Merge tag 'gpio-updates-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

Pull gpio updates from Bartosz Golaszewski:
 "The gpio-sim module is back, this time without any changes to
  configfs. This results in a less elegant user-space interface but I
  never got any follow-up on the committable items and didn't want to
  delay this module for several more months.

  Other than that we have support for several new models and some
  support going away. We started working on converting GPIO drivers to
  using fwnode exclusively in order to limit references to OF symbols to
  gpiolib-of.c exclusively. We also have regular tweaks and improvements
  all over the place.

  Summary:

   - new testing module: gpio-sim that is scheduled to replace
     gpio-mockup

   - initial changes aiming at converting all GPIO drivers to using the
     fwnode interface and limiting any references to OF symbols to
     gpiolib-of.c

   - add support for Tegra234 and Tegra241 to gpio-tegra186

   - add support for new models (SSD201 and SSD202D) to gpio-msc313

   - add basic support for interrupts to gpio-aggregator

   - add support for AMDIF031 HID device to gpio-amdpt

   - drop support for unused platforms in gpio-xlp

   - cleanup leftovers from the removal of the legacy Samsung Exynos
     GPIO driver

   - use raw spinlocks in gpio-aspeed and gpio-aspeed-sgpio to make
     PREEMPT_RT happy

   - generalize the common 'ngpios' device property by reading it in the
     core gpiolib code so that we can remove duplicate reads from
     drivers

   - allow line names from device properties to override names set by
     drivers

   - code shrink in gpiod_add_lookup_table()

   - add new model to the DT bindings for gpio-vf610

   - convert DT bindings for tegra devices to YAML

   - improvements to interrupt handling in gpio-rcar and gpio-rockchip

   - updates to intel drivers from Andy (details in the merge commit)

   - some minor tweaks, improvements and coding-style fixes all around
     the subsystem"

* tag 'gpio-updates-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (59 commits)
  gpio: rcar: Propagate errors from devm_request_irq()
  gpio: rcar: Use platform_get_irq() to get the interrupt
  gpio: ts5500: Use platform_get_irq() to get the interrupt
  gpio: dwapb: Switch to use fwnode instead of of_node
  gpiolib: acpi: make fwnode take precedence in struct gpio_chip
  dt-bindings: gpio: samsung: drop unused bindings
  gpio: max3191x: Use bitmap_free() to free bitmap
  gpio: regmap: Switch to use fwnode instead of of_node
  gpio: tegra186: Add support for Tegra241
  dt-bindings: gpio: Add Tegra241 support
  gpio: brcmstb: Use local variable to access OF node
  gpio: Remove unused local OF node pointers
  gpio: sim: add missing fwnode_handle_put() in gpio_sim_probe()
  gpio: msc313: Add support for SSD201 and SSD202D
  gpio: msc313: Code clean ups
  dt-bindings: gpio: msc313: Add offsets for ssd20xd
  dt-bindings: gpio: msc313: Add compatible for ssd20xd
  gpio: sim: fix uninitialized ret variable
  gpio: Propagate firmware node from a parent device
  gpio: Setup parent device and get rid of unnecessary of_node assignment
  ...

