The Langwell chip is the IO hub for Intel Moorestown platform which has a

64-pin gpio block device inside.  It is exposed as a dedicated PCI device.
 We use it to control outside peripheral as well as to do IRQ demuxing. 
The gpio block uses MSI to send level type interrupt to IOAPIC.
Signed-off-by: Alek Du <alek.du@intel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/gpio/Kconfig

@@ -190,6 +190,12 @@ config GPIO_BT8XX
 
 	  If unsure, say N.
 
+config GPIO_LANGWELL
+	tristate "Intel Moorestown Platform Langwell GPIO support"
+	depends on PCI
+	help
+	  Say Y here to support Intel Moorestown platform GPIO.
+
 comment "SPI GPIO expanders:"
 
 config GPIO_MAX7301

drivers/gpio/Makefile

@@ -4,6 +4,7 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
 
 obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 
+obj-$(CONFIG_GPIO_LANGWELL)	+= langwell_gpio.o
 obj-$(CONFIG_GPIO_MAX7301)	+= max7301.o
 obj-$(CONFIG_GPIO_MAX732X)	+= max732x.o
 obj-$(CONFIG_GPIO_MC33880)	+= mc33880.o

drivers/gpio/langwell_gpio.c

+/* langwell_gpio.c Moorestown platform Langwell chip GPIO driver
+ * Copyright (c) 2008 - 2009,  Intel Corporation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/* Supports:
+ * Moorestown platform Langwell chip.
+ */
+
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/stddef.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+
+struct lnw_gpio_register {
+	u32	GPLR[2];
+	u32	GPDR[2];
+	u32	GPSR[2];
+	u32	GPCR[2];
+	u32	GRER[2];
+	u32	GFER[2];
+	u32	GEDR[2];
+};
+
+struct lnw_gpio {
+	struct gpio_chip		chip;
+	struct lnw_gpio_register 	*reg_base;
+	spinlock_t			lock;
+	unsigned			irq_base;
+};
+
+static int lnw_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct lnw_gpio *lnw = container_of(chip, struct lnw_gpio, chip);
+	u8 reg = offset / 32;
+	void __iomem *gplr;
+
+	gplr = (void __iomem *)(&lnw->reg_base->GPLR[reg]);
+	return readl(gplr) & BIT(offset % 32);
+}
+
+static void lnw_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct lnw_gpio *lnw = container_of(chip, struct lnw_gpio, chip);
+	u8 reg = offset / 32;
+	void __iomem *gpsr, *gpcr;
+
+	if (value) {
+		gpsr = (void __iomem *)(&lnw->reg_base->GPSR[reg]);
+		writel(BIT(offset % 32), gpsr);
+	} else {
+		gpcr = (void __iomem *)(&lnw->reg_base->GPCR[reg]);
+		writel(BIT(offset % 32), gpcr);
+	}
+}
+
+static int lnw_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct lnw_gpio *lnw = container_of(chip, struct lnw_gpio, chip);
+	u8 reg = offset / 32;
+	u32 value;
+	unsigned long flags;
+	void __iomem *gpdr;
+
+	gpdr = (void __iomem *)(&lnw->reg_base->GPDR[reg]);
+	spin_lock_irqsave(&lnw->lock, flags);
+	value = readl(gpdr);
+	value &= ~BIT(offset % 32);
+	writel(value, gpdr);
+	spin_unlock_irqrestore(&lnw->lock, flags);
+	return 0;
+}
+
+static int lnw_gpio_direction_output(struct gpio_chip *chip,
+			unsigned offset, int value)
+{
+	struct lnw_gpio *lnw = container_of(chip, struct lnw_gpio, chip);
