drivers/gpio/gpio-104-dio-48e.c - kernel/msm-4.19 - Gitiles

 /*
  * GPIO driver for the ACCES 104-DIO-48E series
  * Copyright (C) 2016 William Breathitt Gray
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2, as
  * published by the Free Software Foundation.
  *
  * 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.
  *
  * This driver supports the following ACCES devices: 104-DIO-48E and
  * 104-DIO-24E.
  */
 #include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/gpio/driver.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/interrupt.h>
 #include <linux/irqdesc.h>
 #include <linux/isa.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/spinlock.h>

 #define DIO48E_EXTENT 16
 #define MAX_NUM_DIO48E max_num_isa_dev(DIO48E_EXTENT)

 static unsigned int base[MAX_NUM_DIO48E];
 static unsigned int num_dio48e;
 module_param_array(base, uint, &num_dio48e, 0);
 MODULE_PARM_DESC(base, "ACCES 104-DIO-48E base addresses");

 static unsigned int irq[MAX_NUM_DIO48E];
 module_param_array(irq, uint, NULL, 0);
 MODULE_PARM_DESC(irq, "ACCES 104-DIO-48E interrupt line numbers");

 /**
  * struct dio48e_gpio - GPIO device private data structure
  * @chip:	instance of the gpio_chip
  * @io_state:	bit I/O state (whether bit is set to input or output)
  * @out_state:	output bits state
  * @control:	Control registers state
  * @lock:	synchronization lock to prevent I/O race conditions
  * @base:	base port address of the GPIO device
  * @irq_mask:	I/O bits affected by interrupts
  */
 struct dio48e_gpio {
 	struct gpio_chip chip;
 	unsigned char io_state[6];
 	unsigned char out_state[6];
 	unsigned char control[2];
 	raw_spinlock_t lock;
 	unsigned base;
 	unsigned char irq_mask;
 };

 static int dio48e_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned port = offset / 8;
 	const unsigned mask = BIT(offset % 8);

 	return !!(dio48egpio->io_state[port] & mask);
 }

 static int dio48e_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned io_port = offset / 8;
 	const unsigned int control_port = io_port / 3;
 	const unsigned control_addr = dio48egpio->base + 3 + control_port*4;
 	unsigned long flags;
 	unsigned control;

 	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 	/* Check if configuring Port C */
 	if (io_port == 2 || io_port == 5) {
 		/* Port C can be configured by nibble */
 		if (offset % 8 > 3) {
 			dio48egpio->io_state[io_port] |= 0xF0;
 			dio48egpio->control[control_port] |= BIT(3);
 		} else {
 			dio48egpio->io_state[io_port] |= 0x0F;
 			dio48egpio->control[control_port] |= BIT(0);
 		}
 	} else {
 		dio48egpio->io_state[io_port] |= 0xFF;
 		if (io_port == 0 || io_port == 3)
 			dio48egpio->control[control_port] |= BIT(4);
 		else
 			dio48egpio->control[control_port] |= BIT(1);
 	}

 	control = BIT(7) | dio48egpio->control[control_port];
 	outb(control, control_addr);
 	control &= ~BIT(7);
 	outb(control, control_addr);

 	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

 	return 0;
 }

 static int dio48e_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 	int value)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned io_port = offset / 8;
 	const unsigned int control_port = io_port / 3;
 	const unsigned mask = BIT(offset % 8);
 	const unsigned control_addr = dio48egpio->base + 3 + control_port*4;
 	const unsigned out_port = (io_port > 2) ? io_port + 1 : io_port;
 	unsigned long flags;
 	unsigned control;

 	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 	/* Check if configuring Port C */
 	if (io_port == 2 || io_port == 5) {
 		/* Port C can be configured by nibble */
 		if (offset % 8 > 3) {
 			dio48egpio->io_state[io_port] &= 0x0F;
 			dio48egpio->control[control_port] &= ~BIT(3);
 		} else {
 			dio48egpio->io_state[io_port] &= 0xF0;
 			dio48egpio->control[control_port] &= ~BIT(0);
 		}
 	} else {
 		dio48egpio->io_state[io_port] &= 0x00;
 		if (io_port == 0 || io_port == 3)
 			dio48egpio->control[control_port] &= ~BIT(4);
 		else
 			dio48egpio->control[control_port] &= ~BIT(1);
 	}

 	if (value)
 		dio48egpio->out_state[io_port] |= mask;
 	else
 		dio48egpio->out_state[io_port] &= ~mask;

 	control = BIT(7) | dio48egpio->control[control_port];
 	outb(control, control_addr);

 	outb(dio48egpio->out_state[io_port], dio48egpio->base + out_port);

 	control &= ~BIT(7);
 	outb(control, control_addr);