1 files changed, 1592 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
new file mode 100644
index 000000000000..838bbfed11d3
--- /dev/null
+++ b/drivers/gpio/gpio-sim.c
@@ -0,0 +1,1592 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO testing driver based on configfs.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitmap.h>
+#include <linux/completion.h>
+#include <linux/configfs.h>
+#include <linux/device.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/idr.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irq_sim.h>
+#include <linux/list.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/string_helpers.h>
+#include <linux/sysfs.h>
+
+#include "gpiolib.h"
+
+#define GPIO_SIM_PROP_MAX	4 /* Max 3 properties + sentinel. */
+#define GPIO_SIM_NUM_ATTRS	3 /* value, pull and sentinel */
+
+static DEFINE_IDA(gpio_sim_ida);
+
+struct gpio_sim_chip {
+	struct gpio_chip gc;
+	unsigned long *direction_map;
+	unsigned long *value_map;
+	unsigned long *pull_map;
+	struct irq_domain *irq_sim;
+	struct mutex lock;
+	const struct attribute_group **attr_groups;
+};
+
+struct gpio_sim_attribute {
+	struct device_attribute dev_attr;
+	unsigned int offset;
+};
+
+static struct gpio_sim_attribute *
+to_gpio_sim_attr(struct device_attribute *dev_attr)
+{
+	return container_of(dev_attr, struct gpio_sim_attribute, dev_attr);
+}
+
+static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
+			       unsigned int offset, int value)
+{
+	int irq, irq_type, ret;
+	struct gpio_desc *desc;
+	struct gpio_chip *gc;
+
+	gc = &chip->gc;
+	desc = &gc->gpiodev->descs[offset];
+
+	mutex_lock(&chip->lock);
+
+	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
+	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
+		if (value == !!test_bit(offset, chip->value_map))
+			goto set_pull;
+
+		/*
+		 * This is fine - it just means, nobody is listening
+		 * for interrupts on this line, otherwise
+		 * irq_create_mapping() would have been called from
+		 * the to_irq() callback.
+		 */
+		irq = irq_find_mapping(chip->irq_sim, offset);
+		if (!irq)
+			goto set_value;
+
+		irq_type = irq_get_trigger_type(irq);
+
+		if ((value && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
+		    (!value && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
+			ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
+						    true);
+			if (ret)
+				goto set_pull;
+		}
+	}
+
+set_value:
+	/* Change the value unless we're actively driving the line. */
+	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+	    !test_bit(FLAG_IS_OUT, &desc->flags))
+		__assign_bit(offset, chip->value_map, value);
+
+set_pull:
+	__assign_bit(offset, chip->pull_map, value);
+	mutex_unlock(&chip->lock);
+	return 0;
+}
+
+static int gpio_sim_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+	int ret;
+
+	mutex_lock(&chip->lock);
+	ret = !!test_bit(offset, chip->value_map);
+	mutex_unlock(&chip->lock);
+
+	return ret;
+}
+
+static void gpio_sim_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__assign_bit(offset, chip->value_map, value);
+	mutex_unlock(&chip->lock);
+}
+
+static int gpio_sim_get_multiple(struct gpio_chip *gc,
+				 unsigned long *mask, unsigned long *bits)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	bitmap_copy(bits, chip->value_map, gc->ngpio);
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
+static void gpio_sim_set_multiple(struct gpio_chip *gc,
+				  unsigned long *mask, unsigned long *bits)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	bitmap_copy(chip->value_map, bits, gc->ngpio);
+	mutex_unlock(&chip->lock);
+}
+
+static int gpio_sim_direction_output(struct gpio_chip *gc,
+				     unsigned int offset, int value)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__clear_bit(offset, chip->direction_map);
+	__assign_bit(offset, chip->value_map, value);
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
+static int gpio_sim_direction_input(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__set_bit(offset, chip->direction_map);
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
+static int gpio_sim_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+	int direction;
+
+	mutex_lock(&chip->lock);
+	direction = !!test_bit(offset, chip->direction_map);
+	mutex_unlock(&chip->lock);
+
+	return direction ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
+}
+
+static int gpio_sim_set_config(struct gpio_chip *gc,
+				  unsigned int offset, unsigned long config)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_BIAS_PULL_UP:
+		return gpio_sim_apply_pull(chip, offset, 1);
+	case PIN_CONFIG_BIAS_PULL_DOWN:
+		return gpio_sim_apply_pull(chip, offset, 0);
+	default:
+		break;
+	}
+
+	return -ENOTSUPP;
+}
+
+static int gpio_sim_to_irq(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	return irq_create_mapping(chip->irq_sim, offset);
+}
+
+static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__assign_bit(offset, chip->value_map, !!test_bit(offset, chip->pull_map));
+	mutex_unlock(&chip->lock);
+}
+
+static ssize_t gpio_sim_sysfs_val_show(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+	int val;
+
+	mutex_lock(&chip->lock);
+	val = !!test_bit(line_attr->offset, chip->value_map);
+	mutex_unlock(&chip->lock);
+
+	return sysfs_emit(buf, "%d\n", val);
+}
+
+static ssize_t gpio_sim_sysfs_val_store(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	/*
