1 files changed, 290 insertions, 71 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5c1ba87..70e0fff 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -16,6 +16,11 @@
 #include <linux/gpio/driver.h>
 #include <linux/gpio/machine.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/idr.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <uapi/linux/gpio.h>
 
 #include "gpiolib.h"
 
@@ -42,6 +47,14 @@
 #define	extra_checks	0
 #endif
 
+/* Device and char device-related information */
+static DEFINE_IDA(gpio_ida);
+static dev_t gpio_devt;
+#define GPIO_DEV_MAX 256 /* 256 GPIO chip devices supported */
+static struct bus_type gpio_bus_type = {
+	.name = "gpio",
+};
+
 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
  * While any GPIO is requested, its gpio_chip is not removable;
  * each GPIO's "requested" flag serves as a lock and refcount.
@@ -50,8 +63,7 @@ DEFINE_SPINLOCK(gpio_lock);
 
 static DEFINE_MUTEX(gpio_lookup_lock);
 static LIST_HEAD(gpio_lookup_list);
-LIST_HEAD(gpio_chips);
-
+LIST_HEAD(gpio_devices);
 
 static void gpiochip_free_hogs(struct gpio_chip *chip);
 static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
@@ -67,15 +79,16 @@ static inline void desc_set_label(struct gpio_desc *d, const char *label)
  */
 struct gpio_desc *gpio_to_desc(unsigned gpio)
 {
-	struct gpio_chip *chip;
+	struct gpio_device *gdev;
 	unsigned long flags;
 
 	spin_lock_irqsave(&gpio_lock, flags);
 
-	list_for_each_entry(chip, &gpio_chips, list) {
-		if (chip->base <= gpio && chip->base + chip->ngpio > gpio) {
+	list_for_each_entry(gdev, &gpio_devices, list) {
+		if (gdev->chip->base <= gpio &&
+		    gdev->chip->base + gdev->chip->ngpio > gpio) {
 			spin_unlock_irqrestore(&gpio_lock, flags);
-			return &chip->desc[gpio - chip->base];
+			return &gdev->chip->desc[gpio - gdev->chip->base];
 		}
 	}
 
@@ -125,16 +138,16 @@ EXPORT_SYMBOL_GPL(gpiod_to_chip);
 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
 static int gpiochip_find_base(int ngpio)
 {
-	struct gpio_chip *chip;
+	struct gpio_device *gdev;
 	int base = ARCH_NR_GPIOS - ngpio;
 
-	list_for_each_entry_reverse(chip, &gpio_chips, list) {
+	list_for_each_entry_reverse(gdev, &gpio_devices, list) {
 		/* found a free space? */
-		if (chip->base + chip->ngpio <= base)
+		if (gdev->chip->base + gdev->chip->ngpio <= base)
 			break;
 		else
 			/* nope, check the space right before the chip */
-			base = chip->base - ngpio;
+			base = gdev->chip->base - ngpio;
 	}
 
 	if (gpio_is_valid(base)) {
@@ -187,18 +200,28 @@ EXPORT_SYMBOL_GPL(gpiod_get_direction);
  * Return -EBUSY if the new chip overlaps with some other chip's integer
  * space.
  */
-static int gpiochip_add_to_list(struct gpio_chip *chip)
+static int gpiodev_add_to_list(struct gpio_device *gdev)
 {
-	struct gpio_chip *iterator;
-	struct gpio_chip *previous = NULL;
+	struct gpio_device *iterator;
+	struct gpio_device *previous = NULL;
 
-	if (list_empty(&gpio_chips)) {
-		list_add_tail(&chip->list, &gpio_chips);
+	if (!gdev->chip)
+		return -EINVAL;
+
+	if (list_empty(&gpio_devices)) {
+		list_add_tail(&gdev->list, &gpio_devices);
 		return 0;
 	}
 