 	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

 	return 0;
 }

 static int dio48e_gpio_get(struct gpio_chip *chip, unsigned offset)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned port = offset / 8;
 	const unsigned mask = BIT(offset % 8);
 	const unsigned in_port = (port > 2) ? port + 1 : port;
 	unsigned long flags;
 	unsigned port_state;

 	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 	/* ensure that GPIO is set for input */
 	if (!(dio48egpio->io_state[port] & mask)) {
 		raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
 		return -EINVAL;
 	}

 	port_state = inb(dio48egpio->base + in_port);

 	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

 	return !!(port_state & mask);
 }

 static void dio48e_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned port = offset / 8;
 	const unsigned mask = BIT(offset % 8);
 	const unsigned out_port = (port > 2) ? port + 1 : port;
 	unsigned long flags;

 	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 	if (value)
 		dio48egpio->out_state[port] |= mask;
 	else
 		dio48egpio->out_state[port] &= ~mask;

 	outb(dio48egpio->out_state[port], dio48egpio->base + out_port);

 	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
 }

 static void dio48e_gpio_set_multiple(struct gpio_chip *chip,
 	unsigned long *mask, unsigned long *bits)
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	unsigned int i;
 	const unsigned int gpio_reg_size = 8;
 	unsigned int port;
 	unsigned int out_port;
 	unsigned int bitmask;
 	unsigned long flags;

 	/* set bits are evaluated a gpio register size at a time */
 	for (i = 0; i < chip->ngpio; i += gpio_reg_size) {
 		/* no more set bits in this mask word; skip to the next word */
 		if (!mask[BIT_WORD(i)]) {
 			i = (BIT_WORD(i) + 1) * BITS_PER_LONG - gpio_reg_size;
 			continue;
 		}

 		port = i / gpio_reg_size;
 		out_port = (port > 2) ? port + 1 : port;
 		bitmask = mask[BIT_WORD(i)] & bits[BIT_WORD(i)];

 		raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 		/* update output state data and set device gpio register */
 		dio48egpio->out_state[port] &= ~mask[BIT_WORD(i)];
 		dio48egpio->out_state[port] |= bitmask;
 		outb(dio48egpio->out_state[port], dio48egpio->base + out_port);

 		raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

 		/* prepare for next gpio register set */
 		mask[BIT_WORD(i)] >>= gpio_reg_size;
 		bits[BIT_WORD(i)] >>= gpio_reg_size;
 	}
 }

 static void dio48e_irq_ack(struct irq_data *data)
 {
 }

 static void dio48e_irq_mask(struct irq_data *data)
 {
 	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned long offset = irqd_to_hwirq(data);
 	unsigned long flags;

 	/* only bit 3 on each respective Port C supports interrupts */
 	if (offset != 19 && offset != 43)
 		return;

 	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 	if (offset == 19)
 		dio48egpio->irq_mask &= ~BIT(0);
 	else
 		dio48egpio->irq_mask &= ~BIT(1);

 	if (!dio48egpio->irq_mask)
 		/* disable interrupts */
 		inb(dio48egpio->base + 0xB);

 	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
 }

 static void dio48e_irq_unmask(struct irq_data *data)
 {
 	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	const unsigned long offset = irqd_to_hwirq(data);
 	unsigned long flags;

 	/* only bit 3 on each respective Port C supports interrupts */
 	if (offset != 19 && offset != 43)
 		return;

 	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

 	if (!dio48egpio->irq_mask) {
 		/* enable interrupts */
 		outb(0x00, dio48egpio->base + 0xF);
 		outb(0x00, dio48egpio->base + 0xB);
 	}

 	if (offset == 19)
 		dio48egpio->irq_mask |= BIT(0);
 	else
 		dio48egpio->irq_mask |= BIT(1);

