ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 1737 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
new file mode 100644
index 000000000..5ce89f52b
--- /dev/null
+++ b/drivers/gpio/gpio-aggregator.c
@@ -0,0 +1,1737 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// GPIO Aggregator
+//
+// Copyright (C) 2019-2020 Glider bv
+
+#define DRV_NAME       "gpio-aggregator"
+#define pr_fmt(fmt)	DRV_NAME ": " fmt
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/configfs.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/idr.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/overflow.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/forwarder.h>
+#include <linux/gpio/machine.h>
+
+#define AGGREGATOR_MAX_GPIOS 512
+#define AGGREGATOR_LEGACY_PREFIX "_sysfs"
+
+/*
+ * GPIO Aggregator sysfs interface
+ */
+
+struct gpio_aggregator {
+	struct platform_device *pdev;
+	struct config_group group;
+	struct gpiod_lookup_table *lookups;
+	struct mutex lock;
+	int id;
+
+	/* List of gpio_aggregator_line. Always added in order */
+	struct list_head list_head;
+
+	/* used by legacy sysfs interface only */
+	bool init_via_sysfs;
+	char args[];
+};
+
+struct gpio_aggregator_line {
+	struct config_group group;
+	struct gpio_aggregator *parent;
+	struct list_head entry;
+
+	/* Line index within the aggregator device */
+	unsigned int idx;
+
+	/* Custom name for the virtual line */
+	const char *name;
+	/* GPIO chip label or line name */
+	const char *key;
+	/* Can be negative to indicate lookup by line name */
+	int offset;
+
+	enum gpio_lookup_flags flags;
+};
+
+struct gpio_aggregator_pdev_meta {
+	bool init_via_sysfs;
+};
+
+static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
+static DEFINE_IDR(gpio_aggregator_idr);
+
+static int gpio_aggregator_alloc(struct gpio_aggregator **aggr, size_t arg_size)
+{
+	int ret;
+
+	struct gpio_aggregator *new __free(kfree) = kzalloc(
+					sizeof(*new) + arg_size, GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	scoped_guard(mutex, &gpio_aggregator_lock)
+		ret = idr_alloc(&gpio_aggregator_idr, new, 0, 0, GFP_KERNEL);
+
+	if (ret < 0)
+		return ret;
+
+	new->id = ret;
+	INIT_LIST_HEAD(&new->list_head);
+	mutex_init(&new->lock);
+	*aggr = no_free_ptr(new);
+	return 0;
+}
+
+static void gpio_aggregator_free(struct gpio_aggregator *aggr)
+{
+	scoped_guard(mutex, &gpio_aggregator_lock)
+		idr_remove(&gpio_aggregator_idr, aggr->id);
+
+	mutex_destroy(&aggr->lock);
+	kfree(aggr);
+}
+
+static int gpio_aggregator_add_gpio(struct gpio_aggregator *aggr,
+				    const char *key, int hwnum, unsigned int *n)
+{
+	struct gpiod_lookup_table *lookups;
+
+	lookups = krealloc(aggr->lookups, struct_size(lookups, table, *n + 2),
+			   GFP_KERNEL);
+	if (!lookups)
+		return -ENOMEM;
+
+	lookups->table[*n] = GPIO_LOOKUP_IDX(key, hwnum, NULL, *n, 0);
+
+	(*n)++;
+	memset(&lookups->table[*n], 0, sizeof(lookups->table[*n]));
+
+	aggr->lookups = lookups;
+	return 0;
+}
+
+static bool gpio_aggregator_is_active(struct gpio_aggregator *aggr)
+{
+	lockdep_assert_held(&aggr->lock);
+
+	return aggr->pdev && platform_get_drvdata(aggr->pdev);
+}
+
+/* Only aggregators created via legacy sysfs can be "activating". */
+static bool gpio_aggregator_is_activating(struct gpio_aggregator *aggr)
+{
+	lockdep_assert_held(&aggr->lock);
+
+	return aggr->pdev && !platform_get_drvdata(aggr->pdev);
+}
+
+static size_t gpio_aggregator_count_lines(struct gpio_aggregator *aggr)
+{
+	lockdep_assert_held(&aggr->lock);
+
+	return list_count_nodes(&aggr->list_head);
+}
+
+static struct gpio_aggregator_line *
+gpio_aggregator_line_alloc(struct gpio_aggregator *parent, unsigned int idx,
+			   char *key, int offset)
+{
+	struct gpio_aggregator_line *line;
+
+	line = kzalloc_obj(*line);
+	if (!line)
+		return ERR_PTR(-ENOMEM);
+
+	if (key) {
+		line->key = kstrdup(key, GFP_KERNEL);
+		if (!line->key) {
+			kfree(line);
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	line->flags = GPIO_LOOKUP_FLAGS_DEFAULT;
+	line->parent = parent;
+	line->idx = idx;
+	line->offset = offset;
+	INIT_LIST_HEAD(&line->entry);
+
+	return line;
+}
+
+static void gpio_aggregator_line_add(struct gpio_aggregator *aggr,
+				     struct gpio_aggregator_line *line)
+{
+	struct gpio_aggregator_line *tmp;
+
+	lockdep_assert_held(&aggr->lock);
+
+	list_for_each_entry(tmp, &aggr->list_head, entry) {
+		if (tmp->idx > line->idx) {
+			list_add_tail(&line->entry, &tmp->entry);
+			return;
+		}
+	}
+	list_add_tail(&line->entry, &aggr->list_head);
+}
+
+static void gpio_aggregator_line_del(struct gpio_aggregator *aggr,
+				     struct gpio_aggregator_line *line)
+{
+	lockdep_assert_held(&aggr->lock);
+
+	list_del(&line->entry);
+}
+
+static void gpio_aggregator_free_lines(struct gpio_aggregator *aggr)
+{
+	struct gpio_aggregator_line *line, *tmp;
+
+	list_for_each_entry_safe(line, tmp, &aggr->list_head, entry) {
+		configfs_unregister_group(&line->group);
+		/*
+		 * Normally, we acquire aggr->lock within the configfs
+		 * callback. However, in the legacy sysfs interface case,
+		 * calling configfs_(un)register_group while holding
+		 * aggr->lock could cause a deadlock. Fortunately, this is
+		 * unnecessary because the new_device/delete_device path
+		 * and the module unload path are mutually exclusive,
+		 * thanks to an explicit try_module_get. That's why this
+		 * minimal scoped_guard suffices.
