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1 /*
2  * This program is free software; you can redistribute it and/or
3  * modify it under the terms of the GNU General Public License as
4  * published by the Free Software Foundation; either version 2 of
5  * the License, or (at your option) any later version.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * along with this program; if not, write to the Free Software
14  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
15  * MA 02111-1307 USA
16  */
17
18 #include <common.h>
19 #include <exports.h>
20
21 /*
22  * Author: Arun Dharankar <ADharankar@ATTBI.Com>
23  *
24  * A very simple thread/schedular model:
25  *   - only one master thread, and no parent child relation maintained
26  *   - parent thread cannot be stopped or deleted
27  *   - no permissions or credentials
28  *   - no elaborate safety checks
29  *   - cooperative multi threading
30  *   - Simple round-robin scheduleing with no priorities
31  *   - no metering/statistics collection
32  *
33  * Basic idea of implementing this is to allow more than one tests to
34  * execute "simultaneously".
35  *
36  * This may be modified such thread_yield may be called in syscalls, and
37  * timer interrupts.
38  */
39
40
41 #define MAX_THREADS 8
42
43 #define CTX_SIZE 512
44 #define STK_SIZE 8*1024
45
46 #define STATE_EMPTY 0
47 #define STATE_RUNNABLE 1
48 #define STATE_STOPPED 2
49 #define STATE_TERMINATED 2
50
51 #define MASTER_THREAD 0
52
53 #define RC_FAILURE      (-1)
54 #define RC_SUCCESS      (0)
55
56 typedef vu_char *jmp_ctx;
57 unsigned long setctxsp (vu_char *sp);
58 int ppc_setjmp(jmp_ctx env);
59 void ppc_longjmp(jmp_ctx env, int val);
60 #define setjmp  ppc_setjmp
61 #define longjmp ppc_longjmp
62
63 struct lthread {
64         int state;
65         int retval;
66         char stack[STK_SIZE];
67         uchar context[CTX_SIZE];
68         int (*func) (void *);
69         void *arg;
70 };
71 static volatile struct lthread lthreads[MAX_THREADS];
72 static volatile int current_tid = MASTER_THREAD;
73
74
75 static uchar dbg = 0;
76
77 #define PDEBUG(fmt, args...)     {                                      \
78         if(dbg != 0) {                                                  \
79                 printf("[%s %d %s]: ",__FILE__,__LINE__,__FUNCTION__);\
80                 printf(fmt, ##args);                            \
81                 printf("\n");                                   \
82         }                                                               \
83 }
84
85 static int testthread (void *);
86 static void sched_init (void);
87 static int thread_create (int (*func) (void *), void *arg);
88 static int thread_start (int id);
89 static void thread_yield (void);
90 static int thread_delete (int id);
91 static int thread_join (int *ret);
92
93 #if 0                                                   /* not used yet */
94 static int thread_stop (int id);
95 #endif                                                  /* not used yet */
96
97 /* An example of schedular test */
98
99 #define NUMTHREADS 7
100 int sched (int ac, char *av[])
101 {
102         int i, j;
103         int tid[NUMTHREADS];
104         int names[NUMTHREADS];
105
106         app_startup(av);
107
108         sched_init ();
109
110         for (i = 0; i < NUMTHREADS; i++) {
111                 names[i] = i;
112                 j = thread_create (testthread, (void *) &names[i]);
113                 if (j == RC_FAILURE)
114                         printf ("schedtest: Failed to create thread %d\n", i);
115                 if (j > 0) {
116                         printf ("schedtest: Created thread with id %d, name %d\n",
117                                                 j, i);
118                         tid[i] = j;
119                 }
120         }
121         printf ("schedtest: Threads created\n");
122
123         printf ("sched_test: function=0x%08x\n", (unsigned)testthread);
124         for (i = 0; i < NUMTHREADS; i++) {
125                 printf ("schedtest: Setting thread %d runnable\n", tid[i]);
126                 thread_start (tid[i]);
127                 thread_yield ();
128         }
129         printf ("schedtest: Started %d threads\n", NUMTHREADS);
130
131         while (1) {
132                 printf ("schedtest: Waiting for threads to complete\n");
133                 if (tstc () && getc () == 0x3) {
134                         printf ("schedtest: Aborting threads...\n");
