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
14 struct gb_log {
15 struct gb_connection *connection;
16 };
17
gb_log_request_handler(struct gb_operation * op)18 static 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
gb_log_probe(struct gb_bundle * bundle,const struct greybus_bundle_id * id)65 static 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
100 error_connection_destroy:
101 gb_connection_destroy(connection);
102 error_free:
103 kfree(log);
104 return retval;
105 }
106
gb_log_disconnect(struct gb_bundle * bundle)107 static 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
118 static const struct greybus_bundle_id gb_log_id_table[] = {
119 { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
120 { }
121 };
122 MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
123
124 static 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 };
130 module_greybus_driver(gb_log_driver);
131
132 MODULE_LICENSE("GPL v2");
133