+		 */
+		scoped_guard(mutex, &aggr->lock)
+			gpio_aggregator_line_del(aggr, line);
+		kfree(line->key);
+		kfree(line->name);
+		kfree(line);
+	}
+}
+
+
+/*
+ *  GPIO Forwarder
+ */
+
+struct gpiochip_fwd_timing {
+	u32 ramp_up_us;
+	u32 ramp_down_us;
+};
+
+struct gpiochip_fwd {
+	struct gpio_chip chip;
+	struct gpio_desc **descs;
+	union {
+		struct mutex mlock;	/* protects tmp[] if can_sleep */
+		spinlock_t slock;	/* protects tmp[] if !can_sleep */
+	};
+	struct gpiochip_fwd_timing *delay_timings;
+	void *data;
+	unsigned long *valid_mask;
+	unsigned long tmp[];		/* values and descs for multiple ops */
+};
+
+#define fwd_tmp_values(fwd)	(&(fwd)->tmp[0])
+#define fwd_tmp_descs(fwd)	((void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)])
+
+#define fwd_tmp_size(ngpios)	(BITS_TO_LONGS((ngpios)) + (ngpios))
+
+static int gpio_fwd_request(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	return test_bit(offset, fwd->valid_mask) ? 0 : -ENODEV;
+}
+
+static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	/*
+	 * get_direction() is called during gpiochip registration, return
+	 * -ENODEV if there is no GPIO desc for the line.
+	 */
+	if (!test_bit(offset, fwd->valid_mask))
+		return -ENODEV;
+
+	return gpiod_get_direction(fwd->descs[offset]);
+}
+
+static int gpio_fwd_direction_input(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	return gpiod_direction_input(fwd->descs[offset]);
+}
+
+static int gpio_fwd_direction_output(struct gpio_chip *chip,
+				     unsigned int offset, int value)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	return gpiod_direction_output(fwd->descs[offset], value);
+}
+
+static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	return chip->can_sleep ? gpiod_get_value_cansleep(fwd->descs[offset])
+			       : gpiod_get_value(fwd->descs[offset]);
+}
+
+static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
+				 unsigned long *bits)
+{
+	struct gpio_desc **descs = fwd_tmp_descs(fwd);
+	unsigned long *values = fwd_tmp_values(fwd);
+	unsigned int i, j = 0;
+	int error;
+
+	bitmap_clear(values, 0, fwd->chip.ngpio);
+	for_each_set_bit(i, mask, fwd->chip.ngpio)
+		descs[j++] = fwd->descs[i];
+
+	if (fwd->chip.can_sleep)
+		error = gpiod_get_array_value_cansleep(j, descs, NULL, values);
+	else
+		error = gpiod_get_array_value(j, descs, NULL, values);
+	if (error)
+		return error;
+
+	j = 0;
+	for_each_set_bit(i, mask, fwd->chip.ngpio)
+		__assign_bit(i, bits, test_bit(j++, values));
+
+	return 0;
+}
+
+static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip,
+					unsigned long *mask, unsigned long *bits)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+	unsigned long flags;
+	int error;
+
+	if (chip->can_sleep) {
+		mutex_lock(&fwd->mlock);
+		error = gpio_fwd_get_multiple(fwd, mask, bits);
+		mutex_unlock(&fwd->mlock);
+	} else {
+		spin_lock_irqsave(&fwd->slock, flags);
+		error = gpio_fwd_get_multiple(fwd, mask, bits);
+		spin_unlock_irqrestore(&fwd->slock, flags);
+	}
+
+	return error;
+}
+
+static void gpio_fwd_delay(struct gpio_chip *chip, unsigned int offset, int value)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+	const struct gpiochip_fwd_timing *delay_timings;
+	bool is_active_low = gpiod_is_active_low(fwd->descs[offset]);
+	u32 delay_us;
+
+	delay_timings = &fwd->delay_timings[offset];
+	if ((!is_active_low && value) || (is_active_low && !value))
+		delay_us = delay_timings->ramp_up_us;
+	else
+		delay_us = delay_timings->ramp_down_us;
+	if (!delay_us)
+		return;
+
+	if (chip->can_sleep)
+		fsleep(delay_us);
+	else
+		udelay(delay_us);
+}
+
+static int gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+	int ret;
+
+	if (chip->can_sleep)
+		ret = gpiod_set_value_cansleep(fwd->descs[offset], value);
+	else
+		ret = gpiod_set_value(fwd->descs[offset], value);
+	if (ret)
+		return ret;
+
+	if (fwd->delay_timings)
+		gpio_fwd_delay(chip, offset, value);
+
+	return ret;
+}
+
+static int gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
+				 unsigned long *bits)
+{
+	struct gpio_desc **descs = fwd_tmp_descs(fwd);
+	unsigned long *values = fwd_tmp_values(fwd);
+	unsigned int i, j = 0, ret;
+
+	for_each_set_bit(i, mask, fwd->chip.ngpio) {
+		__assign_bit(j, values, test_bit(i, bits));
+		descs[j++] = fwd->descs[i];
+	}
+
+	if (fwd->chip.can_sleep)
+		ret = gpiod_set_array_value_cansleep(j, descs, NULL, values);
+	else
+		ret = gpiod_set_array_value(j, descs, NULL, values);
+
+	return ret;
+}
+
+static int gpio_fwd_set_multiple_locked(struct gpio_chip *chip,
+					unsigned long *mask, unsigned long *bits)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+	unsigned long flags;
+	int ret;
+
+	if (chip->can_sleep) {
+		mutex_lock(&fwd->mlock);
+		ret = gpio_fwd_set_multiple(fwd, mask, bits);
+		mutex_unlock(&fwd->mlock);
+	} else {
+		spin_lock_irqsave(&fwd->slock, flags);
+		ret = gpio_fwd_set_multiple(fwd, mask, bits);
+		spin_unlock_irqrestore(&fwd->slock, flags);
+	}
+
+	return ret;
+}
+
+static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
+			       unsigned long config)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	return gpiod_set_config(fwd->descs[offset], config);
+}
+
+static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+
+	return gpiod_to_irq(fwd->descs[offset]);
+}
+
+/*
+ * The GPIO delay provides a way to configure platform specific delays
+ * for the GPIO ramp-up or ramp-down delays. This can serve the following
+ * purposes:
+ *   - Open-drain output using an RC filter
+ */
+#define FWD_FEATURE_DELAY		BIT(0)
+
+#ifdef CONFIG_OF_GPIO
+static int gpiochip_fwd_delay_of_xlate(struct gpio_chip *chip,
+				       const struct of_phandle_args *gpiospec,
+				       u32 *flags)
+{
+	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
+	struct gpiochip_fwd_timing *timings;
+	u32 line;
+
+	if (gpiospec->args_count != chip->of_gpio_n_cells)
+		return -EINVAL;
+
+	line = gpiospec->args[0];
+	if (line >= chip->ngpio)
+		return -EINVAL;
+
+	timings = &fwd->delay_timings[line];
+	timings->ramp_up_us = gpiospec->args[1];
+	timings->ramp_down_us = gpiospec->args[2];
+
+	return line;
+}
+
+static int gpiochip_fwd_setup_delay_line(struct gpiochip_fwd *fwd)
+{
+	struct gpio_chip *chip = &fwd->chip;
+
+	fwd->delay_timings = devm_kcalloc(chip->parent, chip->ngpio,
+					  sizeof(*fwd->delay_timings),
+					  GFP_KERNEL);
+	if (!fwd->delay_timings)
