1 | /*-------------------------------------------------------------------------+ |
---|
2 | | timer.c v1.1 - PC386 BSP - 1997/08/07 |
---|
3 | +--------------------------------------------------------------------------+ |
---|
4 | | This file contains the PC386 timer package. |
---|
5 | +--------------------------------------------------------------------------+ |
---|
6 | | NOTE: It is important that the timer start/stop overhead be determined |
---|
7 | | when porting or modifying this code. |
---|
8 | +--------------------------------------------------------------------------+ |
---|
9 | | (C) Copyright 1997 - |
---|
10 | | - NavIST Group - Real-Time Distributed Systems and Industrial Automation |
---|
11 | | |
---|
12 | | http://pandora.ist.utl.pt |
---|
13 | | |
---|
14 | | Instituto Superior Tecnico * Lisboa * PORTUGAL |
---|
15 | +--------------------------------------------------------------------------+ |
---|
16 | | Disclaimer: |
---|
17 | | |
---|
18 | | This file is provided "AS IS" without warranty of any kind, either |
---|
19 | | expressed or implied. |
---|
20 | +--------------------------------------------------------------------------+ |
---|
21 | | This code is base on: |
---|
22 | | timer.c,v 1.7 1995/12/19 20:07:43 joel Exp - go32 BSP |
---|
23 | | |
---|
24 | | Rosimildo daSilva -ConnectTel, Inc - Fixed infinite loop in the Calibration |
---|
25 | | routine. I've seen this problems with faster machines ( pentiums ). Sometimes |
---|
26 | | RTEMS just hangs at startup. |
---|
27 | | |
---|
28 | | With the following copyright notice: |
---|
29 | | ************************************************************************** |
---|
30 | | * COPYRIGHT (c) 1989-1998. |
---|
31 | | * On-Line Applications Research Corporation (OAR). |
---|
32 | | * Copyright assigned to U.S. Government, 1994. |
---|
33 | | * |
---|
34 | | * The license and distribution terms for this file may be |
---|
35 | | * found in found in the file LICENSE in this distribution or at |
---|
36 | | * http://www.OARcorp.com/rtems/license.html. |
---|
37 | | ************************************************************************** |
---|
38 | | |
---|
39 | | $Id$ |
---|
40 | +--------------------------------------------------------------------------*/ |
---|
41 | |
---|
42 | |
---|
43 | #include <stdlib.h> |
---|
44 | |
---|
45 | #include <bsp.h> |
---|
46 | #include <irq.h> |
---|
47 | |
---|
48 | /*-------------------------------------------------------------------------+ |
---|
49 | | Constants |
---|
50 | +--------------------------------------------------------------------------*/ |
---|
51 | #define AVG_OVERHEAD 0 /* 0.1 microseconds to start/stop timer. */ |
---|
52 | #define LEAST_VALID 1 /* Don't trust a value lower than this. */ |
---|
53 | #define SLOW_DOWN_IO 0x80 /* io which does nothing */ |
---|
54 | |
---|
55 | #define TWO_MS (rtems_unsigned32)(2000) /* TWO_MS = 2000us (sic!) */ |
---|
56 | |
---|
57 | #define MSK_NULL_COUNT 0x40 /* bit counter available for reading */ |
---|
58 | |
---|
59 | #define CMD_READ_BACK_STATUS 0xE2 /* command read back status */ |
---|
60 | /*-------------------------------------------------------------------------+ |
---|
61 | | Global Variables |
---|
62 | +--------------------------------------------------------------------------*/ |
---|
63 | volatile rtems_unsigned32 Ttimer_val; |
---|
64 | rtems_boolean Timer_driver_Find_average_overhead = TRUE; |
---|
65 | unsigned int loop1ms; |
---|
66 | |
---|
67 | /*-------------------------------------------------------------------------+ |
---|
68 | | External Prototypes |
---|
69 | +--------------------------------------------------------------------------*/ |
---|
70 | extern void timerisr(void); |
---|
71 | /* timer (int 08h) Interrupt Service Routine (defined in 'timerisr.s') */ |
---|
72 | |
---|
73 | /*-------------------------------------------------------------------------+ |
---|
74 | | Pentium optimized timer handling. |
---|
75 | +--------------------------------------------------------------------------*/ |
---|
76 | #if defined(pentium) |
---|
77 | |
---|
