drivers/comedi/drivers/cb_pcidda.c - linux/kernel/git/gregkh/char-misc - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * comedi/drivers/cb_pcidda.c
  * Driver for the ComputerBoards / MeasurementComputing PCI-DDA series.
  *
  * Copyright (C) 2001 Ivan Martinez <ivanmr@altavista.com>
  * Copyright (C) 2001 Frank Mori Hess <fmhess@users.sourceforge.net>
  *
  * COMEDI - Linux Control and Measurement Device Interface
  * Copyright (C) 1997-8 David A. Schleef <ds@schleef.org>
  */

 /*
  * Driver: cb_pcidda
  * Description: MeasurementComputing PCI-DDA series
  * Devices: [Measurement Computing] PCI-DDA08/12 (pci-dda08/12),
  *   PCI-DDA04/12 (pci-dda04/12), PCI-DDA02/12 (pci-dda02/12),
  *   PCI-DDA08/16 (pci-dda08/16), PCI-DDA04/16 (pci-dda04/16),
  *   PCI-DDA02/16 (pci-dda02/16)
  * Author: Ivan Martinez <ivanmr@altavista.com>
  *	   Frank Mori Hess <fmhess@users.sourceforge.net>
  * Status: works
  *
  * Configuration options: not applicable, uses PCI auto config
  *
  * Only simple analog output writing is supported.
  */

 #include <linux/module.h>

 #include "../comedi_pci.h"

 #include "8255.h"

 #define EEPROM_SIZE	128	/*  number of entries in eeprom */
 /* maximum number of ao channels for supported boards */
 #define MAX_AO_CHANNELS 8

 /* Digital I/O registers */
 #define CB_DDA_DIO0_8255_BASE		0x00
 #define CB_DDA_DIO1_8255_BASE		0x04

 /* DAC registers */
 #define CB_DDA_DA_CTRL_REG		0x00	   /* D/A Control Register  */
 #define CB_DDA_DA_CTRL_SU		BIT(0)   /*  Simultaneous update  */
 #define CB_DDA_DA_CTRL_EN		BIT(1)   /*  Enable specified DAC */
 #define CB_DDA_DA_CTRL_DAC(x)		((x) << 2) /*  Specify DAC channel  */
 #define CB_DDA_DA_CTRL_RANGE2V5		(0 << 6)   /*  2.5V range           */
 #define CB_DDA_DA_CTRL_RANGE5V		(2 << 6)   /*  5V range             */
 #define CB_DDA_DA_CTRL_RANGE10V		(3 << 6)   /*  10V range            */
 #define CB_DDA_DA_CTRL_UNIP		BIT(8)   /*  Unipolar range       */

 #define DACALIBRATION1	4	/*  D/A CALIBRATION REGISTER 1 */
 /* write bits */
 /* serial data input for eeprom, caldacs, reference dac */
 #define SERIAL_IN_BIT   0x1
 #define	CAL_CHANNEL_MASK	(0x7 << 1)
 #define	CAL_CHANNEL_BITS(channel)	(((channel) << 1) & CAL_CHANNEL_MASK)
 /* read bits */
 #define	CAL_COUNTER_MASK	0x1f
 /* calibration counter overflow status bit */
 #define CAL_COUNTER_OVERFLOW_BIT        0x20
 /* analog output is less than reference dac voltage */
 #define AO_BELOW_REF_BIT        0x40
 #define	SERIAL_OUT_BIT	0x80	/*  serial data out, for reading from eeprom */

 #define DACALIBRATION2	6	/*  D/A CALIBRATION REGISTER 2 */
 #define	SELECT_EEPROM_BIT	0x1	/*  send serial data in to eeprom */
 /* don't send serial data to MAX542 reference dac */
 #define DESELECT_REF_DAC_BIT    0x2
 /* don't send serial data to caldac n */
 #define DESELECT_CALDAC_BIT(n)  (0x4 << (n))
 /* manual says to set this bit with no explanation */
 #define DUMMY_BIT       0x40

 #define CB_DDA_DA_DATA_REG(x)		(0x08 + ((x) * 2))