135                         for (i = 0; i < NUMTHREADS; i++) {
136                                 printf ("schedtest: Deleting thread %d\n", tid[i]);
137                                 thread_delete (tid[i]);
138                         }
139                         return RC_SUCCESS;
140                 }
141                 j = -1;
142                 i = thread_join (&j);
143                 if (i == RC_FAILURE) {
144                         printf ("schedtest: No threads pending, "
145                                                 "exiting schedular test\n");
146                         return RC_SUCCESS;
147                 }
148                 printf ("schedtest: thread is %d returned %d\n", i, j);
149                 thread_yield ();
150         }
151
152         return RC_SUCCESS;
153 }
154
155 static int testthread (void *name)
156 {
157         int i;
158
159         printf ("testthread: Begin executing thread, myname %d, &i=0x%08x\n",
160                 *(int *) name, (unsigned)&i);
161
162         printf ("Thread %02d, i=%d\n", *(int *) name, i);
163
164         for (i = 0; i < 0xffff * (*(int *) name + 1); i++) {
165                 if (tstc () && getc () == 0x3) {
166                         printf ("testthread: myname %d terminating.\n",
167                                                 *(int *) name);
168                         return *(int *) name + 1;
169                 }
170
171                 if (i % 100 == 0)
172                         thread_yield ();
173         }
174
175         printf ("testthread: returning %d, i=0x%x\n",
176                                 *(int *) name + 1, i);
177
178         return *(int *) name + 1;
179 }
180
181
182 static void sched_init (void)
183 {
184         int i;
185
186         for (i = MASTER_THREAD + 1; i < MAX_THREADS; i++)
187                 lthreads[i].state = STATE_EMPTY;
188
189         current_tid = MASTER_THREAD;
190         lthreads[current_tid].state = STATE_RUNNABLE;
191         PDEBUG ("sched_init: master context = 0x%08x",
192                 (unsigned)lthreads[current_tid].context);
193         return;
194 }
195
196 static void thread_yield (void)
197 {
198         static int i;
199
200         PDEBUG ("thread_yield: current tid=%d", current_tid);
201
202 #define SWITCH(new)                                                     \
203         if(lthreads[new].state == STATE_RUNNABLE) {                     \
204                 PDEBUG("thread_yield: %d match, ctx=0x%08x",            \
205                         new,                                            \
206                         (unsigned)lthreads[current_tid].context);       \
207                 if(setjmp(lthreads[current_tid].context) == 0) {        \
208                         current_tid = new;                              \
209                         PDEBUG("thread_yield: tid %d returns 0",        \
210                                 new);                                   \
211                         longjmp(lthreads[new].context, 1);              \
212                 } else {                                                \
213                         PDEBUG("thread_yield: tid %d returns 1",        \
214                                 new);                                   \
215                         return;                                         \
216                 }                                                       \
217         }
218
219         for (i = current_tid + 1; i < MAX_THREADS; i++) {
220                 SWITCH (i);
221         }
222
223         if (current_tid != 0) {
224                 for (i = 0; i <= current_tid; i++) {
225                         SWITCH (i);
226                 }
227         }
228
229         PDEBUG ("thread_yield: returning from thread_yield");
230         return;
231 }
232
233 static int thread_create (int (*func) (void *), void *arg)
234 {
235         int i;
236
237         for (i = MASTER_THREAD + 1; i < MAX_THREADS; i++) {
238                 if (lthreads[i].state == STATE_EMPTY) {
239                         lthreads[i].state = STATE_STOPPED;
240                         lthreads[i].func = func;
241                         lthreads[i].arg = arg;
242                         PDEBUG ("thread_create: returns new tid %d", i);
243                         return i;
244                 }
245         }
246
247         PDEBUG ("thread_create: returns failure");
248         return RC_FAILURE;
249 }