-	list_for_each_entry(iterator, &gpio_chips, list) {
-		if (iterator->base >= chip->base + chip->ngpio) {
+	list_for_each_entry(iterator, &gpio_devices, list) {
+		/*
+		 * The list may contain dangling GPIO devices with no
+		 * live chip assigned.
+		 */
+		if (!iterator->chip)
+			continue;
+		if (iterator->chip->base >=
+		    gdev->chip->base + gdev->chip->ngpio) {
 			/*
 			 * Iterator is the first GPIO chip so there is no
 			 * previous one
@@ -211,8 +234,8 @@ static int gpiochip_add_to_list(struct gpio_chip *chip)
 				 * [base, base + ngpio - 1]) between previous
 				 * and iterator chip.
 				 */
-				if (previous->base + previous->ngpio
-						<= chip->base)
+				if (previous->chip->base + previous->chip->ngpio
+						<= gdev->chip->base)
 					goto found;
 			}
 		}
@@ -225,18 +248,18 @@ static int gpiochip_add_to_list(struct gpio_chip *chip)
 	 * Let iterator point to the last chip in the list.
 	 */
 
-	iterator = list_last_entry(&gpio_chips, struct gpio_chip, list);
-	if (iterator->base + iterator->ngpio <= chip->base) {
-		list_add(&chip->list, &iterator->list);
+	iterator = list_last_entry(&gpio_devices, struct gpio_device, list);
+	if (iterator->chip->base + iterator->chip->ngpio <= gdev->chip->base) {
+		list_add(&gdev->list, &iterator->list);
 		return 0;
 	}
 
-	dev_err(chip->parent,
+	dev_err(&gdev->dev,
 	       "GPIO integer space overlap, cannot add chip\n");
 	return -EBUSY;
 
 found:
-	list_add_tail(&chip->list, &iterator->list);
+	list_add_tail(&gdev->list, &iterator->list);
 	return 0;
 }
 
@@ -245,16 +268,16 @@ found:
  */
 static struct gpio_desc *gpio_name_to_desc(const char * const name)
 {
-	struct gpio_chip *chip;
+	struct gpio_device *gdev;
 	unsigned long flags;
 
 	spin_lock_irqsave(&gpio_lock, flags);
 
-	list_for_each_entry(chip, &gpio_chips, list) {
+	list_for_each_entry(gdev, &gpio_devices, list) {
 		int i;
 
-		for (i = 0; i != chip->ngpio; ++i) {
-			struct gpio_desc *gpio = &chip->desc[i];
+		for (i = 0; i != gdev->chip->ngpio; ++i) {
+			struct gpio_desc *gpio = &gdev->chip->desc[i];
 
 			if (!gpio->name || !name)
 				continue;
@@ -290,8 +313,8 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc)
 
 		gpio = gpio_name_to_desc(gc->names[i]);
 		if (gpio)
-			dev_warn(gc->parent, "Detected name collision for "
-				 "GPIO name '%s'\n",
+			dev_warn(&gc->gpiodev->dev,
+				 "Detected name collision for GPIO name '%s'\n",
 				 gc->names[i]);
 	}
 