 /* Offsets for the caldac channels */
 #define CB_DDA_CALDAC_FINE_GAIN		0
 #define CB_DDA_CALDAC_COURSE_GAIN	1
 #define CB_DDA_CALDAC_COURSE_OFFSET	2
 #define CB_DDA_CALDAC_FINE_OFFSET	3

 static const struct comedi_lrange cb_pcidda_ranges = {
 	6, {
 		BIP_RANGE(10),
 		BIP_RANGE(5),
 		BIP_RANGE(2.5),
 		UNI_RANGE(10),
 		UNI_RANGE(5),
 		UNI_RANGE(2.5)
 	}
 };

 enum cb_pcidda_boardid {
 	BOARD_DDA02_12,
 	BOARD_DDA04_12,
 	BOARD_DDA08_12,
 	BOARD_DDA02_16,
 	BOARD_DDA04_16,
 	BOARD_DDA08_16,
 };

 struct cb_pcidda_board {
 	const char *name;
 	int ao_chans;
 	int ao_bits;
 };

 static const struct cb_pcidda_board cb_pcidda_boards[] = {
 	[BOARD_DDA02_12] = {
 		.name		= "pci-dda02/12",
 		.ao_chans	= 2,
 		.ao_bits	= 12,
 	},
 	[BOARD_DDA04_12] = {
 		.name		= "pci-dda04/12",
 		.ao_chans	= 4,
 		.ao_bits	= 12,
 	},
 	[BOARD_DDA08_12] = {
 		.name		= "pci-dda08/12",
 		.ao_chans	= 8,
 		.ao_bits	= 12,
 	},
 	[BOARD_DDA02_16] = {
 		.name		= "pci-dda02/16",
 		.ao_chans	= 2,
 		.ao_bits	= 16,
 	},
 	[BOARD_DDA04_16] = {
 		.name		= "pci-dda04/16",
 		.ao_chans	= 4,
 		.ao_bits	= 16,
 	},
 	[BOARD_DDA08_16] = {
 		.name		= "pci-dda08/16",
 		.ao_chans	= 8,
 		.ao_bits	= 16,
 	},
 };

 struct cb_pcidda_private {
 	unsigned long daqio;
 	/* bits last written to da calibration register 1 */
 	unsigned int dac_cal1_bits;
 	/* current range settings for output channels */
 	unsigned int ao_range[MAX_AO_CHANNELS];
 	u16 eeprom_data[EEPROM_SIZE];	/*  software copy of board's eeprom */
 };

 /* lowlevel read from eeprom */
 static unsigned int cb_pcidda_serial_in(struct comedi_device *dev)
 {
 	struct cb_pcidda_private *devpriv = dev->private;
 	unsigned int value = 0;
 	int i;
 	const int value_width = 16;	/*  number of bits wide values are */

 	for (i = 1; i <= value_width; i++) {
 		/*  read bits most significant bit first */
 		if (inw_p(devpriv->daqio + DACALIBRATION1) & SERIAL_OUT_BIT)
 			value |= 1 << (value_width - i);
 	}

 	return value;
 }

 /* lowlevel write to eeprom/dac */
 static void cb_pcidda_serial_out(struct comedi_device *dev, unsigned int value,
 				 unsigned int num_bits)
 {
 	struct cb_pcidda_private *devpriv = dev->private;
 	int i;

 	for (i = 1; i <= num_bits; i++) {
 		/*  send bits most significant bit first */
 		if (value & (1 << (num_bits - i)))
 			devpriv->dac_cal1_bits |= SERIAL_IN_BIT;
 		else
 			devpriv->dac_cal1_bits &= ~SERIAL_IN_BIT;
 		outw_p(devpriv->dac_cal1_bits, devpriv->daqio + DACALIBRATION1);
 	}
 }

 /* reads a 16 bit value from board's eeprom */
 static unsigned int cb_pcidda_read_eeprom(struct comedi_device *dev,
 					  unsigned int address)
 {
 	struct cb_pcidda_private *devpriv = dev->private;
 	unsigned int i;
 	unsigned int cal2_bits;
 	unsigned int value;
 	/* one caldac for every two dac channels */
 	const int max_num_caldacs = 4;
 	/* bits to send to tell eeprom we want to read */
 	const int read_instruction = 0x6;
 	const int instruction_length = 3;
 	const int address_length = 8;