+	u8 reg = offset / 32;
+	unsigned long flags;
+	void __iomem *gpdr;
+
+	lnw_gpio_set(chip, offset, value);
+	gpdr = (void __iomem *)(&lnw->reg_base->GPDR[reg]);
+	spin_lock_irqsave(&lnw->lock, flags);
+	value = readl(gpdr);
+	value |= BIT(offset % 32);;
+	writel(value, gpdr);
+	spin_unlock_irqrestore(&lnw->lock, flags);
+	return 0;
+}
+
+static int lnw_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+	struct lnw_gpio *lnw = container_of(chip, struct lnw_gpio, chip);
+	return lnw->irq_base + offset;
+}
+
+static int lnw_irq_type(unsigned irq, unsigned type)
+{
+	struct lnw_gpio *lnw = get_irq_chip_data(irq);
+	u32 gpio = irq - lnw->irq_base;
+	u8 reg = gpio / 32;
+	unsigned long flags;
+	u32 value;
+	void __iomem *grer = (void __iomem *)(&lnw->reg_base->GRER[reg]);
+	void __iomem *gfer = (void __iomem *)(&lnw->reg_base->GFER[reg]);
+
+	if (gpio < 0 || gpio > lnw->chip.ngpio)
+		return -EINVAL;
+	spin_lock_irqsave(&lnw->lock, flags);
+	if (type & IRQ_TYPE_EDGE_RISING)
+		value = readl(grer) | BIT(gpio % 32);
+	else
+		value = readl(grer) & (~BIT(gpio % 32));
+	writel(value, grer);
+
+	if (type & IRQ_TYPE_EDGE_FALLING)
+		value = readl(gfer) | BIT(gpio % 32);
+	else
+		value = readl(gfer) & (~BIT(gpio % 32));
+	writel(value, gfer);
+	spin_unlock_irqrestore(&lnw->lock, flags);
+
+	return 0;
+};
+
+static void lnw_irq_unmask(unsigned irq)
+{
+	struct lnw_gpio *lnw = get_irq_chip_data(irq);
+	u32 gpio = irq - lnw->irq_base;
+	u8 reg = gpio / 32;
+	void __iomem *gedr;
+
+	gedr = (void __iomem *)(&lnw->reg_base->GEDR[reg]);
+	writel(BIT(gpio % 32), gedr);
+};
+
+static struct irq_chip lnw_irqchip = {
+	.name		= "LNW-GPIO",
+	.unmask		= lnw_irq_unmask,
+	.set_type	= lnw_irq_type,
+};
+
+static struct pci_device_id lnw_gpio_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x080f) },
+	{ 0, }
+};
+MODULE_DEVICE_TABLE(pci, lnw_gpio_ids);
+
+static void lnw_irq_handler(unsigned irq, struct irq_desc *desc)
+{
+	struct lnw_gpio *lnw = (struct lnw_gpio *)get_irq_data(irq);
+	u32 reg, gpio;
+	void __iomem *gedr;
+	u32 gedr_v;
+
+	/* check GPIO controller to check which pin triggered the interrupt */
+	for (reg = 0; reg < lnw->chip.ngpio / 32; reg++) {
+		gedr = (void __iomem *)(&lnw->reg_base->GEDR[reg]);
+		gedr_v = readl(gedr);
+		if (!gedr_v)
+			continue;
+		for (gpio = reg*32; gpio < reg*32+32; gpio++) {
+			gedr_v = readl(gedr);
+			if (gedr_v & BIT(gpio % 32)) {
+				pr_debug("pin %d triggered\n", gpio);
+				generic_handle_irq(lnw->irq_base + gpio);
+			}
+		}
+		/* clear the edge detect status bit */
+		writel(gedr_v, gedr);
+	}
+	desc->chip->eoi(irq);
+}
+
+static int __devinit lnw_gpio_probe(struct pci_dev *pdev,
+			const struct pci_device_id *id)
+{
+	void *base;
+	int i;
+	resource_size_t start, len;
+	struct lnw_gpio *lnw;
+	u32 irq_base;
+	u32 gpio_base;
+	int retval = 0;
+
+	retval = pci_enable_device(pdev);
+	if (retval)
+		goto done;
+
+	retval = pci_request_regions(pdev, "langwell_gpio");
