/*
    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 <Joachim.Wuttke@icn.siemens.de>
    Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net>

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 2000 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.
*/
/*
Driver: comedi_test
Description: generates fake waveforms
Author: Joachim Wuttke <Joachim.Wuttke@icn.siemens.de>, Frank Mori Hess
  <fmhess@users.sourceforge.net>, 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 <linux/module.h>
#include "../comedidev.h"

#include <asm/div64.h>

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

#define N_CHANS 8

enum waveform_state_bits {
        WAVEFORM_AI_RUNNING = 0
};

/* Data unique to this driver */
struct waveform_private {
        struct timer_list timer;
        ktime_t last;   /* time 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 (mod waveform period) */
        unsigned long usec_remainder;   /* usec since last scan */
        unsigned long state_bits;
        unsigned int scan_period;       /* scan period in usec */
        unsigned int convert_period;    /* conversion period in usec */
        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 unsigned 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 unsigned 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 unsigned 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 unsigned 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);
        case SQUARE_CHAN:
                return fake_squarewave(dev, range, current_time);
        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_subdevice *s = dev->read_subdev;
        struct comedi_async *async = s->async;
        struct comedi_cmd *cmd = &async->cmd;
        unsigned int i, j;
        /* all times in microsec */
        unsigned long elapsed_time;
        unsigned int num_scans;
        ktime_t now;

        /* check command is still active */
        if (!test_bit(WAVEFORM_AI_RUNNING, &devpriv->state_bits))
                return;

        now = ktime_get();

        elapsed_time = ktime_to_us(ktime_sub(now, devpriv->last));
        devpriv->last = now;
        num_scans =
            (devpriv->usec_remainder + elapsed_time) / devpriv->scan_period;
        devpriv->usec_remainder =
            (devpriv->usec_remainder + elapsed_time) % devpriv->scan_period;

        num_scans = comedi_nscans_left(s, num_scans);
        for (i = 0; i < num_scans; i++) {
                for (j = 0; j < cmd->chanlist_len; j++) {
                        unsigned short sample;

                        sample = fake_waveform(dev, CR_CHAN(cmd->chanlist[j]),
                                               CR_RANGE(cmd->chanlist[j]),
                                               devpriv->usec_current +
                                                   i * devpriv->scan_period +
                                                   j * devpriv->convert_period);
                        comedi_buf_write_samples(s, &sample, 1);
                }
        }

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

        if (cmd->stop_src == TRIG_COUNT && async->scans_done >= cmd->stop_arg)
                async->events |= COMEDI_CB_EOA;
        else
                mod_timer(&devpriv->timer, jiffies + 1);

        comedi_handle_events(dev, s);
}

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

        /* 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: check if arguments are trivially valid */

        err |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);

        if (cmd->convert_src == TRIG_NOW)
                err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);

        if (cmd->scan_begin_src == TRIG_TIMER) {
                err |= cfc_check_trigger_arg_min(&cmd->scan_begin_arg,
                                                 nano_per_micro);
                if (cmd->convert_src == TRIG_TIMER)
                        err |= cfc_check_trigger_arg_min(&cmd->scan_begin_arg,
                                        cmd->convert_arg * cmd->chanlist_len);
        }

        err |= cfc_check_trigger_arg_min(&cmd->chanlist_len, 1);
        err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);

        if (cmd->stop_src == TRIG_COUNT)
                err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
        else    /* TRIG_NONE */
                err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);

        if (err)
                return 3;

        /* step 4: fix up any arguments */

        if (cmd->scan_begin_src == TRIG_TIMER) {
                arg = cmd->scan_begin_arg;
                /* round to nearest microsec */
                arg = nano_per_micro *
                      ((arg + (nano_per_micro / 2)) / nano_per_micro);
                err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
        }
        if (cmd->convert_src == TRIG_TIMER) {
                arg = cmd->convert_arg;
                /* round to nearest microsec */
                arg = nano_per_micro *
                      ((arg + (nano_per_micro / 2)) / nano_per_micro);
                err |= cfc_check_trigger_arg_is(&cmd->convert_arg, arg);
        }

        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 & CMDF_PRIORITY) {
                dev_err(dev->class_dev,
                        "commands at RT priority not supported in this driver\n");
                return -1;
        }

        devpriv->scan_period = cmd->scan_begin_arg / nano_per_micro;

        if (cmd->convert_src == TRIG_NOW)
                devpriv->convert_period = 0;
        else    /* TRIG_TIMER */
                devpriv->convert_period = cmd->convert_arg / nano_per_micro;

        devpriv->last = ktime_get();
        devpriv->usec_current =
                ((u32)ktime_to_us(devpriv->last)) % devpriv->usec_period;
        devpriv->usec_remainder = 0;

        devpriv->timer.expires = jiffies + 1;
        /* mark command as active */
        smp_mb__before_atomic();
        set_bit(WAVEFORM_AI_RUNNING, &devpriv->state_bits);
        smp_mb__after_atomic();
        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;

        /* mark command as no longer active */
        clear_bit(WAVEFORM_AI_RUNNING, &devpriv->state_bits);
        smp_mb__after_atomic();
        /* cannot call del_timer_sync() as may be called from timer routine */
        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;

        devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
        if (!devpriv)
                return -ENOMEM;

        /* 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_WRITABLE | SDF_GROUND;
        s->n_chan = N_CHANS;
        s->maxdata = 0xffff;
        s->range_table = &waveform_ai_ranges;
        s->insn_write = waveform_ao_insn_write;

        /* 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)
                del_timer_sync(&devpriv->timer);
}

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");