diff --git a/drivers/gpio/gpio-gpio-mm.c b/drivers/gpio/gpio-gpio-mm.c
new file mode 100644
index 0000000..b56ff2e
--- /dev/null
+++ b/drivers/gpio/gpio-gpio-mm.c
@@ -0,0 +1,354 @@
+/*
+ * GPIO driver for the Diamond Systems GPIO-MM
+ * 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 Diamond Systems devices: GPIO-MM and
+ * GPIO-MM-12.
+ */
+#include <linux/bitmap.h>
+#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/isa.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/spinlock.h>
+
+#define GPIOMM_EXTENT 8
+#define MAX_NUM_GPIOMM max_num_isa_dev(GPIOMM_EXTENT)
+
+static unsigned int base[MAX_NUM_GPIOMM];
+static unsigned int num_gpiomm;
+module_param_hw_array(base, uint, ioport, &num_gpiomm, 0);
+MODULE_PARM_DESC(base, "Diamond Systems GPIO-MM base addresses");
+
+/**
+ * struct gpiomm_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
+ */
+struct gpiomm_gpio {
+	struct gpio_chip chip;
+	unsigned char io_state[6];
+	unsigned char out_state[6];
+	unsigned char control[2];
+	spinlock_t lock;
+	unsigned int base;
+};
+
+static int gpiomm_gpio_get_direction(struct gpio_chip *chip,
+	unsigned int offset)
+{
+	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
+	const unsigned int port = offset / 8;
+	const unsigned int mask = BIT(offset % 8);
+
+	return !!(gpiommgpio->io_state[port] & mask);
+}
+
+static int gpiomm_gpio_direction_input(struct gpio_chip *chip,
+	unsigned int offset)
+{
+	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
+	const unsigned int io_port = offset / 8;
+	const unsigned int control_port = io_port / 3;
+	const unsigned int control_addr = gpiommgpio->base + 3 + control_port*4;
+	unsigned long flags;
+	unsigned int control;
+
+	spin_lock_irqsave(&gpiommgpio->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) {
+			gpiommgpio->io_state[io_port] |= 0xF0;
+			gpiommgpio->control[control_port] |= BIT(3);
+		} else {
+			gpiommgpio->io_state[io_port] |= 0x0F;
+			gpiommgpio->control[control_port] |= BIT(0);
+		}
+	} else {
+		gpiommgpio->io_state[io_port] |= 0xFF;
+		if (io_port == 0 || io_port == 3)
+			gpiommgpio->control[control_port] |= BIT(4);
+		else
+			gpiommgpio->control[control_port] |= BIT(1);
+	}
+
+	control = BIT(7) | gpiommgpio->control[control_port];
+	outb(control, control_addr);
+
+	spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+
+	return 0;
+}
+
+static int gpiomm_gpio_direction_output(struct gpio_chip *chip,
+	unsigned int offset, int value)
+{
+	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
+	const unsigned int io_port = offset / 8;
+	const unsigned int control_port = io_port / 3;
+	const unsigned int mask = BIT(offset % 8);
+	const unsigned int control_addr = gpiommgpio->base + 3 + control_port*4;
+	const unsigned int out_port = (io_port > 2) ? io_port + 1 : io_port;
+	unsigned long flags;
+	unsigned int control;
+
+	spin_lock_irqsave(&gpiommgpio->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) {
+			gpiommgpio->io_state[io_port] &= 0x0F;
+			gpiommgpio->control[control_port] &= ~BIT(3);
+		} else {
+			gpiommgpio->io_state[io_port] &= 0xF0;
+			gpiommgpio->control[control_port] &= ~BIT(0);
+		}
+	} else {
+		gpiommgpio->io_state[io_port] &= 0x00;
+		if (io_port == 0 || io_port == 3)
+			gpiommgpio->control[control_port] &= ~BIT(4);
+		else
+			gpiommgpio->control[control_port] &= ~BIT(1);
+	}
+
+	if (value)
+		gpiommgpio->out_state[io_port] |= mask;
+	else
+		gpiommgpio->out_state[io_port] &= ~mask;
+
+	control = BIT(7) | gpiommgpio->control[control_port];
+	outb(control, control_addr);
+
+	outb(gpiommgpio->out_state[io_port], gpiommgpio->base + out_port);
+
+	spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+
+	return 0;
+}
+
+static int gpiomm_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
+	const unsigned int port = offset / 8;
+	const unsigned int mask = BIT(offset % 8);
+	const unsigned int in_port = (port > 2) ? port + 1 : port;
+	unsigned long flags;
+	unsigned int port_state;
+
+	spin_lock_irqsave(&gpiommgpio->lock, flags);
+
+	/* ensure that GPIO is set for input */
+	if (!(gpiommgpio->io_state[port] & mask)) {
+		spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+		return -EINVAL;
+	}
+
+	port_state = inb(gpiommgpio->base + in_port);
+
+	spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+
+	return !!(port_state & mask);
+}
+
+static int gpiomm_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
+	unsigned long *bits)
+{
+	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
+	size_t i;
+	static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
+	const unsigned int gpio_reg_size = 8;
+	unsigned int bits_offset;
+	size_t word_index;