250
251 static int thread_delete (int id)
252 {
253         if (id <= MASTER_THREAD || id > MAX_THREADS)
254                 return RC_FAILURE;
255
256         if (current_tid == id)
257                 return RC_FAILURE;
258
259         lthreads[id].state = STATE_EMPTY;
260         return RC_SUCCESS;
261 }
262
263 static void thread_launcher (void)
264 {
265         PDEBUG ("thread_launcher: invoking func=0x%08x",
266                    (unsigned)lthreads[current_tid].func);
267
268         lthreads[current_tid].retval =
269                         lthreads[current_tid].func (lthreads[current_tid].arg);
270
271         PDEBUG ("thread_launcher: tid %d terminated", current_tid);
272
273         lthreads[current_tid].state = STATE_TERMINATED;
274         thread_yield ();
275         printf ("thread_launcher: should NEVER get here!\n");
276
277         return;
278 }
279
280 static int thread_start (int id)
281 {
282         PDEBUG ("thread_start: id=%d", id);
283         if (id <= MASTER_THREAD || id > MAX_THREADS) {
284                 return RC_FAILURE;
285         }
286
287         if (lthreads[id].state != STATE_STOPPED)
288                 return RC_FAILURE;
289
290         if (setjmp (lthreads[current_tid].context) == 0) {
291                 lthreads[id].state = STATE_RUNNABLE;
292                 current_tid = id;
293                 PDEBUG ("thread_start: to be stack=0%08x",
294                         (unsigned)lthreads[id].stack);
295                 setctxsp ((vu_char *)&lthreads[id].stack[STK_SIZE]);
296                 thread_launcher ();
297         }
298
299         PDEBUG ("thread_start: Thread id=%d started, parent returns", id);
300
301         return RC_SUCCESS;
302 }
303
304 #if 0   /* not used so far */
305 static int thread_stop (int id)
306 {
307         if (id <= MASTER_THREAD || id >= MAX_THREADS)
308                 return RC_FAILURE;
309
310         if (current_tid == id)
311                 return RC_FAILURE;
312
313         lthreads[id].state = STATE_STOPPED;
314         return RC_SUCCESS;
315 }
316 #endif  /* not used so far */
317
318 static int thread_join (int *ret)
319 {
320         int i, j = 0;
321
322         PDEBUG ("thread_join: *ret = %d", *ret);
323
324         if (!(*ret == -1 || *ret > MASTER_THREAD || *ret < MAX_THREADS)) {
325                 PDEBUG ("thread_join: invalid tid %d", *ret);
326                 return RC_FAILURE;
327         }
328
329         if (*ret == -1) {
330                 PDEBUG ("Checking for tid = -1");
331                 while (1) {
332                         /* PDEBUG("thread_join: start while-loopn"); */
333                         j = 0;
334                         for (i = MASTER_THREAD + 1; i < MAX_THREADS; i++) {
335                                 if (lthreads[i].state == STATE_TERMINATED) {
336                                         *ret = lthreads[i].retval;
337                                         lthreads[i].state = STATE_EMPTY;
338                                         /* PDEBUG("thread_join: returning retval %d of tid %d",
339                                            ret, i); */
340                                         return RC_SUCCESS;
341                                 }
342
343                                 if (lthreads[i].state != STATE_EMPTY) {
344                                         PDEBUG ("thread_join: %d used slots tid %d state=%d",
345                                                    j, i, lthreads[i].state);
346                                         j++;
347                                 }
348                         }
349                         if (j == 0) {
350                                 PDEBUG ("thread_join: all slots empty!");
351                                 return RC_FAILURE;
352                         }
353                         /*  PDEBUG("thread_join: yielding"); */
354                         thread_yield ();
355                         /*  PDEBUG("thread_join: back from yield"); */
356                 }
357         }
358
359         if (lthreads[*ret].state == STATE_TERMINATED) {
360                 i = *ret;
361                 *ret = lthreads[*ret].retval;
362                 lthreads[*ret].state = STATE_EMPTY;
363                 PDEBUG ("thread_join: returing %d for tid %d", *ret, i);
364                 return RC_SUCCESS;
365         }
366
367         PDEBUG ("thread_join: thread %d is not terminated!", *ret);
368         return RC_FAILURE;
369 }