drivers/gpio/gpio-grgpio.c - pub/scm/linux/kernel/git/gregkh/tty - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Driver for Aeroflex Gaisler GRGPIO General Purpose I/O cores.
  *
  * 2013 (c) Aeroflex Gaisler AB
  *
  * This driver supports the GRGPIO GPIO core available in the GRLIB VHDL
  * IP core library.
  *
  * Full documentation of the GRGPIO core can be found here:
  * http://www.gaisler.com/products/grlib/grip.pdf
  *
  * See "Documentation/devicetree/bindings/gpio/gpio-grgpio.txt" for
  * information on open firmware properties.
  *
  * Contributors: Andreas Larsson <andreas@gaisler.com>
  */

 #include <linux/bitops.h>
 #include <linux/err.h>
 #include <linux/gpio/driver.h>
 #include <linux/gpio/generic.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/string_choices.h>

 #define GRGPIO_MAX_NGPIO 32

 #define GRGPIO_DATA		0x00
 #define GRGPIO_OUTPUT		0x04
 #define GRGPIO_DIR		0x08
 #define GRGPIO_IMASK		0x0c
 #define GRGPIO_IPOL		0x10
 #define GRGPIO_IEDGE		0x14
 #define GRGPIO_BYPASS		0x18
 #define GRGPIO_IMAP_BASE	0x20

 /* Structure for an irq of the core - called an underlying irq */
 struct grgpio_uirq {
 	u8 refcnt; /* Reference counter to manage requesting/freeing of uirq */
 	u8 uirq; /* Underlying irq of the gpio driver */
 };

 /*
  * Structure for an irq of a gpio line handed out by this driver. The index is
  * used to map to the corresponding underlying irq.
  */
 struct grgpio_lirq {
 	s8 index; /* Index into struct grgpio_priv's uirqs, or -1 */
 	u8 irq; /* irq for the gpio line */
 };

 struct grgpio_priv {
 	struct gpio_generic_chip chip;
 	void __iomem *regs;
 	struct device *dev;

 	u32 imask; /* irq mask shadow register */

 	/*
 	 * The grgpio core can have multiple "underlying" irqs. The gpio lines
 	 * can be mapped to any one or none of these underlying irqs
 	 * independently of each other. This driver sets up an irq domain and
 	 * hands out separate irqs to each gpio line
 	 */
 	struct irq_domain *domain;

 	/*
 	 * This array contains information on each underlying irq, each
 	 * irq of the grgpio core itself.
 	 */
 	struct grgpio_uirq uirqs[GRGPIO_MAX_NGPIO];

 	/*
 	 * This array contains information for each gpio line on the irqs
 	 * obtains from this driver. An index value of -1 for a certain gpio
 	 * line indicates that the line has no irq. Otherwise the index connects
 	 * the irq to the underlying irq by pointing into the uirqs array.
 	 */
 	struct grgpio_lirq lirqs[GRGPIO_MAX_NGPIO];
 };

 static void grgpio_set_imask(struct grgpio_priv *priv, unsigned int offset,
 			     int val)
 {
 	if (val)
 		priv->imask |= BIT(offset);
 	else
 		priv->imask &= ~BIT(offset);

 	gpio_generic_write_reg(&priv->chip, priv->regs + GRGPIO_IMASK, priv->imask);
 }

 static int grgpio_to_irq(struct gpio_chip *gc, unsigned offset)
 {
 	struct grgpio_priv *priv = gpiochip_get_data(gc);

 	if (offset >= gc->ngpio)
 		return -ENXIO;

 	if (priv->lirqs[offset].index < 0)
 		return -ENXIO;

 	return irq_create_mapping(priv->domain, offset);
 }

 /* -------------------- IRQ chip functions -------------------- */

 static int grgpio_irq_set_type(struct irq_data *d, unsigned int type)
 {
 	struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
 	u32 mask = BIT(d->hwirq);
 	u32 ipol;
 	u32 iedge;
 	u32 pol;
 	u32 edge;