@@ -303,6 +326,88 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc)
 }
 
 /**
+ * gpio_ioctl() - ioctl handler for the GPIO chardev
+ */
+static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct gpio_device *gdev = filp->private_data;
+	struct gpio_chip *chip = gdev->chip;
+	int __user *ip = (int __user *)arg;
+	struct gpiochip_info chipinfo;
+
+	/* We fail any subsequent ioctl():s when the chip is gone */
+	if (!chip)
+		return -ENODEV;
+
+	if (cmd == GPIO_GET_CHIPINFO_IOCTL) {
+		/* Fill in the struct and pass to userspace */
+		strncpy(chipinfo.name, dev_name(&gdev->dev),
+			sizeof(chipinfo.name));
+		chipinfo.name[sizeof(chipinfo.name)-1] = '\0';
+		chipinfo.lines = chip->ngpio;
+		if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
+			return -EFAULT;
+		return 0;
+	}
+	return -EINVAL;
+}
+
+/**
+ * gpio_chrdev_open() - open the chardev for ioctl operations
+ * @inode: inode for this chardev
+ * @filp: file struct for storing private data
+ * Returns 0 on success
+ */
+static int gpio_chrdev_open(struct inode *inode, struct file *filp)
+{
+	struct gpio_device *gdev = container_of(inode->i_cdev,
+					      struct gpio_device, chrdev);
+
+	/* Fail on open if the backing gpiochip is gone */
+	if (!gdev || !gdev->chip)
+		return -ENODEV;
+	get_device(&gdev->dev);
+	filp->private_data = gdev;
+	return 0;
+}
+
+/**
+ * gpio_chrdev_release() - close chardev after ioctl operations
+ * @inode: inode for this chardev
+ * @filp: file struct for storing private data
+ * Returns 0 on success
+ */
+static int gpio_chrdev_release(struct inode *inode, struct file *filp)
+{
+	struct gpio_device *gdev = container_of(inode->i_cdev,
+					      struct gpio_device, chrdev);
+
+	if (!gdev)
+		return -ENODEV;
+	put_device(&gdev->dev);
+	return 0;
+}
+
+
+static const struct file_operations gpio_fileops = {
+	.release = gpio_chrdev_release,
+	.open = gpio_chrdev_open,
+	.owner = THIS_MODULE,
+	.llseek = noop_llseek,
+	.unlocked_ioctl = gpio_ioctl,
+	.compat_ioctl = gpio_ioctl,
+};
+
+static void gpiodevice_release(struct device *dev)
+{
+	struct gpio_device *gdev = dev_get_drvdata(dev);
+
+	cdev_del(&gdev->chrdev);
+	list_del(&gdev->list);
+	ida_simple_remove(&gpio_ida, gdev->id);
+}
+
+/**
  * gpiochip_add_data() - register a gpio_chip
  * @chip: the chip to register, with chip->base initialized
  * Context: potentially before irqs will work
@@ -323,19 +428,61 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
 {
 	unsigned long	flags;
 	int		status = 0;
-	unsigned	id;
+	unsigned	i;
 	int		base = chip->base;
 	struct gpio_desc *descs;
+	struct gpio_device *gdev;
 
-	descs = kcalloc(chip->ngpio, sizeof(descs[0]), GFP_KERNEL);
-	if (!descs)
+	/*
+	 * First: allocate and populate the internal stat container, and
+	 * set up the struct device.
+	 */
+	gdev = kmalloc(sizeof(*gdev), GFP_KERNEL);
+	if (!gdev)
 		return -ENOMEM;
+	gdev->dev.bus = &gpio_bus_type;
+	gdev->chip = chip;
+	chip->gpiodev = gdev;
+	if (chip->parent) {
+		gdev->dev.parent = chip->parent;
+		gdev->dev.of_node = chip->parent->of_node;
+	} else {
+#ifdef CONFIG_OF_GPIO
+	/* If the gpiochip has an assigned OF node this takes precedence */
+		if (chip->of_node)
+			gdev->dev.of_node = chip->of_node;
+#endif
+	}
+	gdev->id = ida_simple_get(&gpio_ida, 0, 0, GFP_KERNEL);
+	if (gdev->id < 0) {
+		status = gdev->id;
+		goto err_free_gdev;
+	}
+	dev_set_name(&gdev->dev, "gpiochip%d", gdev->id);
+	device_initialize(&gdev->dev);
+	dev_set_drvdata(&gdev->dev, gdev);
+	if (chip->parent && chip->parent->driver)
+		gdev->owner = chip->parent->driver->owner;
+	else if (chip->owner)
+		/* TODO: remove chip->owner */
+		gdev->owner = chip->owner;
+	else
+		gdev->owner = THIS_MODULE;
+
+	/* FIXME: devm_kcalloc() these and move to gpio_device */
+	descs = kcalloc(chip->ngpio, sizeof(descs[0]), GFP_KERNEL);
+	if (!descs) {
+		status = -ENOMEM;
+		goto err_free_gdev;
+	}
 
