// 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 context;
        int (*io)(struct comedi_device *dev, int dir, int port, int data,
                  unsigned long context);
};

#ifdef CONFIG_HAS_IOPORT

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);
}

#endif /* CONFIG_HAS_IOPORT */

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

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

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 context),
                              unsigned long context)
{
        struct subdev_8255_private *spriv;

        if (!io)
                return -EINVAL;

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

        spriv->context = context;
        spriv->io      = io;

        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;
}

#ifdef CONFIG_HAS_IOPORT

/**
 * subdev_8255_io_init - initialize DIO subdevice for driving I/O mapped 8255
 * @dev: comedi device owning subdevice
 * @s: comedi subdevice to initialize
 * @regbase: offset of 8255 registers from dev->iobase
 *
 * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
 *
 * Return: -ENOMEM if failed to allocate memory, zero on success.
 */
int subdev_8255_io_init(struct comedi_device *dev, struct comedi_subdevice *s,
                     unsigned long regbase)
{
        return __subdev_8255_init(dev, s, subdev_8255_io, regbase);
}
EXPORT_SYMBOL_GPL(subdev_8255_io_init);

#endif  /* CONFIG_HAS_IOPORT */

/**
 * subdev_8255_mm_init - initialize DIO subdevice for driving mmio-mapped 8255
 * @dev: comedi device owning subdevice
 * @s: comedi subdevice to initialize
 * @regbase: offset of 8255 registers from dev->mmio
 *
 * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
 *
 * Return: -ENOMEM if failed to allocate memory, zero on success.
 */
int subdev_8255_mm_init(struct comedi_device *dev, struct comedi_subdevice *s,
                        unsigned long regbase)
{
        return __subdev_8255_init(dev, s, subdev_8255_mmio, regbase);
}
EXPORT_SYMBOL_GPL(subdev_8255_mm_init);

/**
 * subdev_8255_cb_init - initialize DIO subdevice for driving callback-mapped 8255
 * @dev: comedi device owning subdevice
 * @s: comedi subdevice to initialize
 * @io: register I/O call-back function
 * @context: call-back context
 *
 * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
 *
 * The prototype of the I/O call-back function is of the following form:
 *
 *   int my_8255_callback(struct comedi_device *dev, int dir, int port,
 *                        int data, unsigned long context);
 *
 * where 'dev', and 'context' 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.
 *
 *
 * Return: -ENOMEM if failed to allocate memory, zero on success.
 */
int subdev_8255_cb_init(struct comedi_device *dev, struct comedi_subdevice *s,
                        int (*io)(struct comedi_device *dev, int dir, int port,
                                  int data, unsigned long context),
                        unsigned long context)
{
        return __subdev_8255_init(dev, s, io, context);
}
EXPORT_SYMBOL_GPL(subdev_8255_cb_init);

/**
 * subdev_8255_regbase - get offset of 8255 registers or call-back context
 * @s: comedi subdevice
 *
 * Returns the 'regbase' or 'context' parameter that was previously passed to
 * subdev_8255_io_init(), subdev_8255_mm_init(), or subdev_8255_cb_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->context;
}
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");