+	 * Not assigning this function will result in write() returning -EIO
+	 * which is confusing. Return -EPERM explicitly.
+	 */
+	return -EPERM;
+}
+
+static const char *const gpio_sim_sysfs_pull_strings[] = {
+	[0]	= "pull-down",
+	[1]	= "pull-up",
+};
+
+static ssize_t gpio_sim_sysfs_pull_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+	int pull;
+
+	mutex_lock(&chip->lock);
+	pull = !!test_bit(line_attr->offset, chip->pull_map);
+	mutex_unlock(&chip->lock);
+
+	return sysfs_emit(buf, "%s\n", gpio_sim_sysfs_pull_strings[pull]);
+}
+
+static ssize_t gpio_sim_sysfs_pull_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+	int ret, pull;
+
+	pull = sysfs_match_string(gpio_sim_sysfs_pull_strings, buf);
+	if (pull < 0)
+		return pull;
+
+	ret = gpio_sim_apply_pull(chip, line_attr->offset, pull);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static void gpio_sim_mutex_destroy(void *data)
+{
+	struct mutex *lock = data;
+
+	mutex_destroy(lock);
+}
+
+static void gpio_sim_sysfs_remove(void *data)
+{
+	struct gpio_sim_chip *chip = data;
+
+	sysfs_remove_groups(&chip->gc.gpiodev->dev.kobj, chip->attr_groups);
+}
+
+static int gpio_sim_setup_sysfs(struct gpio_sim_chip *chip)
+{
+	struct device_attribute *val_dev_attr, *pull_dev_attr;
+	struct gpio_sim_attribute *val_attr, *pull_attr;
+	unsigned int num_lines = chip->gc.ngpio;
+	struct device *dev = chip->gc.parent;
+	struct attribute_group *attr_group;
+	struct attribute **attrs;
+	int i, ret;
+
+	chip->attr_groups = devm_kcalloc(dev, sizeof(*chip->attr_groups),
+					 num_lines + 1, GFP_KERNEL);
+	if (!chip->attr_groups)
+		return -ENOMEM;
+
+	for (i = 0; i < num_lines; i++) {
+		attr_group = devm_kzalloc(dev, sizeof(*attr_group), GFP_KERNEL);
+		attrs = devm_kcalloc(dev, sizeof(*attrs),
+				     GPIO_SIM_NUM_ATTRS, GFP_KERNEL);
+		val_attr = devm_kzalloc(dev, sizeof(*val_attr), GFP_KERNEL);
+		pull_attr = devm_kzalloc(dev, sizeof(*pull_attr), GFP_KERNEL);
+		if (!attr_group || !attrs || !val_attr || !pull_attr)
+			return -ENOMEM;
+
+		attr_group->name = devm_kasprintf(dev, GFP_KERNEL,
+						  "sim_gpio%u", i);
+		if (!attr_group->name)
+			return -ENOMEM;
+
+		val_attr->offset = pull_attr->offset = i;
+
+		val_dev_attr = &val_attr->dev_attr;
+		pull_dev_attr = &pull_attr->dev_attr;
+
+		sysfs_attr_init(&val_dev_attr->attr);
+		sysfs_attr_init(&pull_dev_attr->attr);
+
+		val_dev_attr->attr.name = "value";
+		pull_dev_attr->attr.name = "pull";
+
+		val_dev_attr->attr.mode = pull_dev_attr->attr.mode = 0644;
+
+		val_dev_attr->show = gpio_sim_sysfs_val_show;
+		val_dev_attr->store = gpio_sim_sysfs_val_store;
+		pull_dev_attr->show = gpio_sim_sysfs_pull_show;
+		pull_dev_attr->store = gpio_sim_sysfs_pull_store;
+
+		attrs[0] = &val_dev_attr->attr;
+		attrs[1] = &pull_dev_attr->attr;
+
+		attr_group->attrs = attrs;
+		chip->attr_groups[i] = attr_group;
+	}
+
+	ret = sysfs_create_groups(&chip->gc.gpiodev->dev.kobj,
+				  chip->attr_groups);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, gpio_sim_sysfs_remove, chip);
+}
+
+static int gpio_sim_add_bank(struct fwnode_handle *swnode, struct device *dev)
+{
+	struct gpio_sim_chip *chip;
+	struct gpio_chip *gc;
+	const char *label;
+	u32 num_lines;
+	int ret;
+
+	ret = fwnode_property_read_u32(swnode, "ngpios", &num_lines);
+	if (ret)
+		return ret;
+
+	ret = fwnode_property_read_string(swnode, "gpio-sim,label", &label);
+	if (ret) {
+		label = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
+				       dev_name(dev), fwnode_get_name(swnode));
+		if (!label)
+			return -ENOMEM;
+	}
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->direction_map = devm_bitmap_alloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->direction_map)
+		return -ENOMEM;
+
+	/* Default to input mode. */
+	bitmap_fill(chip->direction_map, num_lines);
+
+	chip->value_map = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->value_map)
+		return -ENOMEM;
+
+	chip->pull_map = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->pull_map)
+		return -ENOMEM;
+
+	chip->irq_sim = devm_irq_domain_create_sim(dev, NULL, num_lines);
+	if (IS_ERR(chip->irq_sim))
+		return PTR_ERR(chip->irq_sim);
+
+	mutex_init(&chip->lock);
+	ret = devm_add_action_or_reset(dev, gpio_sim_mutex_destroy,
+				       &chip->lock);
+	if (ret)
+		return ret;
+
+	gc = &chip->gc;
+	gc->base = -1;
+	gc->ngpio = num_lines;
+	gc->label = label;
+	gc->owner = THIS_MODULE;
+	gc->parent = dev;
+	gc->fwnode = swnode;
+	gc->get = gpio_sim_get;
+	gc->set = gpio_sim_set;
+	gc->get_multiple = gpio_sim_get_multiple;
+	gc->set_multiple = gpio_sim_set_multiple;
+	gc->direction_output = gpio_sim_direction_output;
+	gc->direction_input = gpio_sim_direction_input;
+	gc->get_direction = gpio_sim_get_direction;
+	gc->set_config = gpio_sim_set_config;
+	gc->to_irq = gpio_sim_to_irq;
+	gc->free = gpio_sim_free;
+
+	ret = devm_gpiochip_add_data(dev, gc, chip);
+	if (ret)
+		return ret;
+
+	/* Used by sysfs and configfs callbacks. */
+	dev_set_drvdata(&gc->gpiodev->dev, chip);
+
+	return gpio_sim_setup_sysfs(chip);
+}
+
+static int gpio_sim_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct fwnode_handle *swnode;
+	int ret;
+
+	device_for_each_child_node(dev, swnode) {
+		ret = gpio_sim_add_bank(swnode, dev);
+		if (ret) {
+			fwnode_handle_put(swnode);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const struct of_device_id gpio_sim_of_match[] = {
