
        }
        
        current = next;
        
        /* Break the loop once we have walked through the list of all
         * sleeping processes. */
        if (current == cores[CURRENT_CORE].sleeping)
            break;
    }
}

static inline void sleep_core(void)
{
    static long last_tick = 0;
    
    for (;;)
    {
        if (last_tick != current_tick)
        {
            check_sleepers();
            last_tick = current_tick;
        }
        
        /* We must sleep until there is at least one process in the list
         * of running processes. */
        if (cores[CURRENT_CORE].running != NULL)
            break;

        /* Enter sleep mode to reduce power usage, woken up on interrupt */
#ifdef CPU_COLDFIRE
        asm volatile ("stop #0x2000");
#elif CONFIG_CPU == SH7034
        and_b(0x7F, &SBYCR);
        asm volatile ("sleep");
#elif CONFIG_CPU == PP5020
        /* This should sleep the CPU. It appears to wake by itself on
           interrupts */
        CPU_CTL = 0x80000000;
#elif CONFIG_CPU == TCC730
	    /* Sleep mode is triggered by the SYS instr on CalmRisc16.
         * Unfortunately, the manual doesn't specify which arg to use.
         __asm__ volatile ("sys #0x0f");
         0x1f seems to trigger a reset;
         0x0f is the only one other argument used by Archos.
         */
#elif CONFIG_CPU == S3C2440
        CLKCON |= 2;
#endif
    }
}

#ifdef RB_PROFILE
static int get_threadnum(struct thread_entry *thread)
{
    int i;
    
    for (i = 0; i < MAXTHREADS; i++)
    {
        if (&cores[CURRENT_CORE].threads[i] == thread)
            return i;
    }
    
    return -1;
}
#endif

/* Compiler trick: Don't declare as static to prevent putting 
 * function in IRAM. */
void change_thread_state(struct thread_entry **blocked_list)
{
    struct thread_entry *old;
    
    /* Remove the thread from the list of running threads. */
    old = cores[CURRENT_CORE].running;
    remove_from_list(&cores[CURRENT_CORE].running, old);
    
    /* And put the thread into a new list of inactive threads. */
    if (GET_STATE(old->statearg) == STATE_BLOCKED)
        add_to_list(blocked_list, old);
    else
        add_to_list(&cores[CURRENT_CORE].sleeping, old);
    
#ifdef HAVE_PRIORITY_SCHEDULING
    /* Reset priorities */
    if (old->priority == highest_priority)
        highest_priority = 100;
#endif
}

/*---------------------------------------------------------------------------
 * Switch thread in round robin fashion.
 *---------------------------------------------------------------------------
 */
void switch_thread(bool save_context, struct thread_entry **blocked_list)
{
#ifdef RB_PROFILE
    profile_thread_stopped(get_threadnum(cores[CURRENT_CORE].running));
#endif
    unsigned int *stackptr;
    
#ifdef SIMULATOR
    /* Do nothing */
#else
    
    /* Begin task switching by saving our current context so that we can
     * restore the state of the current thread later to the point prior
     * to this call. */
    if (save_context)
    {
        store_context(&cores[CURRENT_CORE].running->context);

# if CONFIG_CPU != TCC730
        /* Check if the current thread stack is overflown */
        stackptr = cores[CURRENT_CORE].running->stack;
        if(stackptr[0] != DEADBEEF)
        panicf("Stkov %s", cores[CURRENT_CORE].running->name);
# endif
        
        /* Check if a thread state change has been requested. */
        if (cores[CURRENT_CORE].running->statearg)
        {
            /* Change running thread state and switch to next thread. */
            change_thread_state(blocked_list);
        }
        else
        {
            /* Switch to the next running thread. */
            cores[CURRENT_CORE].running = cores[CURRENT_CORE].running->next;
        }
    }
    
    /* Go through the list of sleeping task to check if we need to wake up
     * any of them due to timeout. Also puts core into sleep state until
     * there is at least one running process again. */
    sleep_core();
    
#ifdef HAVE_PRIORITY_SCHEDULING
    /* Select the new task based on priorities and the last time a process
     * got CPU time. */
    for (;;)
    {
        int priority = cores[CURRENT_CORE].running->priority;
        
        if (priority < highest_priority)
            highest_priority = priority;
        
        if (priority == highest_priority || (current_tick 
            - cores[CURRENT_CORE].running->last_run > priority * 8))
        {
            break;
        }
        cores[CURRENT_CORE].running = cores[CURRENT_CORE].running->next;
    }
    