 	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
 }

 static int dio48e_irq_set_type(struct irq_data *data, unsigned flow_type)
 {
 	const unsigned long offset = irqd_to_hwirq(data);

 	/* only bit 3 on each respective Port C supports interrupts */
 	if (offset != 19 && offset != 43)
 		return -EINVAL;

 	if (flow_type != IRQ_TYPE_NONE && flow_type != IRQ_TYPE_EDGE_RISING)
 		return -EINVAL;

 	return 0;
 }

 static struct irq_chip dio48e_irqchip = {
 	.name = "104-dio-48e",
 	.irq_ack = dio48e_irq_ack,
 	.irq_mask = dio48e_irq_mask,
 	.irq_unmask = dio48e_irq_unmask,
 	.irq_set_type = dio48e_irq_set_type
 };

 static irqreturn_t dio48e_irq_handler(int irq, void *dev_id)
 {
 	struct dio48e_gpio *const dio48egpio = dev_id;
 	struct gpio_chip *const chip = &dio48egpio->chip;
 	const unsigned long irq_mask = dio48egpio->irq_mask;
 	unsigned long gpio;

 	for_each_set_bit(gpio, &irq_mask, 2)
 		generic_handle_irq(irq_find_mapping(chip->irqdomain,
 			19 + gpio*24));

 	raw_spin_lock(&dio48egpio->lock);

 	outb(0x00, dio48egpio->base + 0xF);

 	raw_spin_unlock(&dio48egpio->lock);

 	return IRQ_HANDLED;
 }

 #define DIO48E_NGPIO 48
 static const char *dio48e_names[DIO48E_NGPIO] = {
 	"PPI Group 0 Port A 0", "PPI Group 0 Port A 1", "PPI Group 0 Port A 2",
 	"PPI Group 0 Port A 3", "PPI Group 0 Port A 4", "PPI Group 0 Port A 5",
 	"PPI Group 0 Port A 6", "PPI Group 0 Port A 7",	"PPI Group 0 Port B 0",
 	"PPI Group 0 Port B 1", "PPI Group 0 Port B 2", "PPI Group 0 Port B 3",
 	"PPI Group 0 Port B 4", "PPI Group 0 Port B 5", "PPI Group 0 Port B 6",
 	"PPI Group 0 Port B 7", "PPI Group 0 Port C 0", "PPI Group 0 Port C 1",
 	"PPI Group 0 Port C 2", "PPI Group 0 Port C 3", "PPI Group 0 Port C 4",
 	"PPI Group 0 Port C 5", "PPI Group 0 Port C 6", "PPI Group 0 Port C 7",
 	"PPI Group 1 Port A 0", "PPI Group 1 Port A 1", "PPI Group 1 Port A 2",
 	"PPI Group 1 Port A 3", "PPI Group 1 Port A 4", "PPI Group 1 Port A 5",
 	"PPI Group 1 Port A 6", "PPI Group 1 Port A 7",	"PPI Group 1 Port B 0",
 	"PPI Group 1 Port B 1", "PPI Group 1 Port B 2", "PPI Group 1 Port B 3",
 	"PPI Group 1 Port B 4", "PPI Group 1 Port B 5", "PPI Group 1 Port B 6",
 	"PPI Group 1 Port B 7", "PPI Group 1 Port C 0", "PPI Group 1 Port C 1",
 	"PPI Group 1 Port C 2", "PPI Group 1 Port C 3", "PPI Group 1 Port C 4",
 	"PPI Group 1 Port C 5", "PPI Group 1 Port C 6", "PPI Group 1 Port C 7"
 };

 static int dio48e_probe(struct device *dev, unsigned int id)
 {
 	struct dio48e_gpio *dio48egpio;
 	const char *const name = dev_name(dev);
 	int err;

 	dio48egpio = devm_kzalloc(dev, sizeof(*dio48egpio), GFP_KERNEL);
 	if (!dio48egpio)
 		return -ENOMEM;

 	if (!devm_request_region(dev, base[id], DIO48E_EXTENT, name)) {
 		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 			base[id], base[id] + DIO48E_EXTENT);
 		return -EBUSY;
 	}

