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>
114 #if RTAI_VERSION_CODE < RTAI_MANGLE_VERSION(3,3,0)
115 #define comedi_rt_task_context_t int
117 #define comedi_rt_task_context_t long
122 /* This defines the fastest speed we will emulate. Note that
123 * without a watchdog (like in RTAI), we could easily overrun our
124 * task period because analog input tends to be slow. */
125 #define SPEED_LIMIT 100000 /* in nanoseconds */
127 static int timer_attach(comedi_device * dev, comedi_devconfig * it);
128 static int timer_detach(comedi_device * dev);
129 static int timer_inttrig(comedi_device * dev, comedi_subdevice * s,
130 unsigned int trig_num);
131 static int timer_start_cmd(comedi_device * dev, comedi_subdevice * s);
133 static comedi_driver driver_timer = {
135 driver_name:"comedi_rt_timer",
141 COMEDI_INITCLEANUP(driver_timer);
144 comedi_t *device; // device we are emulating commands for
145 int subd; // subdevice we are emulating commands for
146 RT_TASK *rt_task; // rt task that starts scans
147 RT_TASK *scan_task; // rt task that controls conversion timing in a scan
148 /* io_function can point to either an input or output function
149 * depending on what kind of subdevice we are emulating for */
150 int (*io_function) (comedi_device * dev, comedi_cmd * cmd,
152 // RTIME has units of 1 = 838 nanoseconds
153 // time at which first scan started, used to check scan timing
155 // time between scans
157 // time between conversions in a scan
158 RTIME convert_period;
160 volatile int stop; // indicates we should stop
161 volatile int rt_task_active; // indicates rt_task is servicing a comedi_cmd
162 volatile int scan_task_active; // indicates scan_task is servicing a comedi_cmd
163 unsigned timer_running:1;
165 #define devpriv ((timer_private *)dev->private)
167 static int timer_cancel(comedi_device * dev, comedi_subdevice * s)
174 // checks for scan timing error
175 inline static int check_scan_timing(comedi_device * dev,
176 unsigned long long scan)
178 RTIME now, timing_error;
181 timing_error = now - (devpriv->start + scan * devpriv->scan_period);
182 if (timing_error > devpriv->scan_period) {
183 comedi_error(dev, "timing error");
184 rt_printk("scan started %i ns late\n", timing_error * 838);
191 // checks for conversion timing error
192 inline static int check_conversion_timing(comedi_device * dev,
193 RTIME scan_start, unsigned int conversion)
195 RTIME now, timing_error;
199 now - (scan_start + conversion * devpriv->convert_period);
200 if (timing_error > devpriv->convert_period) {
201 comedi_error(dev, "timing error");
202 rt_printk("conversion started %i ns late\n",
210 // devpriv->io_function for an input subdevice
211 static int timer_data_read(comedi_device * dev, comedi_cmd * cmd,
214 comedi_subdevice *s = dev->read_subdev;
218 ret = comedi_data_read(devpriv->device, devpriv->subd,
219 CR_CHAN(cmd->chanlist[index]),
220 CR_RANGE(cmd->chanlist[index]),
221 CR_AREF(cmd->chanlist[index]), &data);
223 comedi_error(dev, "read error");
226 if (s->flags & SDF_LSAMPL) {
227 cfc_write_long_to_buffer(s, data);
229 comedi_buf_put(s->async, data);
235 // devpriv->io_function for an output subdevice
236 static int timer_data_write(comedi_device * dev, comedi_cmd * cmd,
239 comedi_subdevice *s = dev->write_subdev;
240 unsigned int num_bytes;
245 if (s->flags & SDF_LSAMPL) {
247 cfc_read_array_from_buffer(s, &long_data,
250 num_bytes = cfc_read_array_from_buffer(s, &data, sizeof(data));
