Staging: comedi: add comedi_rt_timer virtual driver

virtual driver for using RTL timing sources

From: David Schleef <ds@schleef.org>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/comedi/drivers/comedi_rt_timer.c

+/*
+    comedi/drivers/comedi_rt_timer.c
+    virtual driver for using RTL timing sources
+
+    Authors: David A. Schleef, Frank M. Hess
+
+    COMEDI - Linux Control and Measurement Device Interface
+    Copyright (C) 1999,2001 David A. Schleef <ds@schleef.org>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+**************************************************************************
+*/
+/*
+Driver: comedi_rt_timer
+Description: Command emulator using real-time tasks
+Author: ds, fmhess
+Devices:
+Status: works
+
+This driver requires RTAI or RTLinux to work correctly.  It doesn't
+actually drive hardware directly, but calls other drivers and uses
+a real-time task to emulate commands for drivers and devices that
+are incapable of native commands.  Thus, you can get accurately
+timed I/O on any device.
+
+Since the timing is all done in software, sampling jitter is much
+higher than with a device that has an on-board timer, and maximum
+sample rate is much lower.
+
+Configuration options:
+  [0] - minor number of device you wish to emulate commands for
+  [1] - subdevice number you wish to emulate commands for
+*/
+/*
+TODO:
+	Support for digital io commands could be added, except I can't see why
+		anyone would want to use them
+	What happens if device we are emulating for is de-configured?
+*/
+
+#include "../comedidev.h"
+#include "../comedilib.h"
+
+#include "comedi_fc.h"
+
+#ifdef CONFIG_COMEDI_RTL_V1
+#include <rtl_sched.h>
+#include <asm/rt_irq.h>
+#endif
+#ifdef CONFIG_COMEDI_RTL
+#include <rtl.h>
+#include <rtl_sched.h>
+#include <rtl_compat.h>
+#include <asm/div64.h>
+
+#ifndef RTLINUX_VERSION_CODE
+#define RTLINUX_VERSION_CODE 0
+#endif
+#ifndef RTLINUX_VERSION
+#define RTLINUX_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
+#endif
+
+// begin hack to workaround broken HRT_TO_8254() function on rtlinux
+#if RTLINUX_VERSION_CODE <= RTLINUX_VERSION(3,0,100)
+// this function sole purpose is to divide a long long by 838
+static inline RTIME nano2count(long long ns)
+{
+	do_div(ns, 838);
+	return ns;
+}
+
+#ifdef rt_get_time()
+#undef rt_get_time()
+#endif
+#define rt_get_time() nano2count(gethrtime())
+
+#else
+
+#define nano2count(x) HRT_TO_8254(x)
+#endif
+// end hack
+
+// rtl-rtai compatibility
+#define rt_task_wait_period() rt_task_wait()
+#define rt_pend_linux_srq(irq) rtl_global_pend_irq(irq)
+#define rt_free_srq(irq) rtl_free_soft_irq(irq)
+#define rt_request_srq(x,y,z) rtl_get_soft_irq(y,"timer")
+#define rt_task_init(a,b,c,d,e,f,g) rt_task_init(a,b,c,d,(e)+1)
+#define rt_task_resume(x) rt_task_wakeup(x)
+#define rt_set_oneshot_mode()
+#define start_rt_timer(x)
+#define stop_rt_timer()
+
+#define comedi_rt_task_context_t	int
+
+#endif
+#ifdef CONFIG_COMEDI_RTAI
+#include <rtai.h>
+#include <rtai_sched.h>
+
+#if RTAI_VERSION_CODE < RTAI_MANGLE_VERSION(3,3,0)
+#define comedi_rt_task_context_t	int
+#else
