drivers/staging/greybus/raw.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Greybus driver for the Raw protocol
  *
  * Copyright 2015 Google Inc.
  * Copyright 2015 Linaro Ltd.
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sizes.h>
 #include <linux/cdev.h>
 #include <linux/fs.h>
 #include <linux/idr.h>
 #include <linux/uaccess.h>
 #include <linux/greybus.h>

 struct gb_raw {
 	struct gb_connection *connection;

 	struct list_head list;
 	int list_data;
 	struct mutex list_lock;
 	dev_t dev;
 	struct cdev cdev;
 	struct device *device;
 };

 struct raw_data {
 	struct list_head entry;
 	u32 len;
 	u8 data[];
 };

 static struct class *raw_class;
 static int raw_major;
 static const struct file_operations raw_fops;
 static DEFINE_IDA(minors);

 /* Number of minor devices this driver supports */
 #define NUM_MINORS	256

 /* Maximum size of any one send data buffer we support */
 #define MAX_PACKET_SIZE	(PAGE_SIZE * 2)

 /*
  * Maximum size of the data in the receive buffer we allow before we start to
  * drop messages on the floor
  */
 #define MAX_DATA_SIZE	(MAX_PACKET_SIZE * 8)

 /*
  * Add the raw data message to the list of received messages.
  */
 static int receive_data(struct gb_raw *raw, u32 len, u8 *data)
 {
 	struct raw_data *raw_data;
 	struct device *dev = &raw->connection->bundle->dev;
 	int retval = 0;

 	if (len > MAX_PACKET_SIZE) {
 		dev_err(dev, "Too big of a data packet, rejected\n");
 		return -EINVAL;
 	}

 	mutex_lock(&raw->list_lock);
 	if ((raw->list_data + len) > MAX_DATA_SIZE) {
 		dev_err(dev, "Too much data in receive buffer, now dropping packets\n");
 		retval = -EINVAL;
 		goto exit;
 	}

 	raw_data = kmalloc(sizeof(*raw_data) + len, GFP_KERNEL);
 	if (!raw_data) {
 		retval = -ENOMEM;
 		goto exit;
 	}

 	raw->list_data += len;
 	raw_data->len = len;
 	memcpy(&raw_data->data[0], data, len);

 	list_add_tail(&raw_data->entry, &raw->list);
 exit:
 	mutex_unlock(&raw->list_lock);
 	return retval;
 }

 static int gb_raw_request_handler(struct gb_operation *op)
 {
 	struct gb_connection *connection = op->connection;
 	struct device *dev = &connection->bundle->dev;
 	struct gb_raw *raw = greybus_get_drvdata(connection->bundle);
 	struct gb_raw_send_request *receive;
 	u32 len;

 	if (op->type != GB_RAW_TYPE_SEND) {
 		dev_err(dev, "unknown request type 0x%02x\n", op->type);
 		return -EINVAL;
 	}

 	/* Verify size of payload */
 	if (op->request->payload_size < sizeof(*receive)) {
 		dev_err(dev, "raw receive request too small (%zu < %zu)\n",
 			op->request->payload_size, sizeof(*receive));
 		return -EINVAL;
 	}
 	receive = op->request->payload;
 	len = le32_to_cpu(receive->len);
 	if (len != (int)(op->request->payload_size - sizeof(__le32))) {
 		dev_err(dev, "raw receive request wrong size %d vs %d\n", len,
 			(int)(op->request->payload_size - sizeof(__le32)));
 		return -EINVAL;
 	}
 	if (len == 0) {
 		dev_err(dev, "raw receive request of 0 bytes?\n");
 		return -EINVAL;
 	}

 	return receive_data(raw, len, receive->data);
 }

 static int gb_raw_send(struct gb_raw *raw, u32 len, const char __user *data)
 {
 	struct gb_connection *connection = raw->connection;
 	struct gb_raw_send_request *request;
 	int retval;

 	request = kmalloc(len + sizeof(*request), GFP_KERNEL);
 	if (!request)
 		return -ENOMEM;

 	if (copy_from_user(&request->data[0], data, len)) {
 		kfree(request);
 		return -EFAULT;
 	}

 	request->len = cpu_to_le32(len);

 	retval = gb_operation_sync(connection, GB_RAW_TYPE_SEND,
 				   request, len + sizeof(*request),
 				   NULL, 0);

