2 comedi/drivers/comedi_rt_timer.c
3 virtual driver for using RTL timing sources
5 Authors: David A. Schleef, Frank M. Hess
7 COMEDI - Linux Control and Measurement Device Interface
8 Copyright (C) 1999,2001 David A. Schleef <ds@schleef.org>
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2 of the License, or
13 (at your option) any later version.
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 **************************************************************************
27 Driver: comedi_rt_timer
28 Description: Command emulator using real-time tasks
33 This driver requires RTAI or RTLinux to work correctly. It doesn't
34 actually drive hardware directly, but calls other drivers and uses
35 a real-time task to emulate commands for drivers and devices that
36 are incapable of native commands. Thus, you can get accurately
37 timed I/O on any device.
39 Since the timing is all done in software, sampling jitter is much
40 higher than with a device that has an on-board timer, and maximum
41 sample rate is much lower.
43 Configuration options:
44 [0] - minor number of device you wish to emulate commands for
45 [1] - subdevice number you wish to emulate commands for
49 Support for digital io commands could be added, except I can't see why
50 anyone would want to use them
51 What happens if device we are emulating for is de-configured?
54 #include "../comedidev.h"
55 #include "../comedilib.h"
57 #include "comedi_fc.h"
59 #ifdef CONFIG_COMEDI_RTL_V1
60 #include <rtl_sched.h>
61 #include <asm/rt_irq.h>
63 #ifdef CONFIG_COMEDI_RTL
65 #include <rtl_sched.h>
66 #include <rtl_compat.h>
67 #include <asm/div64.h>
69 #ifndef RTLINUX_VERSION_CODE
70 #define RTLINUX_VERSION_CODE 0
72 #ifndef RTLINUX_VERSION
73 #define RTLINUX_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
76 /* begin hack to workaround broken HRT_TO_8254() function on rtlinux */
77 #if RTLINUX_VERSION_CODE <= RTLINUX_VERSION(3,0,100)
78 /* this function sole purpose is to divide a long long by 838 */
79 static inline RTIME nano2count(long long ns)
88 #define rt_get_time() nano2count(gethrtime())
92 #define nano2count(x) HRT_TO_8254(x)
96 /* rtl-rtai compatibility */
97 #define rt_task_wait_period() rt_task_wait()
98 #define rt_pend_linux_srq(irq) rtl_global_pend_irq(irq)
99 #define rt_free_srq(irq) rtl_free_soft_irq(irq)
100 #define rt_request_srq(x,y,z) rtl_get_soft_irq(y,"timer")
101 #define rt_task_init(a,b,c,d,e,f,g) rt_task_init(a,b,c,d,(e)+1)
102 #define rt_task_resume(x) rt_task_wakeup(x)
103 #define rt_set_oneshot_mode()
104 #define start_rt_timer(x)
105 #define stop_rt_timer()
107 #define comedi_rt_task_context_t int
110 #ifdef CONFIG_COMEDI_RTAI
112 #include <rtai_sched.h>
113 #include <rtai_version.h>
115 /* RTAI_VERSION_CODE doesn't work for rtai-3.6-cv and other strange versions.