 	/*  send serial output stream to eeprom */
 	cal2_bits = SELECT_EEPROM_BIT | DESELECT_REF_DAC_BIT | DUMMY_BIT;
 	/*  deactivate caldacs (one caldac for every two channels) */
 	for (i = 0; i < max_num_caldacs; i++)
 		cal2_bits |= DESELECT_CALDAC_BIT(i);
 	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);

 	/*  tell eeprom we want to read */
 	cb_pcidda_serial_out(dev, read_instruction, instruction_length);
 	/*  send address we want to read from */
 	cb_pcidda_serial_out(dev, address, address_length);

 	value = cb_pcidda_serial_in(dev);

 	/*  deactivate eeprom */
 	cal2_bits &= ~SELECT_EEPROM_BIT;
 	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);

 	return value;
 }

 /* writes to 8 bit calibration dacs */
 static void cb_pcidda_write_caldac(struct comedi_device *dev,
 				   unsigned int caldac, unsigned int channel,
 				   unsigned int value)
 {
 	struct cb_pcidda_private *devpriv = dev->private;
 	unsigned int cal2_bits;
 	unsigned int i;
 	/* caldacs use 3 bit channel specification */
 	const int num_channel_bits = 3;
 	const int num_caldac_bits = 8;	/*  8 bit calibration dacs */
 	/* one caldac for every two dac channels */
 	const int max_num_caldacs = 4;

 	/* write 3 bit channel */
 	cb_pcidda_serial_out(dev, channel, num_channel_bits);
 	/*  write 8 bit caldac value */
 	cb_pcidda_serial_out(dev, value, num_caldac_bits);

 /*
  * latch stream into appropriate caldac deselect reference dac
  */
 	cal2_bits = DESELECT_REF_DAC_BIT | DUMMY_BIT;
 	/*  deactivate caldacs (one caldac for every two channels) */
 	for (i = 0; i < max_num_caldacs; i++)
 		cal2_bits |= DESELECT_CALDAC_BIT(i);
 	/*  activate the caldac we want */
 	cal2_bits &= ~DESELECT_CALDAC_BIT(caldac);
 	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);
 	/*  deactivate caldac */
 	cal2_bits |= DESELECT_CALDAC_BIT(caldac);
 	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);
 }

 /* set caldacs to eeprom values for given channel and range */
 static void cb_pcidda_calibrate(struct comedi_device *dev, unsigned int channel,
 				unsigned int range)
 {
 	struct cb_pcidda_private *devpriv = dev->private;
 	unsigned int caldac = channel / 2;	/* two caldacs per channel */
 	unsigned int chan = 4 * (channel % 2);	/* caldac channel base */
 	unsigned int index = 2 * range + 12 * channel;
 	unsigned int offset;
 	unsigned int gain;

 	/* save range so we can tell when we need to readjust calibration */
 	devpriv->ao_range[channel] = range;

 	/* get values from eeprom data */
 	offset = devpriv->eeprom_data[0x7 + index];
 	gain = devpriv->eeprom_data[0x8 + index];

 	/* set caldacs */
 	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_COURSE_OFFSET,
 			       (offset >> 8) & 0xff);
 	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_FINE_OFFSET,
 			       offset & 0xff);
 	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_COURSE_GAIN,
 			       (gain >> 8) & 0xff);
 	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_FINE_GAIN,
 			       gain & 0xff);
 }

 static int cb_pcidda_ao_insn_write(struct comedi_device *dev,
 				   struct comedi_subdevice *s,
 				   struct comedi_insn *insn,
 				   unsigned int *data)
 {
 	struct cb_pcidda_private *devpriv = dev->private;
 	unsigned int channel = CR_CHAN(insn->chanspec);
 	unsigned int range = CR_RANGE(insn->chanspec);
 	unsigned int ctrl;
 	unsigned int i;

 	if (range != devpriv->ao_range[channel])
 		cb_pcidda_calibrate(dev, channel, range);

