xref: /openbmc/linux/drivers/comedi/drivers/comedi_8255.c (revision 631e272b)

// SPDX-License-Identifier: GPL-2.0+
/*
 * comedi_8255.c
 * Generic 8255 digital I/O support
 *
 * Split from the Comedi "8255" driver module.
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
 */

/*
 * Module: comedi_8255
 * Description: Generic 8255 support
 * Author: ds
 * Updated: Fri, 22 May 2015 12:14:17 +0000
 * Status: works
 *
 * This module is not used directly by end-users.  Rather, it is used by
 * other drivers to provide support for an 8255 "Programmable Peripheral
 * Interface" (PPI) chip.
 *
 * The classic in digital I/O.  The 8255 appears in Comedi as a single
 * digital I/O subdevice with 24 channels.  The channel 0 corresponds to
 * the 8255's port A, bit 0; channel 23 corresponds to port C, bit 7.
 * Direction configuration is done in blocks, with channels 0-7, 8-15,
 * 16-19, and 20-23 making up the 4 blocks.  The only 8255 mode
 * supported is mode 0.
 */

#include <linux/module.h>
#include <linux/comedi/comedidev.h>
#include <linux/comedi/comedi_8255.h>

struct subdev_8255_private {
	unsigned long regbase;
	int (*io)(struct comedi_device *dev, int dir, int port, int data,
		  unsigned long regbase);
};

static int subdev_8255_io(struct comedi_device *dev,
			  int dir, int port, int data, unsigned long regbase)
{
	if (dir) {
		outb(data, dev->iobase + regbase + port);
		return 0;
	}
	return inb(dev->iobase + regbase + port);
}

static int subdev_8255_mmio(struct comedi_device *dev,
			    int dir, int port, int data, unsigned long regbase)
{
	if (dir) {
		writeb(data, dev->mmio + regbase + port);
		return 0;
	}
	return readb(dev->mmio + regbase + port);
}

static int subdev_8255_insn(struct comedi_device *dev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn,
			    unsigned int *data)
{
	struct subdev_8255_private *spriv = s->private;
	unsigned long regbase = spriv->regbase;
	unsigned int mask;
	unsigned int v;

	mask = comedi_dio_update_state(s, data);
	if (mask) {
		if (mask & 0xff)
			spriv->io(dev, 1, I8255_DATA_A_REG,
				  s->state & 0xff, regbase);
		if (mask & 0xff00)
			spriv->io(dev, 1, I8255_DATA_B_REG,
				  (s->state >> 8) & 0xff, regbase);
		if (mask & 0xff0000)
			spriv->io(dev, 1, I8255_DATA_C_REG,
				  (s->state >> 16) & 0xff, regbase);
	}

	v = spriv->io(dev, 0, I8255_DATA_A_REG, 0, regbase);
	v |= (spriv->io(dev, 0, I8255_DATA_B_REG, 0, regbase) << 8);
	v |= (spriv->io(dev, 0, I8255_DATA_C_REG, 0, regbase) << 16);

	data[1] = v;

	return insn->n;
}

static void subdev_8255_do_config(struct comedi_device *dev,
				  struct comedi_subdevice *s)
{
	struct subdev_8255_private *spriv = s->private;
	unsigned long regbase = spriv->regbase;
	int config;

	config = I8255_CTRL_CW;
	/* 1 in io_bits indicates output, 1 in config indicates input */
	if (!(s->io_bits & 0x0000ff))
		config |= I8255_CTRL_A_IO;
	if (!(s->io_bits & 0x00ff00))
		config |= I8255_CTRL_B_IO;
	if (!(s->io_bits & 0x0f0000))
		config |= I8255_CTRL_C_LO_IO;
	if (!(s->io_bits & 0xf00000))
		config |= I8255_CTRL_C_HI_IO;

	spriv->io(dev, 1, I8255_CTRL_REG, config, regbase);
}

static int subdev_8255_insn_config(struct comedi_device *dev,
				   struct comedi_subdevice *s,
				   struct comedi_insn *insn,
				   unsigned int *data)
{
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int mask;
	int ret;

	if (chan < 8)
		mask = 0x0000ff;
	else if (chan < 16)
		mask = 0x00ff00;
	else if (chan < 20)
		mask = 0x0f0000;
	else
		mask = 0xf00000;

	ret = comedi_dio_insn_config(dev, s, insn, data, mask);
	if (ret)
		return ret;

	subdev_8255_do_config(dev, s);

	return insn->n;
}

static int __subdev_8255_init(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      int (*io)(struct comedi_device *dev,
					int dir, int port, int data,
					unsigned long regbase),
			      unsigned long regbase,
			      bool is_mmio)
{
	struct subdev_8255_private *spriv;