+		return -ENOMEM;
+
+	chip->of_xlate = gpiochip_fwd_delay_of_xlate;
+	chip->of_gpio_n_cells = 3;
+
+	return 0;
+}
+#else
+static int gpiochip_fwd_setup_delay_line(struct gpiochip_fwd *fwd)
+{
+	return 0;
+}
+#endif	/* !CONFIG_OF_GPIO */
+
+/**
+ * gpiochip_fwd_get_gpiochip - Get the GPIO chip for the GPIO forwarder
+ * @fwd: GPIO forwarder
+ *
+ * Returns: The GPIO chip for the GPIO forwarder
+ */
+struct gpio_chip *gpiochip_fwd_get_gpiochip(struct gpiochip_fwd *fwd)
+{
+	return &fwd->chip;
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_get_gpiochip, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_get_data - Get driver-private data for the GPIO forwarder
+ * @fwd: GPIO forwarder
+ *
+ * Returns: The driver-private data for the GPIO forwarder
+ */
+void *gpiochip_fwd_get_data(struct gpiochip_fwd *fwd)
+{
+	return fwd->data;
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_get_data, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_request - Request a line of the GPIO forwarder
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line to request
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_request(struct gpiochip_fwd *fwd, unsigned int offset)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_request(gc, offset);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_request, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_get_direction - Return the current direction of a GPIO forwarder line
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ *
+ * Returns: 0 for output, 1 for input, or an error code in case of error.
+ */
+int gpiochip_fwd_gpio_get_direction(struct gpiochip_fwd *fwd, unsigned int offset)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_get_direction(gc, offset);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_get_direction, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_direction_output - Set a GPIO forwarder line direction to
+ * output
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ * @value: value to set
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_direction_output(struct gpiochip_fwd *fwd, unsigned int offset,
+				       int value)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_direction_output(gc, offset, value);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_direction_output, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_direction_input - Set a GPIO forwarder line direction to input
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_direction_input(struct gpiochip_fwd *fwd, unsigned int offset)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_direction_input(gc, offset);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_direction_input, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_get - Return a GPIO forwarder line's value
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ *
+ * Returns: The GPIO's logical value, i.e. taking the ACTIVE_LOW status into
+ * account, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_get(struct gpiochip_fwd *fwd, unsigned int offset)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_get(gc, offset);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_get, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_get_multiple - Get values for multiple GPIO forwarder lines
+ * @fwd: GPIO forwarder
+ * @mask: bit mask array; one bit per line; BITS_PER_LONG bits per word defines
+ *        which lines are to be read
+ * @bits: bit value array; one bit per line; BITS_PER_LONG bits per word will
+ *        contains the read values for the lines specified by mask
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
+				   unsigned long *bits)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_get_multiple_locked(gc, mask, bits);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_get_multiple, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_set - Assign value to a GPIO forwarder line.
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ * @value: value to set
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_set(struct gpiochip_fwd *fwd, unsigned int offset, int value)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_set(gc, offset, value);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_set, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_set_multiple - Assign values to multiple GPIO forwarder lines
+ * @fwd: GPIO forwarder
+ * @mask: bit mask array; one bit per output; BITS_PER_LONG bits per word
+ *        defines which outputs are to be changed
+ * @bits: bit value array; one bit per output; BITS_PER_LONG bits per word
+ *        defines the values the outputs specified by mask are to be set to
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_gpio_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
+				   unsigned long *bits)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_set_multiple_locked(gc, mask, bits);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_set_multiple, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_set_config - Set @config for a GPIO forwarder line
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ * @config: Same packed config format as generic pinconf
+ *
+ * Returns: 0 on success, %-ENOTSUPP if the controller doesn't support setting
+ * the configuration.
+ */
+int gpiochip_fwd_gpio_set_config(struct gpiochip_fwd *fwd, unsigned int offset,
+				 unsigned long config)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_set_config(gc, offset, config);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_set_config, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_gpio_to_irq - Return the IRQ corresponding to a GPIO forwarder line
+ * @fwd: GPIO forwarder
+ * @offset: the offset of the line
+ *
+ * Returns: The Linux IRQ corresponding to the passed line, or an error code in
+ * case of error.
+ */
+int gpiochip_fwd_gpio_to_irq(struct gpiochip_fwd *fwd, unsigned int offset)
+{
+	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
+
+	return gpio_fwd_to_irq(gc, offset);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_gpio_to_irq, "GPIO_FORWARDER");
+
+/**
+ * devm_gpiochip_fwd_alloc - Allocate and initialize a new GPIO forwarder
+ * @dev: Parent device pointer
+ * @ngpios: Number of GPIOs in the forwarder
+ *
+ * Returns: An opaque object pointer, or an ERR_PTR()-encoded negative error
+ * code on failure.