 	ctrl = CB_DDA_DA_CTRL_EN | CB_DDA_DA_CTRL_DAC(channel);

 	switch (range) {
 	case 0:
 	case 3:
 		ctrl |= CB_DDA_DA_CTRL_RANGE10V;
 		break;
 	case 1:
 	case 4:
 		ctrl |= CB_DDA_DA_CTRL_RANGE5V;
 		break;
 	case 2:
 	case 5:
 		ctrl |= CB_DDA_DA_CTRL_RANGE2V5;
 		break;
 	}

 	if (range > 2)
 		ctrl |= CB_DDA_DA_CTRL_UNIP;

 	outw(ctrl, devpriv->daqio + CB_DDA_DA_CTRL_REG);

 	for (i = 0; i < insn->n; i++)
 		outw(data[i], devpriv->daqio + CB_DDA_DA_DATA_REG(channel));

 	return insn->n;
 }

 static int cb_pcidda_auto_attach(struct comedi_device *dev,
 				 unsigned long context)
 {
 	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
 	const struct cb_pcidda_board *board = NULL;
 	struct cb_pcidda_private *devpriv;
 	struct comedi_subdevice *s;
 	int i;
 	int ret;

 	if (context < ARRAY_SIZE(cb_pcidda_boards))
 		board = &cb_pcidda_boards[context];
 	if (!board)
 		return -ENODEV;
 	dev->board_ptr = board;
 	dev->board_name = board->name;

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

 	ret = comedi_pci_enable(dev);
 	if (ret)
 		return ret;
 	dev->iobase = pci_resource_start(pcidev, 2);
 	devpriv->daqio = pci_resource_start(pcidev, 3);

 	ret = comedi_alloc_subdevices(dev, 3);
 	if (ret)
 		return ret;

 	s = &dev->subdevices[0];
 	/* analog output subdevice */
 	s->type = COMEDI_SUBD_AO;
 	s->subdev_flags = SDF_WRITABLE;
 	s->n_chan = board->ao_chans;
 	s->maxdata = (1 << board->ao_bits) - 1;
 	s->range_table = &cb_pcidda_ranges;
 	s->insn_write = cb_pcidda_ao_insn_write;

 	/* two 8255 digital io subdevices */
 	for (i = 0; i < 2; i++) {
 		s = &dev->subdevices[1 + i];
 		ret = subdev_8255_init(dev, s, NULL, i * I8255_SIZE);
 		if (ret)
 			return ret;
 	}

 	/* Read the caldac eeprom data */
 	for (i = 0; i < EEPROM_SIZE; i++)
 		devpriv->eeprom_data[i] = cb_pcidda_read_eeprom(dev, i);

 	/*  set calibrations dacs */
 	for (i = 0; i < board->ao_chans; i++)
 		cb_pcidda_calibrate(dev, i, devpriv->ao_range[i]);

 	return 0;
 }

 static struct comedi_driver cb_pcidda_driver = {
 	.driver_name	= "cb_pcidda",
 	.module		= THIS_MODULE,
 	.auto_attach	= cb_pcidda_auto_attach,
 	.detach		= comedi_pci_detach,
 };

 static int cb_pcidda_pci_probe(struct pci_dev *dev,
 			       const struct pci_device_id *id)
 {
 	return comedi_pci_auto_config(dev, &cb_pcidda_driver,
 				      id->driver_data);
 }

 static const struct pci_device_id cb_pcidda_pci_table[] = {
 	{ PCI_VDEVICE(CB, 0x0020), BOARD_DDA02_12 },
 	{ PCI_VDEVICE(CB, 0x0021), BOARD_DDA04_12 },
 	{ PCI_VDEVICE(CB, 0x0022), BOARD_DDA08_12 },
 	{ PCI_VDEVICE(CB, 0x0023), BOARD_DDA02_16 },
 	{ PCI_VDEVICE(CB, 0x0024), BOARD_DDA04_16 },
 	{ PCI_VDEVICE(CB, 0x0025), BOARD_DDA08_16 },
 	{ 0 }
 };
 MODULE_DEVICE_TABLE(pci, cb_pcidda_pci_table);

 static struct pci_driver cb_pcidda_pci_driver = {
 	.name		= "cb_pcidda",
 	.id_table	= cb_pcidda_pci_table,
 	.probe		= cb_pcidda_pci_probe,
 	.remove		= comedi_pci_auto_unconfig,
 };
 module_comedi_pci_driver(cb_pcidda_driver, cb_pcidda_pci_driver);