 	switch (type) {
 	case IRQ_TYPE_LEVEL_LOW:
 		pol = 0;
 		edge = 0;
 		break;
 	case IRQ_TYPE_LEVEL_HIGH:
 		pol = mask;
 		edge = 0;
 		break;
 	case IRQ_TYPE_EDGE_FALLING:
 		pol = 0;
 		edge = mask;
 		break;
 	case IRQ_TYPE_EDGE_RISING:
 		pol = mask;
 		edge = mask;
 		break;
 	default:
 		return -EINVAL;
 	}

 	guard(gpio_generic_lock_irqsave)(&priv->chip);

 	ipol = gpio_generic_read_reg(&priv->chip, priv->regs + GRGPIO_IPOL) & ~mask;
 	iedge = gpio_generic_read_reg(&priv->chip, priv->regs + GRGPIO_IEDGE) & ~mask;

 	gpio_generic_write_reg(&priv->chip, priv->regs + GRGPIO_IPOL, ipol | pol);
 	gpio_generic_write_reg(&priv->chip, priv->regs + GRGPIO_IEDGE, iedge | edge);

 	return 0;
 }

 static void grgpio_irq_mask(struct irq_data *d)
 {
 	struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
 	int offset = d->hwirq;

 	scoped_guard(gpio_generic_lock_irqsave, &priv->chip)
 		grgpio_set_imask(priv, offset, 0);

 	gpiochip_disable_irq(&priv->chip.gc, d->hwirq);
 }

 static void grgpio_irq_unmask(struct irq_data *d)
 {
 	struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
 	int offset = d->hwirq;

 	gpiochip_enable_irq(&priv->chip.gc, d->hwirq);

 	guard(gpio_generic_lock_irqsave)(&priv->chip);

 	grgpio_set_imask(priv, offset, 1);
 }

 static const struct irq_chip grgpio_irq_chip = {
 	.name			= "grgpio",
 	.irq_mask		= grgpio_irq_mask,
 	.irq_unmask		= grgpio_irq_unmask,
 	.irq_set_type		= grgpio_irq_set_type,
 	.flags = IRQCHIP_IMMUTABLE,
 	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };

 static irqreturn_t grgpio_irq_handler(int irq, void *dev)
 {
 	struct grgpio_priv *priv = dev;
 	int ngpio = priv->chip.gc.ngpio;
 	int i;
 	int match = 0;

 	guard(gpio_generic_lock_irqsave)(&priv->chip);

 	/*
 	 * For each gpio line, call its interrupt handler if it its underlying
 	 * irq matches the current irq that is handled.
 	 */
 	for (i = 0; i < ngpio; i++) {
 		struct grgpio_lirq *lirq = &priv->lirqs[i];

 		if (priv->imask & BIT(i) && lirq->index >= 0 &&
 		    priv->uirqs[lirq->index].uirq == irq) {
 			generic_handle_irq(lirq->irq);
 			match = 1;
 		}
 	}

 	if (!match)
 		dev_warn(priv->dev, "No gpio line matched irq %d\n", irq);

 	return IRQ_HANDLED;
 }

 /*
  * This function will be called as a consequence of the call to
  * irq_create_mapping in grgpio_to_irq
  */
 static int grgpio_irq_map(struct irq_domain *d, unsigned int irq,
 			  irq_hw_number_t hwirq)
 {
 	struct grgpio_priv *priv = d->host_data;
 	struct grgpio_lirq *lirq;
 	struct grgpio_uirq *uirq;
 	unsigned long flags;
 	int offset = hwirq;
 	int ret = 0;

 	if (!priv)
 		return -EINVAL;

 	lirq = &priv->lirqs[offset];
 	if (lirq->index < 0)
 		return -EINVAL;

 	dev_dbg(priv->dev, "Mapping irq %d for gpio line %d\n",
 		irq, offset);

 	gpio_generic_chip_lock_irqsave(&priv->chip, flags);

 	/* Request underlying irq if not already requested */
 	lirq->irq = irq;
 	uirq = &priv->uirqs[lirq->index];
 	if (uirq->refcnt == 0) {
 		/*
 		 * FIXME: This is not how locking works at all, you can't just
 		 * release the lock for a moment to do something that can't
 		 * sleep...
 		 */
 		gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
 		ret = request_irq(uirq->uirq, grgpio_irq_handler, 0,
 				  dev_name(priv->dev), priv);
 		if (ret) {
 			dev_err(priv->dev,
 				"Could not request underlying irq %d\n",
 				uirq->uirq);
 			return ret;
 		}
 		gpio_generic_chip_lock_irqsave(&priv->chip, flags);
 	}
 	uirq->refcnt++;

 	gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);

