gpio: Add GPIO support for the ACCES 104-IDIO-16

The ACCES 104-IDIO-16 family of PC/104 utility boards feature 16
optically isolated inputs and 16 optically isolated FET solid state
outputs. This driver provides GPIO support for these 32 channels of
digital I/O. Change-of-State detection interrupts are not supported.

GPIO 0-15 correspond to digital outputs 0-15, while GPIO 16-31
correspond to digital inputs 0-15. The base port address for the device
may be set via the idio_16_base module parameter.
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -689,6 +689,16 @@ config GPIO_SX150X
 
 endmenu
 
+menu "ISA GPIO drivers"
+
+config GPIO_104_IDIO_16
+	tristate "ACCES 104-IDIO-16 GPIO support"
+	depends on X86
+	help
+	  Enables GPIO support for the ACCES 104-IDIO-16 family.
+
+endmenu
+
 menu "MFD GPIO expanders"
 
 config GPIO_ADP5520

drivers/gpio/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 # Device drivers. Generally keep list sorted alphabetically
 obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
 
+obj-$(CONFIG_GPIO_104_IDIO_16)	+= gpio-104-idio-16.o
 obj-$(CONFIG_GPIO_74X164)	+= gpio-74x164.o
 obj-$(CONFIG_GPIO_74XX_MMIO)	+= gpio-74xx-mmio.o
 obj-$(CONFIG_GPIO_ADNP)		+= gpio-adnp.o

drivers/gpio/gpio-104-idio-16.c

+/*
+ * GPIO driver for the ACCES 104-IDIO-16 family
+ * Copyright (C) 2015 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.
+ */
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/gpio/driver.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+
+static unsigned idio_16_base;
+module_param(idio_16_base, uint, 0);
+MODULE_PARM_DESC(idio_16_base, "ACCES 104-IDIO-16 base address");
+
+/**
+ * struct idio_16_gpio - GPIO device private data structure
+ * @chip:	instance of the gpio_chip
+ * @lock:	synchronization lock to prevent gpio_set race conditions
+ * @base:	base port address of the GPIO device
+ * @extent:	extent of port address region of the GPIO device
+ * @out_state:	output bits state
+ */
+struct idio_16_gpio {
+	struct gpio_chip chip;
+	spinlock_t lock;
+	unsigned base;
+	unsigned extent;
+	unsigned out_state;
+};
+
+static int idio_16_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+	if (offset > 15)
+		return 1;
+
+	return 0;
+}
+
+static int idio_16_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	return 0;
+}
+
+static int idio_16_gpio_direction_output(struct gpio_chip *chip,
+	unsigned offset, int value)
+{
+	chip->set(chip, offset, value);
+	return 0;
+}
+
+static struct idio_16_gpio *to_idio16gpio(struct gpio_chip *gc)
+{
+	return container_of(gc, struct idio_16_gpio, chip);
+}
+
+static int idio_16_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct idio_16_gpio *const idio16gpio = to_idio16gpio(chip);
+	const unsigned BIT_MASK = 1U << (offset-16);
+
+	if (offset < 16)
+		return -EINVAL;
+
+	if (offset < 24)
+		return !!(inb(idio16gpio->base + 1) & BIT_MASK);
+
+	return !!(inb(idio16gpio->base + 5) & (BIT_MASK>>8));
+}
+
+static void idio_16_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct idio_16_gpio *const idio16gpio = to_idio16gpio(chip);
+	const unsigned BIT_MASK = 1U << offset;
+	unsigned long flags;
+
+	if (offset > 15)
+		return;
+
+	spin_lock_irqsave(&idio16gpio->lock, flags);
+
+	if (value)
+		idio16gpio->out_state |= BIT_MASK;
+	else
+		idio16gpio->out_state &= ~BIT_MASK;
+
+	if (offset > 7)
+		outb(idio16gpio->out_state >> 8, idio16gpio->base + 4);
+	else
+		outb(idio16gpio->out_state, idio16gpio->base);
+
+	spin_unlock_irqrestore(&idio16gpio->lock, flags);
+}
+
+static int __init idio_16_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct idio_16_gpio *idio16gpio;
+	int err;
+
+	const unsigned BASE = idio_16_base;
+	const unsigned EXTENT = 8;
+	const char *const NAME = dev_name(dev);
+
+	idio16gpio = devm_kzalloc(dev, sizeof(*idio16gpio), GFP_KERNEL);
+	if (!idio16gpio)
+		return -ENOMEM;
+
+	if (!request_region(BASE, EXTENT, NAME)) {
+		dev_err(dev, "Unable to lock %s port addresses (0x%X-0x%X)\n",
+			NAME, BASE, BASE + EXTENT);
+		err = -EBUSY;
+		goto err_lock_io_port;
+	}
+
+	idio16gpio->chip.label = NAME;
+	idio16gpio->chip.dev = dev;
+	idio16gpio->chip.owner = THIS_MODULE;
+	idio16gpio->chip.base = -1;
+	idio16gpio->chip.ngpio = 32;
+	idio16gpio->chip.get_direction = idio_16_gpio_get_direction;
+	idio16gpio->chip.direction_input = idio_16_gpio_direction_input;
+	idio16gpio->chip.direction_output = idio_16_gpio_direction_output;
+	idio16gpio->chip.get = idio_16_gpio_get;
+	idio16gpio->chip.set = idio_16_gpio_set;
+	idio16gpio->base = BASE;
+	idio16gpio->extent = EXTENT;
+	idio16gpio->out_state = 0xFFFF;
+
+	spin_lock_init(&idio16gpio->lock);
+
+	dev_set_drvdata(dev, idio16gpio);
+
+	err = gpiochip_add(&idio16gpio->chip);
+	if (err) {
+		dev_err(dev, "GPIO registering failed (%d)\n", err);
+		goto err_gpio_register;
+	}
+
+	return 0;
+
+err_gpio_register:
+	release_region(BASE, EXTENT);
+err_lock_io_port:
+	return err;
+}
+
+static int idio_16_remove(struct platform_device *pdev)
+{
+	struct idio_16_gpio *const idio16gpio = platform_get_drvdata(pdev);
+
+	gpiochip_remove(&idio16gpio->chip);
+	release_region(idio16gpio->base, idio16gpio->extent);
+
+	return 0;
+}
+
+static struct platform_device *idio_16_device;
+
+static struct platform_driver idio_16_driver = {
+	.driver = {
+		.name = "104-idio-16"
+	},
+	.remove = idio_16_remove
+};
+
+static void __exit idio_16_exit(void)
+{
+	platform_device_unregister(idio_16_device);
+	platform_driver_unregister(&idio_16_driver);
+}
+
+static int __init idio_16_init(void)
+{
+	int err;
+
+	idio_16_device = platform_device_alloc(idio_16_driver.driver.name, -1);
+	if (!idio_16_device)
+		return -ENOMEM;
+
+	err = platform_device_add(idio_16_device);
+	if (err)
+		goto err_platform_device;
+
+	err = platform_driver_probe(&idio_16_driver, idio_16_probe);
+	if (err)
+		goto err_platform_driver;
+
+	return 0;
+
+err_platform_driver:
+	platform_device_del(idio_16_device);
+err_platform_device:
+	platform_device_put(idio_16_device);
+	return err;
+}
+
+module_init(idio_16_init);
+module_exit(idio_16_exit);
+
+MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
+MODULE_DESCRIPTION("ACCES 104-IDIO-16 GPIO driver");
+MODULE_LICENSE("GPL");