 	kfree(request);
 	return retval;
 }

 static int gb_raw_probe(struct gb_bundle *bundle,
 			const struct greybus_bundle_id *id)
 {
 	struct greybus_descriptor_cport *cport_desc;
 	struct gb_connection *connection;
 	struct gb_raw *raw;
 	int retval;
 	int minor;

 	if (bundle->num_cports != 1)
 		return -ENODEV;

 	cport_desc = &bundle->cport_desc[0];
 	if (cport_desc->protocol_id != GREYBUS_PROTOCOL_RAW)
 		return -ENODEV;

 	raw = kzalloc(sizeof(*raw), GFP_KERNEL);
 	if (!raw)
 		return -ENOMEM;

 	connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
 					  gb_raw_request_handler);
 	if (IS_ERR(connection)) {
 		retval = PTR_ERR(connection);
 		goto error_free;
 	}

 	INIT_LIST_HEAD(&raw->list);
 	mutex_init(&raw->list_lock);

 	raw->connection = connection;
 	greybus_set_drvdata(bundle, raw);

 	minor = ida_simple_get(&minors, 0, 0, GFP_KERNEL);
 	if (minor < 0) {
 		retval = minor;
 		goto error_connection_destroy;
 	}

 	raw->dev = MKDEV(raw_major, minor);
 	cdev_init(&raw->cdev, &raw_fops);

 	retval = gb_connection_enable(connection);
 	if (retval)
 		goto error_remove_ida;

 	retval = cdev_add(&raw->cdev, raw->dev, 1);
 	if (retval)
 		goto error_connection_disable;

 	raw->device = device_create(raw_class, &connection->bundle->dev,
 				    raw->dev, raw, "gb!raw%d", minor);
 	if (IS_ERR(raw->device)) {
 		retval = PTR_ERR(raw->device);
 		goto error_del_cdev;
 	}

 	return 0;

 error_del_cdev:
 	cdev_del(&raw->cdev);

 error_connection_disable:
 	gb_connection_disable(connection);

 error_remove_ida:
 	ida_simple_remove(&minors, minor);

 error_connection_destroy:
 	gb_connection_destroy(connection);

 error_free:
 	kfree(raw);
 	return retval;
 }

 static void gb_raw_disconnect(struct gb_bundle *bundle)
 {
 	struct gb_raw *raw = greybus_get_drvdata(bundle);
 	struct gb_connection *connection = raw->connection;
 	struct raw_data *raw_data;
 	struct raw_data *temp;

 	// FIXME - handle removing a connection when the char device node is open.
 	device_destroy(raw_class, raw->dev);
 	cdev_del(&raw->cdev);
 	gb_connection_disable(connection);
 	ida_simple_remove(&minors, MINOR(raw->dev));
 	gb_connection_destroy(connection);

 	mutex_lock(&raw->list_lock);
 	list_for_each_entry_safe(raw_data, temp, &raw->list, entry) {
 		list_del(&raw_data->entry);
 		kfree(raw_data);
 	}
 	mutex_unlock(&raw->list_lock);

 	kfree(raw);
 }

 /*
  * Character device node interfaces.
  *
  * Note, we are using read/write to only allow a single read/write per message.
  * This means for read(), you have to provide a big enough buffer for the full
  * message to be copied into.  If the buffer isn't big enough, the read() will
  * fail with -ENOSPC.
  */

 static int raw_open(struct inode *inode, struct file *file)
 {
 	struct cdev *cdev = inode->i_cdev;
 	struct gb_raw *raw = container_of(cdev, struct gb_raw, cdev);

 	file->private_data = raw;
 	return 0;
 }

 static ssize_t raw_write(struct file *file, const char __user *buf,
 			 size_t count, loff_t *ppos)
 {
 	struct gb_raw *raw = file->private_data;
 	int retval;

 	if (!count)
 		return 0;

 	if (count > MAX_PACKET_SIZE)
 		return -E2BIG;

 	retval = gb_raw_send(raw, count, buf);
 	if (retval)
 		return retval;

 	return count;
 }

 static ssize_t raw_read(struct file *file, char __user *buf, size_t count,
 			loff_t *ppos)
 {
 	struct gb_raw *raw = file->private_data;
 	int retval = 0;
 	struct raw_data *raw_data;