+	if (retval) {
+		dev_err(&pdev->dev, "error requesting resources\n");
+		goto err2;
+	}
+	/* get the irq_base from bar1 */
+	start = pci_resource_start(pdev, 1);
+	len = pci_resource_len(pdev, 1);
+	base = ioremap_nocache(start, len);
+	if (!base) {
+		dev_err(&pdev->dev, "error mapping bar1\n");
+		goto err3;
+	}
+	irq_base = *(u32 *)base;
+	gpio_base = *((u32 *)base + 1);
+	/* release the IO mapping, since we already get the info from bar1 */
+	iounmap(base);
+	/* get the register base from bar0 */
+	start = pci_resource_start(pdev, 0);
+	len = pci_resource_len(pdev, 0);
+	base = ioremap_nocache(start, len);
+	if (!base) {
+		dev_err(&pdev->dev, "error mapping bar0\n");
+		retval = -EFAULT;
+		goto err3;
+	}
+
+	lnw = kzalloc(sizeof(struct lnw_gpio), GFP_KERNEL);
+	if (!lnw) {
+		dev_err(&pdev->dev, "can't allocate langwell_gpio chip data\n");
+		retval = -ENOMEM;
+		goto err4;
+	}
+	lnw->reg_base = base;
+	lnw->irq_base = irq_base;
+	lnw->chip.label = dev_name(&pdev->dev);
+	lnw->chip.direction_input = lnw_gpio_direction_input;
+	lnw->chip.direction_output = lnw_gpio_direction_output;
+	lnw->chip.get = lnw_gpio_get;
+	lnw->chip.set = lnw_gpio_set;
+	lnw->chip.to_irq = lnw_gpio_to_irq;
+	lnw->chip.base = gpio_base;
+	lnw->chip.ngpio = 64;
+	lnw->chip.can_sleep = 0;
+	pci_set_drvdata(pdev, lnw);
+	retval = gpiochip_add(&lnw->chip);
+	if (retval) {
+		dev_err(&pdev->dev, "langwell gpiochip_add error %d\n", retval);
+		goto err5;
+	}
+	set_irq_data(pdev->irq, lnw);
+	set_irq_chained_handler(pdev->irq, lnw_irq_handler);
+	for (i = 0; i < lnw->chip.ngpio; i++) {
+		set_irq_chip_and_handler_name(i + lnw->irq_base, &lnw_irqchip,
+					handle_simple_irq, "demux");
+		set_irq_chip_data(i + lnw->irq_base, lnw);
+	}
+
+	spin_lock_init(&lnw->lock);
+	goto done;
+err5:
+	kfree(lnw);
+err4:
+	iounmap(base);
+err3:
+	pci_release_regions(pdev);
+err2:
+	pci_disable_device(pdev);
+done:
+	return retval;
+}
+
+static void __devexit lnw_gpio_remove(struct pci_dev *pdev)
+{
+	struct lnw_gpio *lnw = (struct lnw_gpio *)pci_get_drvdata(pdev);
+
+	if (gpiochip_remove(&lnw->chip)) {
+		dev_err(&pdev->dev, "langwell gpio driver remove error\n");
+		return;
+	}
+	pci_disable_device(pdev);
+	set_irq_chained_handler(pdev->irq, NULL);
+	pci_release_regions(pdev);
+	iounmap(lnw->reg_base);
+	pci_set_drvdata(pdev, NULL);
+	kfree(lnw);
+}
+
+static struct pci_driver lnw_gpio_driver = {
+	.name		= "langwell_gpio",
+	.id_table	= lnw_gpio_ids,
+	.probe		= lnw_gpio_probe,
+	.remove		= lnw_gpio_remove,
+};
+
+static int __init lnw_gpio_init(void)
+{
+	return pci_register_driver(&lnw_gpio_driver);
+}
+
+static void __exit lnw_gpio_exit(void)
+{
+	pci_unregister_driver(&lnw_gpio_driver);
+}
+
+MODULE_AUTHOR("Alek Du <alek.du@intel.com>");
+MODULE_DESCRIPTION("Intel Moorestown Platform Langwell chip GPIO driver");
+MODULE_LICENSE("GPL v2");
+
+module_init(lnw_gpio_init);
+module_exit(lnw_gpio_exit);