 MODULE_AUTHOR("Comedi https://www.comedi.org");
 MODULE_DESCRIPTION("Comedi low-level driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* comedi/drivers/cb_pcidda.c
	* Driver for the ComputerBoards / MeasurementComputing PCI-DDA series.
	*
	* Copyright (C) 2001 Ivan Martinez <ivanmr@altavista.com>
	* Copyright (C) 2001 Frank Mori Hess <fmhess@users.sourceforge.net>
	*
	* COMEDI - Linux Control and Measurement Device Interface
	* Copyright (C) 1997-8 David A. Schleef <ds@schleef.org>
	*/

	/*
	* Driver: cb_pcidda
	* Description: MeasurementComputing PCI-DDA series
	* Devices: [Measurement Computing] PCI-DDA08/12 (pci-dda08/12),
	* PCI-DDA04/12 (pci-dda04/12), PCI-DDA02/12 (pci-dda02/12),
	* PCI-DDA08/16 (pci-dda08/16), PCI-DDA04/16 (pci-dda04/16),
	* PCI-DDA02/16 (pci-dda02/16)
	* Author: Ivan Martinez <ivanmr@altavista.com>
	* Frank Mori Hess <fmhess@users.sourceforge.net>
	* Status: works
	*
	* Configuration options: not applicable, uses PCI auto config
	*
	* Only simple analog output writing is supported.
	*/

	#include <linux/module.h>

	#include "../comedi_pci.h"

	#include "8255.h"

	#define EEPROM_SIZE 128 /* number of entries in eeprom */
	/* maximum number of ao channels for supported boards */
	#define MAX_AO_CHANNELS 8

	/* Digital I/O registers */
	#define CB_DDA_DIO0_8255_BASE 0x00
	#define CB_DDA_DIO1_8255_BASE 0x04

	/* DAC registers */
	#define CB_DDA_DA_CTRL_REG 0x00 /* D/A Control Register */
	#define CB_DDA_DA_CTRL_SU BIT(0) /* Simultaneous update */
	#define CB_DDA_DA_CTRL_EN BIT(1) /* Enable specified DAC */
	#define CB_DDA_DA_CTRL_DAC(x) ((x) << 2) /* Specify DAC channel */
	#define CB_DDA_DA_CTRL_RANGE2V5 (0 << 6) /* 2.5V range */
	#define CB_DDA_DA_CTRL_RANGE5V (2 << 6) /* 5V range */
	#define CB_DDA_DA_CTRL_RANGE10V (3 << 6) /* 10V range */
	#define CB_DDA_DA_CTRL_UNIP BIT(8) /* Unipolar range */

	#define DACALIBRATION1 4 /* D/A CALIBRATION REGISTER 1 */
	/* write bits */
	/* serial data input for eeprom, caldacs, reference dac */
	#define SERIAL_IN_BIT 0x1
	#define CAL_CHANNEL_MASK (0x7 << 1)
	#define CAL_CHANNEL_BITS(channel) (((channel) << 1) & CAL_CHANNEL_MASK)
	/* read bits */
	#define CAL_COUNTER_MASK 0x1f
	/* calibration counter overflow status bit */
	#define CAL_COUNTER_OVERFLOW_BIT 0x20
	/* analog output is less than reference dac voltage */
	#define AO_BELOW_REF_BIT 0x40
	#define SERIAL_OUT_BIT 0x80 /* serial data out, for reading from eeprom */

	#define DACALIBRATION2 6 /* D/A CALIBRATION REGISTER 2 */
	#define SELECT_EEPROM_BIT 0x1 /* send serial data in to eeprom */
	/* don't send serial data to MAX542 reference dac */
	#define DESELECT_REF_DAC_BIT 0x2
	/* don't send serial data to caldac n */
	#define DESELECT_CALDAC_BIT(n) (0x4 << (n))
	/* manual says to set this bit with no explanation */
	#define DUMMY_BIT 0x40