+#define comedi_rt_task_context_t	long
+#endif
+
+#endif
+
+/* This defines the fastest speed we will emulate.  Note that
+ * without a watchdog (like in RTAI), we could easily overrun our
+ * task period because analog input tends to be slow. */
+#define SPEED_LIMIT 100000	/* in nanoseconds */
+
+static int timer_attach(comedi_device * dev, comedi_devconfig * it);
+static int timer_detach(comedi_device * dev);
+static int timer_inttrig(comedi_device * dev, comedi_subdevice * s,
+	unsigned int trig_num);
+static int timer_start_cmd(comedi_device * dev, comedi_subdevice * s);
+
+static comedi_driver driver_timer = {
+      module:THIS_MODULE,
+      driver_name:"comedi_rt_timer",
+      attach:timer_attach,
+      detach:timer_detach,
+//      open:           timer_open,
+};
+
+COMEDI_INITCLEANUP(driver_timer);
+
+typedef struct {
+	comedi_t *device;	// device we are emulating commands for
+	int subd;		// subdevice we are emulating commands for
+	RT_TASK *rt_task;	// rt task that starts scans
+	RT_TASK *scan_task;	// rt task that controls conversion timing in a scan
+	/* io_function can point to either an input or output function
+	 * depending on what kind of subdevice we are emulating for */
+	int (*io_function) (comedi_device * dev, comedi_cmd * cmd,
+		unsigned int index);
+	// RTIME has units of 1 = 838 nanoseconds
+	// time at which first scan started, used to check scan timing
+	RTIME start;
+	// time between scans
+	RTIME scan_period;
+	// time between conversions in a scan
+	RTIME convert_period;
+	// flags
+	volatile int stop;	// indicates we should stop
+	volatile int rt_task_active;	// indicates rt_task is servicing a comedi_cmd
+	volatile int scan_task_active;	// indicates scan_task is servicing a comedi_cmd
+	unsigned timer_running:1;
+} timer_private;
+#define devpriv ((timer_private *)dev->private)
+
+static int timer_cancel(comedi_device * dev, comedi_subdevice * s)
+{
+	devpriv->stop = 1;
+
+	return 0;
+}
+
+// checks for scan timing error
+inline static int check_scan_timing(comedi_device * dev,
+	unsigned long long scan)
+{
+	RTIME now, timing_error;
+
+	now = rt_get_time();
+	timing_error = now - (devpriv->start + scan * devpriv->scan_period);
+	if (timing_error > devpriv->scan_period) {
+		comedi_error(dev, "timing error");
+		rt_printk("scan started %i ns late\n", timing_error * 838);
+		return -1;
+	}
+
+	return 0;
+}
+
+// checks for conversion timing error
+inline static int check_conversion_timing(comedi_device * dev,
+	RTIME scan_start, unsigned int conversion)
+{
+	RTIME now, timing_error;
+
+	now = rt_get_time();
+	timing_error =
+		now - (scan_start + conversion * devpriv->convert_period);
+	if (timing_error > devpriv->convert_period) {
+		comedi_error(dev, "timing error");
+		rt_printk("conversion started %i ns late\n",
+			timing_error * 838);
+		return -1;
+	}
+
+	return 0;
+}
+
+// devpriv->io_function for an input subdevice
+static int timer_data_read(comedi_device * dev, comedi_cmd * cmd,
+	unsigned int index)
+{
+	comedi_subdevice *s = dev->read_subdev;
+	int ret;
+	lsampl_t data;
+
+	ret = comedi_data_read(devpriv->device, devpriv->subd,
