comedi_test.c

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/*
    comedi/drivers/comedi_test.c

    Generates fake waveform signals that can be read through
    the command interface.  It does _not_ read from any board;
    it just generates deterministic waveforms.
    Useful for various testing purposes.

    Copyright (C) 2002 Joachim Wuttke <[email protected]>
    Copyright (C) 2002 Frank Mori Hess <[email protected]>

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 2000 David A. Schleef <[email protected]>

    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_test
Description: generates fake waveforms
Author: Joachim Wuttke <[email protected]>, Frank Mori Hess
  <[email protected]>, ds
Devices:
Status: works
Updated: Sat, 16 Mar 2002 17:34:48 -0800

This driver is mainly for testing purposes, but can also be used to
generate sample waveforms on systems that don't have data acquisition
hardware.

Configuration options:
  [0] - Amplitude in microvolts for fake waveforms (default 1 volt)
  [1] - Period in microseconds for fake waveforms (default 0.1 sec)

Generates a sawtooth wave on channel 0, square wave on channel 1, additional
waveforms could be added to other channels (currently they return flatline
zero volts).

*/

#include "../comedidev.h"

#include <asm/div64.h>

#include "comedi_fc.h"
#include <linux/timer.h>

#define N_CHANS 8

/* Data unique to this driver */
struct waveform_private {
    struct timer_list timer;
    struct timeval last;    /* time at which last timer interrupt occurred */
    unsigned int uvolt_amplitude;   /* waveform amplitude in microvolts */
    unsigned long usec_period;  /* waveform period in microseconds */
    unsigned long usec_current; /* current time (modulo waveform period) */
    unsigned long usec_remainder;   /* usec since last scan; */
    unsigned long ai_count; /* number of conversions remaining */
    unsigned int scan_period;   /* scan period in usec */
    unsigned int convert_period;    /* conversion period in usec */
    unsigned timer_running:1;
    unsigned int ao_loopbacks[N_CHANS];
};

/* 1000 nanosec in a microsec */
static const int nano_per_micro = 1000;

/* fake analog input ranges */
static const struct comedi_lrange waveform_ai_ranges = {
    2,
    {
     BIP_RANGE(10),
     BIP_RANGE(5),
     }
};

static short fake_sawtooth(struct comedi_device *dev, unsigned int range_index,
               unsigned long current_time)
{
    struct waveform_private *devpriv = dev->private;
    struct comedi_subdevice *s = dev->read_subdev;
    unsigned int offset = s->maxdata / 2;
    u64 value;
    const struct comedi_krange *krange =
        &s->range_table->range[range_index];
    u64 binary_amplitude;

    binary_amplitude = s->maxdata;
    binary_amplitude *= devpriv->uvolt_amplitude;
    do_div(binary_amplitude, krange->max - krange->min);

    current_time %= devpriv->usec_period;
    value = current_time;
    value *= binary_amplitude * 2;
    do_div(value, devpriv->usec_period);
    value -= binary_amplitude;  /* get rid of sawtooth's dc offset */

    return offset + value;
}

static short fake_squarewave(struct comedi_device *dev,
                 unsigned int range_index,
                 unsigned long current_time)
{
    struct waveform_private *devpriv = dev->private;
    struct comedi_subdevice *s = dev->read_subdev;
    unsigned int offset = s->maxdata / 2;
    u64 value;
    const struct comedi_krange *krange =
        &s->range_table->range[range_index];
    current_time %= devpriv->usec_period;

    value = s->maxdata;
    value *= devpriv->uvolt_amplitude;
    do_div(value, krange->max - krange->min);

    if (current_time < devpriv->usec_period / 2)
        value *= -1;

    return offset + value;
}

static short fake_flatline(struct comedi_device *dev, unsigned int range_index,
               unsigned long current_time)
{
    return dev->read_subdev->maxdata / 2;
}

/* generates a different waveform depending on what channel is read */
static short fake_waveform(struct comedi_device *dev, unsigned int channel,
               unsigned int range, unsigned long current_time)
{
    enum {
        SAWTOOTH_CHAN,
        SQUARE_CHAN,
    };
    switch (channel) {
    case SAWTOOTH_CHAN:
        return fake_sawtooth(dev, range, current_time);
        break;
    case SQUARE_CHAN:
        return fake_squarewave(dev, range, current_time);
        break;
    default:
        break;
    }

    return fake_flatline(dev, range, current_time);
}

/*
   This is the background routine used to generate arbitrary data.
   It should run in the background; therefore it is scheduled by
   a timer mechanism.
*/
static void waveform_ai_interrupt(unsigned long arg)
{
    struct comedi_device *dev = (struct comedi_device *)arg;
    struct waveform_private *devpriv = dev->private;
    struct comedi_async *async = dev->read_subdev->async;
    struct comedi_cmd *cmd = &async->cmd;
    unsigned int i, j;
    /* all times in microsec */
    unsigned long elapsed_time;
    unsigned int num_scans;
    struct timeval now;

