1 /*
2 * Greybus driver for the log protocol
3 *
4 * Copyright 2016 Google Inc.
5 *
6 * Released under the GPLv2 only.
7 */
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/sizes.h>
12 #include <linux/uaccess.h>
13
14 #include "greybus.h"
15
16 struct gb_log {
17 struct gb_connection *connection;
18 };
19
gb_log_request_handler(struct gb_operation * op)20 static int gb_log_request_handler(struct gb_operation *op)
21 {
22 struct gb_connection *connection = op->connection;
23 struct device *dev = &connection->bundle->dev;
24 struct gb_log_send_log_request *receive;
25 u16 len;
26
27 if (op->type != GB_LOG_TYPE_SEND_LOG) {
28 dev_err(dev, "unknown request type 0x%02x\n", op->type);
29 return -EINVAL;
30 }
31
32 /* Verify size of payload */
33 if (op->request->payload_size < sizeof(*receive)) {
34 dev_err(dev, "log request too small (%zu < %zu)\n",
35 op->request->payload_size, sizeof(*receive));
36 return -EINVAL;
37 }
38 receive = op->request->payload;
39 len = le16_to_cpu(receive->len);
40 if (len != (op->request->payload_size - sizeof(*receive))) {
41 dev_err(dev, "log request wrong size %d vs %zu\n", len,
42 (op->request->payload_size - sizeof(*receive)));
43 return -EINVAL;
44 }
45 if (len == 0) {
46 dev_err(dev, "log request of 0 bytes?\n");
47 return -EINVAL;
48 }
49
50 if (len > GB_LOG_MAX_LEN) {
51 dev_err(dev, "log request too big: %d\n", len);
52 return -EINVAL;
53 }
54
55 /* Ensure the buffer is 0 terminated */
56 receive->msg[len - 1] = '\0';
57
58 /*
59 * Print with dev_dbg() so that it can be easily turned off using
60 * dynamic debugging (and prevent any DoS)
61 */
62 dev_dbg(dev, "%s", receive->msg);
63
64 return 0;
65 }
66
gb_log_probe(struct gb_bundle * bundle,const struct greybus_bundle_id * id)67 static int gb_log_probe(struct gb_bundle *bundle,
68 const struct greybus_bundle_id *id)
69 {
70 struct greybus_descriptor_cport *cport_desc;
71 struct gb_connection *connection;
72 struct gb_log *log;
73 int retval;
74
75 if (bundle->num_cports != 1)
76 return -ENODEV;
77
78 cport_desc = &bundle->cport_desc[0];
79 if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
80 return -ENODEV;
81
82 log = kzalloc(sizeof(*log), GFP_KERNEL);
83 if (!log)
84 return -ENOMEM;
85
86 connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
87 gb_log_request_handler);
88 if (IS_ERR(connection)) {
89 retval = PTR_ERR(connection);
90 goto error_free;
91 }
92
93 log->connection = connection;
94 greybus_set_drvdata(bundle, log);
95
96 retval = gb_connection_enable(connection);
97 if (retval)
98 goto error_connection_destroy;
99
100 return 0;
101
102 error_connection_destroy:
103 gb_connection_destroy(connection);
104 error_free:
105 kfree(log);
106 return retval;
107 }
108
gb_log_disconnect(struct gb_bundle * bundle)109 static void gb_log_disconnect(struct gb_bundle *bundle)
110 {
111 struct gb_log *log = greybus_get_drvdata(bundle);
112 struct gb_connection *connection = log->connection;
113
114 gb_connection_disable(connection);
115 gb_connection_destroy(connection);
116
117 kfree(log);
118 }
119
120 static const struct greybus_bundle_id gb_log_id_table[] = {
121 { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
122 { }
123 };
124 MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
125
126 static struct greybus_driver gb_log_driver = {
127 .name = "log",
128 .probe = gb_log_probe,
129 .disconnect = gb_log_disconnect,
130 .id_table = gb_log_id_table,
131 };
132 module_greybus_driver(gb_log_driver);
133
134 MODULE_LICENSE("GPL v2");
135