 	dio48egpio->chip.label = name;
 	dio48egpio->chip.parent = dev;
 	dio48egpio->chip.owner = THIS_MODULE;
 	dio48egpio->chip.base = -1;
 	dio48egpio->chip.ngpio = DIO48E_NGPIO;
 	dio48egpio->chip.names = dio48e_names;
 	dio48egpio->chip.get_direction = dio48e_gpio_get_direction;
 	dio48egpio->chip.direction_input = dio48e_gpio_direction_input;
 	dio48egpio->chip.direction_output = dio48e_gpio_direction_output;
 	dio48egpio->chip.get = dio48e_gpio_get;
 	dio48egpio->chip.set = dio48e_gpio_set;
 	dio48egpio->chip.set_multiple = dio48e_gpio_set_multiple;
 	dio48egpio->base = base[id];

 	raw_spin_lock_init(&dio48egpio->lock);

 	err = devm_gpiochip_add_data(dev, &dio48egpio->chip, dio48egpio);
 	if (err) {
 		dev_err(dev, "GPIO registering failed (%d)\n", err);
 		return err;
 	}

 	/* initialize all GPIO as output */
 	outb(0x80, base[id] + 3);
 	outb(0x00, base[id]);
 	outb(0x00, base[id] + 1);
 	outb(0x00, base[id] + 2);
 	outb(0x00, base[id] + 3);
 	outb(0x80, base[id] + 7);
 	outb(0x00, base[id] + 4);
 	outb(0x00, base[id] + 5);
 	outb(0x00, base[id] + 6);
 	outb(0x00, base[id] + 7);

 	/* disable IRQ by default */
 	inb(base[id] + 0xB);

 	err = gpiochip_irqchip_add(&dio48egpio->chip, &dio48e_irqchip, 0,
 		handle_edge_irq, IRQ_TYPE_NONE);
 	if (err) {
 		dev_err(dev, "Could not add irqchip (%d)\n", err);
 		return err;
 	}

 	err = devm_request_irq(dev, irq[id], dio48e_irq_handler, 0, name,
 		dio48egpio);
 	if (err) {
 		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
 		return err;
 	}

 	return 0;
 }

 static struct isa_driver dio48e_driver = {
 	.probe = dio48e_probe,
 	.driver = {
 		.name = "104-dio-48e"
 	},
 };
 module_isa_driver(dio48e_driver, num_dio48e);

 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 MODULE_DESCRIPTION("ACCES 104-DIO-48E GPIO driver");
 MODULE_LICENSE("GPL v2");
	/*
	* GPIO driver for the ACCES 104-DIO-48E series
	* Copyright (C) 2016 William Breathitt Gray
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License, version 2, as
	* published by the Free Software Foundation.
	*
	* 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.
	*
	* This driver supports the following ACCES devices: 104-DIO-48E and
	* 104-DIO-24E.
	*/
	#include <linux/bitops.h>
	#include <linux/device.h>
	#include <linux/errno.h>
	#include <linux/gpio/driver.h>
	#include <linux/io.h>
	#include <linux/ioport.h>
	#include <linux/interrupt.h>
	#include <linux/irqdesc.h>
	#include <linux/isa.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/spinlock.h>

	#define DIO48E_EXTENT 16
	#define MAX_NUM_DIO48E max_num_isa_dev(DIO48E_EXTENT)

	static unsigned int base[MAX_NUM_DIO48E];
	static unsigned int num_dio48e;
	module_param_array(base, uint, &num_dio48e, 0);
	MODULE_PARM_DESC(base, "ACCES 104-DIO-48E base addresses");

	static unsigned int irq[MAX_NUM_DIO48E];
	module_param_array(irq, uint, NULL, 0);
	MODULE_PARM_DESC(irq, "ACCES 104-DIO-48E interrupt line numbers");

	/**
	* struct dio48e_gpio - GPIO device private data structure
	* @chip: instance of the gpio_chip
	* @io_state: bit I/O state (whether bit is set to input or output)
	* @out_state: output bits state
	* @control: Control registers state
	* @lock: synchronization lock to prevent I/O race conditions
	* @base: base port address of the GPIO device
	* @irq_mask: I/O bits affected by interrupts
	*/
	struct dio48e_gpio {
	struct gpio_chip chip;
	unsigned char io_state[6];
	unsigned char out_state[6];
	unsigned char control[2];
	raw_spinlock_t lock;
	unsigned base;
	unsigned char irq_mask;
	};

	static int dio48e_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
	{
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned port = offset / 8;
	const unsigned mask = BIT(offset % 8);

	return !!(dio48egpio->io_state[port] & mask);
	}

	static int dio48e_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
	{
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned io_port = offset / 8;
	const unsigned int control_port = io_port / 3;
	const unsigned control_addr = dio48egpio->base + 3 + control_port*4;
	unsigned long flags;
	unsigned control;