	spriv = comedi_alloc_spriv(s, sizeof(*spriv));
	if (!spriv)
		return -ENOMEM;

	if (io)
		spriv->io = io;
	else if (is_mmio)
		spriv->io = subdev_8255_mmio;
	else
		spriv->io = subdev_8255_io;
	spriv->regbase	= regbase;

	s->type		= COMEDI_SUBD_DIO;
	s->subdev_flags	= SDF_READABLE | SDF_WRITABLE;
	s->n_chan	= 24;
	s->range_table	= &range_digital;
	s->maxdata	= 1;
	s->insn_bits	= subdev_8255_insn;
	s->insn_config	= subdev_8255_insn_config;

	subdev_8255_do_config(dev, s);

	return 0;
}

/**
 * subdev_8255_init - initialize DIO subdevice for driving I/O mapped 8255
 * @dev: comedi device owning subdevice
 * @s: comedi subdevice to initialize
 * @io: (optional) register I/O call-back function
 * @regbase: offset of 8255 registers from dev->iobase, or call-back context
 *
 * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
 *
 * If the optional I/O call-back function is provided, its prototype is of
 * the following form:
 *
 *   int my_8255_callback(struct comedi_device *dev, int dir, int port,
 *                        int data, unsigned long regbase);
 *
 * where 'dev', and 'regbase' match the values passed to this function,
 * 'port' is the 8255 port number 0 to 3 (including the control port), 'dir'
 * is the direction (0 for read, 1 for write) and 'data' is the value to be
 * written.  It should return 0 if writing or the value read if reading.
 *
 * If the optional I/O call-back function is not provided, an internal
 * call-back function is used which uses consecutive I/O port addresses
 * starting at dev->iobase + regbase.
 *
 * Return: -ENOMEM if failed to allocate memory, zero on success.
 */
int subdev_8255_init(struct comedi_device *dev, struct comedi_subdevice *s,
		     int (*io)(struct comedi_device *dev, int dir, int port,
			       int data, unsigned long regbase),
		     unsigned long regbase)
{
	return __subdev_8255_init(dev, s, io, regbase, false);
}
EXPORT_SYMBOL_GPL(subdev_8255_init);

/**
 * subdev_8255_mm_init - initialize DIO subdevice for driving mmio-mapped 8255
 * @dev: comedi device owning subdevice
 * @s: comedi subdevice to initialize
 * @io: (optional) register I/O call-back function
 * @regbase: offset of 8255 registers from dev->mmio, or call-back context
 *
 * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
 *
 * If the optional I/O call-back function is provided, its prototype is of
 * the following form:
 *
 *   int my_8255_callback(struct comedi_device *dev, int dir, int port,
 *                        int data, unsigned long regbase);
 *
 * where 'dev', and 'regbase' match the values passed to this function,
 * 'port' is the 8255 port number 0 to 3 (including the control port), 'dir'
 * is the direction (0 for read, 1 for write) and 'data' is the value to be
 * written.  It should return 0 if writing or the value read if reading.
 *
 * If the optional I/O call-back function is not provided, an internal
 * call-back function is used which uses consecutive MMIO virtual addresses
 * starting at dev->mmio + regbase.
 *
 * Return: -ENOMEM if failed to allocate memory, zero on success.
 */
int subdev_8255_mm_init(struct comedi_device *dev, struct comedi_subdevice *s,
			int (*io)(struct comedi_device *dev, int dir, int port,
				  int data, unsigned long regbase),
			unsigned long regbase)
{
	return __subdev_8255_init(dev, s, io, regbase, true);
}
EXPORT_SYMBOL_GPL(subdev_8255_mm_init);

/**
 * subdev_8255_regbase - get offset of 8255 registers or call-back context
 * @s: comedi subdevice
 *
 * Returns the 'regbase' parameter that was previously passed to
 * subdev_8255_init() or subdev_8255_mm_init() to set up the subdevice.
 * Only valid if the subdevice was set up successfully.
 */
unsigned long subdev_8255_regbase(struct comedi_subdevice *s)
{
	struct subdev_8255_private *spriv = s->private;

	return spriv->regbase;
}
EXPORT_SYMBOL_GPL(subdev_8255_regbase);

static int __init comedi_8255_module_init(void)
{
	return 0;
}
module_init(comedi_8255_module_init);

static void __exit comedi_8255_module_exit(void)
{
}
module_exit(comedi_8255_module_exit);

MODULE_AUTHOR("Comedi https://www.comedi.org");
MODULE_DESCRIPTION("Comedi: Generic 8255 digital I/O support");
MODULE_LICENSE("GPL");