+	/* FIXME: move driver data into gpio_device dev_set_drvdata() */
 	chip->data = data;
 
 	if (chip->ngpio == 0) {
 		chip_err(chip, "tried to insert a GPIO chip with zero lines\n");
-		return -EINVAL;
+		status = -EINVAL;
+		goto err_free_descs;
 	}
 
 	spin_lock_irqsave(&gpio_lock, flags);
@@ -350,15 +497,16 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
 		chip->base = base;
 	}
 
-	status = gpiochip_add_to_list(chip);
+	status = gpiodev_add_to_list(gdev);
 	if (status) {
 		spin_unlock_irqrestore(&gpio_lock, flags);
 		goto err_free_descs;
 	}
 
-	for (id = 0; id < chip->ngpio; id++) {
-		struct gpio_desc *desc = &descs[id];
+	for (i = 0; i < chip->ngpio; i++) {
+		struct gpio_desc *desc = &descs[i];
 
+		/* REVISIT: maybe a pointer to gpio_device is better */
 		desc->chip = chip;
 
 		/* REVISIT: most hardware initializes GPIOs as inputs (often
@@ -369,18 +517,15 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
 		 */
 		desc->flags = !chip->direction_input ? (1 << FLAG_IS_OUT) : 0;
 	}
-
 	chip->desc = descs;
 
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
 #ifdef CONFIG_PINCTRL
+	/* FIXME: move pin ranges to gpio_device */
 	INIT_LIST_HEAD(&chip->pin_ranges);
 #endif
 
-	if (!chip->owner && chip->parent && chip->parent->driver)
-		chip->owner = chip->parent->driver->owner;
-
 	status = gpiochip_set_desc_names(chip);
 	if (status)
 		goto err_remove_from_list;
@@ -391,28 +536,58 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
 
 	acpi_gpiochip_add(chip);
 
+	/*
+	 * By first adding the chardev, and then adding the device,
+	 * we get a device node entry in sysfs under
+	 * /sys/bus/gpio/devices/gpiochipN/dev that can be used for
+	 * coldplug of device nodes and other udev business.
+	 */
+	cdev_init(&gdev->chrdev, &gpio_fileops);
+	gdev->chrdev.owner = THIS_MODULE;
+	gdev->chrdev.kobj.parent = &gdev->dev.kobj;
+	gdev->dev.devt = MKDEV(MAJOR(gpio_devt), gdev->id);
+	status = cdev_add(&gdev->chrdev, gdev->dev.devt, 1);
+	if (status < 0)
+		chip_warn(chip, "failed to add char device %d:%d\n",
+			  MAJOR(gpio_devt), gdev->id);
+	else
+		chip_dbg(chip, "added GPIO chardev (%d:%d)\n",
+			 MAJOR(gpio_devt), gdev->id);
+	status = device_add(&gdev->dev);
+	if (status)
+		goto err_remove_chardev;
+
 	status = gpiochip_sysfs_register(chip);
 	if (status)
-		goto err_remove_chip;
+		goto err_remove_device;
 
+	/* From this point, the .release() function cleans up gpio_device */
+	gdev->dev.release = gpiodevice_release;
+	get_device(&gdev->dev);
 	pr_debug("%s: registered GPIOs %d to %d on device: %s\n", __func__,
 		chip->base, chip->base + chip->ngpio - 1,
 		chip->label ? : "generic");
 
 	return 0;
 