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	/* Check if configuring Port C */
	if (io_port == 2 \|\| io_port == 5) {
	/* Port C can be configured by nibble */
	if (offset % 8 > 3) {
	dio48egpio->io_state[io_port] \|= 0xF0;
	dio48egpio->control[control_port] \|= BIT(3);
	} else {
	dio48egpio->io_state[io_port] \|= 0x0F;
	dio48egpio->control[control_port] \|= BIT(0);
	}
	} else {
	dio48egpio->io_state[io_port] \|= 0xFF;
	if (io_port == 0 \|\| io_port == 3)
	dio48egpio->control[control_port] \|= BIT(4);
	else
	dio48egpio->control[control_port] \|= BIT(1);
	}

	control = BIT(7) \| dio48egpio->control[control_port];
	outb(control, control_addr);
	control &= ~BIT(7);
	outb(control, control_addr);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

	return 0;
	}

	static int dio48e_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
	int value)
	{
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned io_port = offset / 8;
	const unsigned int control_port = io_port / 3;
	const unsigned mask = BIT(offset % 8);
	const unsigned control_addr = dio48egpio->base + 3 + control_port*4;
	const unsigned out_port = (io_port > 2) ? io_port + 1 : io_port;
	unsigned long flags;
	unsigned control;

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	/* Check if configuring Port C */
	if (io_port == 2 \|\| io_port == 5) {
	/* Port C can be configured by nibble */
	if (offset % 8 > 3) {
	dio48egpio->io_state[io_port] &= 0x0F;
	dio48egpio->control[control_port] &= ~BIT(3);
	} else {
	dio48egpio->io_state[io_port] &= 0xF0;
	dio48egpio->control[control_port] &= ~BIT(0);
	}
	} else {
	dio48egpio->io_state[io_port] &= 0x00;
	if (io_port == 0 \|\| io_port == 3)
	dio48egpio->control[control_port] &= ~BIT(4);
	else
	dio48egpio->control[control_port] &= ~BIT(1);
	}

	if (value)
	dio48egpio->out_state[io_port] \|= mask;
	else
	dio48egpio->out_state[io_port] &= ~mask;

	control = BIT(7) \| dio48egpio->control[control_port];
	outb(control, control_addr);

	outb(dio48egpio->out_state[io_port], dio48egpio->base + out_port);

	control &= ~BIT(7);
	outb(control, control_addr);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

	return 0;
	}

	static int dio48e_gpio_get(struct gpio_chip *chip, unsigned offset)
	{
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned port = offset / 8;
	const unsigned mask = BIT(offset % 8);
	const unsigned in_port = (port > 2) ? port + 1 : port;
	unsigned long flags;
	unsigned port_state;

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	/* ensure that GPIO is set for input */
	if (!(dio48egpio->io_state[port] & mask)) {
	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
	return -EINVAL;
	}

	port_state = inb(dio48egpio->base + in_port);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

	return !!(port_state & mask);
	}

	static void dio48e_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
	{
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned port = offset / 8;
	const unsigned mask = BIT(offset % 8);
	const unsigned out_port = (port > 2) ? port + 1 : port;
	unsigned long flags;

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	if (value)
	dio48egpio->out_state[port] \|= mask;
	else
	dio48egpio->out_state[port] &= ~mask;

	outb(dio48egpio->out_state[port], dio48egpio->base + out_port);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
	}

	static void dio48e_gpio_set_multiple(struct gpio_chip *chip,
	unsigned long mask, unsigned long bits)
	{
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	unsigned int i;
	const unsigned int gpio_reg_size = 8;
	unsigned int port;
	unsigned int out_port;
	unsigned int bitmask;
	unsigned long flags;