    /* Reset the value of thread's last running time to the current time. */
    cores[CURRENT_CORE].running->last_run = current_tick;
#endif
    
#endif
    /* And finally give control to the next thread. */
    load_context(&cores[CURRENT_CORE].running->context);
    
#ifdef RB_PROFILE
    profile_thread_started(get_threadnum(cores[CURRENT_CORE].running));
#endif
}

void sleep_thread(int ticks)
{
    /* Set the thread's new state and timeout and finally force a task switch
     * so that scheduler removes thread from the list of running processes
     * and puts it in list of sleeping tasks. */
    cores[CURRENT_CORE].running->statearg = 
        SET_STATE(STATE_SLEEPING, current_tick + ticks + 1);
    switch_thread(true, NULL);
    
    /* Clear all flags to indicate we are up and running again. */
    cores[CURRENT_CORE].running->statearg = 0;
}

void block_thread(struct thread_entry **list, int timeout)
{
    struct thread_entry *current;
    
    /* Get the entry for the current running thread. */
    current = cores[CURRENT_CORE].running;
    
    /* At next task switch scheduler will immediately change the thread
     * state (and we also force the task switch to happen). */
    if (timeout)
    {
#ifdef THREAD_EXTRA_CHECKS
        /* We can store only one thread to the "list" if thread is used
         * in other list (such as core's list for sleeping tasks). */
        if (*list)
            panicf("Blocking violation T->*B");
#endif
        
        current->statearg = 
            SET_STATE(STATE_BLOCKED_W_TMO, current_tick + timeout);
        *list = current;

        /* Now force a task switch and block until we have been woken up
         * by another thread or timeout is reached. */
        switch_thread(true, NULL);
        
        /* If timeout is reached, we must set list back to NULL here. */
        *list = NULL;
    }
    else
    {
#ifdef THREAD_EXTRA_CHECKS
        /* We are not allowed to mix blocking types in one queue. */
        if (*list && GET_STATE((*list)->statearg) == STATE_BLOCKED_W_TMO)
            panicf("Blocking violation B->*T");
#endif
        
        current->statearg = SET_STATE(STATE_BLOCKED, 0);
        
        /* Now force a task switch and block until we have been woken up
         * by another thread or timeout is reached. */
        switch_thread(true, list);
    }
    
    /* Clear all flags to indicate we are up and running again. */
    current->statearg = 0;
}

void wakeup_thread(struct thread_entry **list)
{
    struct thread_entry *thread;
    
    /* Check if there is a blocked thread at all. */
    if (*list == NULL)
        return ;
    
    /* Wake up the last thread first. */
    thread = *list;
    
    /* Determine thread's current state. */
    switch (GET_STATE(thread->statearg)) 
    {
        case STATE_BLOCKED:
            /* Remove thread from the list of blocked threads and add it
             * to the scheduler's list of running processes. */
            remove_from_list(list, thread);
            add_to_list(&cores[CURRENT_CORE].running, thread);
            thread->statearg = 0;
            break;
        
        case STATE_BLOCKED_W_TMO:
            /* Just remove the timeout to cause scheduler to immediately
             * wake up the thread. */
            thread->statearg &= 0xC0000000;
            *list = NULL;
            break;
        
        default:
            /* Nothing to do. Thread has already been woken up
             * or it's state is not blocked or blocked with timeout. */
            return ;
    }
}

/*---------------------------------------------------------------------------
 * Create thread on the current core.
 * Return ID if context area could be allocated, else -1.
 *---------------------------------------------------------------------------
 */
struct thread_entry* 
    create_thread(void (*function)(void), void* stack, int stack_size,
                  const char *name IF_PRIO(, int priority))
{
    return create_thread_on_core(CURRENT_CORE, function, stack, stack_size,
                  name IF_PRIO(, priority));
}

/*---------------------------------------------------------------------------
 * Create thread on a specific core.
 * Return ID if context area could be allocated, else -1.
 *---------------------------------------------------------------------------
 */
struct thread_entry* 
    create_thread_on_core(unsigned int core, void (*function)(void), 
                          void* stack, int stack_size,
                          const char *name IF_PRIO(, int priority))
{
    unsigned int i;
    unsigned int stacklen;
    unsigned int *stackptr;
    int n;
    struct regs *regs;
    struct thread_entry *thread;

    for (n = 0; n < MAXTHREADS; n++)
    {
        if (cores[core].threads[n].name == NULL)
            break;
    }
    
    if (n == MAXTHREADS)
        return NULL;
    