+	{ .compatible = "gpio-simulator" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gpio_sim_of_match);
+
+static struct platform_driver gpio_sim_driver = {
+	.driver = {
+		.name = "gpio-sim",
+		.of_match_table = gpio_sim_of_match,
+	},
+	.probe = gpio_sim_probe,
+};
+
+struct gpio_sim_device {
+	struct config_group group;
+
+	/*
+	 * If pdev is NULL, the device is 'pending' (waiting for configuration).
+	 * Once the pointer is assigned, the device has been created and the
+	 * item is 'live'.
+	 */
+	struct platform_device *pdev;
+	int id;
+
+	/*
+	 * Each configfs filesystem operation is protected with the subsystem
+	 * mutex. Each separate attribute is protected with the buffer mutex.
+	 * This structure however can be modified by callbacks of different
+	 * attributes so we need another lock.
+	 *
+	 * We use this lock fo protecting all data structures owned by this
+	 * object too.
+	 */
+	struct mutex lock;
+
+	/*
+	 * This is used to synchronously wait for the driver's probe to complete
+	 * and notify the user-space about any errors.
+	 */
+	struct notifier_block bus_notifier;
+	struct completion probe_completion;
+	bool driver_bound;
+
+	struct gpiod_hog *hogs;
+
+	struct list_head bank_list;
+};
+
+/* This is called with dev->lock already taken. */
+static int gpio_sim_bus_notifier_call(struct notifier_block *nb,
+				      unsigned long action, void *data)
+{
+	struct gpio_sim_device *simdev = container_of(nb,
+						      struct gpio_sim_device,
+						      bus_notifier);
+	struct device *dev = data;
+	char devname[32];
+
+	snprintf(devname, sizeof(devname), "gpio-sim.%u", simdev->id);
+
+	if (strcmp(dev_name(dev), devname) == 0) {
+		if (action == BUS_NOTIFY_BOUND_DRIVER)
+			simdev->driver_bound = true;
+		else if (action == BUS_NOTIFY_DRIVER_NOT_BOUND)
+			simdev->driver_bound = false;
+		else
+			return NOTIFY_DONE;
+
+		complete(&simdev->probe_completion);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct gpio_sim_device *to_gpio_sim_device(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	return container_of(group, struct gpio_sim_device, group);
+}
+
+struct gpio_sim_bank {
+	struct config_group group;
+
+	/*
+	 * We could have used the ci_parent field of the config_item but
+	 * configfs is stupid and calls the item's release callback after
+	 * already having cleared the parent pointer even though the parent
+	 * is guaranteed to survive the child...
+	 *
+	 * So we need to store the pointer to the parent struct here. We can
+	 * dereference it anywhere we need with no checks and no locking as
+	 * it's guaranteed to survive the childred and protected by configfs
+	 * locks.
+	 *
+	 * Same for other structures.
+	 */
+	struct gpio_sim_device *parent;
+	struct list_head siblings;
+
+	char *label;
+	unsigned int num_lines;
+
+	struct list_head line_list;
+
+	struct fwnode_handle *swnode;
+};
+
+static struct gpio_sim_bank *to_gpio_sim_bank(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	return container_of(group, struct gpio_sim_bank, group);
+}
+
+static struct gpio_sim_device *
+gpio_sim_bank_get_device(struct gpio_sim_bank *bank)
+{
+	return bank->parent;
+}
+
+struct gpio_sim_hog;
+
+struct gpio_sim_line {
+	struct config_group group;
+
+	struct gpio_sim_bank *parent;
+	struct list_head siblings;
+
+	unsigned int offset;
+	char *name;
+
+	/* There can only be one hog per line. */
+	struct gpio_sim_hog *hog;
+};
+
+static struct gpio_sim_line *to_gpio_sim_line(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	return container_of(group, struct gpio_sim_line, group);
+}
+
+static struct gpio_sim_device *
+gpio_sim_line_get_device(struct gpio_sim_line *line)
+{
+	struct gpio_sim_bank *bank = line->parent;
+
+	return gpio_sim_bank_get_device(bank);
+}
+
+struct gpio_sim_hog {
+	struct config_item item;
+	struct gpio_sim_line *parent;
+
+	char *name;
+	int dir;
+};
+
+static struct gpio_sim_hog *to_gpio_sim_hog(struct config_item *item)
+{
+	return container_of(item, struct gpio_sim_hog, item);
+}
+
+static struct gpio_sim_device *gpio_sim_hog_get_device(struct gpio_sim_hog *hog)
+{
+	struct gpio_sim_line *line = hog->parent;
+
+	return gpio_sim_line_get_device(line);
+}
+
+static bool gpio_sim_device_is_live_unlocked(struct gpio_sim_device *dev)
+{
+	return !!dev->pdev;
+}
+
+static char *gpio_sim_strdup_trimmed(const char *str, size_t count)
+{
+	char *dup, *trimmed;
+
+	dup = kstrndup(str, count, GFP_KERNEL);
+	if (!dup)
+		return NULL;
+
+	trimmed = strstrip(dup);
+	memmove(dup, trimmed, strlen(trimmed) + 1);
+
+	return dup;
+}
+
+static ssize_t gpio_sim_device_config_dev_name_show(struct config_item *item,
+						    char *page)
+{
+	struct gpio_sim_device *dev = to_gpio_sim_device(item);
+	struct platform_device *pdev;
+	int ret;
+
+	mutex_lock(&dev->lock);
+	pdev = dev->pdev;
+	if (pdev)
+		ret = sprintf(page, "%s\n", dev_name(&pdev->dev));
+	else
+		ret = sprintf(page, "gpio-sim.%d\n", dev->id);
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR_RO(gpio_sim_device_config_, dev_name);
+
+static ssize_t
+gpio_sim_device_config_live_show(struct config_item *item, char *page)
+{
+	struct gpio_sim_device *dev = to_gpio_sim_device(item);
+	bool live;
+
+	mutex_lock(&dev->lock);
+	live = gpio_sim_device_is_live_unlocked(dev);
+	mutex_unlock(&dev->lock);
+
+	return sprintf(page, "%c\n", live ? '1' : '0');
+}
+
