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
13 #include "greybus.h"
14
15 struct gb_log {
16 struct gb_connection *connection;
17 };
18
gb_log_request_handler(struct gb_operation * op)19 static int gb_log_request_handler(struct gb_operation *op)
20 {
21 struct gb_connection *connection = op->connection;
22 struct device *dev = &connection->bundle->dev;
23 struct gb_log_send_log_request *receive;
24 u16 len;
25
26 if (op->type != GB_LOG_TYPE_SEND_LOG) {
27 dev_err(dev, "unknown request type 0x%02x\n", op->type);
28 return -EINVAL;
29 }
30
31 /* Verify size of payload */
32 if (op->request->payload_size < sizeof(*receive)) {
33 dev_err(dev, "log request too small (%zu < %zu)\n",
34 op->request->payload_size, sizeof(*receive));
35 return -EINVAL;
36 }
37 receive = op->request->payload;
38 len = le16_to_cpu(receive->len);
39 if (len != (op->request->payload_size - sizeof(*receive))) {
40 dev_err(dev, "log request wrong size %d vs %zu\n", len,
41 (op->request->payload_size - sizeof(*receive)));
42 return -EINVAL;
43 }
44 if (len == 0) {
45 dev_err(dev, "log request of 0 bytes?\n");
46 return -EINVAL;
47 }
48
49 if (len > GB_LOG_MAX_LEN) {
50 dev_err(dev, "log request too big: %d\n", len);
51 return -EINVAL;
52 }
53
54 /* Ensure the buffer is 0 terminated */
55 receive->msg[len - 1] = '\0';
56
57 /*
58 * Print with dev_dbg() so that it can be easily turned off using
59 * dynamic debugging (and prevent any DoS)
60 */
61 dev_dbg(dev, "%s", receive->msg);
62
63 return 0;
64 }
65
gb_log_probe(struct gb_bundle * bundle,const struct greybus_bundle_id * id)66 static int gb_log_probe(struct gb_bundle *bundle,
67 const struct greybus_bundle_id *id)
68 {
69 struct greybus_descriptor_cport *cport_desc;
70 struct gb_connection *connection;
71 struct gb_log *log;
72 int retval;
73
74 if (bundle->num_cports != 1)
75 return -ENODEV;
76
77 cport_desc = &bundle->cport_desc[0];
78 if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
79 return -ENODEV;
80
81 log = kzalloc(sizeof(*log), GFP_KERNEL);
82 if (!log)
83 return -ENOMEM;
84
85 connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
86 gb_log_request_handler);
87 if (IS_ERR(connection)) {
88 retval = PTR_ERR(connection);
89 goto error_free;
90 }
91
92 log->connection = connection;
93 greybus_set_drvdata(bundle, log);
94
95 retval = gb_connection_enable(connection);
96 if (retval)
97 goto error_connection_destroy;
98
99 return 0;
100
101 error_connection_destroy:
102 gb_connection_destroy(connection);
103 error_free:
104 kfree(log);
105 return retval;
106 }
107
gb_log_disconnect(struct gb_bundle * bundle)108 static void gb_log_disconnect(struct gb_bundle *bundle)
109 {
110 struct gb_log *log = greybus_get_drvdata(bundle);
111 struct gb_connection *connection = log->connection;
112
113 gb_connection_disable(connection);
114 gb_connection_destroy(connection);
115
116 kfree(log);
117 }
118
119 static const struct greybus_bundle_id gb_log_id_table[] = {
120 { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
121 { }
122 };
123 MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
124
125 static struct greybus_driver gb_log_driver = {
126 .name = "log",
127 .probe = gb_log_probe,
128 .disconnect = gb_log_disconnect,
129 .id_table = gb_log_id_table,
130 };
131 module_greybus_driver(gb_log_driver);
132
133 MODULE_LICENSE("GPL v2");
134
