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
sched(int ac,char * av[])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
testthread(void * name)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
sched_init(void)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
thread_yield(void)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
thread_create(int (* func)(void *),void * arg)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
thread_delete(int id)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
thread_launcher(void)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
thread_start(int id)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 *)<hreads[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
thread_join(int * ret)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 }
370