	#define CB_DDA_DA_DATA_REG(x) (0x08 + ((x) * 2))

	/* Offsets for the caldac channels */
	#define CB_DDA_CALDAC_FINE_GAIN 0
	#define CB_DDA_CALDAC_COURSE_GAIN 1
	#define CB_DDA_CALDAC_COURSE_OFFSET 2
	#define CB_DDA_CALDAC_FINE_OFFSET 3

	static const struct comedi_lrange cb_pcidda_ranges = {
	6, {
	BIP_RANGE(10),
	BIP_RANGE(5),
	BIP_RANGE(2.5),
	UNI_RANGE(10),
	UNI_RANGE(5),
	UNI_RANGE(2.5)
	}
	};

	enum cb_pcidda_boardid {
	BOARD_DDA02_12,
	BOARD_DDA04_12,
	BOARD_DDA08_12,
	BOARD_DDA02_16,
	BOARD_DDA04_16,
	BOARD_DDA08_16,
	};

	struct cb_pcidda_board {
	const char *name;
	int ao_chans;
	int ao_bits;
	};

	static const struct cb_pcidda_board cb_pcidda_boards[] = {
	[BOARD_DDA02_12] = {
	.name = "pci-dda02/12",
	.ao_chans = 2,
	.ao_bits = 12,
	},
	[BOARD_DDA04_12] = {
	.name = "pci-dda04/12",
	.ao_chans = 4,
	.ao_bits = 12,
	},
	[BOARD_DDA08_12] = {
	.name = "pci-dda08/12",
	.ao_chans = 8,
	.ao_bits = 12,
	},
	[BOARD_DDA02_16] = {
	.name = "pci-dda02/16",
	.ao_chans = 2,
	.ao_bits = 16,
	},
	[BOARD_DDA04_16] = {
	.name = "pci-dda04/16",
	.ao_chans = 4,
	.ao_bits = 16,
	},
	[BOARD_DDA08_16] = {
	.name = "pci-dda08/16",
	.ao_chans = 8,
	.ao_bits = 16,
	},
	};

	struct cb_pcidda_private {
	unsigned long daqio;
	/* bits last written to da calibration register 1 */
	unsigned int dac_cal1_bits;
	/* current range settings for output channels */
	unsigned int ao_range[MAX_AO_CHANNELS];
	u16 eeprom_data[EEPROM_SIZE]; /* software copy of board's eeprom */
	};

	/* lowlevel read from eeprom */
	static unsigned int cb_pcidda_serial_in(struct comedi_device *dev)
	{
	struct cb_pcidda_private *devpriv = dev->private;
	unsigned int value = 0;
	int i;
	const int value_width = 16; /* number of bits wide values are */

	for (i = 1; i <= value_width; i++) {
	/* read bits most significant bit first */
	if (inw_p(devpriv->daqio + DACALIBRATION1) & SERIAL_OUT_BIT)
	value \|= 1 << (value_width - i);
	}

	return value;
	}

	/* lowlevel write to eeprom/dac */
	static void cb_pcidda_serial_out(struct comedi_device *dev, unsigned int value,
	unsigned int num_bits)
	{
	struct cb_pcidda_private *devpriv = dev->private;
	int i;

	for (i = 1; i <= num_bits; i++) {
	/* send bits most significant bit first */
	if (value & (1 << (num_bits - i)))
	devpriv->dac_cal1_bits \|= SERIAL_IN_BIT;
	else
	devpriv->dac_cal1_bits &= ~SERIAL_IN_BIT;
	outw_p(devpriv->dac_cal1_bits, devpriv->daqio + DACALIBRATION1);
	}
	}

	/* reads a 16 bit value from board's eeprom */
	static unsigned int cb_pcidda_read_eeprom(struct comedi_device *dev,
	unsigned int address)
	{
	struct cb_pcidda_private *devpriv = dev->private;
	unsigned int i;
	unsigned int cal2_bits;
	unsigned int value;
	/* one caldac for every two dac channels */
	const int max_num_caldacs = 4;
	/* bits to send to tell eeprom we want to read */
	const int read_instruction = 0x6;
	const int instruction_length = 3;
	const int address_length = 8;

