Date:   Fri, 16 Sep 2016 16:11:15 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Cc:     Johan Hovold <johan@...oldconsulting.com>,
        Rui Miguel Silva <rmfrfs@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sandeep Patil <sspatil@...gle.com>,
        Matt Porter <mporter@...nel.crashing.org>,
        John Stultz <john.stultz@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Alex Elder <elder@...aro.org>, David Lin <dtwlin@...gle.com>,
        Bryan O'Donoghue <pure.logic@...us-software.ie>,
        Vaibhav Agarwal <vaibhav.agarwal@...aro.org>,
        Mark Greer <mgreer@...malcreek.com>
Subject: [patch 18/32] greybus: raw driver


This driver implements the Greybus raw protocol.

Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/greybus/raw.c |  381 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 381 insertions(+)

--- /dev/null
+++ b/drivers/greybus/raw.c
@@ -0,0 +1,381 @@
+/*
+ * Greybus driver for the Raw protocol
+ *
+ * Copyright 2015 Google Inc.
+ * Copyright 2015 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+#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 "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[0];
+};
+
+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(THIS_MODULE, "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");

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