drivers/gpio/gpio-aggregator.c - linux - Git at Google

 // 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/ctype.h>
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/gpio/driver.h>
 #include <linux/gpio/machine.h>
 #include <linux/idr.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/overflow.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>


 /*
  * GPIO Aggregator sysfs interface
  */

 struct gpio_aggregator {
 	struct gpiod_lookup_table *lookups;
 	struct platform_device *pdev;
 	char args[];
 };

 static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
 static DEFINE_IDR(gpio_aggregator_idr);

 static int aggr_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 int aggr_parse(struct gpio_aggregator *aggr)
 {
 	char *args = skip_spaces(aggr->args);
 	char *name, *offsets, *p;
 	unsigned long *bitmap;
 	unsigned int i, n = 0;
 	int error = 0;

 	bitmap = bitmap_alloc(ARCH_NR_GPIOS, GFP_KERNEL);
 	if (!bitmap)
 		return -ENOMEM;

 	args = next_arg(args, &name, &p);
 	while (*args) {
 		args = next_arg(args, &offsets, &p);

 		p = get_options(offsets, 0, &error);
 		if (error == 0 || *p) {
 			/* Named GPIO line */
 			error = aggr_add_gpio(aggr, name, U16_MAX, &n);
 			if (error)
 				goto free_bitmap;

 			name = offsets;
 			continue;
 		}

 		/* GPIO chip + offset(s) */
 		error = bitmap_parselist(offsets, bitmap, ARCH_NR_GPIOS);
 		if (error) {
 			pr_err("Cannot parse %s: %d\n", offsets, error);
 			goto free_bitmap;
 		}

 		for_each_set_bit(i, bitmap, ARCH_NR_GPIOS) {
 			error = aggr_add_gpio(aggr, name, i, &n);
 			if (error)
 				goto free_bitmap;
 		}

 		args = next_arg(args, &name, &p);
 	}

 	if (!n) {
 		pr_err("No GPIOs specified\n");
 		error = -EINVAL;
 	}

 free_bitmap:
 	bitmap_free(bitmap);
 	return error;
 }

 static ssize_t new_device_store(struct device_driver *driver, const char *buf,
 				size_t count)
 {
 	struct gpio_aggregator *aggr;
 	struct platform_device *pdev;
 	int res, id;

 	/* kernfs guarantees string termination, so count + 1 is safe */
 	aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
 	if (!aggr)
 		return -ENOMEM;

 	memcpy(aggr->args, buf, count + 1);

 	aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1),
 				GFP_KERNEL);
 	if (!aggr->lookups) {
 		res = -ENOMEM;
 		goto free_ga;
 	}

 	mutex_lock(&gpio_aggregator_lock);
 	id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
 	mutex_unlock(&gpio_aggregator_lock);

 	if (id < 0) {
 		res = id;
 		goto free_table;
 	}

 	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
 	if (!aggr->lookups->dev_id) {
 		res = -ENOMEM;
 		goto remove_idr;
 	}

 	res = aggr_parse(aggr);
 	if (res)
 		goto free_dev_id;

 	gpiod_add_lookup_table(aggr->lookups);

 	pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
 	if (IS_ERR(pdev)) {
 		res = PTR_ERR(pdev);
 		goto remove_table;
 	}

 	aggr->pdev = pdev;
 	return count;

 remove_table:
 	gpiod_remove_lookup_table(aggr->lookups);
 free_dev_id:
 	kfree(aggr->lookups->dev_id);
 remove_idr:
 	mutex_lock(&gpio_aggregator_lock);
 	idr_remove(&gpio_aggregator_idr, id);
 	mutex_unlock(&gpio_aggregator_lock);
 free_table:
 	kfree(aggr->lookups);
 free_ga:
 	kfree(aggr);
 	return res;
 }

 static DRIVER_ATTR_WO(new_device);

 static void gpio_aggregator_free(struct gpio_aggregator *aggr)
 {
 	platform_device_unregister(aggr->pdev);
 	gpiod_remove_lookup_table(aggr->lookups);
 	kfree(aggr->lookups->dev_id);
 	kfree(aggr->lookups);
 	kfree(aggr);
 }

 static ssize_t 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;

 	mutex_lock(&gpio_aggregator_lock);
 	aggr = idr_remove(&gpio_aggregator_idr, id);
 	mutex_unlock(&gpio_aggregator_lock);
 	if (!aggr)
 		return -ENOENT;

 	gpio_aggregator_free(aggr);
 	return count;
 }
 static DRIVER_ATTR_WO(delete_device);

 static struct attribute *gpio_aggregator_attrs[] = {
 	&driver_attr_new_device.attr,
 	&driver_attr_delete_device.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(gpio_aggregator);

 static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data)
 {
 	gpio_aggregator_free(p);
 	return 0;
 }

 static void __exit gpio_aggregator_remove_all(void)
 {
 	mutex_lock(&gpio_aggregator_lock);
 	idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
 	idr_destroy(&gpio_aggregator_idr);
 	mutex_unlock(&gpio_aggregator_lock);
 }