	/* set bits are evaluated a gpio register size at a time */
	for (i = 0; i < chip->ngpio; i += gpio_reg_size) {
	/* no more set bits in this mask word; skip to the next word */
	if (!mask[BIT_WORD(i)]) {
	i = (BIT_WORD(i) + 1) * BITS_PER_LONG - gpio_reg_size;
	continue;
	}

	port = i / gpio_reg_size;
	out_port = (port > 2) ? port + 1 : port;
	bitmask = mask[BIT_WORD(i)] & bits[BIT_WORD(i)];

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	/* update output state data and set device gpio register */
	dio48egpio->out_state[port] &= ~mask[BIT_WORD(i)];
	dio48egpio->out_state[port] \|= bitmask;
	outb(dio48egpio->out_state[port], dio48egpio->base + out_port);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);

	/* prepare for next gpio register set */
	mask[BIT_WORD(i)] >>= gpio_reg_size;
	bits[BIT_WORD(i)] >>= gpio_reg_size;
	}
	}

	static void dio48e_irq_ack(struct irq_data *data)
	{
	}

	static void dio48e_irq_mask(struct irq_data *data)
	{
	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned long offset = irqd_to_hwirq(data);
	unsigned long flags;

	/* only bit 3 on each respective Port C supports interrupts */
	if (offset != 19 && offset != 43)
	return;

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	if (offset == 19)
	dio48egpio->irq_mask &= ~BIT(0);
	else
	dio48egpio->irq_mask &= ~BIT(1);

	if (!dio48egpio->irq_mask)
	/* disable interrupts */
	inb(dio48egpio->base + 0xB);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
	}

	static void dio48e_irq_unmask(struct irq_data *data)
	{
	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
	const unsigned long offset = irqd_to_hwirq(data);
	unsigned long flags;

	/* only bit 3 on each respective Port C supports interrupts */
	if (offset != 19 && offset != 43)
	return;

	raw_spin_lock_irqsave(&dio48egpio->lock, flags);

	if (!dio48egpio->irq_mask) {
	/* enable interrupts */
	outb(0x00, dio48egpio->base + 0xF);
	outb(0x00, dio48egpio->base + 0xB);
	}

	if (offset == 19)
	dio48egpio->irq_mask \|= BIT(0);
	else
	dio48egpio->irq_mask \|= BIT(1);

	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
	}

	static int dio48e_irq_set_type(struct irq_data *data, unsigned flow_type)
	{
	const unsigned long offset = irqd_to_hwirq(data);

	/* only bit 3 on each respective Port C supports interrupts */
	if (offset != 19 && offset != 43)
	return -EINVAL;

	if (flow_type != IRQ_TYPE_NONE && flow_type != IRQ_TYPE_EDGE_RISING)
	return -EINVAL;

	return 0;
	}

	static struct irq_chip dio48e_irqchip = {
	.name = "104-dio-48e",
	.irq_ack = dio48e_irq_ack,
	.irq_mask = dio48e_irq_mask,
	.irq_unmask = dio48e_irq_unmask,
	.irq_set_type = dio48e_irq_set_type
	};

	static irqreturn_t dio48e_irq_handler(int irq, void *dev_id)
	{
	struct dio48e_gpio *const dio48egpio = dev_id;
	struct gpio_chip *const chip = &dio48egpio->chip;
	const unsigned long irq_mask = dio48egpio->irq_mask;
	unsigned long gpio;

	for_each_set_bit(gpio, &irq_mask, 2)
	generic_handle_irq(irq_find_mapping(chip->irqdomain,
	19 + gpio*24));

	raw_spin_lock(&dio48egpio->lock);

	outb(0x00, dio48egpio->base + 0xF);

	raw_spin_unlock(&dio48egpio->lock);