 	/* Setup irq  */
 	irq_set_chip_data(irq, priv);
 	irq_set_chip_and_handler(irq, &grgpio_irq_chip,
 				 handle_simple_irq);
 	irq_set_noprobe(irq);

 	return ret;
 }

 static void grgpio_irq_unmap(struct irq_domain *d, unsigned int irq)
 {
 	struct grgpio_priv *priv = d->host_data;
 	int index;
 	struct grgpio_lirq *lirq;
 	struct grgpio_uirq *uirq;
 	unsigned long flags;
 	int ngpio = priv->chip.gc.ngpio;
 	int i;

 	irq_set_chip_and_handler(irq, NULL, NULL);
 	irq_set_chip_data(irq, NULL);

 	gpio_generic_chip_lock_irqsave(&priv->chip, flags);

 	/* Free underlying irq if last user unmapped */
 	index = -1;
 	for (i = 0; i < ngpio; i++) {
 		lirq = &priv->lirqs[i];
 		if (lirq->irq == irq) {
 			grgpio_set_imask(priv, i, 0);
 			lirq->irq = 0;
 			index = lirq->index;
 			break;
 		}
 	}
 	WARN_ON(index < 0);

 	if (index >= 0) {
 		uirq = &priv->uirqs[lirq->index];
 		uirq->refcnt--;
 		if (uirq->refcnt == 0) {
 			gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
 			free_irq(uirq->uirq, priv);
 			return;
 		}
 	}

 	gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
 }

 static void grgpio_irq_domain_remove(void *data)
 {
 	struct irq_domain *domain = data;

 	irq_domain_remove(domain);
 }

 static const struct irq_domain_ops grgpio_irq_domain_ops = {
 	.map	= grgpio_irq_map,
 	.unmap	= grgpio_irq_unmap,
 };

 /* ------------------------------------------------------------ */

 static int grgpio_probe(struct platform_device *ofdev)
 {
 	struct device_node *np = ofdev->dev.of_node;
 	struct gpio_generic_chip_config config;
 	struct device *dev = &ofdev->dev;
 	void  __iomem *regs;
 	struct gpio_chip *gc;
 	struct grgpio_priv *priv;
 	int err;
 	u32 prop;
 	s32 *irqmap;
 	int size;
 	int i;

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

 	regs = devm_platform_ioremap_resource(ofdev, 0);
 	if (IS_ERR(regs))
 		return PTR_ERR(regs);

 	config = (struct gpio_generic_chip_config) {
 		.dev = dev,
 		.sz = 4,
 		.dat = regs + GRGPIO_DATA,
 		.set = regs + GRGPIO_OUTPUT,
 		.dirout = regs + GRGPIO_DIR,
 		.flags = GPIO_GENERIC_BIG_ENDIAN_BYTE_ORDER,
 	};

 	gc = &priv->chip.gc;
 	err = gpio_generic_chip_init(&priv->chip, &config);
 	if (err) {
 		dev_err(dev, "failed to initialize the generic GPIO chip\n");
 		return err;
 	}

 	priv->regs = regs;
 	priv->imask = gpio_generic_read_reg(&priv->chip, regs + GRGPIO_IMASK);
 	priv->dev = dev;

 	gc->owner = THIS_MODULE;
 	gc->to_irq = grgpio_to_irq;
 	gc->label = devm_kasprintf(dev, GFP_KERNEL, "%pOF", np);
 	if (!gc->label)
 		return -ENOMEM;

 	gc->base = -1;

 	err = of_property_read_u32(np, "nbits", &prop);
 	if (err || prop <= 0 || prop > GRGPIO_MAX_NGPIO) {
 		gc->ngpio = GRGPIO_MAX_NGPIO;
 		dev_dbg(dev, "No or invalid nbits property: assume %d\n",
 			gc->ngpio);
 	} else {
 		gc->ngpio = prop;
 	}