+ */
+struct gpiochip_fwd *devm_gpiochip_fwd_alloc(struct device *dev,
+					     unsigned int ngpios)
+{
+	struct gpiochip_fwd *fwd;
+	struct gpio_chip *chip;
+
+	fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)), GFP_KERNEL);
+	if (!fwd)
+		return ERR_PTR(-ENOMEM);
+
+	fwd->descs = devm_kcalloc(dev, ngpios, sizeof(*fwd->descs), GFP_KERNEL);
+	if (!fwd->descs)
+		return ERR_PTR(-ENOMEM);
+
+	fwd->valid_mask = devm_bitmap_zalloc(dev, ngpios, GFP_KERNEL);
+	if (!fwd->valid_mask)
+		return ERR_PTR(-ENOMEM);
+
+	chip = &fwd->chip;
+
+	chip->label = dev_name(dev);
+	chip->parent = dev;
+	chip->owner = THIS_MODULE;
+	chip->request = gpio_fwd_request;
+	chip->get_direction = gpio_fwd_get_direction;
+	chip->direction_input = gpio_fwd_direction_input;
+	chip->direction_output = gpio_fwd_direction_output;
+	chip->get = gpio_fwd_get;
+	chip->get_multiple = gpio_fwd_get_multiple_locked;
+	chip->set = gpio_fwd_set;
+	chip->set_multiple = gpio_fwd_set_multiple_locked;
+	chip->set_config = gpio_fwd_set_config;
+	chip->to_irq = gpio_fwd_to_irq;
+	chip->base = -1;
+	chip->ngpio = ngpios;
+
+	return fwd;
+}
+EXPORT_SYMBOL_NS_GPL(devm_gpiochip_fwd_alloc, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_desc_add - Add a GPIO desc in the forwarder
+ * @fwd: GPIO forwarder
+ * @desc: GPIO descriptor to register
+ * @offset: offset for the GPIO in the forwarder
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_desc_add(struct gpiochip_fwd *fwd, struct gpio_desc *desc,
+			  unsigned int offset)
+{
+	struct gpio_chip *chip = &fwd->chip;
+
+	if (offset >= chip->ngpio)
+		return -EINVAL;
+
+	if (test_and_set_bit(offset, fwd->valid_mask))
+		return -EEXIST;
+
+	/*
+	 * If any of the GPIO lines are sleeping, then the entire forwarder
+	 * will be sleeping.
+	 */
+	if (gpiod_cansleep(desc))
+		chip->can_sleep = true;
+
+	fwd->descs[offset] = desc;
+
+	dev_dbg(chip->parent, "%u => gpio %d irq %d\n", offset,
+		desc_to_gpio(desc), gpiod_to_irq(desc));
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_desc_add, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_desc_free - Remove a GPIO desc from the forwarder
+ * @fwd: GPIO forwarder
+ * @offset: offset of GPIO desc to remove
+ */
+void gpiochip_fwd_desc_free(struct gpiochip_fwd *fwd, unsigned int offset)
+{
+	if (test_and_clear_bit(offset, fwd->valid_mask))
+		gpiod_put(fwd->descs[offset]);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_desc_free, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_register - Register a GPIO forwarder
+ * @fwd: GPIO forwarder
+ * @data: driver-private data associated with this forwarder
+ *
+ * Returns: 0 on success, or negative errno on failure.
+ */
+int gpiochip_fwd_register(struct gpiochip_fwd *fwd, void *data)
+{
+	struct gpio_chip *chip = &fwd->chip;
+
+	/*
+	 * Some gpio_desc were not registered. They will be registered at runtime
+	 * but we have to suppose they can sleep.
+	 */
+	if (!bitmap_full(fwd->valid_mask, chip->ngpio))
+		chip->can_sleep = true;
+
+	if (chip->can_sleep)
+		mutex_init(&fwd->mlock);
+	else
+		spin_lock_init(&fwd->slock);
+
+	fwd->data = data;
+
+	return devm_gpiochip_add_data(chip->parent, chip, fwd);
+}
+EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_register, "GPIO_FORWARDER");
+
+/**
+ * gpiochip_fwd_create() - Create a new GPIO forwarder
+ * @dev: Parent device pointer
+ * @ngpios: Number of GPIOs in the forwarder.
+ * @descs: Array containing the GPIO descriptors to forward to.
+ *         This array must contain @ngpios entries, and can be deallocated
+ *         as the forwarder has its own array.
+ * @features: Bitwise ORed features as defined with FWD_FEATURE_*.
+ *
+ * This function creates a new gpiochip, which forwards all GPIO operations to
+ * the passed GPIO descriptors.
+ *
+ * Return: An opaque object pointer, or an ERR_PTR()-encoded negative error
+ *         code on failure.
+ */
+static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
+						unsigned int ngpios,
+						struct gpio_desc *descs[],
+						unsigned long features)
+{
+	struct gpiochip_fwd *fwd;
+	unsigned int i;
+	int error;
+
+	fwd = devm_gpiochip_fwd_alloc(dev, ngpios);
+	if (IS_ERR(fwd))
+		return fwd;
+
+	for (i = 0; i < ngpios; i++) {
+		error = gpiochip_fwd_desc_add(fwd, descs[i], i);
+		if (error)
+			return ERR_PTR(error);
+	}
+
+	if (features & FWD_FEATURE_DELAY) {
+		error = gpiochip_fwd_setup_delay_line(fwd);
+		if (error)
+			return ERR_PTR(error);
+	}
+
+	error = gpiochip_fwd_register(fwd, NULL);
+	if (error)
+		return ERR_PTR(error);
+
+	return fwd;
+}
+
+/*
+ * Configfs interface
+ */
+
+static struct gpio_aggregator *
+to_gpio_aggregator(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	return container_of(group, struct gpio_aggregator, group);
+}
+
+static struct gpio_aggregator_line *
+to_gpio_aggregator_line(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	return container_of(group, struct gpio_aggregator_line, group);
+}
+
+static struct fwnode_handle *
+gpio_aggregator_make_device_sw_node(struct gpio_aggregator *aggr)
+{
+	struct property_entry properties[2];
+	struct gpio_aggregator_line *line;
+	size_t num_lines;
+	int n = 0;
+
+	memset(properties, 0, sizeof(properties));
+
+	num_lines = gpio_aggregator_count_lines(aggr);
+	if (num_lines == 0)
+		return NULL;
+
+	const char **line_names __free(kfree) = kcalloc(
+				num_lines, sizeof(*line_names), GFP_KERNEL);
+	if (!line_names)
+		return ERR_PTR(-ENOMEM);
+
+	/* The list is always sorted as new elements are inserted in order. */
+	list_for_each_entry(line, &aggr->list_head, entry)
+		line_names[n++] = line->name ?: "";
+
+	properties[0] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
+					"gpio-line-names",
+					line_names, num_lines);
+
+	return fwnode_create_software_node(properties, NULL);
+}
+
+static int gpio_aggregator_activate(struct gpio_aggregator *aggr)
+{
+	struct platform_device_info pdevinfo;
+	struct gpio_aggregator_line *line;
+	struct platform_device *pdev;
+	struct fwnode_handle *swnode;
+	unsigned int n = 0;
+	int ret = 0;
+
+	if (gpio_aggregator_count_lines(aggr) == 0)
+		return -EINVAL;
+
+	aggr->lookups = kzalloc_flex(*aggr->lookups, table, 1);
+	if (!aggr->lookups)
+		return -ENOMEM;
+
+	swnode = gpio_aggregator_make_device_sw_node(aggr);
+	if (IS_ERR(swnode)) {
+		ret = PTR_ERR(swnode);
+		goto err_remove_lookups;
+	}
+
+	memset(&pdevinfo, 0, sizeof(pdevinfo));
+	pdevinfo.name = DRV_NAME;
+	pdevinfo.id = aggr->id;
+	pdevinfo.fwnode = swnode;
+
+	/* The list is always sorted as new elements are inserted in order. */
+	list_for_each_entry(line, &aggr->list_head, entry) {
+		/*
+		 * - Either GPIO chip label or line name must be configured
+		 *   (i.e. line->key must be non-NULL)
+		 * - Line directories must be named with sequential numeric
+		 *   suffixes starting from 0. (i.e. ./line0, ./line1, ...)