254 if (num_bytes == 0) {
255 comedi_error(dev, "buffer underrun");
258 ret = comedi_data_write(devpriv->device, devpriv->subd,
259 CR_CHAN(cmd->chanlist[index]),
260 CR_RANGE(cmd->chanlist[index]),
261 CR_AREF(cmd->chanlist[index]), long_data);
263 comedi_error(dev, "write error");
270 // devpriv->io_function for DIO subdevices
271 static int timer_dio_read(comedi_device * dev, comedi_cmd * cmd,
274 comedi_subdevice *s = dev->read_subdev;
278 ret = comedi_dio_bitfield(devpriv->device, devpriv->subd, 0, &data);
280 comedi_error(dev, "read error");
284 if (s->flags & SDF_LSAMPL)
285 cfc_write_long_to_buffer(s, data);
287 cfc_write_to_buffer(s, data);
293 static void scan_task_func(comedi_rt_task_context_t d)
295 comedi_device *dev = (comedi_device *) d;
296 comedi_subdevice *s = dev->subdevices + 0;
297 comedi_async *async = s->async;
298 comedi_cmd *cmd = &async->cmd;
300 unsigned long long n;
303 // every comedi_cmd causes one execution of while loop
305 devpriv->scan_task_active = 1;
306 // each for loop completes one scan
307 for (n = 0; n < cmd->stop_arg || cmd->stop_src == TRIG_NONE;
310 // suspend task until next scan
311 ret = rt_task_suspend(devpriv->scan_task);
314 "error suspending scan task");
315 async->events |= COMEDI_CB_ERROR;
319 // check if stop flag was set (by timer_cancel())
322 ret = check_scan_timing(dev, n);
324 async->events |= COMEDI_CB_ERROR;
327 scan_start = rt_get_time();
328 for (i = 0; i < cmd->scan_end_arg; i++) {
330 if (cmd->convert_src == TRIG_TIMER && i) {
331 rt_task_wait_period();
332 ret = check_conversion_timing(dev,
340 ret = devpriv->io_function(dev, cmd, i);
342 async->events |= COMEDI_CB_ERROR;
346 s->async->events |= COMEDI_CB_BLOCK;
347 comedi_event(dev, s);
348 s->async->events = 0;
353 comedi_unlock(devpriv->device, devpriv->subd);
354 async->events |= COMEDI_CB_EOA;
355 comedi_event(dev, s);
357 devpriv->scan_task_active = 0;
358 // suspend task until next comedi_cmd
359 rt_task_suspend(devpriv->scan_task);
363 static void timer_task_func(comedi_rt_task_context_t d)
365 comedi_device *dev = (comedi_device *) d;
366 comedi_subdevice *s = dev->subdevices + 0;
367 comedi_cmd *cmd = &s->async->cmd;
369 unsigned long long n;
371 // every comedi_cmd causes one execution of while loop
373 devpriv->rt_task_active = 1;
374 devpriv->scan_task_active = 1;
375 devpriv->start = rt_get_time();
377 for (n = 0; n < cmd->stop_arg || cmd->stop_src == TRIG_NONE;
381 rt_task_wait_period();
382 if (devpriv->scan_task_active == 0) {
385 ret = rt_task_make_periodic(devpriv->scan_task,
386 devpriv->start + devpriv->scan_period * n,
387 devpriv->convert_period);
389 comedi_error(dev, "bug!");
395 devpriv->rt_task_active = 0;
396 // suspend until next comedi_cmd
397 rt_task_suspend(devpriv->rt_task);
401 static int timer_insn(comedi_device * dev, comedi_subdevice * s,
402 comedi_insn * insn, lsampl_t * data)
404 comedi_insn xinsn = *insn;
407 xinsn.subdev = devpriv->subd;
409 return comedi_do_insn(devpriv->device, &xinsn);
412 static int cmdtest_helper(comedi_cmd * cmd,
413 unsigned int start_src,
414 unsigned int scan_begin_src,
415 unsigned int convert_src,
416 unsigned int scan_end_src, unsigned int stop_src)
421 tmp = cmd->start_src;
422 cmd->start_src &= start_src;
423 if (!cmd->start_src || tmp != cmd->start_src)
426 tmp = cmd->scan_begin_src;
427 cmd->scan_begin_src &= scan_begin_src;
428 if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
431 tmp = cmd->convert_src;
432 cmd->convert_src &= convert_src;