+static char **gpio_sim_make_line_names(struct gpio_sim_bank *bank,
+				       unsigned int *line_names_size)
+{
+	unsigned int max_offset = 0;
+	bool has_line_names = false;
+	struct gpio_sim_line *line;
+	char **line_names;
+
+	list_for_each_entry(line, &bank->line_list, siblings) {
+		if (line->name) {
+			if (line->offset > max_offset)
+				max_offset = line->offset;
+
+			/*
+			 * max_offset can stay at 0 so it's not an indicator
+			 * of whether line names were configured at all.
+			 */
+			has_line_names = true;
+		}
+	}
+
+	if (!has_line_names)
+		/*
+		 * This is not an error - NULL means, there are no line
+		 * names configured.
+		 */
+		return NULL;
+
+	*line_names_size = max_offset + 1;
+
+	line_names = kcalloc(*line_names_size, sizeof(*line_names), GFP_KERNEL);
+	if (!line_names)
+		return ERR_PTR(-ENOMEM);
+
+	list_for_each_entry(line, &bank->line_list, siblings)
+		line_names[line->offset] = line->name;
+
+	return line_names;
+}
+
+static void gpio_sim_remove_hogs(struct gpio_sim_device *dev)
+{
+	struct gpiod_hog *hog;
+
+	if (!dev->hogs)
+		return;
+
+	gpiod_remove_hogs(dev->hogs);
+
+	for (hog = dev->hogs; !hog->chip_label; hog++) {
+		kfree(hog->chip_label);
+		kfree(hog->line_name);
+	}
+
+	kfree(dev->hogs);
+	dev->hogs = NULL;
+}
+
+static int gpio_sim_add_hogs(struct gpio_sim_device *dev)
+{
+	unsigned int num_hogs = 0, idx = 0;
+	struct gpio_sim_bank *bank;
+	struct gpio_sim_line *line;
+	struct gpiod_hog *hog;
+
+	list_for_each_entry(bank, &dev->bank_list, siblings) {
+		list_for_each_entry(line, &bank->line_list, siblings) {
+			if (line->hog)
+				num_hogs++;
+		}
+	}
+
+	if (!num_hogs)
+		return 0;
+
+	/* Allocate one more for the sentinel. */
+	dev->hogs = kcalloc(num_hogs + 1, sizeof(*dev->hogs), GFP_KERNEL);
+	if (!dev->hogs)
+		return -ENOMEM;
+
+	list_for_each_entry(bank, &dev->bank_list, siblings) {
+		list_for_each_entry(line, &bank->line_list, siblings) {
+			if (!line->hog)
+				continue;
+
+			hog = &dev->hogs[idx++];
+
+			/*
+			 * We need to make this string manually because at this
+			 * point the device doesn't exist yet and so dev_name()
+			 * is not available.
+			 */
+			hog->chip_label = kasprintf(GFP_KERNEL,
+						    "gpio-sim.%u-%s", dev->id,
+						    fwnode_get_name(bank->swnode));
+			if (!hog->chip_label) {
+				gpio_sim_remove_hogs(dev);
+				return -ENOMEM;
+			}
+
+			/*
+			 * We need to duplicate this because the hog config
+			 * item can be removed at any time (and we can't block
+			 * it) and gpiolib doesn't make a deep copy of the hog
+			 * data.
+			 */
+			if (line->hog->name) {
+				hog->line_name = kstrdup(line->hog->name,
+							 GFP_KERNEL);
+				if (!hog->line_name) {
+					gpio_sim_remove_hogs(dev);
+					return -ENOMEM;
+				}
+			}
+
+			hog->chip_hwnum = line->offset;
+			hog->dflags = line->hog->dir;
+		}
+	}
+
+	gpiod_add_hogs(dev->hogs);
+
+	return 0;
+}
+
+static struct fwnode_handle *
+gpio_sim_make_bank_swnode(struct gpio_sim_bank *bank,
+			  struct fwnode_handle *parent)
+{
+	struct property_entry properties[GPIO_SIM_PROP_MAX];
+	unsigned int prop_idx = 0, line_names_size = 0;
+	struct fwnode_handle *swnode;
+	char **line_names;
+
+	memset(properties, 0, sizeof(properties));
+
+	properties[prop_idx++] = PROPERTY_ENTRY_U32("ngpios", bank->num_lines);
+
+	if (bank->label)
+		properties[prop_idx++] = PROPERTY_ENTRY_STRING("gpio-sim,label",
+							       bank->label);
+
+	line_names = gpio_sim_make_line_names(bank, &line_names_size);
+	if (IS_ERR(line_names))
+		return ERR_CAST(line_names);
+
+	if (line_names)
+		properties[prop_idx++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
+						"gpio-line-names",
+						line_names, line_names_size);
+
+	swnode = fwnode_create_software_node(properties, parent);
+	kfree(line_names);
+	return swnode;
+}
+
+static void gpio_sim_remove_swnode_recursive(struct fwnode_handle *swnode)
+{
+	struct fwnode_handle *child;
+
+	fwnode_for_each_child_node(swnode, child)
+		fwnode_remove_software_node(child);
+
+	fwnode_remove_software_node(swnode);
+}
+
+static bool gpio_sim_bank_labels_non_unique(struct gpio_sim_device *dev)
+{
+	struct gpio_sim_bank *this, *pos;
+
+	list_for_each_entry(this, &dev->bank_list, siblings) {
+		list_for_each_entry(pos, &dev->bank_list, siblings) {
+			if (this == pos || (!this->label || !pos->label))
+				continue;
+
+			if (strcmp(this->label, pos->label) == 0)
+				return true;
+		}
+	}
+
+	return false;
+}
+
+static int gpio_sim_device_activate_unlocked(struct gpio_sim_device *dev)
+{
+	struct platform_device_info pdevinfo;
+	struct fwnode_handle *swnode;
+	struct platform_device *pdev;
+	struct gpio_sim_bank *bank;
+	int ret;
+
+	if (list_empty(&dev->bank_list))
+		return -ENODATA;
+
+	/*
+	 * Non-unique GPIO device labels are a corner-case we don't support
+	 * as it would interfere with machine hogging mechanism and has little
+	 * use in real life.
+	 */
+	if (gpio_sim_bank_labels_non_unique(dev))
+		return -EINVAL;
+
+	memset(&pdevinfo, 0, sizeof(pdevinfo));
+
+	swnode = fwnode_create_software_node(NULL, NULL);
+	if (IS_ERR(swnode))
+		return PTR_ERR(swnode);
+
+	list_for_each_entry(bank, &dev->bank_list, siblings) {
+		bank->swnode = gpio_sim_make_bank_swnode(bank, swnode);
+		if (IS_ERR(bank->swnode)) {
+			ret = PTR_ERR(bank->swnode);
+			gpio_sim_remove_swnode_recursive(swnode);
+			return ret;
+		}
+	}
+