 	mutex_lock(&raw->list_lock);
 	if (list_empty(&raw->list))
 		goto exit;

 	raw_data = list_first_entry(&raw->list, struct raw_data, entry);
 	if (raw_data->len > count) {
 		retval = -ENOSPC;
 		goto exit;
 	}

 	if (copy_to_user(buf, &raw_data->data[0], raw_data->len)) {
 		retval = -EFAULT;
 		goto exit;
 	}

 	list_del(&raw_data->entry);
 	raw->list_data -= raw_data->len;
 	retval = raw_data->len;
 	kfree(raw_data);

 exit:
 	mutex_unlock(&raw->list_lock);
 	return retval;
 }

 static const struct file_operations raw_fops = {
 	.owner		= THIS_MODULE,
 	.write		= raw_write,
 	.read		= raw_read,
 	.open		= raw_open,
 	.llseek		= noop_llseek,
 };

 static const struct greybus_bundle_id gb_raw_id_table[] = {
 	{ GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_RAW) },
 	{ }
 };
 MODULE_DEVICE_TABLE(greybus, gb_raw_id_table);

 static struct greybus_driver gb_raw_driver = {
 	.name		= "raw",
 	.probe		= gb_raw_probe,
 	.disconnect	= gb_raw_disconnect,
 	.id_table	= gb_raw_id_table,
 };

 static int raw_init(void)
 {
 	dev_t dev;
 	int retval;

 	raw_class = class_create("gb_raw");
 	if (IS_ERR(raw_class)) {
 		retval = PTR_ERR(raw_class);
 		goto error_class;
 	}

 	retval = alloc_chrdev_region(&dev, 0, NUM_MINORS, "gb_raw");
 	if (retval < 0)
 		goto error_chrdev;

 	raw_major = MAJOR(dev);

 	retval = greybus_register(&gb_raw_driver);
 	if (retval)
 		goto error_gb;

 	return 0;

 error_gb:
 	unregister_chrdev_region(dev, NUM_MINORS);
 error_chrdev:
 	class_destroy(raw_class);
 error_class:
 	return retval;
 }
 module_init(raw_init);

 static void __exit raw_exit(void)
 {
 	greybus_deregister(&gb_raw_driver);
 	unregister_chrdev_region(MKDEV(raw_major, 0), NUM_MINORS);
 	class_destroy(raw_class);
 	ida_destroy(&minors);
 }
 module_exit(raw_exit);

 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Greybus driver for the Raw protocol
	*
	* Copyright 2015 Google Inc.
	* Copyright 2015 Linaro Ltd.
	*/
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sizes.h>
	#include <linux/cdev.h>
	#include <linux/fs.h>
	#include <linux/idr.h>
	#include <linux/uaccess.h>
	#include <linux/greybus.h>

	struct gb_raw {
	struct gb_connection *connection;

	struct list_head list;
	int list_data;
	struct mutex list_lock;
	dev_t dev;
	struct cdev cdev;
	struct device *device;
	};

	struct raw_data {
	struct list_head entry;
	u32 len;
	u8 data[];
	};

	static struct class *raw_class;
	static int raw_major;
	static const struct file_operations raw_fops;
	static DEFINE_IDA(minors);

	/* Number of minor devices this driver supports */
	#define NUM_MINORS 256

	/* Maximum size of any one send data buffer we support */
	#define MAX_PACKET_SIZE (PAGE_SIZE * 2)

	/*
	* Maximum size of the data in the receive buffer we allow before we start to
	* drop messages on the floor
	*/
	#define MAX_DATA_SIZE (MAX_PACKET_SIZE * 8)

	/*
	* Add the raw data message to the list of received messages.
	*/
	static int receive_data(struct gb_raw raw, u32 len, u8 data)
	{
	struct raw_data *raw_data;
	struct device *dev = &raw->connection->bundle->dev;
	int retval = 0;

	if (len > MAX_PACKET_SIZE) {
	dev_err(dev, "Too big of a data packet, rejected\n");
	return -EINVAL;
	}

	mutex_lock(&raw->list_lock);
	if ((raw->list_data + len) > MAX_DATA_SIZE) {
	dev_err(dev, "Too much data in receive buffer, now dropping packets\n");
	retval = -EINVAL;
	goto exit;
	}