433 if (!cmd->convert_src || tmp != cmd->convert_src)
436 tmp = cmd->scan_end_src;
437 cmd->scan_end_src &= scan_end_src;
438 if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
442 cmd->stop_src &= stop_src;
443 if (!cmd->stop_src || tmp != cmd->stop_src)
449 static int timer_cmdtest(comedi_device * dev, comedi_subdevice * s,
453 unsigned int start_src = 0;
455 if (s->type == COMEDI_SUBD_AO)
456 start_src = TRIG_INT;
458 start_src = TRIG_NOW;
460 err = cmdtest_helper(cmd, start_src, /* start_src */
461 TRIG_TIMER | TRIG_FOLLOW, /* scan_begin_src */
462 TRIG_NOW | TRIG_TIMER, /* convert_src */
463 TRIG_COUNT, /* scan_end_src */
464 TRIG_COUNT | TRIG_NONE); /* stop_src */
468 /* step 2: make sure trigger sources are unique and mutually
471 if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_INT)
473 if (cmd->scan_begin_src != TRIG_TIMER &&
474 cmd->scan_begin_src != TRIG_FOLLOW)
476 if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_NOW)
478 if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
480 if (cmd->scan_begin_src == TRIG_FOLLOW
481 && cmd->convert_src != TRIG_TIMER)
483 if (cmd->convert_src == TRIG_NOW && cmd->scan_begin_src != TRIG_TIMER)
489 /* step 3: make sure arguments are trivially compatible */
490 // limit frequency, this is fairly arbitrary
491 if (cmd->scan_begin_src == TRIG_TIMER) {
492 if (cmd->scan_begin_arg < SPEED_LIMIT) {
493 cmd->scan_begin_arg = SPEED_LIMIT;
497 if (cmd->convert_src == TRIG_TIMER) {
498 if (cmd->convert_arg < SPEED_LIMIT) {
499 cmd->convert_arg = SPEED_LIMIT;
503 // make sure conversion and scan frequencies are compatible
504 if (cmd->convert_src == TRIG_TIMER && cmd->scan_begin_src == TRIG_TIMER) {
505 if (cmd->convert_arg * cmd->scan_end_arg > cmd->scan_begin_arg) {
506 cmd->scan_begin_arg =
507 cmd->convert_arg * cmd->scan_end_arg;
514 /* step 4: fix up and arguments */
521 static int timer_cmd(comedi_device * dev, comedi_subdevice * s)
524 comedi_cmd *cmd = &s->async->cmd;
526 /* hack attack: drivers are not supposed to do this: */
529 // make sure tasks have finished cleanup of last comedi_cmd
530 if (devpriv->rt_task_active || devpriv->scan_task_active)
533 ret = comedi_lock(devpriv->device, devpriv->subd);
535 comedi_error(dev, "failed to obtain lock");
538 switch (cmd->scan_begin_src) {
540 devpriv->scan_period = nano2count(cmd->scan_begin_arg);
543 devpriv->scan_period =
544 nano2count(cmd->convert_arg * cmd->scan_end_arg);
547 comedi_error(dev, "bug setting scan period!");
551 switch (cmd->convert_src) {
553 devpriv->convert_period = nano2count(cmd->convert_arg);
556 devpriv->convert_period = 1;
559 comedi_error(dev, "bug setting conversion period!");
564 if (cmd->start_src == TRIG_NOW)
565 return timer_start_cmd(dev, s);
567 s->async->inttrig = timer_inttrig;
572 static int timer_inttrig(comedi_device * dev, comedi_subdevice * s,
573 unsigned int trig_num)
578 s->async->inttrig = NULL;
580 return timer_start_cmd(dev, s);
583 static int timer_start_cmd(comedi_device * dev, comedi_subdevice * s)
585 comedi_async *async = s->async;
586 comedi_cmd *cmd = &async->cmd;
587 RTIME now, delay, period;
591 s->async->events = 0;
593 if (cmd->start_src == TRIG_NOW)
594 delay = nano2count(cmd->start_arg);
599 /* Using 'period' this way gets around some weird bug in gcc-2.95.2
600 * that generates the compile error 'internal error--unrecognizable insn'
601 * when rt_task_make_period() is called (observed with rtlinux-3.1, linux-2.2.19).