+err_remove_device:
+	device_del(&gdev->dev);
+err_remove_chardev:
+	cdev_del(&gdev->chrdev);
 err_remove_chip:
 	acpi_gpiochip_remove(chip);
 	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
 err_remove_from_list:
 	spin_lock_irqsave(&gpio_lock, flags);
-	list_del(&chip->list);
+	list_del(&gdev->list);
 	spin_unlock_irqrestore(&gpio_lock, flags);
 	chip->desc = NULL;
 err_free_descs:
 	kfree(descs);
-
+err_free_gdev:
+	ida_simple_remove(&gpio_ida, gdev->id);
+	kfree(gdev);
 	/* failures here can mean systems won't boot... */
 	pr_err("%s: GPIOs %d..%d (%s) failed to register\n", __func__,
 		chip->base, chip->base + chip->ngpio - 1,
@@ -429,15 +604,18 @@ EXPORT_SYMBOL_GPL(gpiochip_add_data);
  */
 void gpiochip_remove(struct gpio_chip *chip)
 {
+	struct gpio_device *gdev = chip->gpiodev;
 	struct gpio_desc *desc;
 	unsigned long	flags;
 	unsigned	id;
 	bool		requested = false;
 
-	gpiochip_sysfs_unregister(chip);
+	/* Numb the device, cancelling all outstanding operations */
+	gdev->chip = NULL;
 
+	/* FIXME: should the legacy sysfs handling be moved to gpio_device? */
+	gpiochip_sysfs_unregister(chip);
 	gpiochip_irqchip_remove(chip);
-
 	acpi_gpiochip_remove(chip);
 	gpiochip_remove_pin_ranges(chip);
 	gpiochip_free_hogs(chip);
@@ -450,15 +628,23 @@ void gpiochip_remove(struct gpio_chip *chip)
 		if (test_bit(FLAG_REQUESTED, &desc->flags))
 			requested = true;
 	}
-	list_del(&chip->list);
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
 	if (requested)
-		dev_crit(chip->parent,
+		dev_crit(&chip->gpiodev->dev,
 			 "REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
 
+	/* FIXME: need to be moved to gpio_device and held there */
 	kfree(chip->desc);
 	chip->desc = NULL;
+
+	/*
+	 * The gpiochip side puts its use of the device to rest here:
+	 * if there are no userspace clients, the chardev and device will
+	 * be removed, else it will be dangling until the last user is
+	 * gone.
+	 */
+	put_device(&gdev->dev);
 }
 EXPORT_SYMBOL_GPL(gpiochip_remove);
 
@@ -477,17 +663,21 @@ struct gpio_chip *gpiochip_find(void *data,
 				int (*match)(struct gpio_chip *chip,
 					     void *data))
 {
+	struct gpio_device *gdev;
 	struct gpio_chip *chip;
 	unsigned long flags;
 
 	spin_lock_irqsave(&gpio_lock, flags);
-	list_for_each_entry(chip, &gpio_chips, list)
-		if (match(chip, data))
+	list_for_each_entry(gdev, &gpio_devices, list)
+		if (match(gdev->chip, data))
 			break;
 
 	/* No match? */
-	if (&chip->list == &gpio_chips)
+	if (&gdev->list == &gpio_devices)
 		chip = NULL;
+	else
+		chip = gdev->chip;
+
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
 	return chip;
@@ -617,14 +807,14 @@ static int gpiochip_irq_reqres(struct irq_data *d)
 {
 	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
 
-	if (!try_module_get(chip->owner))
+	if (!try_module_get(chip->gpiodev->owner))
 		return -ENODEV;
 
 	if (gpiochip_lock_as_irq(chip, d->hwirq)) {
 		chip_err(chip,
 			"unable to lock HW IRQ %lu for IRQ\n",
 			d->hwirq);
-		module_put(chip->owner);
+		module_put(chip->gpiodev->owner);
 		return -EINVAL;
 	}
 	return 0;
@@ -635,7 +825,7 @@ static void gpiochip_irq_relres(struct irq_data *d)
 	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
 
 	gpiochip_unlock_as_irq(chip, d->hwirq);
-	module_put(chip->owner);
+	module_put(chip->gpiodev->owner);
 }
 
 static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
@@ -985,10 +1175,10 @@ int gpiod_request(struct gpio_desc *desc, const char *label)
 	if (!chip)
 		goto done;
 