 	/*
 	 * The irqmap contains the index values indicating which underlying irq,
 	 * if anyone, is connected to that line
 	 */
 	irqmap = (s32 *)of_get_property(np, "irqmap", &size);
 	if (irqmap) {
 		if (size < gc->ngpio) {
 			dev_err(dev,
 				"irqmap shorter than ngpio (%d < %d)\n",
 				size, gc->ngpio);
 			return -EINVAL;
 		}

 		priv->domain = irq_domain_create_linear(dev_fwnode(&ofdev->dev), gc->ngpio,
 							&grgpio_irq_domain_ops, priv);
 		if (!priv->domain) {
 			dev_err(dev, "Could not add irq domain\n");
 			return -EINVAL;
 		}

 		err = devm_add_action_or_reset(dev, grgpio_irq_domain_remove,
 					       priv->domain);
 		if (err)
 			return err;

 		for (i = 0; i < gc->ngpio; i++) {
 			struct grgpio_lirq *lirq;
 			int ret;

 			lirq = &priv->lirqs[i];
 			lirq->index = irqmap[i];

 			if (lirq->index < 0)
 				continue;

 			ret = platform_get_irq(ofdev, lirq->index);
 			if (ret <= 0) {
 				/*
 				 * Continue without irq functionality for that
 				 * gpio line
 				 */
 				continue;
 			}
 			priv->uirqs[lirq->index].uirq = ret;
 		}
 	}

 	err = devm_gpiochip_add_data(dev, gc, priv);
 	if (err) {
 		dev_err(dev, "Could not add gpiochip\n");
 		return err;
 	}

 	dev_info(dev, "regs=0x%p, base=%d, ngpio=%d, irqs=%s\n",
 		 priv->regs, gc->base, gc->ngpio, str_on_off(priv->domain));

 	return 0;
 }

 static const struct of_device_id grgpio_match[] = {
 	{.name = "GAISLER_GPIO"},
 	{.name = "01_01a"},
 	{},
 };

 MODULE_DEVICE_TABLE(of, grgpio_match);

 static struct platform_driver grgpio_driver = {
 	.driver = {
 		.name = "grgpio",
 		.of_match_table = grgpio_match,
 	},
 	.probe = grgpio_probe,
 };
 module_platform_driver(grgpio_driver);

 MODULE_AUTHOR("Aeroflex Gaisler AB.");
 MODULE_DESCRIPTION("Driver for Aeroflex Gaisler GRGPIO");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Driver for Aeroflex Gaisler GRGPIO General Purpose I/O cores.
	*
	* 2013 (c) Aeroflex Gaisler AB
	*
	* This driver supports the GRGPIO GPIO core available in the GRLIB VHDL
	* IP core library.
	*
	* Full documentation of the GRGPIO core can be found here:
	* http://www.gaisler.com/products/grlib/grip.pdf
	*
	* See "Documentation/devicetree/bindings/gpio/gpio-grgpio.txt" for
	* information on open firmware properties.
	*
	* Contributors: Andreas Larsson <andreas@gaisler.com>
	*/

	#include <linux/bitops.h>
	#include <linux/err.h>
	#include <linux/gpio/driver.h>
	#include <linux/gpio/generic.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/irq.h>
	#include <linux/irqdomain.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <linux/string_choices.h>

	#define GRGPIO_MAX_NGPIO 32

	#define GRGPIO_DATA 0x00
	#define GRGPIO_OUTPUT 0x04
	#define GRGPIO_DIR 0x08
	#define GRGPIO_IMASK 0x0c
	#define GRGPIO_IPOL 0x10
	#define GRGPIO_IEDGE 0x14
	#define GRGPIO_BYPASS 0x18
	#define GRGPIO_IMAP_BASE 0x20

	/* Structure for an irq of the core - called an underlying irq */
	struct grgpio_uirq {
	u8 refcnt; /* Reference counter to manage requesting/freeing of uirq */
	u8 uirq; /* Underlying irq of the gpio driver */
	};