116 * These are characterized by CONFIG_RTAI_REVISION_LEVEL being defined as an
117 * empty macro and CONFIG_RTAI_VERSION_MINOR being defined as something like
118 * '6-cv' or '7-test1'. The problem has been noted by the RTAI folks and they
119 * promise not to do it again. :-) Try and work around it here. */
120 #if !(CONFIG_RTAI_REVISION_LEVEL + 0)
121 #undef CONFIG_RTAI_REVISION_LEVEL
122 #define CONFIG_RTAI_REVISION_LEVEL 0
129 #if RTAI_VERSION_CODE < RTAI_MANGLE_VERSION(3,3,0)
130 #define comedi_rt_task_context_t int
132 #define comedi_rt_task_context_t long
135 /* Finished checking RTAI_VERSION_CODE. */
143 /* This defines the fastest speed we will emulate. Note that
144 * without a watchdog (like in RTAI), we could easily overrun our
145 * task period because analog input tends to be slow. */
146 #define SPEED_LIMIT 100000 /* in nanoseconds */
148 static int timer_attach(struct comedi_device *dev, struct comedi_devconfig *it);
149 static int timer_detach(struct comedi_device *dev);
150 static int timer_inttrig(struct comedi_device *dev, struct comedi_subdevice *s,
151 unsigned int trig_num);
152 static int timer_start_cmd(struct comedi_device *dev, struct comedi_subdevice *s);
154 static struct comedi_driver driver_timer = {
156 driver_name:"comedi_rt_timer",
159 /* open: timer_open, */
162 COMEDI_INITCLEANUP(driver_timer);
164 struct timer_private {
165 comedi_t *device; /* device we are emulating commands for */
166 int subd; /* subdevice we are emulating commands for */
167 RT_TASK *rt_task; /* rt task that starts scans */
168 RT_TASK *scan_task; /* rt task that controls conversion timing in a scan */
169 /* io_function can point to either an input or output function
170 * depending on what kind of subdevice we are emulating for */
171 int (*io_function) (struct comedi_device *dev, struct comedi_cmd *cmd,
174 * RTIME has units of 1 = 838 nanoseconds time at which first scan
175 * started, used to check scan timing
178 /* time between scans */
180 /* time between conversions in a scan */
181 RTIME convert_period;
183 volatile int stop; /* indicates we should stop */
184 volatile int rt_task_active; /* indicates rt_task is servicing a struct comedi_cmd */
185 volatile int scan_task_active; /* indicates scan_task is servicing a struct comedi_cmd */
186 unsigned timer_running:1;
188 #define devpriv ((struct timer_private *)dev->private)
190 static int timer_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
197 /* checks for scan timing error */
198 inline static int check_scan_timing(struct comedi_device *dev,
199 unsigned long long scan)
201 RTIME now, timing_error;
204 timing_error = now - (devpriv->start + scan * devpriv->scan_period);
205 if (timing_error > devpriv->scan_period) {
206 comedi_error(dev, "timing error");
207 rt_printk("scan started %i ns late\n", timing_error * 838);
214 /* checks for conversion timing error */
215 inline static int check_conversion_timing(struct comedi_device *dev,
216 RTIME scan_start, unsigned int conversion)
218 RTIME now, timing_error;
222 now - (scan_start + conversion * devpriv->convert_period);
223 if (timing_error > devpriv->convert_period) {
224 comedi_error(dev, "timing error");
225 rt_printk("conversion started %i ns late\n",
233 /* devpriv->io_function for an input subdevice */
234 static int timer_data_read(struct comedi_device *dev, struct comedi_cmd *cmd,
237 struct comedi_subdevice *s = dev->read_subdev;
241 ret = comedi_data_read(devpriv->device, devpriv->subd,
242 CR_CHAN(cmd->chanlist[index]),
243 CR_RANGE(cmd->chanlist[index]),
244 CR_AREF(cmd->chanlist[index]), &data);
246 comedi_error(dev, "read error");
249 if (s->flags & SDF_LSAMPL) {
250 cfc_write_long_to_buffer(s, data);
252 comedi_buf_put(s->async, data);
258 /* devpriv->io_function for an output subdevice */