+	unsigned int word_offset;
+	unsigned long word_mask;
+	const unsigned long port_mask = GENMASK(gpio_reg_size - 1, 0);
+	unsigned long port_state;
+
+	/* clear bits array to a clean slate */
+	bitmap_zero(bits, chip->ngpio);
+
+	/* get bits are evaluated a gpio port register at a time */
+	for (i = 0; i < ARRAY_SIZE(ports); i++) {
+		/* gpio offset in bits array */
+		bits_offset = i * gpio_reg_size;
+
+		/* word index for bits array */
+		word_index = BIT_WORD(bits_offset);
+
+		/* gpio offset within current word of bits array */
+		word_offset = bits_offset % BITS_PER_LONG;
+
+		/* mask of get bits for current gpio within current word */
+		word_mask = mask[word_index] & (port_mask << word_offset);
+		if (!word_mask) {
+			/* no get bits in this port so skip to next one */
+			continue;
+		}
+
+		/* read bits from current gpio port */
+		port_state = inb(gpiommgpio->base + ports[i]);
+
+		/* store acquired bits at respective bits array offset */
+		bits[word_index] |= port_state << word_offset;
+	}
+
+	return 0;
+}
+
+static void gpiomm_gpio_set(struct gpio_chip *chip, unsigned int offset,
+	int value)
+{
+	struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
+	const unsigned int port = offset / 8;
+	const unsigned int mask = BIT(offset % 8);
+	const unsigned int out_port = (port > 2) ? port + 1 : port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpiommgpio->lock, flags);
+
+	if (value)
+		gpiommgpio->out_state[port] |= mask;
+	else
+		gpiommgpio->out_state[port] &= ~mask;
+
+	outb(gpiommgpio->out_state[port], gpiommgpio->base + out_port);
+
+	spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+}
+
+static void gpiomm_gpio_set_multiple(struct gpio_chip *chip,
+	unsigned long *mask, unsigned long *bits)
+{
+	struct gpiomm_gpio *const gpiommgpio = 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)];
+
+		spin_lock_irqsave(&gpiommgpio->lock, flags);
+
+		/* update output state data and set device gpio register */
+		gpiommgpio->out_state[port] &= ~mask[BIT_WORD(i)];
+		gpiommgpio->out_state[port] |= bitmask;
+		outb(gpiommgpio->out_state[port], gpiommgpio->base + out_port);
+
+		spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+
+		/* prepare for next gpio register set */
+		mask[BIT_WORD(i)] >>= gpio_reg_size;
+		bits[BIT_WORD(i)] >>= gpio_reg_size;
+	}
+}
+
+#define GPIOMM_NGPIO 48
+static const char *gpiomm_names[GPIOMM_NGPIO] = {
+	"Port 1A0", "Port 1A1", "Port 1A2", "Port 1A3", "Port 1A4", "Port 1A5",
+	"Port 1A6", "Port 1A7", "Port 1B0", "Port 1B1", "Port 1B2", "Port 1B3",
+	"Port 1B4", "Port 1B5", "Port 1B6", "Port 1B7", "Port 1C0", "Port 1C1",
+	"Port 1C2", "Port 1C3", "Port 1C4", "Port 1C5", "Port 1C6", "Port 1C7",
+	"Port 2A0", "Port 2A1", "Port 2A2", "Port 2A3", "Port 2A4", "Port 2A5",
+	"Port 2A6", "Port 2A7", "Port 2B0", "Port 2B1", "Port 2B2", "Port 2B3",
+	"Port 2B4", "Port 2B5", "Port 2B6", "Port 2B7", "Port 2C0", "Port 2C1",
+	"Port 2C2", "Port 2C3", "Port 2C4", "Port 2C5", "Port 2C6", "Port 2C7",
+};
+
+static int gpiomm_probe(struct device *dev, unsigned int id)
+{
+	struct gpiomm_gpio *gpiommgpio;
+	const char *const name = dev_name(dev);
+	int err;
+
+	gpiommgpio = devm_kzalloc(dev, sizeof(*gpiommgpio), GFP_KERNEL);
+	if (!gpiommgpio)
+		return -ENOMEM;
+
+	if (!devm_request_region(dev, base[id], GPIOMM_EXTENT, name)) {
+		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
+			base[id], base[id] + GPIOMM_EXTENT);
+		return -EBUSY;
+	}
+
+	gpiommgpio->chip.label = name;
+	gpiommgpio->chip.parent = dev;
+	gpiommgpio->chip.owner = THIS_MODULE;
+	gpiommgpio->chip.base = -1;
+	gpiommgpio->chip.ngpio = GPIOMM_NGPIO;
+	gpiommgpio->chip.names = gpiomm_names;
+	gpiommgpio->chip.get_direction = gpiomm_gpio_get_direction;
+	gpiommgpio->chip.direction_input = gpiomm_gpio_direction_input;
+	gpiommgpio->chip.direction_output = gpiomm_gpio_direction_output;
+	gpiommgpio->chip.get = gpiomm_gpio_get;
+	gpiommgpio->chip.get_multiple = gpiomm_gpio_get_multiple;
+	gpiommgpio->chip.set = gpiomm_gpio_set;
+	gpiommgpio->chip.set_multiple = gpiomm_gpio_set_multiple;
+	gpiommgpio->base = base[id];
+
+	spin_lock_init(&gpiommgpio->lock);
+
+	err = devm_gpiochip_add_data(dev, &gpiommgpio->chip, gpiommgpio);
+	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(0x80, base[id] + 7);
+	outb(0x00, base[id] + 4);
+	outb(0x00, base[id] + 5);
+	outb(0x00, base[id] + 6);
+
+	return 0;
+}
+
+static struct isa_driver gpiomm_driver = {
+	.probe = gpiomm_probe,
+	.driver = {
+		.name = "gpio-mm"
+	},
+};
+
+module_isa_driver(gpiomm_driver, num_gpiomm);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("Diamond Systems GPIO-MM GPIO driver");
+MODULE_LICENSE("GPL v2");