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

	if (err)
		return 1;

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

	err |= comedi_check_trigger_is_unique(cmd->convert_src);
	err |= comedi_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 |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);

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

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

	err |= comedi_check_trigger_arg_min(&cmd->chanlist_len, 1);
	err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg,
					   cmd->chanlist_len);

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

	setup_timer(&devpriv->timer, waveform_ai_interrupt,
		    (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");