259 static int timer_data_write(struct comedi_device *dev, struct comedi_cmd *cmd,
262 struct comedi_subdevice *s = dev->write_subdev;
263 unsigned int num_bytes;
265 unsigned int long_data;
268 if (s->flags & SDF_LSAMPL) {
270 cfc_read_array_from_buffer(s, &long_data,
273 num_bytes = cfc_read_array_from_buffer(s, &data, sizeof(data));
277 if (num_bytes == 0) {
278 comedi_error(dev, "buffer underrun");
281 ret = comedi_data_write(devpriv->device, devpriv->subd,
282 CR_CHAN(cmd->chanlist[index]),
283 CR_RANGE(cmd->chanlist[index]),
284 CR_AREF(cmd->chanlist[index]), long_data);
286 comedi_error(dev, "write error");
293 /* devpriv->io_function for DIO subdevices */
294 static int timer_dio_read(struct comedi_device *dev, struct comedi_cmd *cmd,
297 struct comedi_subdevice *s = dev->read_subdev;
301 ret = comedi_dio_bitfield(devpriv->device, devpriv->subd, 0, &data);
303 comedi_error(dev, "read error");
307 if (s->flags & SDF_LSAMPL)
308 cfc_write_long_to_buffer(s, data);
310 cfc_write_to_buffer(s, data);
316 static void scan_task_func(comedi_rt_task_context_t d)
318 struct comedi_device *dev = (struct comedi_device *) d;
319 struct comedi_subdevice *s = dev->subdevices + 0;
320 struct comedi_async *async = s->async;
321 struct comedi_cmd *cmd = &async->cmd;
323 unsigned long long n;
326 /* every struct comedi_cmd causes one execution of while loop */
328 devpriv->scan_task_active = 1;
329 /* each for loop completes one scan */
330 for (n = 0; n < cmd->stop_arg || cmd->stop_src == TRIG_NONE;
333 /* suspend task until next scan */
334 ret = rt_task_suspend(devpriv->scan_task);
337 "error suspending scan task");
338 async->events |= COMEDI_CB_ERROR;
342 /* check if stop flag was set (by timer_cancel()) */
345 ret = check_scan_timing(dev, n);
347 async->events |= COMEDI_CB_ERROR;
350 scan_start = rt_get_time();
351 for (i = 0; i < cmd->scan_end_arg; i++) {
352 /* conversion timing */
353 if (cmd->convert_src == TRIG_TIMER && i) {
354 rt_task_wait_period();
355 ret = check_conversion_timing(dev,
363 ret = devpriv->io_function(dev, cmd, i);
365 async->events |= COMEDI_CB_ERROR;
369 s->async->events |= COMEDI_CB_BLOCK;
370 comedi_event(dev, s);
371 s->async->events = 0;
376 comedi_unlock(devpriv->device, devpriv->subd);
377 async->events |= COMEDI_CB_EOA;
378 comedi_event(dev, s);
380 devpriv->scan_task_active = 0;
381 /* suspend task until next struct comedi_cmd */
382 rt_task_suspend(devpriv->scan_task);
386 static void timer_task_func(comedi_rt_task_context_t d)
388 struct comedi_device *dev = (struct comedi_device *) d;
389 struct comedi_subdevice *s = dev->subdevices + 0;
390 struct comedi_cmd *cmd = &s->async->cmd;
392 unsigned long long n;
394 /* every struct comedi_cmd causes one execution of while loop */
396 devpriv->rt_task_active = 1;
397 devpriv->scan_task_active = 1;
398 devpriv->start = rt_get_time();
400 for (n = 0; n < cmd->stop_arg || cmd->stop_src == TRIG_NONE;
404 rt_task_wait_period();
405 if (devpriv->scan_task_active == 0) {
408 ret = rt_task_make_periodic(devpriv->scan_task,
409 devpriv->start + devpriv->scan_period * n,
410 devpriv->convert_period);
412 comedi_error(dev, "bug!");
418 devpriv->rt_task_active = 0;
419 /* suspend until next struct comedi_cmd */
420 rt_task_suspend(devpriv->rt_task);
424 static int timer_insn(struct comedi_device *dev, struct comedi_subdevice *s,
425 struct comedi_insn *insn, unsigned int *data)
427 struct comedi_insn xinsn = *insn;
430 xinsn.subdev = devpriv->subd;
432 return comedi_do_insn(devpriv->device, &xinsn);
435 static int cmdtest_helper(struct comedi_cmd *cmd,
436 unsigned int start_src,
437 unsigned int scan_begin_src,
438 unsigned int convert_src,
439 unsigned int scan_end_src, unsigned int stop_src)
444 tmp = cmd->start_src;
445 cmd->start_src &= start_src;