78 | /*-------------------------------------------------------------------------+ |
---|
79 | | Function: rdtsc |
---|
80 | | Description: Read the value of PENTIUM on-chip cycle counter. |
---|
81 | | Global Variables: None. |
---|
82 | | Arguments: None. |
---|
83 | | Returns: Value of PENTIUM on-chip cycle counter. |
---|
84 | +--------------------------------------------------------------------------*/ |
---|
85 | static inline unsigned long long |
---|
86 | rdtsc(void) |
---|
87 | { |
---|
88 | /* Return the value of the on-chip cycle counter. */ |
---|
89 | unsigned long long result; |
---|
90 | asm volatile(".byte 0x0F, 0x31" : "=A" (result)); |
---|
91 | return result; |
---|
92 | } /* rdtsc */ |
---|
93 | |
---|
94 | |
---|
95 | /*-------------------------------------------------------------------------+ |
---|
96 | | Function: Timer_exit |
---|
97 | | Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is |
---|
98 | | not really necessary, since there will be a reset at exit. |
---|
99 | | Global Variables: None. |
---|
100 | | Arguments: None. |
---|
101 | | Returns: Nothing. |
---|
102 | +--------------------------------------------------------------------------*/ |
---|
103 | void |
---|
104 | Timer_exit(void) |
---|
105 | { |
---|
106 | } /* Timer_exit */ |
---|
107 | |
---|
108 | |
---|
109 | /*-------------------------------------------------------------------------+ |
---|
110 | | Function: Timer_initialize |
---|
111 | | Description: Timer initialization routine. |
---|
112 | | Global Variables: Ttimer_val. |
---|
113 | | Arguments: None. |
---|
114 | | Returns: Nothing. |
---|
115 | +--------------------------------------------------------------------------*/ |
---|
116 | void |
---|
117 | Timer_initialize(void) |
---|
118 | { |
---|
119 | static rtems_boolean First = TRUE; |
---|
120 | |
---|
121 | if (First) |
---|
122 | { |
---|
123 | First = FALSE; |
---|
124 | |
---|
125 | atexit(Timer_exit); /* Try not to hose the system at exit. */ |
---|
126 | } |
---|
127 | Ttimer_val = rdtsc(); /* read starting time */ |
---|
128 | } /* Timer_initialize */ |
---|
129 | |
---|
130 | |
---|
131 | /*-------------------------------------------------------------------------+ |
---|
132 | | Function: Read_timer |
---|
133 | | Description: Read hardware timer value. |
---|
134 | | Global Variables: Ttimer_val, Timer_driver_Find_average_overhead. |
---|
135 | | Arguments: None. |
---|
136 | | Returns: Nothing. |
---|
137 | +--------------------------------------------------------------------------*/ |
---|
138 | rtems_unsigned32 |
---|
139 | Read_timer(void) |
---|
140 | { |
---|
141 | register rtems_unsigned32 total; |
---|
142 | |
---|
143 | total = (rtems_unsigned32)(rdtsc() - Ttimer_val); |
---|
144 | |
---|
145 | if (Timer_driver_Find_average_overhead) |
---|
146 | return total; |
---|
147 | else if (total < LEAST_VALID) |
---|
148 | return 0; /* below timer resolution */ |
---|
149 | else |
---|
150 | return (total - AVG_OVERHEAD); |
---|
151 | } /* Read_timer */ |
---|
152 | |
---|
153 | #else /* pentium */ |
---|
154 | |
---|
155 | /*-------------------------------------------------------------------------+ |
---|
156 | | Non-Pentium timer handling. |
---|
157 | +--------------------------------------------------------------------------*/ |
---|
158 | #define US_PER_ISR 250 /* Number of micro-seconds per timer interruption */ |
---|
159 | |
---|
160 | |
---|
161 | /*-------------------------------------------------------------------------+ |
---|
162 | | Function: Timer_exit |
---|
163 | | Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is |
---|
164 | | not really necessary, since there will be a reset at exit. |
---|
165 | | Global Variables: None. |
---|
166 | | Arguments: None. |
---|
167 | | Returns: Nothing. |
---|
168 | +--------------------------------------------------------------------------*/ |
---|
169 | static void |
---|
170 | timerOff(const rtems_raw_irq_connect_data* used) |
---|
171 | { |
---|
172 | /* |
---|
173 | * disable interrrupt at i8259 level |
---|
174 | */ |
---|
175 | BSP_irq_disable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE); |
