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+/*
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+ * comedi_8255.c
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+ * Generic 8255 digital I/O support
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+ *
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+ * Split from the Comedi "8255" driver module.
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+ *
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+ * COMEDI - Linux Control and Measurement Device Interface
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+ * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ */
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+
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+/*
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+ * Module: comedi_8255
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+ * Description: Generic 8255 support
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+ * Author: ds
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+ * Updated: Fri, 22 May 2015 12:14:17 +0000
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+ * Status: works
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+ *
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+ * This module is not used directly by end-users. Rather, it is used by
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+ * other drivers to provide support for an 8255 "Programmable Peripheral
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+ * Interface" (PPI) chip.
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+ *
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+ * The classic in digital I/O. The 8255 appears in Comedi as a single
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+ * digital I/O subdevice with 24 channels. The channel 0 corresponds to
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+ * the 8255's port A, bit 0; channel 23 corresponds to port C, bit 7.
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+ * Direction configuration is done in blocks, with channels 0-7, 8-15,
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+ * 16-19, and 20-23 making up the 4 blocks. The only 8255 mode
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+ * supported is mode 0.
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+ */
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+
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+#include <linux/module.h>
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+#include "../comedidev.h"
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+
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+#include "8255.h"
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+
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+struct subdev_8255_private {
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+ unsigned long regbase;
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+ int (*io)(struct comedi_device *dev, int dir, int port, int data,
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+ unsigned long regbase);
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+};
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+
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+static int subdev_8255_io(struct comedi_device *dev,
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+ int dir, int port, int data, unsigned long regbase)
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+{
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+ if (dir) {
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+ outb(data, dev->iobase + regbase + port);
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+ return 0;
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+ }
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+ return inb(dev->iobase + regbase + port);
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+}
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+
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+static int subdev_8255_mmio(struct comedi_device *dev,
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+ int dir, int port, int data, unsigned long regbase)
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+{
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+ if (dir) {
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+ writeb(data, dev->mmio + regbase + port);
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+ return 0;
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+ }
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+ return readb(dev->mmio + regbase + port);
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+}
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+
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+static int subdev_8255_insn(struct comedi_device *dev,
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+ struct comedi_subdevice *s,
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+ struct comedi_insn *insn,
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+ unsigned int *data)
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+{
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+ struct subdev_8255_private *spriv = s->private;
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+ unsigned long regbase = spriv->regbase;
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+ unsigned int mask;
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+ unsigned int v;
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+
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+ mask = comedi_dio_update_state(s, data);
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+ if (mask) {
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+ if (mask & 0xff)
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+ spriv->io(dev, 1, I8255_DATA_A_REG,
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+ s->state & 0xff, regbase);
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+ if (mask & 0xff00)
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+ spriv->io(dev, 1, I8255_DATA_B_REG,
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+ (s->state >> 8) & 0xff, regbase);
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+ if (mask & 0xff0000)
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+ spriv->io(dev, 1, I8255_DATA_C_REG,
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+ (s->state >> 16) & 0xff, regbase);
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+ }
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+
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+ v = spriv->io(dev, 0, I8255_DATA_A_REG, 0, regbase);
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+ v |= (spriv->io(dev, 0, I8255_DATA_B_REG, 0, regbase) << 8);
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+ v |= (spriv->io(dev, 0, I8255_DATA_C_REG, 0, regbase) << 16);
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+
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+ data[1] = v;
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+
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+ return insn->n;
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+}
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+
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+static void subdev_8255_do_config(struct comedi_device *dev,
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+ struct comedi_subdevice *s)
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+{
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+ struct subdev_8255_private *spriv = s->private;
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+ unsigned long regbase = spriv->regbase;
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+ int config;
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+
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+ config = I8255_CTRL_CW;
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+ /* 1 in io_bits indicates output, 1 in config indicates input */
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+ if (!(s->io_bits & 0x0000ff))
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+ config |= I8255_CTRL_A_IO;
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+ if (!(s->io_bits & 0x00ff00))
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+ config |= I8255_CTRL_B_IO;
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+ if (!(s->io_bits & 0x0f0000))
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+ config |= I8255_CTRL_C_LO_IO;
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+ if (!(s->io_bits & 0xf00000))
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+ config |= I8255_CTRL_C_HI_IO;
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+
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+ spriv->io(dev, 1, I8255_CTRL_REG, config, regbase);
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+}
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+
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+static int subdev_8255_insn_config(struct comedi_device *dev,
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+ struct comedi_subdevice *s,
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+ struct comedi_insn *insn,
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+ unsigned int *data)
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+{
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+ unsigned int chan = CR_CHAN(insn->chanspec);
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+ unsigned int mask;
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+ int ret;
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+
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+ if (chan < 8)
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+ mask = 0x0000ff;
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+ else if (chan < 16)
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+ mask = 0x00ff00;
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+ else if (chan < 20)
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+ mask = 0x0f0000;
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+ else
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+ mask = 0xf00000;
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+
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+ ret = comedi_dio_insn_config(dev, s, insn, data, mask);
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+ if (ret)
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+ return ret;
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+
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+ subdev_8255_do_config(dev, s);
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+
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+ return insn->n;
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+}
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+
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+static int __subdev_8255_init(struct comedi_device *dev,
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+ struct comedi_subdevice *s,
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+ int (*io)(struct comedi_device *dev,
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+ int dir, int port, int data,