	/*
	* Structure for an irq of a gpio line handed out by this driver. The index is
	* used to map to the corresponding underlying irq.
	*/
	struct grgpio_lirq {
	s8 index; /* Index into struct grgpio_priv's uirqs, or -1 */
	u8 irq; /* irq for the gpio line */
	};

	struct grgpio_priv {
	struct gpio_generic_chip chip;
	void __iomem *regs;
	struct device *dev;

	u32 imask; /* irq mask shadow register */

	/*
	* The grgpio core can have multiple "underlying" irqs. The gpio lines
	* can be mapped to any one or none of these underlying irqs
	* independently of each other. This driver sets up an irq domain and
	* hands out separate irqs to each gpio line
	*/
	struct irq_domain *domain;

	/*
	* This array contains information on each underlying irq, each
	* irq of the grgpio core itself.
	*/
	struct grgpio_uirq uirqs[GRGPIO_MAX_NGPIO];

	/*
	* This array contains information for each gpio line on the irqs
	* obtains from this driver. An index value of -1 for a certain gpio
	* line indicates that the line has no irq. Otherwise the index connects
	* the irq to the underlying irq by pointing into the uirqs array.
	*/
	struct grgpio_lirq lirqs[GRGPIO_MAX_NGPIO];
	};

	static void grgpio_set_imask(struct grgpio_priv *priv, unsigned int offset,
	int val)
	{
	if (val)
	priv->imask \|= BIT(offset);
	else
	priv->imask &= ~BIT(offset);

	gpio_generic_write_reg(&priv->chip, priv->regs + GRGPIO_IMASK, priv->imask);
	}

	static int grgpio_to_irq(struct gpio_chip *gc, unsigned offset)
	{
	struct grgpio_priv *priv = gpiochip_get_data(gc);

	if (offset >= gc->ngpio)
	return -ENXIO;

	if (priv->lirqs[offset].index < 0)
	return -ENXIO;

	return irq_create_mapping(priv->domain, offset);
	}

	/* -------------------- IRQ chip functions -------------------- */

	static int grgpio_irq_set_type(struct irq_data *d, unsigned int type)
	{
	struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
	u32 mask = BIT(d->hwirq);
	u32 ipol;
	u32 iedge;
	u32 pol;
	u32 edge;

	switch (type) {
	case IRQ_TYPE_LEVEL_LOW:
	pol = 0;
	edge = 0;
	break;
	case IRQ_TYPE_LEVEL_HIGH:
	pol = mask;
	edge = 0;
	break;
	case IRQ_TYPE_EDGE_FALLING:
	pol = 0;
	edge = mask;
	break;
	case IRQ_TYPE_EDGE_RISING:
	pol = mask;
	edge = mask;
	break;
	default:
	return -EINVAL;
	}

	guard(gpio_generic_lock_irqsave)(&priv->chip);

	ipol = gpio_generic_read_reg(&priv->chip, priv->regs + GRGPIO_IPOL) & ~mask;
	iedge = gpio_generic_read_reg(&priv->chip, priv->regs + GRGPIO_IEDGE) & ~mask;

	gpio_generic_write_reg(&priv->chip, priv->regs + GRGPIO_IPOL, ipol \| pol);
	gpio_generic_write_reg(&priv->chip, priv->regs + GRGPIO_IEDGE, iedge \| edge);

	return 0;
	}

	static void grgpio_irq_mask(struct irq_data *d)
	{
	struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
	int offset = d->hwirq;

	scoped_guard(gpio_generic_lock_irqsave, &priv->chip)
	grgpio_set_imask(priv, offset, 0);

	gpiochip_disable_irq(&priv->chip.gc, d->hwirq);
	}

	static void grgpio_irq_unmask(struct irq_data *d)
	{
	struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
	int offset = d->hwirq;

	gpiochip_enable_irq(&priv->chip.gc, d->hwirq);

	guard(gpio_generic_lock_irqsave)(&priv->chip);

	grgpio_set_imask(priv, offset, 1);
	}

	static const struct irq_chip grgpio_irq_chip = {
	.name = "grgpio",
	.irq_mask = grgpio_irq_mask,
	.irq_unmask = grgpio_irq_unmask,
	.irq_set_type = grgpio_irq_set_type,
	.flags = IRQCHIP_IMMUTABLE,
	GPIOCHIP_IRQ_RESOURCE_HELPERS,
	};

	static irqreturn_t grgpio_irq_handler(int irq, void *dev)
	{
	struct grgpio_priv *priv = dev;
	int ngpio = priv->chip.gc.ngpio;
	int i;
	int match = 0;

	guard(gpio_generic_lock_irqsave)(&priv->chip);