---|
176 | /* reset timer mode to standard (DOS) value */ |
---|
177 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN); |
---|
178 | outport_byte(TIMER_CNTR0, 0); |
---|
179 | outport_byte(TIMER_CNTR0, 0); |
---|
180 | } /* Timer_exit */ |
---|
181 | |
---|
182 | |
---|
183 | static void |
---|
184 | timerOn(const rtems_raw_irq_connect_data* used) |
---|
185 | { |
---|
186 | /* load timer for US_PER_ISR microsecond period */ |
---|
187 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN); |
---|
188 | outport_byte(TIMER_CNTR0, US_TO_TICK(US_PER_ISR) >> 0 & 0xff); |
---|
189 | outport_byte(TIMER_CNTR0, US_TO_TICK(US_PER_ISR) >> 8 & 0xff); |
---|
190 | /* |
---|
191 | * enable interrrupt at i8259 level |
---|
192 | */ |
---|
193 | BSP_irq_enable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE); |
---|
194 | } |
---|
195 | |
---|
196 | static int |
---|
197 | timerIsOn(const rtems_raw_irq_connect_data *used) |
---|
198 | { |
---|
199 | return BSP_irq_enabled_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);} |
---|
200 | |
---|
201 | static rtems_raw_irq_connect_data timer_raw_irq_data = { |
---|
202 | BSP_PERIODIC_TIMER + BSP_IRQ_VECTOR_BASE, |
---|
203 | timerisr, |
---|
204 | timerOn, |
---|
205 | timerOff, |
---|
206 | timerIsOn |
---|
207 | }; |
---|
208 | |
---|
209 | /*-------------------------------------------------------------------------+ |
---|
210 | | Function: Timer_exit |
---|
211 | | Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is |
---|
212 | | not really necessary, since there will be a reset at exit. |
---|
213 | | Global Variables: None. |
---|
214 | | Arguments: None. |
---|
215 | | Returns: Nothing. |
---|
216 | +--------------------------------------------------------------------------*/ |
---|
217 | void |
---|
218 | Timer_exit(void) |
---|
219 | { |
---|
220 | i386_delete_idt_entry (&timer_raw_irq_data); |
---|
221 | } /* Timer_exit */ |
---|
222 | |
---|
223 | /*-------------------------------------------------------------------------+ |
---|
224 | | Function: Timer_initialize |
---|
225 | | Description: Timer initialization routine. |
---|
226 | | Global Variables: Ttimer_val. |
---|
227 | | Arguments: None. |
---|
228 | | Returns: Nothing. |
---|
229 | +--------------------------------------------------------------------------*/ |
---|
230 | void |
---|
231 | Timer_initialize(void) |
---|
232 | { |
---|
233 | static rtems_boolean First = TRUE; |
---|
234 | |
---|
235 | if (First) |
---|
236 | { |
---|
237 | First = FALSE; |
---|
238 | |
---|
239 | atexit(Timer_exit); /* Try not to hose the system at exit. */ |
---|
240 | if (!i386_set_idt_entry (&timer_raw_irq_data)) { |
---|
241 | printk("raw handler connexion failed\n"); |
---|
242 | rtems_fatal_error_occurred(1); |
---|
243 | } |
---|
244 | } |
---|
245 | /* wait for ISR to be called at least once */ |
---|
246 | Ttimer_val = 0; |
---|
247 | while (Ttimer_val == 0) |
---|
248 | continue; |
---|
249 | Ttimer_val = 0; |
---|
250 | } /* Timer_initialize */ |
---|
251 | |
---|
252 | |
---|
253 | /*-------------------------------------------------------------------------+ |
---|
254 | | Function: Read_timer |
---|
255 | | Description: Read hardware timer value. |
---|
256 | | Global Variables: Ttimer_val, Timer_driver_Find_average_overhead. |
---|
257 | | Arguments: None. |
---|
258 | | Returns: Nothing. |
---|
259 | +--------------------------------------------------------------------------*/ |
---|
260 | rtems_unsigned32 |
---|
261 | Read_timer(void) |
---|
262 | { |
---|
263 | register rtems_unsigned32 total, clicks; |
---|
264 | register rtems_unsigned8 lsb, msb; |
---|
265 | |
---|
266 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_LATCH); |
---|
267 | inport_byte(TIMER_CNTR0, lsb); |
---|
268 | inport_byte(TIMER_CNTR0, msb); |
---|
269 | clicks = (msb << 8) | lsb; |
---|
270 | total = (Ttimer_val * US_PER_ISR) + (US_PER_ISR - TICK_TO_US(clicks)); |
---|
271 | |
---|
272 | if (Timer_driver_Find_average_overhead) |
---|
273 | return total; |
---|
274 | else if (total < LEAST_VALID) |
---|