    do_gettimeofday(&now);

    elapsed_time =
        1000000 * (now.tv_sec - devpriv->last.tv_sec) + now.tv_usec -
        devpriv->last.tv_usec;
    devpriv->last = now;
    num_scans =
        (devpriv->usec_remainder + elapsed_time) / devpriv->scan_period;
    devpriv->usec_remainder =
        (devpriv->usec_remainder + elapsed_time) % devpriv->scan_period;
    async->events = 0;

    for (i = 0; i < num_scans; i++) {
        for (j = 0; j < cmd->chanlist_len; j++) {
            cfc_write_to_buffer(dev->read_subdev,
                        fake_waveform(dev,
                              CR_CHAN(cmd->
                                  chanlist[j]),
                              CR_RANGE(cmd->
                                   chanlist[j]),
                              devpriv->
                              usec_current +
                              i *
                              devpriv->scan_period +
                              j *
                              devpriv->
                              convert_period));
        }
        devpriv->ai_count++;
        if (cmd->stop_src == TRIG_COUNT
            && devpriv->ai_count >= cmd->stop_arg) {
            async->events |= COMEDI_CB_EOA;
            break;
        }
    }

    devpriv->usec_current += elapsed_time;
    devpriv->usec_current %= devpriv->usec_period;

    if ((async->events & COMEDI_CB_EOA) == 0 && devpriv->timer_running)
        mod_timer(&devpriv->timer, jiffies + 1);
    else
        del_timer(&devpriv->timer);

    comedi_event(dev, dev->read_subdev);
}

static int waveform_ai_cmdtest(struct comedi_device *dev,
                   struct comedi_subdevice *s,
                   struct comedi_cmd *cmd)
{
    int err = 0;
    int tmp;

    /* Step 1 : check if triggers are trivially valid */

    err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
    err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
    err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_NOW | TRIG_TIMER);
    err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
    err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);

    if (err)
        return 1;

    /* Step 2a : make sure trigger sources are unique */

    err |= cfc_check_trigger_is_unique(cmd->convert_src);
    err |= cfc_check_trigger_is_unique(cmd->stop_src);

    /* Step 2b : and mutually compatible */

    if (err)
        return 2;

    /* step 3: make sure arguments are trivially compatible */

    if (cmd->start_arg != 0) {
        cmd->start_arg = 0;
        err++;
    }
    if (cmd->convert_src == TRIG_NOW) {
        if (cmd->convert_arg != 0) {
            cmd->convert_arg = 0;
            err++;
        }
    }
    if (cmd->scan_begin_src == TRIG_TIMER) {
        if (cmd->scan_begin_arg < nano_per_micro) {
            cmd->scan_begin_arg = nano_per_micro;
            err++;
        }
        if (cmd->convert_src == TRIG_TIMER &&
            cmd->scan_begin_arg <
            cmd->convert_arg * cmd->chanlist_len) {
            cmd->scan_begin_arg =
                cmd->convert_arg * cmd->chanlist_len;
            err++;
        }
    }
    /*
     * XXX these checks are generic and should go in core if not there
     * already
     */
    if (!cmd->chanlist_len) {
        cmd->chanlist_len = 1;
        err++;
    }
    if (cmd->scan_end_arg != cmd->chanlist_len) {
        cmd->scan_end_arg = cmd->chanlist_len;
        err++;
    }

    if (cmd->stop_src == TRIG_COUNT) {
        if (!cmd->stop_arg) {
            cmd->stop_arg = 1;
            err++;
        }
    } else {        /* TRIG_NONE */
        if (cmd->stop_arg != 0) {
            cmd->stop_arg = 0;
            err++;
        }
    }

    if (err)
        return 3;

    /* step 4: fix up any arguments */

    if (cmd->scan_begin_src == TRIG_TIMER) {
        tmp = cmd->scan_begin_arg;
        /* round to nearest microsec */
        cmd->scan_begin_arg =
            nano_per_micro * ((tmp +
                       (nano_per_micro / 2)) / nano_per_micro);
        if (tmp != cmd->scan_begin_arg)
            err++;
    }
    if (cmd->convert_src == TRIG_TIMER) {
        tmp = cmd->convert_arg;
        /* round to nearest microsec */
        cmd->convert_arg =
            nano_per_micro * ((tmp +
                       (nano_per_micro / 2)) / nano_per_micro);
        if (tmp != cmd->convert_arg)
            err++;
    }

    if (err)
        return 4;

    return 0;
}

static int waveform_ai_cmd(struct comedi_device *dev,
               struct comedi_subdevice *s)
{
    struct waveform_private *devpriv = dev->private;
    struct comedi_cmd *cmd = &s->async->cmd;

    if (cmd->flags & TRIG_RT) {
        comedi_error(dev,
                 "commands at RT priority not supported in this driver");
        return -1;
    }

    devpriv->timer_running = 1;
    devpriv->ai_count = 0;
    devpriv->scan_period = cmd->scan_begin_arg / nano_per_micro;