	/*
	* For each gpio line, call its interrupt handler if it its underlying
	* irq matches the current irq that is handled.
	*/
	for (i = 0; i < ngpio; i++) {
	struct grgpio_lirq *lirq = &priv->lirqs[i];

	if (priv->imask & BIT(i) && lirq->index >= 0 &&
	priv->uirqs[lirq->index].uirq == irq) {
	generic_handle_irq(lirq->irq);
	match = 1;
	}
	}

	if (!match)
	dev_warn(priv->dev, "No gpio line matched irq %d\n", irq);

	return IRQ_HANDLED;
	}

	/*
	* This function will be called as a consequence of the call to
	* irq_create_mapping in grgpio_to_irq
	*/
	static int grgpio_irq_map(struct irq_domain *d, unsigned int irq,
	irq_hw_number_t hwirq)
	{
	struct grgpio_priv *priv = d->host_data;
	struct grgpio_lirq *lirq;
	struct grgpio_uirq *uirq;
	unsigned long flags;
	int offset = hwirq;
	int ret = 0;

	if (!priv)
	return -EINVAL;

	lirq = &priv->lirqs[offset];
	if (lirq->index < 0)
	return -EINVAL;

	dev_dbg(priv->dev, "Mapping irq %d for gpio line %d\n",
	irq, offset);

	gpio_generic_chip_lock_irqsave(&priv->chip, flags);

	/* Request underlying irq if not already requested */
	lirq->irq = irq;
	uirq = &priv->uirqs[lirq->index];
	if (uirq->refcnt == 0) {
	/*
	* FIXME: This is not how locking works at all, you can't just
	* release the lock for a moment to do something that can't
	* sleep...
	*/
	gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
	ret = request_irq(uirq->uirq, grgpio_irq_handler, 0,
	dev_name(priv->dev), priv);
	if (ret) {
	dev_err(priv->dev,
	"Could not request underlying irq %d\n",
	uirq->uirq);
	return ret;
	}
	gpio_generic_chip_lock_irqsave(&priv->chip, flags);
	}
	uirq->refcnt++;

	gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);

	/* Setup irq */
	irq_set_chip_data(irq, priv);
	irq_set_chip_and_handler(irq, &grgpio_irq_chip,
	handle_simple_irq);
	irq_set_noprobe(irq);

	return ret;
	}

	static void grgpio_irq_unmap(struct irq_domain *d, unsigned int irq)
	{
	struct grgpio_priv *priv = d->host_data;
	int index;
	struct grgpio_lirq *lirq;
	struct grgpio_uirq *uirq;
	unsigned long flags;
	int ngpio = priv->chip.gc.ngpio;
	int i;

	irq_set_chip_and_handler(irq, NULL, NULL);
	irq_set_chip_data(irq, NULL);

	gpio_generic_chip_lock_irqsave(&priv->chip, flags);

	/* Free underlying irq if last user unmapped */
	index = -1;
	for (i = 0; i < ngpio; i++) {
	lirq = &priv->lirqs[i];
	if (lirq->irq == irq) {
	grgpio_set_imask(priv, i, 0);
	lirq->irq = 0;
	index = lirq->index;
	break;
	}
	}
	WARN_ON(index < 0);

	if (index >= 0) {
	uirq = &priv->uirqs[lirq->index];
	uirq->refcnt--;
	if (uirq->refcnt == 0) {
	gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
	free_irq(uirq->uirq, priv);
	return;
	}
	}

	gpio_generic_chip_unlock_irqrestore(&priv->chip, flags);
	}

	static void grgpio_irq_domain_remove(void *data)
	{
	struct irq_domain *domain = data;

	irq_domain_remove(domain);
	}

	static const struct irq_domain_ops grgpio_irq_domain_ops = {
	.map = grgpio_irq_map,
	.unmap = grgpio_irq_unmap,
	};