+	ret = gpio_sim_add_hogs(dev);
+	if (ret) {
+		gpio_sim_remove_swnode_recursive(swnode);
+		return ret;
+	}
+
+	pdevinfo.name = "gpio-sim";
+	pdevinfo.fwnode = swnode;
+	pdevinfo.id = dev->id;
+
+	reinit_completion(&dev->probe_completion);
+	dev->driver_bound = false;
+	bus_register_notifier(&platform_bus_type, &dev->bus_notifier);
+
+	pdev = platform_device_register_full(&pdevinfo);
+	if (IS_ERR(pdev)) {
+		bus_unregister_notifier(&platform_bus_type, &dev->bus_notifier);
+		gpio_sim_remove_hogs(dev);
+		gpio_sim_remove_swnode_recursive(swnode);
+		return PTR_ERR(pdev);
+	}
+
+	wait_for_completion(&dev->probe_completion);
+	bus_unregister_notifier(&platform_bus_type, &dev->bus_notifier);
+
+	if (!dev->driver_bound) {
+		/* Probe failed, check kernel log. */
+		platform_device_unregister(pdev);
+		gpio_sim_remove_hogs(dev);
+		gpio_sim_remove_swnode_recursive(swnode);
+		return -ENXIO;
+	}
+
+	dev->pdev = pdev;
+
+	return 0;
+}
+
+static void gpio_sim_device_deactivate_unlocked(struct gpio_sim_device *dev)
+{
+	struct fwnode_handle *swnode;
+
+	swnode = dev_fwnode(&dev->pdev->dev);
+	platform_device_unregister(dev->pdev);
+	gpio_sim_remove_swnode_recursive(swnode);
+	dev->pdev = NULL;
+	gpio_sim_remove_hogs(dev);
+}
+
+static ssize_t
+gpio_sim_device_config_live_store(struct config_item *item,
+				  const char *page, size_t count)
+{
+	struct gpio_sim_device *dev = to_gpio_sim_device(item);
+	bool live;
+	int ret;
+
+	ret = kstrtobool(page, &live);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev->lock);
+
+	if ((!live && !gpio_sim_device_is_live_unlocked(dev)) ||
+	    (live && gpio_sim_device_is_live_unlocked(dev)))
+		ret = -EPERM;
+	else if (live)
+		ret = gpio_sim_device_activate_unlocked(dev);
+	else
+		gpio_sim_device_deactivate_unlocked(dev);
+
+	mutex_unlock(&dev->lock);
+
+	return ret ?: count;
+}
+
+CONFIGFS_ATTR(gpio_sim_device_config_, live);
+
+static struct configfs_attribute *gpio_sim_device_config_attrs[] = {
+	&gpio_sim_device_config_attr_dev_name,
+	&gpio_sim_device_config_attr_live,
+	NULL
+};
+
+struct gpio_sim_chip_name_ctx {
+	struct gpio_sim_device *dev;
+	char *page;
+};
+
+static int gpio_sim_emit_chip_name(struct device *dev, void *data)
+{
+	struct gpio_sim_chip_name_ctx *ctx = data;
+	struct fwnode_handle *swnode;
+	struct gpio_sim_bank *bank;
+
+	/* This would be the sysfs device exported in /sys/class/gpio. */
+	if (dev->class)
+		return 0;
+
+	swnode = dev_fwnode(dev);
+
+	list_for_each_entry(bank, &ctx->dev->bank_list, siblings) {
+		if (bank->swnode == swnode)
+			return sprintf(ctx->page, "%s\n", dev_name(dev));
+	}
+
+	return -ENODATA;
+}
+
+static ssize_t gpio_sim_bank_config_chip_name_show(struct config_item *item,
+						   char *page)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+	struct gpio_sim_chip_name_ctx ctx = { dev, page };
+	int ret;
+
+	mutex_lock(&dev->lock);
+	if (gpio_sim_device_is_live_unlocked(dev))
+		ret = device_for_each_child(&dev->pdev->dev, &ctx,
+					    gpio_sim_emit_chip_name);
+	else
+		ret = sprintf(page, "none\n");
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR_RO(gpio_sim_bank_config_, chip_name);
+
+static ssize_t
+gpio_sim_bank_config_label_show(struct config_item *item, char *page)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+	int ret;
+
+	mutex_lock(&dev->lock);
+	ret = sprintf(page, "%s\n", bank->label ?: "");
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+static ssize_t gpio_sim_bank_config_label_store(struct config_item *item,
+						const char *page, size_t count)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+	char *trimmed;
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return -EBUSY;
+	}
+
+	trimmed = gpio_sim_strdup_trimmed(page, count);
+	if (!trimmed) {
+		mutex_unlock(&dev->lock);
+		return -ENOMEM;
+	}
+
+	kfree(bank->label);
+	bank->label = trimmed;
+
+	mutex_unlock(&dev->lock);
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_bank_config_, label);
+
+static ssize_t
+gpio_sim_bank_config_num_lines_show(struct config_item *item, char *page)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+	int ret;
+
+	mutex_lock(&dev->lock);
+	ret = sprintf(page, "%u\n", bank->num_lines);
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+static ssize_t
+gpio_sim_bank_config_num_lines_store(struct config_item *item,
+				     const char *page, size_t count)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+	unsigned int num_lines;
+	int ret;
+
+	ret = kstrtouint(page, 0, &num_lines);
+	if (ret)
+		return ret;
+
+	if (num_lines == 0)
+		return -EINVAL;
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return -EBUSY;
+	}
+
+	bank->num_lines = num_lines;
+
+	mutex_unlock(&dev->lock);
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_bank_config_, num_lines);
+
+static struct configfs_attribute *gpio_sim_bank_config_attrs[] = {
+	&gpio_sim_bank_config_attr_chip_name,
+	&gpio_sim_bank_config_attr_label,
+	&gpio_sim_bank_config_attr_num_lines,
+	NULL
+};
+
+static ssize_t
+gpio_sim_line_config_name_show(struct config_item *item, char *page)
+{
+	struct gpio_sim_line *line = to_gpio_sim_line(item);
+	struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
+	int ret;
+
+	mutex_lock(&dev->lock);
+	ret = sprintf(page, "%s\n", line->name ?: "");
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+static ssize_t gpio_sim_line_config_name_store(struct config_item *item,