 /*
  *  GPIO Forwarder
  */

 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 */
 	};
 	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_get_direction(struct gpio_chip *chip, unsigned int offset)
 {
 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);

 	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 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];

 	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_set(struct gpio_chip *chip, unsigned int offset, int value)
 {
 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);

 	gpiod_set_value(fwd->descs[offset], value);
 }

 static void 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;

 	for_each_set_bit(i, mask, fwd->chip.ngpio) {
 		__assign_bit(j, values, test_bit(i, bits));
 		descs[j++] = fwd->descs[i];
 	}

 	gpiod_set_array_value(j, descs, NULL, values);
 }

 static void 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;

 	if (chip->can_sleep) {
 		mutex_lock(&fwd->mlock);
 		gpio_fwd_set_multiple(fwd, mask, bits);
 		mutex_unlock(&fwd->mlock);
 	} else {
 		spin_lock_irqsave(&fwd->slock, flags);
 		gpio_fwd_set_multiple(fwd, mask, bits);
 		spin_unlock_irqrestore(&fwd->slock, flags);
 	}
 }

 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);
 }

 /**
  * 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 must not be deallocated
  *         before the forwarder has been destroyed again.
  *
  * 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[])
 {
 	const char *label = dev_name(dev);
 	struct gpiochip_fwd *fwd;
 	struct gpio_chip *chip;
 	unsigned int i;
 	int error;

 	fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
 			   GFP_KERNEL);
 	if (!fwd)
 		return ERR_PTR(-ENOMEM);

 	chip = &fwd->chip;

 	/*
 	 * If any of the GPIO lines are sleeping, then the entire forwarder
 	 * will be sleeping.
 	 * If any of the chips support .set_config(), then the forwarder will
 	 * support setting configs.
 	 */
 	for (i = 0; i < ngpios; i++) {
 		struct gpio_chip *parent = gpiod_to_chip(descs[i]);

 		dev_dbg(dev, "%u => gpio-%d\n", i, desc_to_gpio(descs[i]));

 		if (gpiod_cansleep(descs[i]))
 			chip->can_sleep = true;
 		if (parent && parent->set_config)
 			chip->set_config = gpio_fwd_set_config;
 	}

 	chip->label = label;
 	chip->parent = dev;
 	chip->owner = THIS_MODULE;
 	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->base = -1;
 	chip->ngpio = ngpios;
 	fwd->descs = descs;

 	if (chip->can_sleep)
 		mutex_init(&fwd->mlock);
 	else
 		spin_lock_init(&fwd->slock);

 	error = devm_gpiochip_add_data(dev, chip, fwd);
 	if (error)
 		return ERR_PTR(error);

 	return fwd;
 }


 /*
  *  GPIO Aggregator platform device
  */

 static int gpio_aggregator_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct gpio_desc **descs;
 	struct gpiochip_fwd *fwd;
 	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;

 	for (i = 0; i < n; i++) {
 		descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
 		if (IS_ERR(descs[i]))
 			return PTR_ERR(descs[i]);
 	}

 	fwd = gpiochip_fwd_create(dev, n, descs);
 	if (IS_ERR(fwd))
 		return PTR_ERR(fwd);

 	platform_set_drvdata(pdev, fwd);
 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id gpio_aggregator_dt_ids[] = {
 	/*
 	 * Add GPIO-operated devices controlled from userspace below,
 	 * or use "driver_override" in sysfs
 	 */
 	{}
 };
 MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
 #endif

 static struct platform_driver gpio_aggregator_driver = {
 	.probe = gpio_aggregator_probe,
 	.driver = {
 		.name = DRV_NAME,
 		.groups = gpio_aggregator_groups,
 		.of_match_table = of_match_ptr(gpio_aggregator_dt_ids),
 	},
 };

 static int __init gpio_aggregator_init(void)
 {
 	return platform_driver_register(&gpio_aggregator_driver);
 }
 module_init(gpio_aggregator_init);

 static void __exit gpio_aggregator_exit(void)
 {
 	gpio_aggregator_remove_all();
 	platform_driver_unregister(&gpio_aggregator_driver);
 }
 module_exit(gpio_aggregator_exit);