	raw_data = kmalloc(sizeof(*raw_data) + len, GFP_KERNEL);
	if (!raw_data) {
	retval = -ENOMEM;
	goto exit;
	}

	raw->list_data += len;
	raw_data->len = len;
	memcpy(&raw_data->data[0], data, len);

	list_add_tail(&raw_data->entry, &raw->list);
	exit:
	mutex_unlock(&raw->list_lock);
	return retval;
	}

	static int gb_raw_request_handler(struct gb_operation *op)
	{
	struct gb_connection *connection = op->connection;
	struct device *dev = &connection->bundle->dev;
	struct gb_raw *raw = greybus_get_drvdata(connection->bundle);
	struct gb_raw_send_request *receive;
	u32 len;

	if (op->type != GB_RAW_TYPE_SEND) {
	dev_err(dev, "unknown request type 0x%02x\n", op->type);
	return -EINVAL;
	}

	/* Verify size of payload */
	if (op->request->payload_size < sizeof(*receive)) {
	dev_err(dev, "raw receive request too small (%zu < %zu)\n",
	op->request->payload_size, sizeof(*receive));
	return -EINVAL;
	}
	receive = op->request->payload;
	len = le32_to_cpu(receive->len);
	if (len != (int)(op->request->payload_size - sizeof(__le32))) {
	dev_err(dev, "raw receive request wrong size %d vs %d\n", len,
	(int)(op->request->payload_size - sizeof(__le32)));
	return -EINVAL;
	}
	if (len == 0) {
	dev_err(dev, "raw receive request of 0 bytes?\n");
	return -EINVAL;
	}

	return receive_data(raw, len, receive->data);
	}

	static int gb_raw_send(struct gb_raw raw, u32 len, const char __user data)
	{
	struct gb_connection *connection = raw->connection;
	struct gb_raw_send_request *request;
	int retval;

	request = kmalloc(len + sizeof(*request), GFP_KERNEL);
	if (!request)
	return -ENOMEM;

	if (copy_from_user(&request->data[0], data, len)) {
	kfree(request);
	return -EFAULT;
	}

	request->len = cpu_to_le32(len);

	retval = gb_operation_sync(connection, GB_RAW_TYPE_SEND,
	request, len + sizeof(*request),
	NULL, 0);

	kfree(request);
	return retval;
	}

	static int gb_raw_probe(struct gb_bundle *bundle,
	const struct greybus_bundle_id *id)
	{
	struct greybus_descriptor_cport *cport_desc;
	struct gb_connection *connection;
	struct gb_raw *raw;
	int retval;
	int minor;

	if (bundle->num_cports != 1)
	return -ENODEV;

	cport_desc = &bundle->cport_desc[0];
	if (cport_desc->protocol_id != GREYBUS_PROTOCOL_RAW)
	return -ENODEV;

	raw = kzalloc(sizeof(*raw), GFP_KERNEL);
	if (!raw)
	return -ENOMEM;

	connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
	gb_raw_request_handler);
	if (IS_ERR(connection)) {
	retval = PTR_ERR(connection);
	goto error_free;
	}

	INIT_LIST_HEAD(&raw->list);
	mutex_init(&raw->list_lock);

	raw->connection = connection;
	greybus_set_drvdata(bundle, raw);

	minor = ida_simple_get(&minors, 0, 0, GFP_KERNEL);
	if (minor < 0) {
	retval = minor;
	goto error_connection_destroy;
	}

	raw->dev = MKDEV(raw_major, minor);
	cdev_init(&raw->cdev, &raw_fops);

	retval = gb_connection_enable(connection);
	if (retval)
	goto error_remove_ida;

	retval = cdev_add(&raw->cdev, raw->dev, 1);
	if (retval)
	goto error_connection_disable;

	raw->device = device_create(raw_class, &connection->bundle->dev,
	raw->dev, raw, "gb!raw%d", minor);
	if (IS_ERR(raw->device)) {
	retval = PTR_ERR(raw->device);
	goto error_del_cdev;
	}

	return 0;

	error_del_cdev:
	cdev_del(&raw->cdev);

	error_connection_disable:
	gb_connection_disable(connection);

	error_remove_ida:
	ida_simple_remove(&minors, minor);

	error_connection_destroy:
	gb_connection_destroy(connection);

	error_free:
	kfree(raw);
	return retval;
	}

	static void gb_raw_disconnect(struct gb_bundle *bundle)
	{
	struct gb_raw *raw = greybus_get_drvdata(bundle);
	struct gb_connection *connection = raw->connection;
	struct raw_data *raw_data;
	struct raw_data *temp;