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+ unsigned long regbase),
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+ unsigned long regbase,
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+ bool is_mmio)
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+{
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+ struct subdev_8255_private *spriv;
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+
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+ spriv = comedi_alloc_spriv(s, sizeof(*spriv));
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+ if (!spriv)
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+ return -ENOMEM;
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+
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+ if (io)
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+ spriv->io = io;
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+ else if (is_mmio)
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+ spriv->io = subdev_8255_mmio;
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+ else
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+ spriv->io = subdev_8255_io;
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+ spriv->regbase = regbase;
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+
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+ s->type = COMEDI_SUBD_DIO;
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+ s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
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+ s->n_chan = 24;
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+ s->range_table = &range_digital;
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+ s->maxdata = 1;
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+ s->insn_bits = subdev_8255_insn;
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+ s->insn_config = subdev_8255_insn_config;
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+
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+ subdev_8255_do_config(dev, s);
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+
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+ return 0;
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+}
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+
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+/**
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+ * subdev_8255_init - initialize DIO subdevice for driving I/O mapped 8255
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+ * @dev: comedi device owning subdevice
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+ * @s: comedi subdevice to initialize
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+ * @io: (optional) register I/O call-back function
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+ * @regbase: offset of 8255 registers from dev->iobase, or call-back context
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+ *
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+ * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
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+ *
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+ * If the optional I/O call-back function is provided, its prototype is of
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+ * the following form:
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+ *
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+ * int my_8255_callback(struct comedi_device *dev, int dir, int port,
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+ * int data, unsigned long regbase);
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+ *
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+ * where 'dev', and 'regbase' match the values passed to this function,
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+ * 'port' is the 8255 port number 0 to 3 (including the control port), 'dir'
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+ * is the direction (0 for read, 1 for write) and 'data' is the value to be
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+ * written. It should return 0 if writing or the value read if reading.
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+ *
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+ * If the optional I/O call-back function is not provided, an internal
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+ * call-back function is used which uses consecutive I/O port addresses
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+ * starting at dev->iobase + regbase.
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+ *
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+ * Return: -ENOMEM if failed to allocate memory, zero on success.
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+ */
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+int subdev_8255_init(struct comedi_device *dev, struct comedi_subdevice *s,
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+ int (*io)(struct comedi_device *dev, int dir, int port,
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+ int data, unsigned long regbase),
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+ unsigned long regbase)
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+{
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+ return __subdev_8255_init(dev, s, io, regbase, false);
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+}
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+EXPORT_SYMBOL_GPL(subdev_8255_init);
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+
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+/**
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+ * subdev_8255_mm_init - initialize DIO subdevice for driving mmio-mapped 8255
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+ * @dev: comedi device owning subdevice
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+ * @s: comedi subdevice to initialize
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+ * @io: (optional) register I/O call-back function
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+ * @regbase: offset of 8255 registers from dev->mmio, or call-back context
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+ *
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+ * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
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+ *
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+ * If the optional I/O call-back function is provided, its prototype is of
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+ * the following form:
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+ *
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+ * int my_8255_callback(struct comedi_device *dev, int dir, int port,
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+ * int data, unsigned long regbase);
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+ *
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+ * where 'dev', and 'regbase' match the values passed to this function,
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+ * 'port' is the 8255 port number 0 to 3 (including the control port), 'dir'
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+ * is the direction (0 for read, 1 for write) and 'data' is the value to be
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+ * written. It should return 0 if writing or the value read if reading.
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+ *
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+ * If the optional I/O call-back function is not provided, an internal
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+ * call-back function is used which uses consecutive MMIO virtual addresses
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+ * starting at dev->mmio + regbase.
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+ *
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+ * Return: -ENOMEM if failed to allocate memory, zero on success.
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+ */
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+int subdev_8255_mm_init(struct comedi_device *dev, struct comedi_subdevice *s,
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+ int (*io)(struct comedi_device *dev, int dir, int port,
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+ int data, unsigned long regbase),
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+ unsigned long regbase)
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+{
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+ return __subdev_8255_init(dev, s, io, regbase, true);
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+}
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+EXPORT_SYMBOL_GPL(subdev_8255_mm_init);
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+
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+/**
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+ * subdev_8255_regbase - get offset of 8255 registers or call-back context
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+ * @s: comedi subdevice
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+ *
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+ * Returns the 'regbase' parameter that was previously passed to to
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+ * subdev_8255_init() or subdev_8255_mm_init() to set up the subdevice.
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+ * Only valid if the subdevice was set up successfully.
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+ */
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+unsigned long subdev_8255_regbase(struct comedi_subdevice *s)
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+{
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+ struct subdev_8255_private *spriv = s->private;
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+
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+ return spriv->regbase;
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+}
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+EXPORT_SYMBOL_GPL(subdev_8255_regbase);
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+
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+static int __init comedi_8255_module_init(void)
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+{
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+ return 0;
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+}
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+module_init(comedi_8255_module_init);
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+
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+static void __exit comedi_8255_module_exit(void)
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+{
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+}
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+module_exit(comedi_8255_module_exit);
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+
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+MODULE_AUTHOR("Comedi http://www.comedi.org");
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+MODULE_DESCRIPTION("Comedi: Generic 8255 digital I/O support");
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+MODULE_LICENSE("GPL");
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Ian Abbott