446 if (!cmd->start_src || tmp != cmd->start_src)
449 tmp = cmd->scan_begin_src;
450 cmd->scan_begin_src &= scan_begin_src;
451 if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
454 tmp = cmd->convert_src;
455 cmd->convert_src &= convert_src;
456 if (!cmd->convert_src || tmp != cmd->convert_src)
459 tmp = cmd->scan_end_src;
460 cmd->scan_end_src &= scan_end_src;
461 if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
465 cmd->stop_src &= stop_src;
466 if (!cmd->stop_src || tmp != cmd->stop_src)
472 static int timer_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
473 struct comedi_cmd *cmd)
476 unsigned int start_src = 0;
478 if (s->type == COMEDI_SUBD_AO)
479 start_src = TRIG_INT;
481 start_src = TRIG_NOW;
483 err = cmdtest_helper(cmd, start_src, /* start_src */
484 TRIG_TIMER | TRIG_FOLLOW, /* scan_begin_src */
485 TRIG_NOW | TRIG_TIMER, /* convert_src */
486 TRIG_COUNT, /* scan_end_src */
487 TRIG_COUNT | TRIG_NONE); /* stop_src */
491 /* step 2: make sure trigger sources are unique and mutually
494 if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_INT)
496 if (cmd->scan_begin_src != TRIG_TIMER &&
497 cmd->scan_begin_src != TRIG_FOLLOW)
499 if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_NOW)
501 if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
503 if (cmd->scan_begin_src == TRIG_FOLLOW
504 && cmd->convert_src != TRIG_TIMER)
506 if (cmd->convert_src == TRIG_NOW && cmd->scan_begin_src != TRIG_TIMER)
512 /* step 3: make sure arguments are trivially compatible */
513 /* limit frequency, this is fairly arbitrary */
514 if (cmd->scan_begin_src == TRIG_TIMER) {
515 if (cmd->scan_begin_arg < SPEED_LIMIT) {
516 cmd->scan_begin_arg = SPEED_LIMIT;
520 if (cmd->convert_src == TRIG_TIMER) {
521 if (cmd->convert_arg < SPEED_LIMIT) {
522 cmd->convert_arg = SPEED_LIMIT;
526 /* make sure conversion and scan frequencies are compatible */
527 if (cmd->convert_src == TRIG_TIMER && cmd->scan_begin_src == TRIG_TIMER) {
528 if (cmd->convert_arg * cmd->scan_end_arg > cmd->scan_begin_arg) {
529 cmd->scan_begin_arg =
530 cmd->convert_arg * cmd->scan_end_arg;
537 /* step 4: fix up and arguments */
544 static int timer_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
547 struct comedi_cmd *cmd = &s->async->cmd;
549 /* hack attack: drivers are not supposed to do this: */
552 /* make sure tasks have finished cleanup of last struct comedi_cmd */
553 if (devpriv->rt_task_active || devpriv->scan_task_active)
556 ret = comedi_lock(devpriv->device, devpriv->subd);
558 comedi_error(dev, "failed to obtain lock");
561 switch (cmd->scan_begin_src) {
563 devpriv->scan_period = nano2count(cmd->scan_begin_arg);
566 devpriv->scan_period =
567 nano2count(cmd->convert_arg * cmd->scan_end_arg);
570 comedi_error(dev, "bug setting scan period!");
574 switch (cmd->convert_src) {
576 devpriv->convert_period = nano2count(cmd->convert_arg);
579 devpriv->convert_period = 1;
582 comedi_error(dev, "bug setting conversion period!");
587 if (cmd->start_src == TRIG_NOW)
588 return timer_start_cmd(dev, s);
590 s->async->inttrig = timer_inttrig;
595 static int timer_inttrig(struct comedi_device *dev, struct comedi_subdevice *s,
596 unsigned int trig_num)
601 s->async->inttrig = NULL;
603 return timer_start_cmd(dev, s);
606 static int timer_start_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
608 struct comedi_async *async = s->async;
609 struct comedi_cmd *cmd = &async->cmd;
610 RTIME now, delay, period;
614 s->async->events = 0;
616 if (cmd->start_src == TRIG_NOW)
617 delay = nano2count(cmd->start_arg);
622 /* Using 'period' this way gets around some weird bug in gcc-2.95.2
623 * that generates the compile error 'internal error--unrecognizable insn'
624 * when rt_task_make_period() is called (observed with rtlinux-3.1, linux-2.2.19).