603 period = devpriv->scan_period;
604 ret = rt_task_make_periodic(devpriv->rt_task, now + delay, period);
606 comedi_error(dev, "error starting rt_task");
612 static int timer_attach(comedi_device * dev, comedi_devconfig * it)
615 comedi_subdevice *s, *emul_s;
616 comedi_device *emul_dev;
617 /* These should probably be devconfig options[] */
618 const int timer_priority = 4;
619 const int scan_priority = timer_priority + 1;
622 printk("comedi%d: timer: ", dev->minor);
624 dev->board_name = "timer";
626 if ((ret = alloc_subdevices(dev, 1)) < 0)
628 if ((ret = alloc_private(dev, sizeof(timer_private))) < 0)
631 sprintf(path, "/dev/comedi%d", it->options[0]);
632 devpriv->device = comedi_open(path);
633 devpriv->subd = it->options[1];
635 printk("emulating commands for minor %i, subdevice %d\n",
636 it->options[0], devpriv->subd);
638 emul_dev = devpriv->device;
639 emul_s = emul_dev->subdevices + devpriv->subd;
641 // input or output subdevice
642 s = dev->subdevices + 0;
643 s->type = emul_s->type;
644 s->subdev_flags = emul_s->subdev_flags; /* SDF_GROUND (to fool check_driver) */
645 s->n_chan = emul_s->n_chan;
646 s->len_chanlist = 1024;
647 s->do_cmd = timer_cmd;
648 s->do_cmdtest = timer_cmdtest;
649 s->cancel = timer_cancel;
650 s->maxdata = emul_s->maxdata;
651 s->range_table = emul_s->range_table;
652 s->range_table_list = emul_s->range_table_list;
653 switch (emul_s->type) {
655 s->insn_read = timer_insn;
656 dev->read_subdev = s;
657 s->subdev_flags |= SDF_CMD_READ;
658 devpriv->io_function = timer_data_read;
661 s->insn_write = timer_insn;
662 s->insn_read = timer_insn;
663 dev->write_subdev = s;
664 s->subdev_flags |= SDF_CMD_WRITE;
665 devpriv->io_function = timer_data_write;
667 case COMEDI_SUBD_DIO:
668 s->insn_write = timer_insn;
669 s->insn_read = timer_insn;
670 s->insn_bits = timer_insn;
671 dev->read_subdev = s;
672 s->subdev_flags |= SDF_CMD_READ;
673 devpriv->io_function = timer_dio_read;
676 comedi_error(dev, "failed to determine subdevice type!");
680 rt_set_oneshot_mode();
682 devpriv->timer_running = 1;
684 devpriv->rt_task = kzalloc(sizeof(RT_TASK), GFP_KERNEL);
686 // initialize real-time tasks
687 ret = rt_task_init(devpriv->rt_task, timer_task_func,
688 (comedi_rt_task_context_t) dev, 3000, timer_priority, 0, 0);
690 comedi_error(dev, "error initalizing rt_task");
691 kfree(devpriv->rt_task);
692 devpriv->rt_task = 0;
696 devpriv->scan_task = kzalloc(sizeof(RT_TASK), GFP_KERNEL);
698 ret = rt_task_init(devpriv->scan_task, scan_task_func,
699 (comedi_rt_task_context_t) dev, 3000, scan_priority, 0, 0);
701 comedi_error(dev, "error initalizing scan_task");
702 kfree(devpriv->scan_task);
703 devpriv->scan_task = 0;
710 // free allocated resources
711 static int timer_detach(comedi_device * dev)
713 printk("comedi%d: timer: remove\n", dev->minor);
716 if (devpriv->rt_task) {
717 rt_task_delete(devpriv->rt_task);
718 kfree(devpriv->rt_task);
720 if (devpriv->scan_task) {
721 rt_task_delete(devpriv->scan_task);
722 kfree(devpriv->scan_task);
724 if (devpriv->timer_running)
727 comedi_close(devpriv->device);