1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Greybus driver for the log protocol
  4 *
  5 * Copyright 2016 Google Inc.
  6 */
  7#include <linux/kernel.h>
  8#include <linux/module.h>
  9#include <linux/slab.h>
 10#include <linux/sizes.h>
 11#include <linux/uaccess.h>
 12#include <linux/greybus.h>
 13
 14struct gb_log {
 15	struct gb_connection *connection;
 16};
 17
 18static int gb_log_request_handler(struct gb_operation *op)
 19{
 20	struct gb_connection *connection = op->connection;
 21	struct device *dev = &connection->bundle->dev;
 22	struct gb_log_send_log_request *receive;
 23	u16 len;
 24
 25	if (op->type != GB_LOG_TYPE_SEND_LOG) {
 26		dev_err(dev, "unknown request type 0x%02x\n", op->type);
 27		return -EINVAL;
 28	}
 29
 30	/* Verify size of payload */
 31	if (op->request->payload_size < sizeof(*receive)) {
 32		dev_err(dev, "log request too small (%zu < %zu)\n",
 33			op->request->payload_size, sizeof(*receive));
 34		return -EINVAL;
 35	}
 36	receive = op->request->payload;
 37	len = le16_to_cpu(receive->len);
 38	if (len != (op->request->payload_size - sizeof(*receive))) {
 39		dev_err(dev, "log request wrong size %d vs %zu\n", len,
 40			(op->request->payload_size - sizeof(*receive)));
 41		return -EINVAL;
 42	}
 43	if (len == 0) {
 44		dev_err(dev, "log request of 0 bytes?\n");
 45		return -EINVAL;
 46	}
 47
 48	if (len > GB_LOG_MAX_LEN) {
 49		dev_err(dev, "log request too big: %d\n", len);
 50		return -EINVAL;
 51	}
 52
 53	/* Ensure the buffer is 0 terminated */
 54	receive->msg[len - 1] = '\0';
 55
 56	/*
 57	 * Print with dev_dbg() so that it can be easily turned off using
 58	 * dynamic debugging (and prevent any DoS)
 59	 */
 60	dev_dbg(dev, "%s", receive->msg);
 61
 62	return 0;
 63}
 64
 65static int gb_log_probe(struct gb_bundle *bundle,
 66			const struct greybus_bundle_id *id)
 67{
 68	struct greybus_descriptor_cport *cport_desc;
 69	struct gb_connection *connection;
 70	struct gb_log *log;
 71	int retval;
 72
 73	if (bundle->num_cports != 1)
 74		return -ENODEV;
 75
 76	cport_desc = &bundle->cport_desc[0];
 77	if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
 78		return -ENODEV;
 79
 80	log = kzalloc(sizeof(*log), GFP_KERNEL);
 81	if (!log)
 82		return -ENOMEM;
 83
 84	connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
 85					  gb_log_request_handler);
 86	if (IS_ERR(connection)) {
 87		retval = PTR_ERR(connection);
 88		goto error_free;
 89	}
 90
 91	log->connection = connection;
 92	greybus_set_drvdata(bundle, log);
 93
 94	retval = gb_connection_enable(connection);
 95	if (retval)
 96		goto error_connection_destroy;
 97
 98	return 0;
 99
100error_connection_destroy:
101	gb_connection_destroy(connection);
102error_free:
103	kfree(log);
104	return retval;
105}
106
107static void gb_log_disconnect(struct gb_bundle *bundle)
108{
109	struct gb_log *log = greybus_get_drvdata(bundle);
110	struct gb_connection *connection = log->connection;
111
112	gb_connection_disable(connection);
113	gb_connection_destroy(connection);
114
115	kfree(log);
116}
117
118static const struct greybus_bundle_id gb_log_id_table[] = {
119	{ GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
120	{ }
121};
122MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
123
124static struct greybus_driver gb_log_driver = {
125	.name           = "log",
126	.probe          = gb_log_probe,
127	.disconnect     = gb_log_disconnect,
128	.id_table       = gb_log_id_table,
129};
130module_greybus_driver(gb_log_driver);
131
132MODULE_LICENSE("GPL v2");