275 | return 0; /* below timer resolution */ |
---|
276 | else |
---|
277 | return (total - AVG_OVERHEAD); |
---|
278 | } |
---|
279 | |
---|
280 | #endif /* pentium */ |
---|
281 | |
---|
282 | |
---|
283 | /*-------------------------------------------------------------------------+ |
---|
284 | | Function: Empty_function |
---|
285 | | Description: Empty function used in time tests. |
---|
286 | | Global Variables: None. |
---|
287 | | Arguments: None. |
---|
288 | | Returns: Nothing. |
---|
289 | +--------------------------------------------------------------------------*/ |
---|
290 | rtems_status_code Empty_function(void) |
---|
291 | { |
---|
292 | return RTEMS_SUCCESSFUL; |
---|
293 | } /* Empty function */ |
---|
294 | |
---|
295 | |
---|
296 | /*-------------------------------------------------------------------------+ |
---|
297 | | Function: Set_find_average_overhead |
---|
298 | | Description: Set internal Timer_driver_Find_average_overhead flag value. |
---|
299 | | Global Variables: Timer_driver_Find_average_overhead. |
---|
300 | | Arguments: find_flag - new value of the flag. |
---|
301 | | Returns: Nothing. |
---|
302 | +--------------------------------------------------------------------------*/ |
---|
303 | void |
---|
304 | Set_find_average_overhead(rtems_boolean find_flag) |
---|
305 | { |
---|
306 | Timer_driver_Find_average_overhead = find_flag; |
---|
307 | } /* Set_find_average_overhead */ |
---|
308 | |
---|
309 | |
---|
310 | |
---|
311 | /*-------------------------------------------------------------------------+ |
---|
312 | | Description: Loads timer 0 with value passed as arguemnt. |
---|
313 | | Returns: Nothing. |
---|
314 | +--------------------------------------------------------------------------*/ |
---|
315 | inline void loadTimerValue( unsigned short loadedValue ) |
---|
316 | { |
---|
317 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN); |
---|
318 | outport_byte(TIMER_CNTR0, loadedValue >> 0 & 0xff); |
---|
319 | outport_byte(TIMER_CNTR0, loadedValue >> 8 & 0xff); |
---|
320 | } |
---|
321 | |
---|
322 | |
---|
323 | /*-------------------------------------------------------------------------+ |
---|
324 | | Description: Waits until the counter on timer 0 reaches 0. |
---|
325 | | Returns: Nothing. |
---|
326 | +--------------------------------------------------------------------------*/ |
---|
327 | inline void waitTimerStatus( void ) |
---|
328 | { |
---|
329 | unsigned char status; |
---|
330 | outport_byte(TIMER_MODE, CMD_READ_BACK_STATUS); /* read Status counter 0 */ |
---|
331 | inport_byte(TIMER_CNTR0, status); |
---|
332 | while (status & MSK_NULL_COUNT){ /* wait for counter ready */ |
---|
333 | outport_byte(TIMER_MODE, CMD_READ_BACK_STATUS); |
---|
334 | inport_byte(TIMER_CNTR0, status); |
---|
335 | } |
---|
336 | } |
---|
337 | |
---|
338 | |
---|
339 | /*-------------------------------------------------------------------------+ |
---|
340 | | Description: Reads the current value of the timer, and converts the |
---|
341 | | number of ticks to micro-seconds. |
---|
342 | | Returns: current number of microseconds since last value loaded.. |
---|
343 | +--------------------------------------------------------------------------*/ |
---|
344 | inline unsigned short readCurrentTimer() |
---|
345 | { |
---|
346 | unsigned short lsb, msb; |
---|
347 | outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_LATCH); |
---|
348 | inport_byte(TIMER_CNTR0, lsb); |
---|
349 | inport_byte(TIMER_CNTR0, msb); |
---|
350 | return TICK_TO_US( ( msb << 8 ) | lsb ); |
---|
351 | } |
---|
352 | |
---|
353 | |
---|
354 | /*-------------------------------------------------------------------------+ |
---|
355 | * clockbits - Read low order bits of timer 0 (the TOD clock) |
---|
356 | * This works only for the 8254 chips used in ATs and 386s. |
---|
357 | * |
---|
358 | * The timer runs in mode 3 (square wave mode), counting down |
---|
359 | * by twos, twice for each cycle. So it is necessary to read back the |
---|
360 | * OUTPUT pin to see which half of the cycle we're in. I.e., the OUTPUT |
---|