    if (cmd->convert_src == TRIG_NOW)
        devpriv->convert_period = 0;
    else if (cmd->convert_src == TRIG_TIMER)
        devpriv->convert_period = cmd->convert_arg / nano_per_micro;
    else {
        comedi_error(dev, "bug setting conversion period");
        return -1;
    }

    do_gettimeofday(&devpriv->last);
    devpriv->usec_current = devpriv->last.tv_usec % devpriv->usec_period;
    devpriv->usec_remainder = 0;

    devpriv->timer.expires = jiffies + 1;
    add_timer(&devpriv->timer);
    return 0;
}

static int waveform_ai_cancel(struct comedi_device *dev,
                  struct comedi_subdevice *s)
{
    struct waveform_private *devpriv = dev->private;

    devpriv->timer_running = 0;
    del_timer(&devpriv->timer);
    return 0;
}

static int waveform_ai_insn_read(struct comedi_device *dev,
                 struct comedi_subdevice *s,
                 struct comedi_insn *insn, unsigned int *data)
{
    struct waveform_private *devpriv = dev->private;
    int i, chan = CR_CHAN(insn->chanspec);

    for (i = 0; i < insn->n; i++)
        data[i] = devpriv->ao_loopbacks[chan];

    return insn->n;
}

static int waveform_ao_insn_write(struct comedi_device *dev,
                  struct comedi_subdevice *s,
                  struct comedi_insn *insn, unsigned int *data)
{
    struct waveform_private *devpriv = dev->private;
    int i, chan = CR_CHAN(insn->chanspec);

    for (i = 0; i < insn->n; i++)
        devpriv->ao_loopbacks[chan] = data[i];

    return insn->n;
}

static int waveform_attach(struct comedi_device *dev,
               struct comedi_devconfig *it)
{
    struct waveform_private *devpriv;
    struct comedi_subdevice *s;
    int amplitude = it->options[0];
    int period = it->options[1];
    int i;
    int ret;

    dev->board_name = dev->driver->driver_name;

    ret = alloc_private(dev, sizeof(*devpriv));
    if (ret < 0)
        return ret;
    devpriv = dev->private;

    /* set default amplitude and period */
    if (amplitude <= 0)
        amplitude = 1000000;    /* 1 volt */
    if (period <= 0)
        period = 100000;    /* 0.1 sec */

    devpriv->uvolt_amplitude = amplitude;
    devpriv->usec_period = period;

    ret = comedi_alloc_subdevices(dev, 2);
    if (ret)
        return ret;

    s = &dev->subdevices[0];
    dev->read_subdev = s;
    /* analog input subdevice */
    s->type = COMEDI_SUBD_AI;
    s->subdev_flags = SDF_READABLE | SDF_GROUND | SDF_CMD_READ;
    s->n_chan = N_CHANS;
    s->maxdata = 0xffff;
    s->range_table = &waveform_ai_ranges;
    s->len_chanlist = s->n_chan * 2;
    s->insn_read = waveform_ai_insn_read;
    s->do_cmd = waveform_ai_cmd;
    s->do_cmdtest = waveform_ai_cmdtest;
    s->cancel = waveform_ai_cancel;

    s = &dev->subdevices[1];
    dev->write_subdev = s;
    /* analog output subdevice (loopback) */
    s->type = COMEDI_SUBD_AO;
    s->subdev_flags = SDF_WRITEABLE | SDF_GROUND;
    s->n_chan = N_CHANS;
    s->maxdata = 0xffff;
    s->range_table = &waveform_ai_ranges;
    s->len_chanlist = s->n_chan * 2;
    s->insn_write = waveform_ao_insn_write;
    s->do_cmd = NULL;
    s->do_cmdtest = NULL;
    s->cancel = NULL;

    /* Our default loopback value is just a 0V flatline */
    for (i = 0; i < s->n_chan; i++)
        devpriv->ao_loopbacks[i] = s->maxdata / 2;

    init_timer(&(devpriv->timer));
    devpriv->timer.function = waveform_ai_interrupt;
    devpriv->timer.data = (unsigned long)dev;

    dev_info(dev->class_dev,
        "%s: %i microvolt, %li microsecond waveform attached\n",
        dev->board_name,
        devpriv->uvolt_amplitude, devpriv->usec_period);

    return 0;
}

static void waveform_detach(struct comedi_device *dev)
{
    struct waveform_private *devpriv = dev->private;

    if (devpriv)
        waveform_ai_cancel(dev, dev->read_subdev);
}

static struct comedi_driver waveform_driver = {
    .driver_name    = "comedi_test",
    .module     = THIS_MODULE,
    .attach     = waveform_attach,
    .detach     = waveform_detach,
};
module_comedi_driver(waveform_driver);

MODULE_AUTHOR("Comedi http://www.comedi.org");
MODULE_DESCRIPTION("Comedi low-level driver");
MODULE_LICENSE("GPL");