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/*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <exports.h>
/*
* Author: Arun Dharankar <ADharankar@ATTBI.Com>
*
* A very simple thread/schedular model:
* - only one master thread, and no parent child relation maintained
* - parent thread cannot be stopped or deleted
* - no permissions or credentials
* - no elaborate safety checks
* - cooperative multi threading
* - Simple round-robin scheduleing with no priorities
* - no metering/statistics collection
*
* Basic idea of implementing this is to allow more than one tests to
* execute "simultaneously".
*
* This may be modified such thread_yield may be called in syscalls, and
* timer interrupts.
*/
#define MAX_THREADS 8
#define CTX_SIZE 512
#define STK_SIZE 8*1024
#define STATE_EMPTY 0
#define STATE_RUNNABLE 1
#define STATE_STOPPED 2
#define STATE_TERMINATED 2
#define MASTER_THREAD 0
#define RC_FAILURE (-1)
#define RC_SUCCESS (0)
typedef vu_char *jmp_ctx;
unsigned long setctxsp (vu_char *sp);
int ppc_setjmp(jmp_ctx env);
void ppc_longjmp(jmp_ctx env, int val);
#define setjmp ppc_setjmp
#define longjmp ppc_longjmp
struct lthread {
int state;
int retval;
char stack[STK_SIZE];
uchar context[CTX_SIZE];
int (*func) (void *);
void *arg;
};
static volatile struct lthread lthreads[MAX_THREADS];
static volatile int current_tid = MASTER_THREAD;
static uchar dbg = 0;
#define PDEBUG(fmt, args...) { \
if(dbg != 0) { \
printf("[%s %d %s]: ",__FILE__,__LINE__,__FUNCTION__);\
printf(fmt, ##args); \
printf("\n"); \
} \
}
static int testthread (void *);
static void sched_init (void);
static int thread_create (int (*func) (void *), void *arg);
static int thread_start (int id);
static void thread_yield (void);
static int thread_delete (int id);
static int thread_join (int *ret);
#if 0 /* not used yet */
static int thread_stop (int id);
#endif /* not used yet */
/* An example of schedular test */
#define NUMTHREADS 7
int sched (int ac, char *av[])
{
int i, j;
int tid[NUMTHREADS];
int names[NUMTHREADS];
app_startup(av);
sched_init ();
for (i = 0; i < NUMTHREADS; i++) {
names[i] = i;
j = thread_create (testthread, (void *) &names[i]);
if (j == RC_FAILURE)
printf ("schedtest: Failed to create thread %d\n", i);
if (j > 0) {
printf ("schedtest: Created thread with id %d, name %d\n",
j, i);
tid[i] = j;
}
}
printf ("schedtest: Threads created\n");
printf ("sched_test: function=0x%08x\n", (unsigned)testthread);
for (i = 0; i < NUMTHREADS; i++) {
printf ("schedtest: Setting thread %d runnable\n", tid[i]);
thread_start (tid[i]);
thread_yield ();
}
printf ("schedtest: Started %d threads\n", NUMTHREADS);
while (1) {
printf ("schedtest: Waiting for threads to complete\n");
if (tstc () && getc () == 0x3) {
printf ("schedtest: Aborting threads...\n");
for (i = 0; i < NUMTHREADS; i++) {
printf ("schedtest: Deleting thread %d\n", tid[i]);
thread_delete (tid[i]);
}
return RC_SUCCESS;
}
j = -1;
i = thread_join (&j);
if (i == RC_FAILURE) {
printf ("schedtest: No threads pending, "
"exiting schedular test\n");
return RC_SUCCESS;
}
printf ("schedtest: thread is %d returned %d\n", i, j);
thread_yield ();
}
return RC_SUCCESS;
}
static int testthread (void *name)
{
int i;
printf ("testthread: Begin executing thread, myname %d, &i=0x%08x\n",
*(int *) name, (unsigned)&i);
printf ("Thread %02d, i=%d\n", *(int *) name, i);
for (i = 0; i < 0xffff * (*(int *) name + 1); i++) {
if (tstc () && getc () == 0x3) {
printf ("testthread: myname %d terminating.\n",
*(int *) name);
return *(int *) name + 1;
}
if (i % 100 == 0)
thread_yield ();
}
printf ("testthread: returning %d, i=0x%x\n",
*(int *) name + 1, i);
return *(int *) name + 1;
}
static void sched_init (void)
{
int i;
for (i = MASTER_THREAD + 1; i < MAX_THREADS; i++)
lthreads[i].state = STATE_EMPTY;
current_tid = MASTER_THREAD;