361 | * pin forms the most significant bit of the count. Unfortunately, |
---|
362 | * the 8253 in the PC/XT lacks a command to read the OUTPUT pin... |
---|
363 | * |
---|
364 | * The PC's clock design is soooo brain damaged... |
---|
365 | * |
---|
366 | * Rosimildo - I've got this routine from the KA9Q32 distribution and |
---|
367 | * have updated it for the RTEMS environment. |
---|
368 | +--------------------------------------------------------------------------*/ |
---|
369 | unsigned int clockbits(void) |
---|
370 | { |
---|
371 | unsigned int stat,count1, count; |
---|
372 | |
---|
373 | do |
---|
374 | { |
---|
375 | outport_byte( 0x43, 0xc2 ); /* latch timer 0 count and status for reading */ |
---|
376 | inport_byte( 0x40, stat ); /* get status of timer 0 */ |
---|
377 | inport_byte( 0x40, count1 ); /* lsb of count */ |
---|
378 | inport_byte( 0x40, count ); /* msb of count */ |
---|
379 | count = count1 | ( count << 8 ); |
---|
380 | } while(stat & 0x40); /* reread if NULL COUNT bit set */ |
---|
381 | stat = (stat & 0x80) << 8; /* Shift OUTPUT to msb of 16-bit word */ |
---|
382 | if(count == 0) |
---|
383 | return stat ^ 0x8000; /* return complement of OUTPUT bit */ |
---|
384 | else |
---|
385 | return count | stat; /* Combine OUTPUT with counter */ |
---|
386 | } |
---|
387 | |
---|
388 | |
---|
389 | /*-------------------------------------------------------------------------+ |
---|
390 | | Function: Calibrate_loop_1ms |
---|
391 | | Description: Set loop variable to calibrate a 1ms loop |
---|
392 | | Global Variables: loop1ms |
---|
393 | | Arguments: none |
---|
394 | | Returns: Nothing. |
---|
395 | +--------------------------------------------------------------------------*/ |
---|
396 | void |
---|
397 | Calibrate_loop_1ms(void) |
---|
398 | { |
---|
399 | unsigned int i; |
---|
400 | unsigned short loadedValue, offset; |
---|
401 | unsigned int timerValue, t1_ref, t2_ref=0; |
---|
402 | rtems_interrupt_level level; |
---|
403 | |
---|
404 | |
---|
405 | printk( "Calibrate_loop_1ms is starting, please wait ( but not too loooong. )\n" ); |
---|
406 | |
---|
407 | loop1ms = 200; |
---|
408 | timerValue = 0; |
---|
409 | |
---|
410 | /* Let's load the timer with 2ms, initially */ |
---|
411 | loadedValue = US_TO_TICK( 2000 ); |
---|
412 | |
---|
413 | rtems_interrupt_disable(level); |
---|
414 | /* |
---|
415 | * Compute the offset to apply due to read counter register |
---|
416 | */ |
---|
417 | offset = 0; |
---|
418 | loadTimerValue( loadedValue + offset ); |
---|
419 | waitTimerStatus(); |
---|
420 | t1_ref = clockbits(); |
---|
421 | offset = loadedValue - readCurrentTimer(); |
---|
422 | while( timerValue < 1000 ) |
---|
423 | { |
---|
424 | loop1ms++; |
---|
425 | loadTimerValue( loadedValue + offset ); |
---|
426 | waitTimerStatus(); |
---|
427 | t1_ref = clockbits(); |
---|
428 | for( i=0; i < loop1ms; i++ ) |
---|
429 | outport_byte( SLOW_DOWN_IO, 0 ); /* write is # 1us */ |
---|
430 | t2_ref = clockbits(); |
---|
431 | timerValue = TICK_TO_US( t1_ref - t2_ref ); /* timer0 is decrementing number of ticks */ |
---|
432 | } |
---|
433 | printk( "Calibrate_loop_1ms timerValue=%d, loop1ms=%d, t1_ref=%x, clockbits=%x, delta=%d\n", |
---|
434 | timerValue, loop1ms, t1_ref, t2_ref, t1_ref - t2_ref ); |
---|
435 | rtems_interrupt_enable(level); |
---|
436 | } |
---|
437 | |
---|
438 | |
---|
439 | |
---|
440 | /*-------------------------------------------------------------------------+ |
---|
441 | | Function: Wait_X_1ms |
---|
442 | | Description: loop which waits at least timeToWait ms |
---|
443 | | Global Variables: loop1ms |
---|
444 | | Arguments: timeToWait |
---|
445 | | Returns: Nothing. |
---|
446 | +--------------------------------------------------------------------------*/ |
---|
447 | void |
---|
448 | Wait_X_ms( unsigned int timeToWait){ |
---|
449 | |
---|
450 | unsigned int i, j; |
---|
451 | |
---|
452 | for (j=0; j<timeToWait ; j++) |
---|
453 | for (i=0; i<loop1ms; i++) |
---|
454 | outport_byte(SLOW_DOWN_IO, 0); /* write is # 1us */ |
---|
455 | } |
---|
456 | |
---|
457 | |
---|
458 | |
---|
459 | |
---|
460 | |
---|
461 | |
---|