	return IRQ_HANDLED;
	}

	#define DIO48E_NGPIO 48
	static const char *dio48e_names[DIO48E_NGPIO] = {
	"PPI Group 0 Port A 0", "PPI Group 0 Port A 1", "PPI Group 0 Port A 2",
	"PPI Group 0 Port A 3", "PPI Group 0 Port A 4", "PPI Group 0 Port A 5",
	"PPI Group 0 Port A 6", "PPI Group 0 Port A 7", "PPI Group 0 Port B 0",
	"PPI Group 0 Port B 1", "PPI Group 0 Port B 2", "PPI Group 0 Port B 3",
	"PPI Group 0 Port B 4", "PPI Group 0 Port B 5", "PPI Group 0 Port B 6",
	"PPI Group 0 Port B 7", "PPI Group 0 Port C 0", "PPI Group 0 Port C 1",
	"PPI Group 0 Port C 2", "PPI Group 0 Port C 3", "PPI Group 0 Port C 4",
	"PPI Group 0 Port C 5", "PPI Group 0 Port C 6", "PPI Group 0 Port C 7",
	"PPI Group 1 Port A 0", "PPI Group 1 Port A 1", "PPI Group 1 Port A 2",
	"PPI Group 1 Port A 3", "PPI Group 1 Port A 4", "PPI Group 1 Port A 5",
	"PPI Group 1 Port A 6", "PPI Group 1 Port A 7", "PPI Group 1 Port B 0",
	"PPI Group 1 Port B 1", "PPI Group 1 Port B 2", "PPI Group 1 Port B 3",
	"PPI Group 1 Port B 4", "PPI Group 1 Port B 5", "PPI Group 1 Port B 6",
	"PPI Group 1 Port B 7", "PPI Group 1 Port C 0", "PPI Group 1 Port C 1",
	"PPI Group 1 Port C 2", "PPI Group 1 Port C 3", "PPI Group 1 Port C 4",
	"PPI Group 1 Port C 5", "PPI Group 1 Port C 6", "PPI Group 1 Port C 7"
	};

	static int dio48e_probe(struct device *dev, unsigned int id)
	{
	struct dio48e_gpio *dio48egpio;
	const char *const name = dev_name(dev);
	int err;

	dio48egpio = devm_kzalloc(dev, sizeof(*dio48egpio), GFP_KERNEL);
	if (!dio48egpio)
	return -ENOMEM;

	if (!devm_request_region(dev, base[id], DIO48E_EXTENT, name)) {
	dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
	base[id], base[id] + DIO48E_EXTENT);
	return -EBUSY;
	}

	dio48egpio->chip.label = name;
	dio48egpio->chip.parent = dev;
	dio48egpio->chip.owner = THIS_MODULE;
	dio48egpio->chip.base = -1;
	dio48egpio->chip.ngpio = DIO48E_NGPIO;
	dio48egpio->chip.names = dio48e_names;
	dio48egpio->chip.get_direction = dio48e_gpio_get_direction;
	dio48egpio->chip.direction_input = dio48e_gpio_direction_input;
	dio48egpio->chip.direction_output = dio48e_gpio_direction_output;
	dio48egpio->chip.get = dio48e_gpio_get;
	dio48egpio->chip.set = dio48e_gpio_set;
	dio48egpio->chip.set_multiple = dio48e_gpio_set_multiple;
	dio48egpio->base = base[id];

	raw_spin_lock_init(&dio48egpio->lock);

	err = devm_gpiochip_add_data(dev, &dio48egpio->chip, dio48egpio);
	if (err) {
	dev_err(dev, "GPIO registering failed (%d)\n", err);
	return err;
	}

	/* initialize all GPIO as output */
	outb(0x80, base[id] + 3);
	outb(0x00, base[id]);
	outb(0x00, base[id] + 1);
	outb(0x00, base[id] + 2);
	outb(0x00, base[id] + 3);
	outb(0x80, base[id] + 7);
	outb(0x00, base[id] + 4);
	outb(0x00, base[id] + 5);
	outb(0x00, base[id] + 6);
	outb(0x00, base[id] + 7);

	/* disable IRQ by default */
	inb(base[id] + 0xB);

	err = gpiochip_irqchip_add(&dio48egpio->chip, &dio48e_irqchip, 0,
	handle_edge_irq, IRQ_TYPE_NONE);
	if (err) {
	dev_err(dev, "Could not add irqchip (%d)\n", err);
	return err;
	}

	err = devm_request_irq(dev, irq[id], dio48e_irq_handler, 0, name,
	dio48egpio);
	if (err) {
	dev_err(dev, "IRQ handler registering failed (%d)\n", err);
	return err;
	}

	return 0;
	}

	static struct isa_driver dio48e_driver = {
	.probe = dio48e_probe,
	.driver = {
	.name = "104-dio-48e"
	},
	};
	module_isa_driver(dio48e_driver, num_dio48e);

	MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
	MODULE_DESCRIPTION("ACCES 104-DIO-48E GPIO driver");
	MODULE_LICENSE("GPL v2");