    
    /* Munge the stack to make it easy to spot stack overflows */
    stacklen = stack_size / sizeof(int);
    stackptr = stack;
    for(i = 0;i < stacklen;i++)
    {
        stackptr[i] = DEADBEEF;
    }

    /* Store interesting information */
    thread = &cores[core].threads[n];
    thread->name = name;
    thread->stack = stack;
    thread->stack_size = stack_size;
    thread->statearg = 0;
#ifdef HAVE_PRIORITY_SCHEDULING
    thread->priority = priority;
    highest_priority = 100;
#endif
    add_to_list(&cores[core].running, thread);
    
    regs = &thread->context;
#if defined(CPU_COLDFIRE) || (CONFIG_CPU == SH7034) || defined(CPU_ARM)
    /* Align stack to an even 32 bit boundary */
    regs->sp = (void*)(((unsigned int)stack + stack_size) & ~3);
#elif CONFIG_CPU == TCC730
   /* Align stack on word boundary */
    regs->sp = (void*)(((unsigned long)stack + stack_size - 2) & ~1);
    regs->started = 0;
#endif
    regs->start = (void*)function;

    return thread;
}

/*---------------------------------------------------------------------------
 * Remove a thread on the current core from the scheduler.
 * Parameter is the ID as returned from create_thread().
 *---------------------------------------------------------------------------
 */
void remove_thread(struct thread_entry *thread)
{
    if (thread == NULL)
        thread = cores[CURRENT_CORE].running;
    
    /* Free the entry by removing thread name. */
    thread->name = NULL;
#ifdef HAVE_PRIORITY_SCHEDULING
    highest_priority = 100;
#endif
    
    if (thread == cores[CURRENT_CORE].running)
    {
        remove_from_list(&cores[CURRENT_CORE].running, thread);
        switch_thread(false, NULL);
        return ;
    }
    
    if (thread == cores[CURRENT_CORE].sleeping)
        remove_from_list(&cores[CURRENT_CORE].sleeping, thread);
    else
        remove_from_list(NULL, thread);
}

#ifdef HAVE_PRIORITY_SCHEDULING
void thread_set_priority(struct thread_entry *thread, int priority)
{
    if (thread == NULL)
        thread = cores[CURRENT_CORE].running;
    
    thread->priority = priority;
    highest_priority = 100;
}
#endif

void init_threads(void)
{
    unsigned int core = CURRENT_CORE;

    memset(cores, 0, sizeof cores);
    cores[core].sleeping = NULL;
    cores[core].running = NULL;
    cores[core].threads[0].name = main_thread_name;
    cores[core].threads[0].statearg = 0;
#ifdef HAVE_PRIORITY_SCHEDULING
    cores[core].threads[0].priority = PRIORITY_USER_INTERFACE;
    highest_priority = 100;
#endif
    add_to_list(&cores[core].running, &cores[core].threads[0]);
    
    /* In multiple core setups, each core has a different stack.  There is probably
     a much better way to do this. */
    if (core == CPU)
    {
        cores[CPU].threads[0].stack = stackbegin;
        cores[CPU].threads[0].stack_size = (int)stackend - (int)stackbegin;
    } else {
#if NUM_CORES > 1  /* This code path will not be run on single core targets */
        cores[COP].threads[0].stack = cop_stackbegin;
        cores[COP].threads[0].stack_size = (int)cop_stackend - (int)cop_stackbegin;
#endif
    }
#if CONFIG_CPU == TCC730
    cores[core].threads[0].context.started = 1;
#else
    cores[core].threads[0].context.start = 0; /* thread 0 already running */
#endif
}

int thread_stack_usage(const struct thread_entry *thread)
{
    unsigned int i;
    unsigned int *stackptr = thread->stack;

    for (i = 0;i < thread->stack_size/sizeof(int);i++)
    {
        if (stackptr[i] != DEADBEEF)
            break;
    }

    return ((thread->stack_size - i * sizeof(int)) * 100) /
        thread->stack_size;
}

int thread_get_status(const struct thread_entry *thread)
{
    return GET_STATE(thread->statearg);
}