+		CR_CHAN(cmd->chanlist[index]),
+		CR_RANGE(cmd->chanlist[index]),
+		CR_AREF(cmd->chanlist[index]), &data);
+	if (ret < 0) {
+		comedi_error(dev, "read error");
+		return -EIO;
+	}
+	if (s->flags & SDF_LSAMPL) {
+		cfc_write_long_to_buffer(s, data);
+	} else {
+		comedi_buf_put(s->async, data);
+	}
+
+	return 0;
+}
+
+// devpriv->io_function for an output subdevice
+static int timer_data_write(comedi_device * dev, comedi_cmd * cmd,
+	unsigned int index)
+{
+	comedi_subdevice *s = dev->write_subdev;
+	unsigned int num_bytes;
+	sampl_t data;
+	lsampl_t long_data;
+	int ret;
+
+	if (s->flags & SDF_LSAMPL) {
+		num_bytes =
+			cfc_read_array_from_buffer(s, &long_data,
+			sizeof(long_data));
+	} else {
+		num_bytes = cfc_read_array_from_buffer(s, &data, sizeof(data));
+		long_data = data;
+	}
+
+	if (num_bytes == 0) {
+		comedi_error(dev, "buffer underrun");
+		return -EAGAIN;
+	}
+	ret = comedi_data_write(devpriv->device, devpriv->subd,
+		CR_CHAN(cmd->chanlist[index]),
+		CR_RANGE(cmd->chanlist[index]),
+		CR_AREF(cmd->chanlist[index]), long_data);
+	if (ret < 0) {
+		comedi_error(dev, "write error");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+// devpriv->io_function for DIO subdevices
+static int timer_dio_read(comedi_device * dev, comedi_cmd * cmd,
+	unsigned int index)
+{
+	comedi_subdevice *s = dev->read_subdev;
+	int ret;
+	lsampl_t data;
+
+	ret = comedi_dio_bitfield(devpriv->device, devpriv->subd, 0, &data);
+	if (ret < 0) {
+		comedi_error(dev, "read error");
+		return -EIO;
+	}
+
+	if (s->flags & SDF_LSAMPL)
+		cfc_write_long_to_buffer(s, data);
+	else
+		cfc_write_to_buffer(s, data);
+
+	return 0;
+}
+
+// performs scans
+static void scan_task_func(comedi_rt_task_context_t d)
+{
+	comedi_device *dev = (comedi_device *) d;
+	comedi_subdevice *s = dev->subdevices + 0;
+	comedi_async *async = s->async;
+	comedi_cmd *cmd = &async->cmd;
+	int i, ret;
+	unsigned long long n;
+	RTIME scan_start;
+
+	// every comedi_cmd causes one execution of while loop
+	while (1) {
+		devpriv->scan_task_active = 1;
+		// each for loop completes one scan
+		for (n = 0; n < cmd->stop_arg || cmd->stop_src == TRIG_NONE;
+			n++) {
+			if (n) {
+				// suspend task until next scan
+				ret = rt_task_suspend(devpriv->scan_task);
+				if (ret < 0) {
+					comedi_error(dev,
+						"error suspending scan task");
+					async->events |= COMEDI_CB_ERROR;
+					goto cleanup;
+				}
+			}
+			// check if stop flag was set (by timer_cancel())
+			if (devpriv->stop)
+				goto cleanup;
+			ret = check_scan_timing(dev, n);
+			if (ret < 0) {
+				async->events |= COMEDI_CB_ERROR;
+				goto cleanup;
+			}
+			scan_start = rt_get_time();
+			for (i = 0; i < cmd->scan_end_arg; i++) {
+				// conversion timing
+				if (cmd->convert_src == TRIG_TIMER && i) {
+					rt_task_wait_period();
+					ret = check_conversion_timing(dev,
+						scan_start, i);
+					if (ret < 0) {
+						async->events |=
+							COMEDI_CB_ERROR;
+						goto cleanup;
+					}
+				}
+				ret = devpriv->io_function(dev, cmd, i);
+				if (ret < 0) {
+					async->events |= COMEDI_CB_ERROR;
+					goto cleanup;
+				}
+			}