	/* send serial output stream to eeprom */
	cal2_bits = SELECT_EEPROM_BIT \| DESELECT_REF_DAC_BIT \| DUMMY_BIT;
	/* deactivate caldacs (one caldac for every two channels) */
	for (i = 0; i < max_num_caldacs; i++)
	cal2_bits \|= DESELECT_CALDAC_BIT(i);
	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);

	/* tell eeprom we want to read */
	cb_pcidda_serial_out(dev, read_instruction, instruction_length);
	/* send address we want to read from */
	cb_pcidda_serial_out(dev, address, address_length);

	value = cb_pcidda_serial_in(dev);

	/* deactivate eeprom */
	cal2_bits &= ~SELECT_EEPROM_BIT;
	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);

	return value;
	}

	/* writes to 8 bit calibration dacs */
	static void cb_pcidda_write_caldac(struct comedi_device *dev,
	unsigned int caldac, unsigned int channel,
	unsigned int value)
	{
	struct cb_pcidda_private *devpriv = dev->private;
	unsigned int cal2_bits;
	unsigned int i;
	/* caldacs use 3 bit channel specification */
	const int num_channel_bits = 3;
	const int num_caldac_bits = 8; /* 8 bit calibration dacs */
	/* one caldac for every two dac channels */
	const int max_num_caldacs = 4;

	/* write 3 bit channel */
	cb_pcidda_serial_out(dev, channel, num_channel_bits);
	/* write 8 bit caldac value */
	cb_pcidda_serial_out(dev, value, num_caldac_bits);

	/*
	* latch stream into appropriate caldac deselect reference dac
	*/
	cal2_bits = DESELECT_REF_DAC_BIT \| DUMMY_BIT;
	/* deactivate caldacs (one caldac for every two channels) */
	for (i = 0; i < max_num_caldacs; i++)
	cal2_bits \|= DESELECT_CALDAC_BIT(i);
	/* activate the caldac we want */
	cal2_bits &= ~DESELECT_CALDAC_BIT(caldac);
	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);
	/* deactivate caldac */
	cal2_bits \|= DESELECT_CALDAC_BIT(caldac);
	outw_p(cal2_bits, devpriv->daqio + DACALIBRATION2);
	}

	/* set caldacs to eeprom values for given channel and range */
	static void cb_pcidda_calibrate(struct comedi_device *dev, unsigned int channel,
	unsigned int range)
	{
	struct cb_pcidda_private *devpriv = dev->private;
	unsigned int caldac = channel / 2; /* two caldacs per channel */
	unsigned int chan = 4 * (channel % 2); /* caldac channel base */
	unsigned int index = 2 * range + 12 * channel;
	unsigned int offset;
	unsigned int gain;

	/* save range so we can tell when we need to readjust calibration */
	devpriv->ao_range[channel] = range;

	/* get values from eeprom data */
	offset = devpriv->eeprom_data[0x7 + index];
	gain = devpriv->eeprom_data[0x8 + index];

	/* set caldacs */
	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_COURSE_OFFSET,
	(offset >> 8) & 0xff);
	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_FINE_OFFSET,
	offset & 0xff);
	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_COURSE_GAIN,
	(gain >> 8) & 0xff);
	cb_pcidda_write_caldac(dev, caldac, chan + CB_DDA_CALDAC_FINE_GAIN,
	gain & 0xff);
	}

	static int cb_pcidda_ao_insn_write(struct comedi_device *dev,
	struct comedi_subdevice *s,
	struct comedi_insn *insn,
	unsigned int *data)
	{
	struct cb_pcidda_private *devpriv = dev->private;
	unsigned int channel = CR_CHAN(insn->chanspec);
	unsigned int range = CR_RANGE(insn->chanspec);
	unsigned int ctrl;
	unsigned int i;

	if (range != devpriv->ao_range[channel])
	cb_pcidda_calibrate(dev, channel, range);

	ctrl = CB_DDA_DA_CTRL_EN \| CB_DDA_DA_CTRL_DAC(channel);