+		 */
+		if (!line->key || line->idx != n) {
+			ret = -EINVAL;
+			goto err_remove_swnode;
+		}
+
+		if (line->offset < 0)
+			ret = gpio_aggregator_add_gpio(aggr, line->key,
+						       U16_MAX, &n);
+		else
+			ret = gpio_aggregator_add_gpio(aggr, line->key,
+						       line->offset, &n);
+		if (ret)
+			goto err_remove_swnode;
+	}
+
+	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, aggr->id);
+	if (!aggr->lookups->dev_id) {
+		ret = -ENOMEM;
+		goto err_remove_swnode;
+	}
+
+	gpiod_add_lookup_table(aggr->lookups);
+
+	pdev = platform_device_register_full(&pdevinfo);
+	if (IS_ERR(pdev)) {
+		ret = PTR_ERR(pdev);
+		goto err_remove_lookup_table;
+	}
+
+	wait_for_device_probe();
+
+	scoped_guard(device, &pdev->dev) {
+		if (!device_is_bound(&pdev->dev)) {
+			ret = -ENXIO;
+			goto err_unregister_pdev;
+		}
+	}
+
+	aggr->pdev = pdev;
+	return 0;
+
+err_unregister_pdev:
+	platform_device_unregister(pdev);
+err_remove_lookup_table:
+	gpiod_remove_lookup_table(aggr->lookups);
+	kfree(aggr->lookups->dev_id);
+err_remove_swnode:
+	fwnode_remove_software_node(swnode);
+err_remove_lookups:
+	kfree(aggr->lookups);
+
+	return ret;
+}
+
+static void gpio_aggregator_deactivate(struct gpio_aggregator *aggr)
+{
+	struct fwnode_handle *swnode;
+
+	swnode = dev_fwnode(&aggr->pdev->dev);
+	platform_device_unregister(aggr->pdev);
+	aggr->pdev = NULL;
+	gpiod_remove_lookup_table(aggr->lookups);
+	kfree(aggr->lookups->dev_id);
+	kfree(aggr->lookups);
+	fwnode_remove_software_node(swnode);
+}
+
+static void gpio_aggregator_lockup_configfs(struct gpio_aggregator *aggr,
+					    bool lock)
+{
+	struct configfs_subsystem *subsys = aggr->group.cg_subsys;
+	struct gpio_aggregator_line *line;
+
+	/*
+	 * The device only needs to depend on leaf lines. This is
+	 * sufficient to lock up all the configfs entries that the
+	 * instantiated, alive device depends on.
+	 */
+	list_for_each_entry(line, &aggr->list_head, entry) {
+		if (lock)
+			configfs_depend_item_unlocked(
+					subsys, &line->group.cg_item);
+		else
+			configfs_undepend_item_unlocked(
+					&line->group.cg_item);
+	}
+}
+
+static ssize_t
+gpio_aggregator_line_key_show(struct config_item *item, char *page)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	guard(mutex)(&aggr->lock);
+
+	return sysfs_emit(page, "%s\n", line->key ?: "");
+}
+
+static ssize_t
+gpio_aggregator_line_key_store(struct config_item *item, const char *page,
+			       size_t count)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	char *key __free(kfree) = kstrndup(skip_spaces(page), count,
+					   GFP_KERNEL);
+	if (!key)
+		return -ENOMEM;
+
+	strim(key);
+
+	guard(mutex)(&aggr->lock);
+
+	if (gpio_aggregator_is_activating(aggr) ||
+	    gpio_aggregator_is_active(aggr))
+		return -EBUSY;
+
+	kfree(line->key);
+	line->key = no_free_ptr(key);
+
+	return count;
+}
+CONFIGFS_ATTR(gpio_aggregator_line_, key);
+
+static ssize_t
+gpio_aggregator_line_name_show(struct config_item *item, char *page)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	guard(mutex)(&aggr->lock);
+
+	return sysfs_emit(page, "%s\n", line->name ?: "");
+}
+
+static ssize_t
+gpio_aggregator_line_name_store(struct config_item *item, const char *page,
+				size_t count)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	char *name __free(kfree) = kstrndup(skip_spaces(page), count,
+					    GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	strim(name);
+
+	guard(mutex)(&aggr->lock);
+
+	if (gpio_aggregator_is_activating(aggr) ||
+	    gpio_aggregator_is_active(aggr))
+		return -EBUSY;
+
+	kfree(line->name);
+	line->name = no_free_ptr(name);
+
+	return count;
+}
+CONFIGFS_ATTR(gpio_aggregator_line_, name);
+
+static ssize_t
+gpio_aggregator_line_offset_show(struct config_item *item, char *page)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	guard(mutex)(&aggr->lock);
+
+	return sysfs_emit(page, "%d\n", line->offset);
+}
+
+static ssize_t
+gpio_aggregator_line_offset_store(struct config_item *item, const char *page,
+				  size_t count)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+	int offset, ret;
+
+	ret = kstrtoint(page, 0, &offset);
+	if (ret)
+		return ret;
+
+	/*
+	 * When offset == -1, 'key' represents a line name to lookup.
+	 * When 0 <= offset < 65535, 'key' represents the label of the chip with
+	 * the 'offset' value representing the line within that chip.
+	 *
+	 * GPIOLIB uses the U16_MAX value to indicate lookup by line name so
+	 * the greatest offset we can accept is (U16_MAX - 1).