+			s->async->events |= COMEDI_CB_BLOCK;
+			comedi_event(dev, s);
+			s->async->events = 0;
+		}
+
+	      cleanup:
+
+		comedi_unlock(devpriv->device, devpriv->subd);
+		async->events |= COMEDI_CB_EOA;
+		comedi_event(dev, s);
+		async->events = 0;
+		devpriv->scan_task_active = 0;
+		// suspend task until next comedi_cmd
+		rt_task_suspend(devpriv->scan_task);
+	}
+}
+
+static void timer_task_func(comedi_rt_task_context_t d)
+{
+	comedi_device *dev = (comedi_device *) d;
+	comedi_subdevice *s = dev->subdevices + 0;
+	comedi_cmd *cmd = &s->async->cmd;
+	int ret;
+	unsigned long long n;
+
+	// every comedi_cmd causes one execution of while loop
+	while (1) {
+		devpriv->rt_task_active = 1;
+		devpriv->scan_task_active = 1;
+		devpriv->start = rt_get_time();
+
+		for (n = 0; n < cmd->stop_arg || cmd->stop_src == TRIG_NONE;
+			n++) {
+			// scan timing
+			if (n)
+				rt_task_wait_period();
+			if (devpriv->scan_task_active == 0) {
+				goto cleanup;
+			}
+			ret = rt_task_make_periodic(devpriv->scan_task,
+				devpriv->start + devpriv->scan_period * n,
+				devpriv->convert_period);
+			if (ret < 0) {
+				comedi_error(dev, "bug!");
+			}
+		}
+
+	      cleanup:
+
+		devpriv->rt_task_active = 0;
+		// suspend until next comedi_cmd
+		rt_task_suspend(devpriv->rt_task);
+	}
+}
+
+static int timer_insn(comedi_device * dev, comedi_subdevice * s,
+	comedi_insn * insn, lsampl_t * data)
+{
+	comedi_insn xinsn = *insn;
+
+	xinsn.data = data;
+	xinsn.subdev = devpriv->subd;
+
+	return comedi_do_insn(devpriv->device, &xinsn);
+}
+
+static int cmdtest_helper(comedi_cmd * cmd,
+	unsigned int start_src,
+	unsigned int scan_begin_src,
+	unsigned int convert_src,
+	unsigned int scan_end_src, unsigned int stop_src)
+{
+	int err = 0;
+	int tmp;
+
+	tmp = cmd->start_src;
+	cmd->start_src &= start_src;
+	if (!cmd->start_src || tmp != cmd->start_src)
+		err++;
+
+	tmp = cmd->scan_begin_src;
+	cmd->scan_begin_src &= scan_begin_src;
+	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
+		err++;
+
+	tmp = cmd->convert_src;
+	cmd->convert_src &= convert_src;
+	if (!cmd->convert_src || tmp != cmd->convert_src)
+		err++;
+
+	tmp = cmd->scan_end_src;
+	cmd->scan_end_src &= scan_end_src;
+	if (!cmd->scan_end_src || tmp != cmd->scan_end_src)
+		err++;
+
+	tmp = cmd->stop_src;
+	cmd->stop_src &= stop_src;
+	if (!cmd->stop_src || tmp != cmd->stop_src)
+		err++;
+
+	return err;
+}
+
+static int timer_cmdtest(comedi_device * dev, comedi_subdevice * s,
+	comedi_cmd * cmd)
+{
+	int err = 0;
+	unsigned int start_src = 0;
+
+	if (s->type == COMEDI_SUBD_AO)
+		start_src = TRIG_INT;
+	else
+		start_src = TRIG_NOW;
+
+	err = cmdtest_helper(cmd, start_src,	/* start_src */
+		TRIG_TIMER | TRIG_FOLLOW,	/* scan_begin_src */
+		TRIG_NOW | TRIG_TIMER,	/* convert_src */
+		TRIG_COUNT,	/* scan_end_src */
+		TRIG_COUNT | TRIG_NONE);	/* stop_src */
+	if (err)
+		return 1;
+
+	/* step 2: make sure trigger sources are unique and mutually
+	 * compatible */
+
+	if (cmd->start_src != TRIG_NOW && cmd->start_src != TRIG_INT)
+		err++;
+	if (cmd->scan_begin_src != TRIG_TIMER &&
+		cmd->scan_begin_src != TRIG_FOLLOW)
+		err++;