-	if (try_module_get(chip->owner)) {
+	if (try_module_get(chip->gpiodev->owner)) {
 		status = __gpiod_request(desc, label);
 		if (status < 0)
-			module_put(chip->owner);
+			module_put(chip->gpiodev->owner);
 	}
 
 done:
@@ -1034,7 +1224,7 @@ static bool __gpiod_free(struct gpio_desc *desc)
 void gpiod_free(struct gpio_desc *desc)
 {
 	if (desc && __gpiod_free(desc))
-		module_put(desc->chip->owner);
+		module_put(desc->chip->gpiodev->owner);
 	else
 		WARN_ON(extra_checks);
 }
@@ -2456,6 +2646,26 @@ void gpiod_put_array(struct gpio_descs *descs)
 }
 EXPORT_SYMBOL_GPL(gpiod_put_array);
 
+static int __init gpiolib_dev_init(void)
+{
+	int ret;
+
+	/* Register GPIO sysfs bus */
+	ret  = bus_register(&gpio_bus_type);
+	if (ret < 0) {
+		pr_err("gpiolib: could not register GPIO bus type\n");
+		return ret;
+	}
+
+	ret = alloc_chrdev_region(&gpio_devt, 0, GPIO_DEV_MAX, "gpiochip");
+	if (ret < 0) {
+		pr_err("gpiolib: failed to allocate char dev region\n");
+		bus_unregister(&gpio_bus_type);
+	}
+	return ret;
+}
+core_initcall(gpiolib_dev_init);
+
 #ifdef CONFIG_DEBUG_FS
 
 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
@@ -2492,16 +2702,16 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
 {
 	unsigned long flags;
-	struct gpio_chip *chip = NULL;
+	struct gpio_device *gdev = NULL;
 	loff_t index = *pos;
 
 	s->private = "";
 
 	spin_lock_irqsave(&gpio_lock, flags);
-	list_for_each_entry(chip, &gpio_chips, list)
+	list_for_each_entry(gdev, &gpio_devices, list)
 		if (index-- == 0) {
 			spin_unlock_irqrestore(&gpio_lock, flags);
-			return chip;
+			return gdev;
 		}
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
@@ -2511,14 +2721,14 @@ static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
 static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
 	unsigned long flags;
-	struct gpio_chip *chip = v;
+	struct gpio_device *gdev = v;
 	void *ret = NULL;
 
 	spin_lock_irqsave(&gpio_lock, flags);
-	if (list_is_last(&chip->list, &gpio_chips))
+	if (list_is_last(&gdev->list, &gpio_devices))
 		ret = NULL;
 	else
-		ret = list_entry(chip->list.next, struct gpio_chip, list);
+		ret = list_entry(gdev->list.next, struct gpio_device, list);
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
 	s->private = "\n";
@@ -2533,15 +2743,24 @@ static void gpiolib_seq_stop(struct seq_file *s, void *v)
 
 static int gpiolib_seq_show(struct seq_file *s, void *v)
 {
-	struct gpio_chip *chip = v;
-	struct device *dev;
+	struct gpio_device *gdev = v;
+	struct gpio_chip *chip = gdev->chip;
+	struct device *parent;
+
+	if (!chip) {
+		seq_printf(s, "%s%s: (dangling chip)", (char *)s->private,
+			   dev_name(&gdev->dev));
+		return 0;
+	}
 
-	seq_printf(s, "%sGPIOs %d-%d", (char *)s->private,
-			chip->base, chip->base + chip->ngpio - 1);
-	dev = chip->parent;
-	if (dev)
-		seq_printf(s, ", %s/%s", dev->bus ? dev->bus->name : "no-bus",
-			dev_name(dev));
+	seq_printf(s, "%s%s: GPIOs %d-%d", (char *)s->private,
+		   dev_name(&gdev->dev),
+		   chip->base, chip->base + chip->ngpio - 1);
+	parent = chip->parent;
+	if (parent)
+		seq_printf(s, ", parent: %s/%s",
+			   parent->bus ? parent->bus->name : "no-bus",
+			   dev_name(parent));
 	if (chip->label)
 		seq_printf(s, ", %s", chip->label);
 	if (chip->can_sleep)