+	 */
+	if (offset > (U16_MAX - 1) || offset < -1)
+		return -EINVAL;
+
+	guard(mutex)(&aggr->lock);
+
+	if (gpio_aggregator_is_activating(aggr) ||
+	    gpio_aggregator_is_active(aggr))
+		return -EBUSY;
+
+	line->offset = offset;
+
+	return count;
+}
+CONFIGFS_ATTR(gpio_aggregator_line_, offset);
+
+static struct configfs_attribute *gpio_aggregator_line_attrs[] = {
+	&gpio_aggregator_line_attr_key,
+	&gpio_aggregator_line_attr_name,
+	&gpio_aggregator_line_attr_offset,
+	NULL
+};
+
+static ssize_t
+gpio_aggregator_device_dev_name_show(struct config_item *item, char *page)
+{
+	struct gpio_aggregator *aggr = to_gpio_aggregator(item);
+	struct platform_device *pdev;
+
+	guard(mutex)(&aggr->lock);
+
+	pdev = aggr->pdev;
+	if (pdev)
+		return sysfs_emit(page, "%s\n", dev_name(&pdev->dev));
+
+	return sysfs_emit(page, "%s.%d\n", DRV_NAME, aggr->id);
+}
+CONFIGFS_ATTR_RO(gpio_aggregator_device_, dev_name);
+
+static ssize_t
+gpio_aggregator_device_live_show(struct config_item *item, char *page)
+{
+	struct gpio_aggregator *aggr = to_gpio_aggregator(item);
+
+	guard(mutex)(&aggr->lock);
+
+	return sysfs_emit(page, "%c\n",
+			  gpio_aggregator_is_active(aggr) ? '1' : '0');
+}
+
+static ssize_t
+gpio_aggregator_device_live_store(struct config_item *item, const char *page,
+				  size_t count)
+{
+	struct gpio_aggregator *aggr = to_gpio_aggregator(item);
+	int ret = 0;
+	bool live;
+
+	ret = kstrtobool(page, &live);
+	if (ret)
+		return ret;
+
+	if (!try_module_get(THIS_MODULE))
+		return -ENOENT;
+
+	if (live && !aggr->init_via_sysfs)
+		gpio_aggregator_lockup_configfs(aggr, true);
+
+	scoped_guard(mutex, &aggr->lock) {
+		if (gpio_aggregator_is_activating(aggr) ||
+		    (live == gpio_aggregator_is_active(aggr)))
+			ret = -EPERM;
+		else if (live)
+			ret = gpio_aggregator_activate(aggr);
+		else
+			gpio_aggregator_deactivate(aggr);
+	}
+
+	/*
+	 * Undepend is required only if device disablement (live == 0)
+	 * succeeds or if device enablement (live == 1) fails.
+	 */
+	if (live == !!ret && !aggr->init_via_sysfs)
+		gpio_aggregator_lockup_configfs(aggr, false);
+
+	module_put(THIS_MODULE);
+
+	return ret ?: count;
+}
+CONFIGFS_ATTR(gpio_aggregator_device_, live);
+
+static struct configfs_attribute *gpio_aggregator_device_attrs[] = {
+	&gpio_aggregator_device_attr_dev_name,
+	&gpio_aggregator_device_attr_live,
+	NULL
+};
+
+static void
+gpio_aggregator_line_release(struct config_item *item)
+{
+	struct gpio_aggregator_line *line = to_gpio_aggregator_line(item);
+	struct gpio_aggregator *aggr = line->parent;
+
+	guard(mutex)(&aggr->lock);
+
+	gpio_aggregator_line_del(aggr, line);
+	kfree(line->key);
+	kfree(line->name);
+	kfree(line);
+}
+
+static const struct configfs_item_operations gpio_aggregator_line_item_ops = {
+	.release	= gpio_aggregator_line_release,
+};
+
+static const struct config_item_type gpio_aggregator_line_type = {
+	.ct_item_ops	= &gpio_aggregator_line_item_ops,
+	.ct_attrs	= gpio_aggregator_line_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static void gpio_aggregator_device_release(struct config_item *item)
+{
+	struct gpio_aggregator *aggr = to_gpio_aggregator(item);
+
+	/*
+	 * At this point, aggr is neither active nor activating,
+	 * so calling gpio_aggregator_deactivate() is always unnecessary.
+	 */
+	gpio_aggregator_free(aggr);
+}
+
+static const struct configfs_item_operations gpio_aggregator_device_item_ops = {
+	.release	= gpio_aggregator_device_release,
+};
+
+static struct config_group *
+gpio_aggregator_device_make_group(struct config_group *group, const char *name)
+{
+	struct gpio_aggregator *aggr = to_gpio_aggregator(&group->cg_item);
+	struct gpio_aggregator_line *line;
+	unsigned int idx;
+	int ret, nchar;
+
+	ret = sscanf(name, "line%u%n", &idx, &nchar);
+	if (ret != 1 || nchar != strlen(name))
+		return ERR_PTR(-EINVAL);
+
+	if (aggr->init_via_sysfs)
+		/*
+		 * Aggregators created via legacy sysfs interface are exposed as
+		 * default groups, which means rmdir(2) is prohibited for them.
+		 * For simplicity, and to avoid confusion, we also prohibit
+		 * mkdir(2).
+		 */
+		return ERR_PTR(-EPERM);
+
+	guard(mutex)(&aggr->lock);
+
+	if (gpio_aggregator_is_active(aggr))
+		return ERR_PTR(-EBUSY);
+
+	list_for_each_entry(line, &aggr->list_head, entry)
+		if (line->idx == idx)
+			return ERR_PTR(-EINVAL);
+
+	line = gpio_aggregator_line_alloc(aggr, idx, NULL, -1);
+	if (IS_ERR(line))
+		return ERR_CAST(line);
+
+	config_group_init_type_name(&line->group, name, &gpio_aggregator_line_type);
+
+	gpio_aggregator_line_add(aggr, line);
+
+	return &line->group;
+}
+
+static const struct configfs_group_operations gpio_aggregator_device_group_ops = {
+	.make_group	= gpio_aggregator_device_make_group,
+};
+
+static const struct config_item_type gpio_aggregator_device_type = {
+	.ct_group_ops	= &gpio_aggregator_device_group_ops,
+	.ct_item_ops	= &gpio_aggregator_device_item_ops,
+	.ct_attrs	= gpio_aggregator_device_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *
+gpio_aggregator_make_group(struct config_group *group, const char *name)
+{
+	struct gpio_aggregator *aggr;
+	int ret;
+
+	/*
+	 * "_sysfs" prefix is reserved for auto-generated config group
+	 * for devices create via legacy sysfs interface.
