// 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/mod_devicetable.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>

#include "dev-sync-probe.h"

#define AGGREGATOR_MAX_GPIOS 512
#define AGGREGATOR_LEGACY_PREFIX "_sysfs"

/*
 * GPIO Aggregator sysfs interface
 */

struct gpio_aggregator {
        struct dev_sync_probe_data probe_data;
        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->probe_data.pdev && platform_get_drvdata(aggr->probe_data.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->probe_data.pdev && !platform_get_drvdata(aggr->probe_data.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 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);

        ret = dev_sync_probe_register(&aggr->probe_data, &pdevinfo);
        if (ret)
                goto err_remove_lookup_table;

        return 0;

err_remove_lookup_table:
        kfree(aggr->lookups->dev_id);
        gpiod_remove_lookup_table(aggr->lookups);
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)
{
        dev_sync_probe_unregister(&aggr->probe_data);
        gpiod_remove_lookup_table(aggr->lookups);
        kfree(aggr->lookups->dev_id);
        kfree(aggr->lookups);
}

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->probe_data.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);
        dev_sync_probe_init(&aggr->probe_data);

        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);

        /*
         * Since the device created by sysfs might be toggled via configfs
         * 'live' attribute later, this initialization is needed.
         */
        dev_sync_probe_init(&aggr->probe_data);

        /* 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->probe_data.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");