+					       const char *page, size_t count)
+{
+	struct gpio_sim_line *line = to_gpio_sim_line(item);
+	struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
+	char *trimmed;
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return -EBUSY;
+	}
+
+	trimmed = gpio_sim_strdup_trimmed(page, count);
+	if (!trimmed) {
+		mutex_unlock(&dev->lock);
+		return -ENOMEM;
+	}
+
+	kfree(line->name);
+	line->name = trimmed;
+
+	mutex_unlock(&dev->lock);
+
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_line_config_, name);
+
+static struct configfs_attribute *gpio_sim_line_config_attrs[] = {
+	&gpio_sim_line_config_attr_name,
+	NULL
+};
+
+static ssize_t gpio_sim_hog_config_name_show(struct config_item *item,
+					     char *page)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+	int ret;
+
+	mutex_lock(&dev->lock);
+	ret = sprintf(page, "%s\n", hog->name ?: "");
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+static ssize_t gpio_sim_hog_config_name_store(struct config_item *item,
+					      const char *page, size_t count)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+	char *trimmed;
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return -EBUSY;
+	}
+
+	trimmed = gpio_sim_strdup_trimmed(page, count);
+	if (!trimmed) {
+		mutex_unlock(&dev->lock);
+		return -ENOMEM;
+	}
+
+	kfree(hog->name);
+	hog->name = trimmed;
+
+	mutex_unlock(&dev->lock);
+
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_hog_config_, name);
+
+static ssize_t gpio_sim_hog_config_direction_show(struct config_item *item,
+						  char *page)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+	char *repr;
+	int dir;
+
+	mutex_lock(&dev->lock);
+	dir = hog->dir;
+	mutex_unlock(&dev->lock);
+
+	switch (dir) {
+	case GPIOD_IN:
+		repr = "input";
+		break;
+	case GPIOD_OUT_HIGH:
+		repr = "output-high";
+		break;
+	case GPIOD_OUT_LOW:
+		repr = "output-low";
+		break;
+	default:
+		/* This would be a programmer bug. */
+		WARN(1, "Unexpected hog direction value: %d", dir);
+		return -EINVAL;
+	}
+
+	return sprintf(page, "%s\n", repr);
+}
+
+static ssize_t
+gpio_sim_hog_config_direction_store(struct config_item *item,
+				    const char *page, size_t count)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+	char *trimmed;
+	int dir;
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return -EBUSY;
+	}
+
+	trimmed = gpio_sim_strdup_trimmed(page, count);
+	if (!trimmed) {
+		mutex_unlock(&dev->lock);
+		return -ENOMEM;
+	}
+
+	if (strcmp(trimmed, "input") == 0)
+		dir = GPIOD_IN;
+	else if (strcmp(trimmed, "output-high") == 0)
+		dir = GPIOD_OUT_HIGH;
+	else if (strcmp(trimmed, "output-low") == 0)
+		dir = GPIOD_OUT_LOW;
+	else
+		dir = -EINVAL;
+
+	kfree(trimmed);
+
+	if (dir < 0) {
+		mutex_unlock(&dev->lock);
+		return dir;
+	}
+
+	hog->dir = dir;
+
+	mutex_unlock(&dev->lock);
+
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_hog_config_, direction);
+
+static struct configfs_attribute *gpio_sim_hog_config_attrs[] = {
+	&gpio_sim_hog_config_attr_name,
+	&gpio_sim_hog_config_attr_direction,
+	NULL
+};
+
+static void gpio_sim_hog_config_item_release(struct config_item *item)
+{
+	struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
+	struct gpio_sim_line *line = hog->parent;
+	struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
+
+	mutex_lock(&dev->lock);
+	line->hog = NULL;
+	mutex_unlock(&dev->lock);
+
+	kfree(hog->name);
+	kfree(hog);
+}
+
+struct configfs_item_operations gpio_sim_hog_config_item_ops = {
+	.release	= gpio_sim_hog_config_item_release,
+};
+
+static const struct config_item_type gpio_sim_hog_config_type = {
+	.ct_item_ops	= &gpio_sim_hog_config_item_ops,
+	.ct_attrs	= gpio_sim_hog_config_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item *
+gpio_sim_line_config_make_hog_item(struct config_group *group, const char *name)
+{
+	struct gpio_sim_line *line = to_gpio_sim_line(&group->cg_item);
+	struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
+	struct gpio_sim_hog *hog;
+
+	if (strcmp(name, "hog") != 0)
+		return ERR_PTR(-EINVAL);
+
+	mutex_lock(&dev->lock);
+
+	hog = kzalloc(sizeof(*hog), GFP_KERNEL);
+	if (!hog) {
+		mutex_unlock(&dev->lock);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	config_item_init_type_name(&hog->item, name,
+				   &gpio_sim_hog_config_type);
+
+	hog->dir = GPIOD_IN;
+	hog->name = NULL;
+	hog->parent = line;
+	line->hog = hog;
+
+	mutex_unlock(&dev->lock);
+
+	return &hog->item;
+}
+
+static void gpio_sim_line_config_group_release(struct config_item *item)
+{
+	struct gpio_sim_line *line = to_gpio_sim_line(item);
+	struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
+
+	mutex_lock(&dev->lock);
+	list_del(&line->siblings);
+	mutex_unlock(&dev->lock);
+
+	kfree(line->name);
+	kfree(line);
+}
+
+static struct configfs_item_operations gpio_sim_line_config_item_ops = {
+	.release	= gpio_sim_line_config_group_release,
+};
+
+static struct configfs_group_operations gpio_sim_line_config_group_ops = {
+	.make_item	= gpio_sim_line_config_make_hog_item,
+};
+
+static const struct config_item_type gpio_sim_line_config_type = {
+	.ct_item_ops	= &gpio_sim_line_config_item_ops,
+	.ct_group_ops	= &gpio_sim_line_config_group_ops,
+	.ct_attrs	= gpio_sim_line_config_attrs,
+	.ct_owner       = THIS_MODULE,
+};
+
+static struct config_group *
+gpio_sim_bank_config_make_line_group(struct config_group *group,