 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
 MODULE_DESCRIPTION("GPIO Aggregator");
 MODULE_LICENSE("GPL v2");
	// 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/ctype.h>
	#include <linux/gpio.h>
	#include <linux/gpio/consumer.h>
	#include <linux/gpio/driver.h>
	#include <linux/gpio/machine.h>
	#include <linux/idr.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/overflow.h>
	#include <linux/platform_device.h>
	#include <linux/spinlock.h>
	#include <linux/string.h>


	/*
	* GPIO Aggregator sysfs interface
	*/

	struct gpio_aggregator {
	struct gpiod_lookup_table *lookups;
	struct platform_device *pdev;
	char args[];
	};

	static DEFINE_MUTEX(gpio_aggregator_lock); /* protects idr */
	static DEFINE_IDR(gpio_aggregator_idr);

	static int aggr_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 int aggr_parse(struct gpio_aggregator *aggr)
	{
	char *args = skip_spaces(aggr->args);
	char name, offsets, *p;
	unsigned long *bitmap;
	unsigned int i, n = 0;
	int error = 0;

	bitmap = bitmap_alloc(ARCH_NR_GPIOS, GFP_KERNEL);
	if (!bitmap)
	return -ENOMEM;

	args = next_arg(args, &name, &p);
	while (*args) {
	args = next_arg(args, &offsets, &p);

	p = get_options(offsets, 0, &error);
	if (error == 0 \|\| *p) {
	/* Named GPIO line */
	error = aggr_add_gpio(aggr, name, U16_MAX, &n);
	if (error)
	goto free_bitmap;

	name = offsets;
	continue;
	}

	/* GPIO chip + offset(s) */
	error = bitmap_parselist(offsets, bitmap, ARCH_NR_GPIOS);
	if (error) {
	pr_err("Cannot parse %s: %d\n", offsets, error);
	goto free_bitmap;
	}

	for_each_set_bit(i, bitmap, ARCH_NR_GPIOS) {
	error = aggr_add_gpio(aggr, name, i, &n);
	if (error)
	goto free_bitmap;
	}

	args = next_arg(args, &name, &p);
	}

	if (!n) {
	pr_err("No GPIOs specified\n");
	error = -EINVAL;
	}

	free_bitmap:
	bitmap_free(bitmap);
	return error;
	}

	static ssize_t new_device_store(struct device_driver driver, const char buf,
	size_t count)
	{
	struct gpio_aggregator *aggr;
	struct platform_device *pdev;
	int res, id;

	/* kernfs guarantees string termination, so count + 1 is safe */
	aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
	if (!aggr)
	return -ENOMEM;

	memcpy(aggr->args, buf, count + 1);

	aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1),
	GFP_KERNEL);
	if (!aggr->lookups) {
	res = -ENOMEM;
	goto free_ga;
	}

	mutex_lock(&gpio_aggregator_lock);
	id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
	mutex_unlock(&gpio_aggregator_lock);

	if (id < 0) {
	res = id;
	goto free_table;
	}

	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
	if (!aggr->lookups->dev_id) {
	res = -ENOMEM;
	goto remove_idr;
	}

	res = aggr_parse(aggr);
	if (res)
	goto free_dev_id;

	gpiod_add_lookup_table(aggr->lookups);

	pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
	if (IS_ERR(pdev)) {
	res = PTR_ERR(pdev);
	goto remove_table;
	}

	aggr->pdev = pdev;
	return count;

	remove_table:
	gpiod_remove_lookup_table(aggr->lookups);
	free_dev_id:
	kfree(aggr->lookups->dev_id);
	remove_idr:
	mutex_lock(&gpio_aggregator_lock);
	idr_remove(&gpio_aggregator_idr, id);
	mutex_unlock(&gpio_aggregator_lock);
	free_table:
	kfree(aggr->lookups);
	free_ga:
	kfree(aggr);
	return res;
	}

	static DRIVER_ATTR_WO(new_device);

	static void gpio_aggregator_free(struct gpio_aggregator *aggr)
	{
	platform_device_unregister(aggr->pdev);
	gpiod_remove_lookup_table(aggr->lookups);
	kfree(aggr->lookups->dev_id);
	kfree(aggr->lookups);
	kfree(aggr);
	}

	static ssize_t 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;

	mutex_lock(&gpio_aggregator_lock);
	aggr = idr_remove(&gpio_aggregator_idr, id);
	mutex_unlock(&gpio_aggregator_lock);
	if (!aggr)
	return -ENOENT;

	gpio_aggregator_free(aggr);
	return count;
	}
	static DRIVER_ATTR_WO(delete_device);

	static struct attribute *gpio_aggregator_attrs[] = {
	&driver_attr_new_device.attr,
	&driver_attr_delete_device.attr,
	NULL
	};
	ATTRIBUTE_GROUPS(gpio_aggregator);

	static int __exit gpio_aggregator_idr_remove(int id, void p, void data)
	{
	gpio_aggregator_free(p);
	return 0;
	}

	static void __exit gpio_aggregator_remove_all(void)
	{
	mutex_lock(&gpio_aggregator_lock);
	idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
	idr_destroy(&gpio_aggregator_idr);
	mutex_unlock(&gpio_aggregator_lock);
	}