626 period = devpriv->scan_period;
627 ret = rt_task_make_periodic(devpriv->rt_task, now + delay, period);
629 comedi_error(dev, "error starting rt_task");
635 static int timer_attach(struct comedi_device *dev, struct comedi_devconfig *it)
638 struct comedi_subdevice *s, *emul_s;
639 struct comedi_device *emul_dev;
640 /* These should probably be devconfig options[] */
641 const int timer_priority = 4;
642 const int scan_priority = timer_priority + 1;
645 printk("comedi%d: timer: ", dev->minor);
647 dev->board_name = "timer";
649 if ((ret = alloc_subdevices(dev, 1)) < 0)
651 if ((ret = alloc_private(dev, sizeof(struct timer_private))) < 0)
654 sprintf(path, "/dev/comedi%d", it->options[0]);
655 devpriv->device = comedi_open(path);
656 devpriv->subd = it->options[1];
658 printk("emulating commands for minor %i, subdevice %d\n",
659 it->options[0], devpriv->subd);
661 emul_dev = devpriv->device;
662 emul_s = emul_dev->subdevices + devpriv->subd;
664 /* input or output subdevice */
665 s = dev->subdevices + 0;
666 s->type = emul_s->type;
667 s->subdev_flags = emul_s->subdev_flags; /* SDF_GROUND (to fool check_driver) */
668 s->n_chan = emul_s->n_chan;
669 s->len_chanlist = 1024;
670 s->do_cmd = timer_cmd;
671 s->do_cmdtest = timer_cmdtest;
672 s->cancel = timer_cancel;
673 s->maxdata = emul_s->maxdata;
674 s->range_table = emul_s->range_table;
675 s->range_table_list = emul_s->range_table_list;
676 switch (emul_s->type) {
678 s->insn_read = timer_insn;
679 dev->read_subdev = s;
680 s->subdev_flags |= SDF_CMD_READ;
681 devpriv->io_function = timer_data_read;
684 s->insn_write = timer_insn;
685 s->insn_read = timer_insn;
686 dev->write_subdev = s;
687 s->subdev_flags |= SDF_CMD_WRITE;
688 devpriv->io_function = timer_data_write;
690 case COMEDI_SUBD_DIO:
691 s->insn_write = timer_insn;
692 s->insn_read = timer_insn;
693 s->insn_bits = timer_insn;
694 dev->read_subdev = s;
695 s->subdev_flags |= SDF_CMD_READ;
696 devpriv->io_function = timer_dio_read;
699 comedi_error(dev, "failed to determine subdevice type!");
703 rt_set_oneshot_mode();
705 devpriv->timer_running = 1;
707 devpriv->rt_task = kzalloc(sizeof(RT_TASK), GFP_KERNEL);
709 /* initialize real-time tasks */
710 ret = rt_task_init(devpriv->rt_task, timer_task_func,
711 (comedi_rt_task_context_t) dev, 3000, timer_priority, 0, 0);
713 comedi_error(dev, "error initalizing rt_task");
714 kfree(devpriv->rt_task);
715 devpriv->rt_task = 0;
719 devpriv->scan_task = kzalloc(sizeof(RT_TASK), GFP_KERNEL);
721 ret = rt_task_init(devpriv->scan_task, scan_task_func,
722 (comedi_rt_task_context_t) dev, 3000, scan_priority, 0, 0);
724 comedi_error(dev, "error initalizing scan_task");
725 kfree(devpriv->scan_task);
726 devpriv->scan_task = 0;
733 /* free allocated resources */
734 static int timer_detach(struct comedi_device *dev)
736 printk("comedi%d: timer: remove\n", dev->minor);
739 if (devpriv->rt_task) {
740 rt_task_delete(devpriv->rt_task);
741 kfree(devpriv->rt_task);
743 if (devpriv->scan_task) {
744 rt_task_delete(devpriv->scan_task);
745 kfree(devpriv->scan_task);
747 if (devpriv->timer_running)
750 comedi_close(devpriv->device);