+				     const char *name)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(&group->cg_item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+	struct gpio_sim_line *line;
+	unsigned int offset;
+	int ret, nchar;
+
+	ret = sscanf(name, "line%u%n", &offset, &nchar);
+	if (ret != 1 || nchar != strlen(name))
+		return ERR_PTR(-EINVAL);
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return ERR_PTR(-EBUSY);
+	}
+
+	line = kzalloc(sizeof(*line), GFP_KERNEL);
+	if (!line) {
+		mutex_unlock(&dev->lock);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	config_group_init_type_name(&line->group, name,
+				    &gpio_sim_line_config_type);
+
+	line->parent = bank;
+	line->offset = offset;
+	list_add_tail(&line->siblings, &bank->line_list);
+
+	mutex_unlock(&dev->lock);
+
+	return &line->group;
+}
+
+static void gpio_sim_bank_config_group_release(struct config_item *item)
+{
+	struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
+	struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
+
+	mutex_lock(&dev->lock);
+	list_del(&bank->siblings);
+	mutex_unlock(&dev->lock);
+
+	kfree(bank->label);
+	kfree(bank);
+}
+
+static struct configfs_item_operations gpio_sim_bank_config_item_ops = {
+	.release	= gpio_sim_bank_config_group_release,
+};
+
+static struct configfs_group_operations gpio_sim_bank_config_group_ops = {
+	.make_group	= gpio_sim_bank_config_make_line_group,
+};
+
+static const struct config_item_type gpio_sim_bank_config_group_type = {
+	.ct_item_ops	= &gpio_sim_bank_config_item_ops,
+	.ct_group_ops	= &gpio_sim_bank_config_group_ops,
+	.ct_attrs	= gpio_sim_bank_config_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *
+gpio_sim_device_config_make_bank_group(struct config_group *group,
+				       const char *name)
+{
+	struct gpio_sim_device *dev = to_gpio_sim_device(&group->cg_item);
+	struct gpio_sim_bank *bank;
+
+	mutex_lock(&dev->lock);
+
+	if (gpio_sim_device_is_live_unlocked(dev)) {
+		mutex_unlock(&dev->lock);
+		return ERR_PTR(-EBUSY);
+	}
+
+	bank = kzalloc(sizeof(*bank), GFP_KERNEL);
+	if (!bank) {
+		mutex_unlock(&dev->lock);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	config_group_init_type_name(&bank->group, name,
+				    &gpio_sim_bank_config_group_type);
+	bank->num_lines = 1;
+	bank->parent = dev;
+	INIT_LIST_HEAD(&bank->line_list);
+	list_add_tail(&bank->siblings, &dev->bank_list);
+
+	mutex_unlock(&dev->lock);
+
+	return &bank->group;
+}
+
+static void gpio_sim_device_config_group_release(struct config_item *item)
+{
+	struct gpio_sim_device *dev = to_gpio_sim_device(item);
+
+	mutex_lock(&dev->lock);
+	if (gpio_sim_device_is_live_unlocked(dev))
+		gpio_sim_device_deactivate_unlocked(dev);
+	mutex_unlock(&dev->lock);
+
+	mutex_destroy(&dev->lock);
+	ida_free(&gpio_sim_ida, dev->id);
+	kfree(dev);
+}
+
+static struct configfs_item_operations gpio_sim_device_config_item_ops = {
+	.release	= gpio_sim_device_config_group_release,
+};
+
+static struct configfs_group_operations gpio_sim_device_config_group_ops = {
+	.make_group	= gpio_sim_device_config_make_bank_group,
+};
+
+static const struct config_item_type gpio_sim_device_config_group_type = {
+	.ct_item_ops	= &gpio_sim_device_config_item_ops,
+	.ct_group_ops	= &gpio_sim_device_config_group_ops,
+	.ct_attrs	= gpio_sim_device_config_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *
+gpio_sim_config_make_device_group(struct config_group *group, const char *name)
+{
+	struct gpio_sim_device *dev;
+	int id;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
+	if (id < 0) {
+		kfree(dev);
+		return ERR_PTR(id);
+	}
+
+	config_group_init_type_name(&dev->group, name,
+				    &gpio_sim_device_config_group_type);
+	dev->id = id;
+	mutex_init(&dev->lock);
+	INIT_LIST_HEAD(&dev->bank_list);
+
+	dev->bus_notifier.notifier_call = gpio_sim_bus_notifier_call;
+	init_completion(&dev->probe_completion);
+
+	return &dev->group;
+}
+
+static struct configfs_group_operations gpio_sim_config_group_ops = {
+	.make_group	= gpio_sim_config_make_device_group,
+};
+
+static const struct config_item_type gpio_sim_config_type = {
+	.ct_group_ops	= &gpio_sim_config_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem gpio_sim_config_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf	= "gpio-sim",
+			.ci_type	= &gpio_sim_config_type,
+		},
+	},
+};
+
+static int __init gpio_sim_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&gpio_sim_driver);
+	if (ret) {
+		pr_err("Error %d while registering the platform driver\n", ret);
+		return ret;
+	}
+
+	config_group_init(&gpio_sim_config_subsys.su_group);
+	mutex_init(&gpio_sim_config_subsys.su_mutex);
+	ret = configfs_register_subsystem(&gpio_sim_config_subsys);
+	if (ret) {
+		pr_err("Error %d while registering the configfs subsystem %s\n",
+		       ret, gpio_sim_config_subsys.su_group.cg_item.ci_namebuf);
+		mutex_destroy(&gpio_sim_config_subsys.su_mutex);
+		platform_driver_unregister(&gpio_sim_driver);
+		return ret;
+	}
+
+	return 0;
+}
+module_init(gpio_sim_init);
+
+static void __exit gpio_sim_exit(void)
+{
+	configfs_unregister_subsystem(&gpio_sim_config_subsys);
+	mutex_destroy(&gpio_sim_config_subsys.su_mutex);
+	platform_driver_unregister(&gpio_sim_driver);
+}
+module_exit(gpio_sim_exit);
+
+MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl");
+MODULE_DESCRIPTION("GPIO Simulator Module");
+MODULE_LICENSE("GPL");