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-rw-r--r--examples/sched.c361
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+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <syscall.h>
+#include <setjmp.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)
+
+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 DEBUG(fmt, args...) { \
+ if(dbg != 0) { \
+ mon_printf("[%s %d %s]: ", __FILE__, __LINE__, __FUNCTION__); \
+ mon_printf(fmt, ##args); \
+ mon_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 (bd_t *bd, int ac, char *av[])
+{
+ int i, j;
+ int tid[NUMTHREADS];
+ int names[NUMTHREADS];
+
+ sched_init ();
+
+ for (i = 0; i < NUMTHREADS; i++) {
+ names[i] = i;
+ j = thread_create (testthread, (void *) &names[i]);
+ if (j == RC_FAILURE)
+ mon_printf ("schedtest: Failed to create thread %d\n",
+ i);
+ if (j > 0) {
+ mon_printf ("schedtest: Created thread with id %d, name %d\n",
+ j, i);
+ tid[i] = j;
+ }
+ }
+ mon_printf ("schedtest: Threads created\n");
+
+ mon_printf ("sched_test: function=0x%08x\n", testthread);
+ for (i = 0; i < NUMTHREADS; i++) {
+ mon_printf ("schedtest: Setting thread %d runnable\n", tid[i]);
+ thread_start (tid[i]);
+ thread_yield ();
+ }
+ mon_printf ("schedtest: Started %d threads\n", NUMTHREADS);
+
+ while (1) {
+ mon_printf ("schedtest: Waiting for threads to complete\n");
+ if (mon_tstc () && mon_getc () == 0x3) {
+ mon_printf ("schedtest: Aborting threads...\n");
+ for (i = 0; i < NUMTHREADS; i++) {
+ mon_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) {
+ mon_printf ("schedtest: No threads pending, "
+ "exiting schedular test\n");
+ return RC_SUCCESS;
+ }
+ mon_printf ("schedtest: thread is %d returned %d\n", i,
+ j);
+ thread_yield ();
+ }
+
+ return RC_SUCCESS;
+}
+
+static int testthread (void *name)
+{
+ int i;
+
+ mon_printf ("testthread: Begin executing thread, myname %d, &i=0x%08x\n",
+ *(int *) name, &i);
+
+ mon_printf ("Thread %02d, i=%d\n", *(int *) name);
+
+ for (i = 0; i < 0xffff * (*(int *) name + 1); i++) {
+ if (mon_tstc () && mon_getc () == 0x3) {
+ mon_printf ("testthread: myname %d terminating.\n",
+ *(int *) name);
+ return *(int *) name + 1;
+ }
+
+ if (i % 100 == 0)
+ thread_yield ();
+ }
+
+ mon_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;
+ DEBUG ("sched_init: master context = 0x%08x",
+ lthreads[current_tid].context);
+ return;
+}
+
+static void thread_yield (void)
+{
+ static int i;
+
+ DEBUG ("thread_yield: current tid=%d", current_tid);
+
+#define SWITCH(new) \
+ if(lthreads[new].state == STATE_RUNNABLE) { \
+ DEBUG("thread_yield: %d match, ctx=0x%08x", \
+ new, lthreads[current_tid].context); \
+ if(setjmp(lthreads[current_tid].context) == 0) { \
+ current_tid = new; \
+ DEBUG("thread_yield: tid %d returns 0", \
+ new); \
+ longjmp(lthreads[new].context, 1); \
+ } else { \
+ DEBUG("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);
+ }
+ }
+
+ DEBUG ("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;
+ DEBUG ("thread_create: returns new tid %d", i);
+ return i;
+ }
+ }
+
+ DEBUG ("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)
+{
+ DEBUG ("thread_launcher: invoking func=0x%08x",
+ lthreads[current_tid].func);
+
+ lthreads[current_tid].retval =
+ lthreads[current_tid].func(lthreads[current_tid].arg);
+
+ DEBUG ("thread_launcher: tid %d terminated", current_tid);
+
+ lthreads[current_tid].state = STATE_TERMINATED;
+ thread_yield ();
+ mon_printf ("thread_launcher: should NEVER get here!\n");
+
+ return;
+}
+
+static int thread_start (int id)
+{
+ DEBUG ("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;
+ DEBUG ("thread_start: to be stack=0%08x", lthreads[id].stack);
+ setctxsp (&lthreads[id].stack[STK_SIZE]);
+ thread_launcher ();
+ }
+
+ DEBUG ("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;
+
+ DEBUG ("thread_join: *ret = %d", *ret);
+
+ if (!(*ret == -1 || *ret > MASTER_THREAD || *ret < MAX_THREADS)) {
+ DEBUG ("thread_join: invalid tid %d", *ret);
+ return RC_FAILURE;
+ }
+
+ if (*ret == -1) {
+ DEBUG ("Checking for tid = -1");
+ while (1) {
+ /* DEBUG("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;
+ /* DEBUG("thread_join: returning retval %d of tid %d",
+ ret, i); */
+ return RC_SUCCESS;
+ }
+
+ if (lthreads[i].state != STATE_EMPTY) {
+ DEBUG ("thread_join: %d used slots tid %d state=%d",
+ j, i, lthreads[i].state);
+ j++;
+ }
+ }
+ if (j == 0) {
+ DEBUG ("thread_join: all slots empty!");
+ return RC_FAILURE;
+ }
+ /* DEBUG("thread_join: yielding"); */
+ thread_yield ();
+ /* DEBUG("thread_join: back from yield"); */
+ }
+ }
+
+ if (lthreads[*ret].state == STATE_TERMINATED) {
+ i = *ret;
+ *ret = lthreads[*ret].retval;
+ lthreads[*ret].state = STATE_EMPTY;
+ DEBUG ("thread_join: returing %d for tid %d", *ret, i);
+ return RC_SUCCESS;
+ }
+
+ DEBUG ("thread_join: thread %d is not terminated!", *ret);
+ return RC_FAILURE;
+}
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