	/*
	* GPIO Forwarder
	*/

	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 */
	};
	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_get_direction(struct gpio_chip *chip, unsigned int offset)
	{
	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);

	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 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];

	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_set(struct gpio_chip *chip, unsigned int offset, int value)
	{
	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);

	gpiod_set_value(fwd->descs[offset], value);
	}

	static void 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;

	for_each_set_bit(i, mask, fwd->chip.ngpio) {
	__assign_bit(j, values, test_bit(i, bits));
	descs[j++] = fwd->descs[i];
	}

	gpiod_set_array_value(j, descs, NULL, values);
	}

	static void 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;

	if (chip->can_sleep) {
	mutex_lock(&fwd->mlock);
	gpio_fwd_set_multiple(fwd, mask, bits);
	mutex_unlock(&fwd->mlock);
	} else {
	spin_lock_irqsave(&fwd->slock, flags);
	gpio_fwd_set_multiple(fwd, mask, bits);
	spin_unlock_irqrestore(&fwd->slock, flags);
	}
	}

	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);
	}

	/**
	* 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 must not be deallocated
	* before the forwarder has been destroyed again.
	*
	* 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[])
	{
	const char *label = dev_name(dev);
	struct gpiochip_fwd *fwd;
	struct gpio_chip *chip;
	unsigned int i;
	int error;

	fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
	GFP_KERNEL);
	if (!fwd)
	return ERR_PTR(-ENOMEM);

	chip = &fwd->chip;

	/*
	* If any of the GPIO lines are sleeping, then the entire forwarder
	* will be sleeping.
	* If any of the chips support .set_config(), then the forwarder will
	* support setting configs.
	*/
	for (i = 0; i < ngpios; i++) {
	struct gpio_chip *parent = gpiod_to_chip(descs[i]);

	dev_dbg(dev, "%u => gpio-%d\n", i, desc_to_gpio(descs[i]));

	if (gpiod_cansleep(descs[i]))
	chip->can_sleep = true;
	if (parent && parent->set_config)
	chip->set_config = gpio_fwd_set_config;
	}

	chip->label = label;
	chip->parent = dev;
	chip->owner = THIS_MODULE;
	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->base = -1;
	chip->ngpio = ngpios;
	fwd->descs = descs;

	if (chip->can_sleep)
	mutex_init(&fwd->mlock);
	else
	spin_lock_init(&fwd->slock);

	error = devm_gpiochip_add_data(dev, chip, fwd);
	if (error)
	return ERR_PTR(error);

	return fwd;
	}


	/*
	* GPIO Aggregator platform device
	*/

	static int gpio_aggregator_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct gpio_desc **descs;
	struct gpiochip_fwd *fwd;
	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;

	for (i = 0; i < n; i++) {
	descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
	if (IS_ERR(descs[i]))
	return PTR_ERR(descs[i]);
	}

	fwd = gpiochip_fwd_create(dev, n, descs);
	if (IS_ERR(fwd))
	return PTR_ERR(fwd);

	platform_set_drvdata(pdev, fwd);
	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id gpio_aggregator_dt_ids[] = {
	/*
	* Add GPIO-operated devices controlled from userspace below,
	* or use "driver_override" in sysfs
	*/
	{}
	};
	MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
	#endif

	static struct platform_driver gpio_aggregator_driver = {
	.probe = gpio_aggregator_probe,
	.driver = {
	.name = DRV_NAME,
	.groups = gpio_aggregator_groups,
	.of_match_table = of_match_ptr(gpio_aggregator_dt_ids),
	},
	};

	static int __init gpio_aggregator_init(void)
	{
	return platform_driver_register(&gpio_aggregator_driver);
	}
	module_init(gpio_aggregator_init);

	static void __exit gpio_aggregator_exit(void)
	{
	gpio_aggregator_remove_all();
	platform_driver_unregister(&gpio_aggregator_driver);
	}
	module_exit(gpio_aggregator_exit);

	MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
	MODULE_DESCRIPTION("GPIO Aggregator");
	MODULE_LICENSE("GPL v2");