	/* ------------------------------------------------------------ */

	static int grgpio_probe(struct platform_device *ofdev)
	{
	struct device_node *np = ofdev->dev.of_node;
	struct gpio_generic_chip_config config;
	struct device *dev = &ofdev->dev;
	void __iomem *regs;
	struct gpio_chip *gc;
	struct grgpio_priv *priv;
	int err;
	u32 prop;
	s32 *irqmap;
	int size;
	int i;

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

	regs = devm_platform_ioremap_resource(ofdev, 0);
	if (IS_ERR(regs))
	return PTR_ERR(regs);

	config = (struct gpio_generic_chip_config) {
	.dev = dev,
	.sz = 4,
	.dat = regs + GRGPIO_DATA,
	.set = regs + GRGPIO_OUTPUT,
	.dirout = regs + GRGPIO_DIR,
	.flags = GPIO_GENERIC_BIG_ENDIAN_BYTE_ORDER,
	};

	gc = &priv->chip.gc;
	err = gpio_generic_chip_init(&priv->chip, &config);
	if (err) {
	dev_err(dev, "failed to initialize the generic GPIO chip\n");
	return err;
	}

	priv->regs = regs;
	priv->imask = gpio_generic_read_reg(&priv->chip, regs + GRGPIO_IMASK);
	priv->dev = dev;

	gc->owner = THIS_MODULE;
	gc->to_irq = grgpio_to_irq;
	gc->label = devm_kasprintf(dev, GFP_KERNEL, "%pOF", np);
	if (!gc->label)
	return -ENOMEM;

	gc->base = -1;

	err = of_property_read_u32(np, "nbits", &prop);
	if (err \|\| prop <= 0 \|\| prop > GRGPIO_MAX_NGPIO) {
	gc->ngpio = GRGPIO_MAX_NGPIO;
	dev_dbg(dev, "No or invalid nbits property: assume %d\n",
	gc->ngpio);
	} else {
	gc->ngpio = prop;
	}

	/*
	* The irqmap contains the index values indicating which underlying irq,
	* if anyone, is connected to that line
	*/
	irqmap = (s32 *)of_get_property(np, "irqmap", &size);
	if (irqmap) {
	if (size < gc->ngpio) {
	dev_err(dev,
	"irqmap shorter than ngpio (%d < %d)\n",
	size, gc->ngpio);
	return -EINVAL;
	}

	priv->domain = irq_domain_create_linear(dev_fwnode(&ofdev->dev), gc->ngpio,
	&grgpio_irq_domain_ops, priv);
	if (!priv->domain) {
	dev_err(dev, "Could not add irq domain\n");
	return -EINVAL;
	}

	err = devm_add_action_or_reset(dev, grgpio_irq_domain_remove,
	priv->domain);
	if (err)
	return err;

	for (i = 0; i < gc->ngpio; i++) {
	struct grgpio_lirq *lirq;
	int ret;

	lirq = &priv->lirqs[i];
	lirq->index = irqmap[i];

	if (lirq->index < 0)
	continue;

	ret = platform_get_irq(ofdev, lirq->index);
	if (ret <= 0) {
	/*
	* Continue without irq functionality for that
	* gpio line
	*/
	continue;
	}
	priv->uirqs[lirq->index].uirq = ret;
	}
	}

	err = devm_gpiochip_add_data(dev, gc, priv);
	if (err) {
	dev_err(dev, "Could not add gpiochip\n");
	return err;
	}

	dev_info(dev, "regs=0x%p, base=%d, ngpio=%d, irqs=%s\n",
	priv->regs, gc->base, gc->ngpio, str_on_off(priv->domain));

	return 0;
	}

	static const struct of_device_id grgpio_match[] = {
	{.name = "GAISLER_GPIO"},
	{.name = "01_01a"},
	{},
	};

	MODULE_DEVICE_TABLE(of, grgpio_match);

	static struct platform_driver grgpio_driver = {
	.driver = {
	.name = "grgpio",
	.of_match_table = grgpio_match,
	},
	.probe = grgpio_probe,
	};
	module_platform_driver(grgpio_driver);

	MODULE_AUTHOR("Aeroflex Gaisler AB.");
	MODULE_DESCRIPTION("Driver for Aeroflex Gaisler GRGPIO");
	MODULE_LICENSE("GPL");