+	 */
+	if (strncmp(name, AGGREGATOR_LEGACY_PREFIX,
+		    sizeof(AGGREGATOR_LEGACY_PREFIX) - 1) == 0)
+		return ERR_PTR(-EINVAL);
+
+	/* arg space is unneeded */
+	ret = gpio_aggregator_alloc(&aggr, 0);
+	if (ret)
+		return ERR_PTR(ret);
+
+	config_group_init_type_name(&aggr->group, name, &gpio_aggregator_device_type);
+
+	return &aggr->group;
+}
+
+static const struct configfs_group_operations gpio_aggregator_group_ops = {
+	.make_group	= gpio_aggregator_make_group,
+};
+
+static const struct config_item_type gpio_aggregator_type = {
+	.ct_group_ops	= &gpio_aggregator_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem gpio_aggregator_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf	= DRV_NAME,
+			.ci_type	= &gpio_aggregator_type,
+		},
+	},
+};
+
+/*
+ * Sysfs interface
+ */
+static int gpio_aggregator_parse(struct gpio_aggregator *aggr)
+{
+	char *args = skip_spaces(aggr->args);
+	struct gpio_aggregator_line *line;
+	char name[CONFIGFS_ITEM_NAME_LEN];
+	char *key, *offsets, *p;
+	unsigned int i, n = 0;
+	int error = 0;
+
+	unsigned long *bitmap __free(bitmap) =
+			bitmap_alloc(AGGREGATOR_MAX_GPIOS, GFP_KERNEL);
+	if (!bitmap)
+		return -ENOMEM;
+
+	args = next_arg(args, &key, &p);
+	while (*args) {
+		args = next_arg(args, &offsets, &p);
+
+		p = get_options(offsets, 0, &error);
+		if (error == 0 || *p) {
+			/* Named GPIO line */
+			scnprintf(name, sizeof(name), "line%u", n);
+			line = gpio_aggregator_line_alloc(aggr, n, key, -1);
+			if (IS_ERR(line)) {
+				error = PTR_ERR(line);
+				goto err;
+			}
+			config_group_init_type_name(&line->group, name,
+						    &gpio_aggregator_line_type);
+			error = configfs_register_group(&aggr->group,
+							&line->group);
+			if (error)
+				goto err;
+			scoped_guard(mutex, &aggr->lock)
+				gpio_aggregator_line_add(aggr, line);
+
+			error = gpio_aggregator_add_gpio(aggr, key, U16_MAX, &n);
+			if (error)
+				goto err;
+
+			key = offsets;
+			continue;
+		}
+
+		/* GPIO chip + offset(s) */
+		error = bitmap_parselist(offsets, bitmap, AGGREGATOR_MAX_GPIOS);
+		if (error) {
+			pr_err("Cannot parse %s: %d\n", offsets, error);
+			goto err;
+		}
+
+		for_each_set_bit(i, bitmap, AGGREGATOR_MAX_GPIOS) {
+			scnprintf(name, sizeof(name), "line%u", n);
+			line = gpio_aggregator_line_alloc(aggr, n, key, i);
+			if (IS_ERR(line)) {
+				error = PTR_ERR(line);
+				goto err;
+			}
+			config_group_init_type_name(&line->group, name,
+						    &gpio_aggregator_line_type);
+			error = configfs_register_group(&aggr->group,
+							&line->group);
+			if (error)
+				goto err;
+			scoped_guard(mutex, &aggr->lock)
+				gpio_aggregator_line_add(aggr, line);
+
+			error = gpio_aggregator_add_gpio(aggr, key, i, &n);
+			if (error)
+				goto err;
+		}
+
+		args = next_arg(args, &key, &p);
+	}
+
+	if (!n) {
+		pr_err("No GPIOs specified\n");
+		error = -EINVAL;
+		goto err;
+	}
+
+	return 0;
+
+err:
+	gpio_aggregator_free_lines(aggr);
+	return error;
+}
+
+static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
+						const char *buf, size_t count)
+{
+	struct gpio_aggregator_pdev_meta meta = { .init_via_sysfs = true };
+	char name[CONFIGFS_ITEM_NAME_LEN];
+	struct gpio_aggregator *aggr;
+	struct platform_device *pdev;
+	int res;
+
+	if (!try_module_get(THIS_MODULE))
+		return -ENOENT;
+
+	/* kernfs guarantees string termination, so count + 1 is safe */
+	res = gpio_aggregator_alloc(&aggr, count + 1);
+	if (res)
+		goto put_module;
+
+	memcpy(aggr->args, buf, count + 1);
+
+	aggr->init_via_sysfs = true;
+	aggr->lookups = kzalloc_flex(*aggr->lookups, table, 1);
+	if (!aggr->lookups) {
+		res = -ENOMEM;
+		goto free_ga;
+	}
+
+	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, aggr->id);
+	if (!aggr->lookups->dev_id) {
+		res = -ENOMEM;
+		goto free_table;
+	}
+
+	scnprintf(name, sizeof(name), "%s.%d", AGGREGATOR_LEGACY_PREFIX, aggr->id);
+	config_group_init_type_name(&aggr->group, name, &gpio_aggregator_device_type);
+
+	/* Expose to configfs */
+	res = configfs_register_group(&gpio_aggregator_subsys.su_group,
+				      &aggr->group);
+	if (res)
+		goto free_dev_id;
+
+	res = gpio_aggregator_parse(aggr);
+	if (res)
+		goto unregister_group;
+
+	gpiod_add_lookup_table(aggr->lookups);
+
+	pdev = platform_device_register_data(NULL, DRV_NAME, aggr->id, &meta, sizeof(meta));
+	if (IS_ERR(pdev)) {
+		res = PTR_ERR(pdev);
+		goto remove_table;
+	}
+
+	aggr->pdev = pdev;
+	module_put(THIS_MODULE);
+	return count;
+
+remove_table:
+	gpiod_remove_lookup_table(aggr->lookups);
+unregister_group:
+	configfs_unregister_group(&aggr->group);
+free_dev_id:
+	kfree(aggr->lookups->dev_id);
+free_table:
+	kfree(aggr->lookups);
+free_ga:
+	gpio_aggregator_free(aggr);
+put_module:
+	module_put(THIS_MODULE);
+	return res;
+}
+
+static struct driver_attribute driver_attr_gpio_aggregator_new_device =
+	__ATTR(new_device, 0200, NULL, gpio_aggregator_new_device_store);
+
+static void gpio_aggregator_destroy(struct gpio_aggregator *aggr)
+{
+	scoped_guard(mutex, &aggr->lock) {
+		if (gpio_aggregator_is_activating(aggr) ||
+		    gpio_aggregator_is_active(aggr))
+			gpio_aggregator_deactivate(aggr);
+	}
+	gpio_aggregator_free_lines(aggr);
+	configfs_unregister_group(&aggr->group);
+	kfree(aggr);
+}
+
+static ssize_t gpio_aggregator_delete_device_store(struct device_driver *driver,
+						   const char *buf, size_t count)
+{
+	struct gpio_aggregator *aggr;
+	unsigned int id;
+	int error;
+
+	if (!str_has_prefix(buf, DRV_NAME "."))