lthreads[current_tid].state = STATE_RUNNABLE;
PDEBUG ("sched_init: master context = 0x%08x",
(unsigned)lthreads[current_tid].context);
return;
}
static void thread_yield (void)
{
static int i;
PDEBUG ("thread_yield: current tid=%d", current_tid);
#define SWITCH(new) \
if(lthreads[new].state == STATE_RUNNABLE) { \
PDEBUG("thread_yield: %d match, ctx=0x%08x", \
new, \
(unsigned)lthreads[current_tid].context); \
if(setjmp(lthreads[current_tid].context) == 0) { \
current_tid = new; \
PDEBUG("thread_yield: tid %d returns 0", \
new); \
longjmp(lthreads[new].context, 1); \
} else { \
PDEBUG("thread_yield: tid %d returns 1", \
new); \
return; \
} \
}
for (i = current_tid + 1; i < MAX_THREADS; i++) {
SWITCH (i);
}
if (current_tid != 0) {
for (i = 0; i <= current_tid; i++) {
SWITCH (i);
}
}
PDEBUG ("thread_yield: returning from thread_yield");
return;
}
static int thread_create (int (*func) (void *), void *arg)
{
int i;
for (i = MASTER_THREAD + 1; i < MAX_THREADS; i++) {
if (lthreads[i].state == STATE_EMPTY) {
lthreads[i].state = STATE_STOPPED;
lthreads[i].func = func;
lthreads[i].arg = arg;
PDEBUG ("thread_create: returns new tid %d", i);
return i;
}
}
PDEBUG ("thread_create: returns failure");
return RC_FAILURE;
}
static int thread_delete (int id)
{
if (id <= MASTER_THREAD || id > MAX_THREADS)
return RC_FAILURE;
if (current_tid == id)
return RC_FAILURE;
lthreads[id].state = STATE_EMPTY;
return RC_SUCCESS;
}
static void thread_launcher (void)
{
PDEBUG ("thread_launcher: invoking func=0x%08x",
(unsigned)lthreads[current_tid].func);
lthreads[current_tid].retval =
lthreads[current_tid].func (lthreads[current_tid].arg);
PDEBUG ("thread_launcher: tid %d terminated", current_tid);
lthreads[current_tid].state = STATE_TERMINATED;
thread_yield ();
printf ("thread_launcher: should NEVER get here!\n");
return;
}
static int thread_start (int id)
{
PDEBUG ("thread_start: id=%d", id);
if (id <= MASTER_THREAD || id > MAX_THREADS) {
return RC_FAILURE;
}
if (lthreads[id].state != STATE_STOPPED)
return RC_FAILURE;
if (setjmp (lthreads[current_tid].context) == 0) {
lthreads[id].state = STATE_RUNNABLE;
current_tid = id;
PDEBUG ("thread_start: to be stack=0%08x",
(unsigned)lthreads[id].stack);
setctxsp ((vu_char *)&lthreads[id].stack[STK_SIZE]);
thread_launcher ();
}
PDEBUG ("thread_start: Thread id=%d started, parent returns", id);
return RC_SUCCESS;
}
#if 0 /* not used so far */
static int thread_stop (int id)
{
if (id <= MASTER_THREAD || id >= MAX_THREADS)
return RC_FAILURE;
if (current_tid == id)
return RC_FAILURE;
lthreads[id].state = STATE_STOPPED;
return RC_SUCCESS;
}
#endif /* not used so far */
static int thread_join (int *ret)
{
int i, j = 0;
PDEBUG ("thread_join: *ret = %d", *ret);
if (!(*ret == -1 || *ret > MASTER_THREAD || *ret < MAX_THREADS)) {
PDEBUG ("thread_join: invalid tid %d", *ret);
return RC_FAILURE;
}
if (*ret == -1) {
PDEBUG ("Checking for tid = -1");
while (1) {
/* PDEBUG("thread_join: start while-loopn"); */
j = 0;
for (i = MASTER_THREAD + 1; i < MAX_THREADS; i++) {
if (lthreads[i].state == STATE_TERMINATED) {
*ret = lthreads[i].retval;
lthreads[i].state = STATE_EMPTY;
/* PDEBUG("thread_join: returning retval %d of tid %d",
ret, i); */
return RC_SUCCESS;
}
if (lthreads[i].state != STATE_EMPTY) {
PDEBUG ("thread_join: %d used slots tid %d state=%d",
j, i, lthreads[i].state);
j++;
}
}
if (j == 0) {
PDEBUG ("thread_join: all slots empty!");
return RC_FAILURE;
}
/* PDEBUG("thread_join: yielding"); */
thread_yield ();
/* PDEBUG("thread_join: back from yield"); */
}
}
if (lthreads[*ret].state == STATE_TERMINATED) {
i = *ret;
*ret = lthreads[*ret].retval;
lthreads[*ret].state = STATE_EMPTY;
PDEBUG ("thread_join: returing %d for tid %d", *ret, i);
return RC_SUCCESS;
}
PDEBUG ("thread_join: thread %d is not terminated!", *ret);
return RC_FAILURE;
}