+	if (cmd->convert_src != TRIG_TIMER && cmd->convert_src != TRIG_NOW)
+		err++;
+	if (cmd->stop_src != TRIG_COUNT && cmd->stop_src != TRIG_NONE)
+		err++;
+	if (cmd->scan_begin_src == TRIG_FOLLOW
+		&& cmd->convert_src != TRIG_TIMER)
+		err++;
+	if (cmd->convert_src == TRIG_NOW && cmd->scan_begin_src != TRIG_TIMER)
+		err++;
+
+	if (err)
+		return 2;
+
+	/* step 3: make sure arguments are trivially compatible */
+	// limit frequency, this is fairly arbitrary
+	if (cmd->scan_begin_src == TRIG_TIMER) {
+		if (cmd->scan_begin_arg < SPEED_LIMIT) {
+			cmd->scan_begin_arg = SPEED_LIMIT;
+			err++;
+		}
+	}
+	if (cmd->convert_src == TRIG_TIMER) {
+		if (cmd->convert_arg < SPEED_LIMIT) {
+			cmd->convert_arg = SPEED_LIMIT;
+			err++;
+		}
+	}
+	// make sure conversion and scan frequencies are compatible
+	if (cmd->convert_src == TRIG_TIMER && cmd->scan_begin_src == TRIG_TIMER) {
+		if (cmd->convert_arg * cmd->scan_end_arg > cmd->scan_begin_arg) {
+			cmd->scan_begin_arg =
+				cmd->convert_arg * cmd->scan_end_arg;
+			err++;
+		}
+	}
+	if (err)
+		return 3;
+
+	/* step 4: fix up and arguments */
+	if (err)
+		return 4;
+
+	return 0;
+}
+
+static int timer_cmd(comedi_device * dev, comedi_subdevice * s)
+{
+	int ret;
+	comedi_cmd *cmd = &s->async->cmd;
+
+	/* hack attack: drivers are not supposed to do this: */
+	dev->rt = 1;
+
+	// make sure tasks have finished cleanup of last comedi_cmd
+	if (devpriv->rt_task_active || devpriv->scan_task_active)
+		return -EBUSY;
+
+	ret = comedi_lock(devpriv->device, devpriv->subd);
+	if (ret < 0) {
+		comedi_error(dev, "failed to obtain lock");
+		return ret;
+	}
+	switch (cmd->scan_begin_src) {
+	case TRIG_TIMER:
+		devpriv->scan_period = nano2count(cmd->scan_begin_arg);
+		break;
+	case TRIG_FOLLOW:
+		devpriv->scan_period =
+			nano2count(cmd->convert_arg * cmd->scan_end_arg);
+		break;
+	default:
+		comedi_error(dev, "bug setting scan period!");
+		return -1;
+		break;
+	}
+	switch (cmd->convert_src) {
+	case TRIG_TIMER:
+		devpriv->convert_period = nano2count(cmd->convert_arg);
+		break;
+	case TRIG_NOW:
+		devpriv->convert_period = 1;
+		break;
+	default:
+		comedi_error(dev, "bug setting conversion period!");
+		return -1;
+		break;
+	}
+
+	if (cmd->start_src == TRIG_NOW)
+		return timer_start_cmd(dev, s);
+
+	s->async->inttrig = timer_inttrig;
+
+	return 0;
+}
+
+static int timer_inttrig(comedi_device * dev, comedi_subdevice * s,
+	unsigned int trig_num)
+{
+	if (trig_num != 0)
+		return -EINVAL;
+
+	s->async->inttrig = NULL;
+
+	return timer_start_cmd(dev, s);
+}
+
+static int timer_start_cmd(comedi_device * dev, comedi_subdevice * s)
+{
+	comedi_async *async = s->async;
+	comedi_cmd *cmd = &async->cmd;
+	RTIME now, delay, period;
+	int ret;
+
+	devpriv->stop = 0;
+	s->async->events = 0;
+
+	if (cmd->start_src == TRIG_NOW)
+		delay = nano2count(cmd->start_arg);
+	else
+		delay = 0;
+
+	now = rt_get_time();
+	/* Using 'period' this way gets around some weird bug in gcc-2.95.2
+	 * that generates the compile error 'internal error--unrecognizable insn'
+	 * when rt_task_make_period() is called (observed with rtlinux-3.1, linux-2.2.19).