	switch (range) {
	case 0:
	case 3:
	ctrl \|= CB_DDA_DA_CTRL_RANGE10V;
	break;
	case 1:
	case 4:
	ctrl \|= CB_DDA_DA_CTRL_RANGE5V;
	break;
	case 2:
	case 5:
	ctrl \|= CB_DDA_DA_CTRL_RANGE2V5;
	break;
	}

	if (range > 2)
	ctrl \|= CB_DDA_DA_CTRL_UNIP;

	outw(ctrl, devpriv->daqio + CB_DDA_DA_CTRL_REG);

	for (i = 0; i < insn->n; i++)
	outw(data[i], devpriv->daqio + CB_DDA_DA_DATA_REG(channel));

	return insn->n;
	}

	static int cb_pcidda_auto_attach(struct comedi_device *dev,
	unsigned long context)
	{
	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
	const struct cb_pcidda_board *board = NULL;
	struct cb_pcidda_private *devpriv;
	struct comedi_subdevice *s;
	int i;
	int ret;

	if (context < ARRAY_SIZE(cb_pcidda_boards))
	board = &cb_pcidda_boards[context];
	if (!board)
	return -ENODEV;
	dev->board_ptr = board;
	dev->board_name = board->name;

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

	ret = comedi_pci_enable(dev);
	if (ret)
	return ret;
	dev->iobase = pci_resource_start(pcidev, 2);
	devpriv->daqio = pci_resource_start(pcidev, 3);

	ret = comedi_alloc_subdevices(dev, 3);
	if (ret)
	return ret;

	s = &dev->subdevices[0];
	/* analog output subdevice */
	s->type = COMEDI_SUBD_AO;
	s->subdev_flags = SDF_WRITABLE;
	s->n_chan = board->ao_chans;
	s->maxdata = (1 << board->ao_bits) - 1;
	s->range_table = &cb_pcidda_ranges;
	s->insn_write = cb_pcidda_ao_insn_write;

	/* two 8255 digital io subdevices */
	for (i = 0; i < 2; i++) {
	s = &dev->subdevices[1 + i];
	ret = subdev_8255_init(dev, s, NULL, i * I8255_SIZE);
	if (ret)
	return ret;
	}

	/* Read the caldac eeprom data */
	for (i = 0; i < EEPROM_SIZE; i++)
	devpriv->eeprom_data[i] = cb_pcidda_read_eeprom(dev, i);

	/* set calibrations dacs */
	for (i = 0; i < board->ao_chans; i++)
	cb_pcidda_calibrate(dev, i, devpriv->ao_range[i]);

	return 0;
	}

	static struct comedi_driver cb_pcidda_driver = {
	.driver_name = "cb_pcidda",
	.module = THIS_MODULE,
	.auto_attach = cb_pcidda_auto_attach,
	.detach = comedi_pci_detach,
	};

	static int cb_pcidda_pci_probe(struct pci_dev *dev,
	const struct pci_device_id *id)
	{
	return comedi_pci_auto_config(dev, &cb_pcidda_driver,
	id->driver_data);
	}

	static const struct pci_device_id cb_pcidda_pci_table[] = {
	{ PCI_VDEVICE(CB, 0x0020), BOARD_DDA02_12 },
	{ PCI_VDEVICE(CB, 0x0021), BOARD_DDA04_12 },
	{ PCI_VDEVICE(CB, 0x0022), BOARD_DDA08_12 },
	{ PCI_VDEVICE(CB, 0x0023), BOARD_DDA02_16 },
	{ PCI_VDEVICE(CB, 0x0024), BOARD_DDA04_16 },
	{ PCI_VDEVICE(CB, 0x0025), BOARD_DDA08_16 },
	{ 0 }
	};
	MODULE_DEVICE_TABLE(pci, cb_pcidda_pci_table);

	static struct pci_driver cb_pcidda_pci_driver = {
	.name = "cb_pcidda",
	.id_table = cb_pcidda_pci_table,
	.probe = cb_pcidda_pci_probe,
	.remove = comedi_pci_auto_unconfig,
	};
	module_comedi_pci_driver(cb_pcidda_driver, cb_pcidda_pci_driver);

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