	// FIXME - handle removing a connection when the char device node is open.
	device_destroy(raw_class, raw->dev);
	cdev_del(&raw->cdev);
	gb_connection_disable(connection);
	ida_simple_remove(&minors, MINOR(raw->dev));
	gb_connection_destroy(connection);

	mutex_lock(&raw->list_lock);
	list_for_each_entry_safe(raw_data, temp, &raw->list, entry) {
	list_del(&raw_data->entry);
	kfree(raw_data);
	}
	mutex_unlock(&raw->list_lock);

	kfree(raw);
	}

	/*
	* Character device node interfaces.
	*
	* Note, we are using read/write to only allow a single read/write per message.
	* This means for read(), you have to provide a big enough buffer for the full
	* message to be copied into. If the buffer isn't big enough, the read() will
	* fail with -ENOSPC.
	*/

	static int raw_open(struct inode inode, struct file file)
	{
	struct cdev *cdev = inode->i_cdev;
	struct gb_raw *raw = container_of(cdev, struct gb_raw, cdev);

	file->private_data = raw;
	return 0;
	}

	static ssize_t raw_write(struct file file, const char __user buf,
	size_t count, loff_t *ppos)
	{
	struct gb_raw *raw = file->private_data;
	int retval;

	if (!count)
	return 0;

	if (count > MAX_PACKET_SIZE)
	return -E2BIG;

	retval = gb_raw_send(raw, count, buf);
	if (retval)
	return retval;

	return count;
	}

	static ssize_t raw_read(struct file file, char __user buf, size_t count,
	loff_t *ppos)
	{
	struct gb_raw *raw = file->private_data;
	int retval = 0;
	struct raw_data *raw_data;

	mutex_lock(&raw->list_lock);
	if (list_empty(&raw->list))
	goto exit;

	raw_data = list_first_entry(&raw->list, struct raw_data, entry);
	if (raw_data->len > count) {
	retval = -ENOSPC;
	goto exit;
	}

	if (copy_to_user(buf, &raw_data->data[0], raw_data->len)) {
	retval = -EFAULT;
	goto exit;
	}

	list_del(&raw_data->entry);
	raw->list_data -= raw_data->len;
	retval = raw_data->len;
	kfree(raw_data);

	exit:
	mutex_unlock(&raw->list_lock);
	return retval;
	}

	static const struct file_operations raw_fops = {
	.owner = THIS_MODULE,
	.write = raw_write,
	.read = raw_read,
	.open = raw_open,
	.llseek = noop_llseek,
	};

	static const struct greybus_bundle_id gb_raw_id_table[] = {
	{ GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_RAW) },
	{ }
	};
	MODULE_DEVICE_TABLE(greybus, gb_raw_id_table);

	static struct greybus_driver gb_raw_driver = {
	.name = "raw",
	.probe = gb_raw_probe,
	.disconnect = gb_raw_disconnect,
	.id_table = gb_raw_id_table,
	};

	static int raw_init(void)
	{
	dev_t dev;
	int retval;

	raw_class = class_create("gb_raw");
	if (IS_ERR(raw_class)) {
	retval = PTR_ERR(raw_class);
	goto error_class;
	}

	retval = alloc_chrdev_region(&dev, 0, NUM_MINORS, "gb_raw");
	if (retval < 0)
	goto error_chrdev;

	raw_major = MAJOR(dev);

	retval = greybus_register(&gb_raw_driver);
	if (retval)
	goto error_gb;

	return 0;

	error_gb:
	unregister_chrdev_region(dev, NUM_MINORS);
	error_chrdev:
	class_destroy(raw_class);
	error_class:
	return retval;
	}
	module_init(raw_init);

	static void __exit raw_exit(void)
	{
	greybus_deregister(&gb_raw_driver);
	unregister_chrdev_region(MKDEV(raw_major, 0), NUM_MINORS);
	class_destroy(raw_class);
	ida_destroy(&minors);
	}
	module_exit(raw_exit);

	MODULE_LICENSE("GPL v2");