+	 *  - fmhess */
+	period = devpriv->scan_period;
+	ret = rt_task_make_periodic(devpriv->rt_task, now + delay, period);
+	if (ret < 0) {
+		comedi_error(dev, "error starting rt_task");
+		return ret;
+	}
+	return 0;
+}
+
+static int timer_attach(comedi_device * dev, comedi_devconfig * it)
+{
+	int ret;
+	comedi_subdevice *s, *emul_s;
+	comedi_device *emul_dev;
+	/* These should probably be devconfig options[] */
+	const int timer_priority = 4;
+	const int scan_priority = timer_priority + 1;
+	char path[20];
+
+	printk("comedi%d: timer: ", dev->minor);
+
+	dev->board_name = "timer";
+
+	if ((ret = alloc_subdevices(dev, 1)) < 0)
+		return ret;
+	if ((ret = alloc_private(dev, sizeof(timer_private))) < 0)
+		return ret;
+
+	sprintf(path, "/dev/comedi%d", it->options[0]);
+	devpriv->device = comedi_open(path);
+	devpriv->subd = it->options[1];
+
+	printk("emulating commands for minor %i, subdevice %d\n",
+		it->options[0], devpriv->subd);
+
+	emul_dev = devpriv->device;
+	emul_s = emul_dev->subdevices + devpriv->subd;
+
+	// input or output subdevice
+	s = dev->subdevices + 0;
+	s->type = emul_s->type;
+	s->subdev_flags = emul_s->subdev_flags;	/* SDF_GROUND (to fool check_driver) */
+	s->n_chan = emul_s->n_chan;
+	s->len_chanlist = 1024;
+	s->do_cmd = timer_cmd;
+	s->do_cmdtest = timer_cmdtest;
+	s->cancel = timer_cancel;
+	s->maxdata = emul_s->maxdata;
+	s->range_table = emul_s->range_table;
+	s->range_table_list = emul_s->range_table_list;
+	switch (emul_s->type) {
+	case COMEDI_SUBD_AI:
+		s->insn_read = timer_insn;
+		dev->read_subdev = s;
+		s->subdev_flags |= SDF_CMD_READ;
+		devpriv->io_function = timer_data_read;
+		break;
+	case COMEDI_SUBD_AO:
+		s->insn_write = timer_insn;
+		s->insn_read = timer_insn;
+		dev->write_subdev = s;
+		s->subdev_flags |= SDF_CMD_WRITE;
+		devpriv->io_function = timer_data_write;
+		break;
+	case COMEDI_SUBD_DIO:
+		s->insn_write = timer_insn;
+		s->insn_read = timer_insn;
+		s->insn_bits = timer_insn;
+		dev->read_subdev = s;
+		s->subdev_flags |= SDF_CMD_READ;
+		devpriv->io_function = timer_dio_read;
+		break;
+	default:
+		comedi_error(dev, "failed to determine subdevice type!");
+		return -EINVAL;
+	}
+
+	rt_set_oneshot_mode();
+	start_rt_timer(1);
+	devpriv->timer_running = 1;
+
+	devpriv->rt_task = kzalloc(sizeof(RT_TASK), GFP_KERNEL);
+
+	// initialize real-time tasks
+	ret = rt_task_init(devpriv->rt_task, timer_task_func,
+		(comedi_rt_task_context_t) dev, 3000, timer_priority, 0, 0);
+	if (ret < 0) {
+		comedi_error(dev, "error initalizing rt_task");
+		kfree(devpriv->rt_task);
+		devpriv->rt_task = 0;
+		return ret;
+	}
+
+	devpriv->scan_task = kzalloc(sizeof(RT_TASK), GFP_KERNEL);
+
+	ret = rt_task_init(devpriv->scan_task, scan_task_func,
+		(comedi_rt_task_context_t) dev, 3000, scan_priority, 0, 0);
+	if (ret < 0) {
+		comedi_error(dev, "error initalizing scan_task");
+		kfree(devpriv->scan_task);
+		devpriv->scan_task = 0;
+		return ret;
+	}
+
+	return 1;
+}
+
+// free allocated resources
+static int timer_detach(comedi_device * dev)
+{
+	printk("comedi%d: timer: remove\n", dev->minor);
+
+	if (devpriv) {
+		if (devpriv->rt_task) {
+			rt_task_delete(devpriv->rt_task);
+			kfree(devpriv->rt_task);
+		}
+		if (devpriv->scan_task) {
+			rt_task_delete(devpriv->scan_task);
+			kfree(devpriv->scan_task);
+		}
+		if (devpriv->timer_running)
+			stop_rt_timer();
+		if (devpriv->device)
+			comedi_close(devpriv->device);
+	}
+	return 0;
+}