+		return -EINVAL;
+
+	error = kstrtouint(buf + strlen(DRV_NAME "."), 10, &id);
+	if (error)
+		return error;
+
+	if (!try_module_get(THIS_MODULE))
+		return -ENOENT;
+
+	mutex_lock(&gpio_aggregator_lock);
+	aggr = idr_find(&gpio_aggregator_idr, id);
+	/*
+	 * For simplicity, devices created via configfs cannot be deleted
+	 * via sysfs.
+	 */
+	if (aggr && aggr->init_via_sysfs)
+		idr_remove(&gpio_aggregator_idr, id);
+	else {
+		mutex_unlock(&gpio_aggregator_lock);
+		module_put(THIS_MODULE);
+		return -ENOENT;
+	}
+	mutex_unlock(&gpio_aggregator_lock);
+
+	gpio_aggregator_destroy(aggr);
+	module_put(THIS_MODULE);
+	return count;
+}
+
+static struct driver_attribute driver_attr_gpio_aggregator_delete_device =
+	__ATTR(delete_device, 0200, NULL, gpio_aggregator_delete_device_store);
+
+static struct attribute *gpio_aggregator_attrs[] = {
+	&driver_attr_gpio_aggregator_new_device.attr,
+	&driver_attr_gpio_aggregator_delete_device.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(gpio_aggregator);
+
+/*
+ *  GPIO Aggregator platform device
+ */
+
+static int gpio_aggregator_probe(struct platform_device *pdev)
+{
+	struct gpio_aggregator_pdev_meta *meta;
+	struct device *dev = &pdev->dev;
+	bool init_via_sysfs = false;
+	struct gpio_desc **descs;
+	struct gpiochip_fwd *fwd;
+	unsigned long features;
+	int i, n;
+
+	n = gpiod_count(dev, NULL);
+	if (n < 0)
+		return n;
+
+	descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL);
+	if (!descs)
+		return -ENOMEM;
+
+	meta = dev_get_platdata(&pdev->dev);
+	if (meta && meta->init_via_sysfs)
+		init_via_sysfs = true;
+
+	for (i = 0; i < n; i++) {
+		descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
+		if (IS_ERR(descs[i])) {
+			/*
+			 * Deferred probing is not suitable when the aggregator
+			 * is created via configfs. They should just retry later
+			 * whenever they like. For device creation via sysfs,
+			 * error is propagated without overriding for backward
+			 * compatibility. .prevent_deferred_probe is kept unset
+			 * for other cases.
+			 */
+			if (!init_via_sysfs && !dev_of_node(dev) &&
+			    descs[i] == ERR_PTR(-EPROBE_DEFER)) {
+				pr_warn("Deferred probe canceled for creation via configfs.\n");
+				return -ENODEV;
+			}
+			return PTR_ERR(descs[i]);
+		}
+	}
+
+	features = (uintptr_t)device_get_match_data(dev);
+	fwd = gpiochip_fwd_create(dev, n, descs, features);
+	if (IS_ERR(fwd))
+		return PTR_ERR(fwd);
+
+	platform_set_drvdata(pdev, fwd);
+	devm_kfree(dev, descs);
+	return 0;
+}
+
+static const struct of_device_id gpio_aggregator_dt_ids[] = {
+	{
+		.compatible = "gpio-delay",
+		.data = (void *)FWD_FEATURE_DELAY,
+	},
+	/*
+	 * Add GPIO-operated devices controlled from userspace below,
+	 * or use "driver_override" in sysfs.
+	 */
+	{}
+};
+MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
+
+static struct platform_driver gpio_aggregator_driver = {
+	.probe = gpio_aggregator_probe,
+	.driver = {
+		.name = DRV_NAME,
+		.groups = gpio_aggregator_groups,
+		.of_match_table = gpio_aggregator_dt_ids,
+	},
+};
+
+static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data)
+{
+	/*
+	 * There should be no aggregator created via configfs, as their
+	 * presence would prevent module unloading.
+	 */
+	gpio_aggregator_destroy(p);
+	return 0;
+}
+
+static void __exit gpio_aggregator_remove_all(void)
+{
+	/*
+	 * Configfs callbacks acquire gpio_aggregator_lock when accessing
+	 * gpio_aggregator_idr, so to prevent lock inversion deadlock, we
+	 * cannot protect idr_for_each invocation here with
+	 * gpio_aggregator_lock, as gpio_aggregator_idr_remove() accesses
+	 * configfs groups. Fortunately, the new_device/delete_device path
+	 * and the module unload path are mutually exclusive, thanks to an
+	 * explicit try_module_get inside of those driver attr handlers.
+	 * Also, when we reach here, no configfs entries present or being
+	 * created. Therefore, no need to protect with gpio_aggregator_lock
+	 * below.
+	 */
+	idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
+	idr_destroy(&gpio_aggregator_idr);
+}
+
+static int __init gpio_aggregator_init(void)
+{
+	int ret = 0;
+
+	config_group_init(&gpio_aggregator_subsys.su_group);
+	mutex_init(&gpio_aggregator_subsys.su_mutex);
+	ret = configfs_register_subsystem(&gpio_aggregator_subsys);
+	if (ret) {
+		pr_err("Failed to register the '%s' configfs subsystem: %d\n",
+		       gpio_aggregator_subsys.su_group.cg_item.ci_namebuf, ret);
+		mutex_destroy(&gpio_aggregator_subsys.su_mutex);
+		return ret;
+	}
+
+	/*
+	 * CAVEAT: This must occur after configfs registration. Otherwise,
+	 * a race condition could arise: driver attribute groups might be
+	 * exposed and accessed by users before configfs registration
+	 * completes. new_device_store() does not expect a partially
+	 * initialized configfs state.
+	 */
+	ret = platform_driver_register(&gpio_aggregator_driver);
+	if (ret) {
+		pr_err("Failed to register the platform driver: %d\n", ret);
+		mutex_destroy(&gpio_aggregator_subsys.su_mutex);
+		configfs_unregister_subsystem(&gpio_aggregator_subsys);
+	}
+
+	return ret;
+}
+module_init(gpio_aggregator_init);
+
+static void __exit gpio_aggregator_exit(void)
+{
+	gpio_aggregator_remove_all();
+	platform_driver_unregister(&gpio_aggregator_driver);
+	configfs_unregister_subsystem(&gpio_aggregator_subsys);
+}
+module_exit(gpio_aggregator_exit);
+
+MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
+MODULE_DESCRIPTION("GPIO Aggregator");
+MODULE_LICENSE("GPL v2");