1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Greybus driver for the Raw protocol
4 *
5 * Copyright 2015 Google Inc.
6 * Copyright 2015 Linaro Ltd.
7 */
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/slab.h>
11#include <linux/sizes.h>
12#include <linux/cdev.h>
13#include <linux/fs.h>
14#include <linux/idr.h>
15#include <linux/uaccess.h>
16#include <linux/greybus.h>
17
18struct gb_raw {
19 struct gb_connection *connection;
20
21 struct list_head list;
22 int list_data;
23 struct mutex list_lock;
24 dev_t dev;
25 struct cdev cdev;
26 struct device *device;
27};
28
29struct raw_data {
30 struct list_head entry;
31 u32 len;
32 u8 data[] __counted_by(len);
33};
34
35static const struct class raw_class = {
36 .name = "gb_raw",
37};
38
39static int raw_major;
40static const struct file_operations raw_fops;
41static DEFINE_IDA(minors);
42
43/* Number of minor devices this driver supports */
44#define NUM_MINORS 256
45
46/* Maximum size of any one send data buffer we support */
47#define MAX_PACKET_SIZE (PAGE_SIZE * 2)
48
49/*
50 * Maximum size of the data in the receive buffer we allow before we start to
51 * drop messages on the floor
52 */
53#define MAX_DATA_SIZE (MAX_PACKET_SIZE * 8)
54
55/*
56 * Add the raw data message to the list of received messages.
57 */
58static int receive_data(struct gb_raw *raw, u32 len, u8 *data)
59{
60 struct raw_data *raw_data;
61 struct device *dev = &raw->connection->bundle->dev;
62 int retval = 0;
63
64 if (len > MAX_PACKET_SIZE) {
65 dev_err(dev, "Too big of a data packet, rejected\n");
66 return -EINVAL;
67 }
68
69 mutex_lock(&raw->list_lock);
70 if ((raw->list_data + len) > MAX_DATA_SIZE) {
71 dev_err(dev, "Too much data in receive buffer, now dropping packets\n");
72 retval = -EINVAL;
73 goto exit;
74 }
75
76 raw_data = kmalloc(struct_size(raw_data, data, len), GFP_KERNEL);
77 if (!raw_data) {
78 retval = -ENOMEM;
79 goto exit;
80 }
81
82 raw->list_data += len;
83 raw_data->len = len;
84 memcpy(&raw_data->data[0], data, len);
85
86 list_add_tail(new: &raw_data->entry, head: &raw->list);
87exit:
88 mutex_unlock(lock: &raw->list_lock);
89 return retval;
90}
91
92static int gb_raw_request_handler(struct gb_operation *op)
93{
94 struct gb_connection *connection = op->connection;
95 struct device *dev = &connection->bundle->dev;
96 struct gb_raw *raw = greybus_get_drvdata(bundle: connection->bundle);
97 struct gb_raw_send_request *receive;
98 u32 len;
99
100 if (op->type != GB_RAW_TYPE_SEND) {
101 dev_err(dev, "unknown request type 0x%02x\n", op->type);
102 return -EINVAL;
103 }
104
105 /* Verify size of payload */
106 if (op->request->payload_size < sizeof(*receive)) {
107 dev_err(dev, "raw receive request too small (%zu < %zu)\n",
108 op->request->payload_size, sizeof(*receive));
109 return -EINVAL;
110 }
111 receive = op->request->payload;
112 len = le32_to_cpu(receive->len);
113 if (len != (int)(op->request->payload_size - sizeof(__le32))) {
114 dev_err(dev, "raw receive request wrong size %d vs %d\n", len,
115 (int)(op->request->payload_size - sizeof(__le32)));
116 return -EINVAL;
117 }
118 if (len == 0) {
119 dev_err(dev, "raw receive request of 0 bytes?\n");
120 return -EINVAL;
121 }
122
123 return receive_data(raw, len, data: receive->data);
124}
125
126static int gb_raw_send(struct gb_raw *raw, u32 len, const char __user *data)
127{
128 struct gb_connection *connection = raw->connection;
129 struct gb_raw_send_request *request;
130 int retval;
131
132 request = kmalloc(size: len + sizeof(*request), GFP_KERNEL);
133 if (!request)
134 return -ENOMEM;
135
136 if (copy_from_user(to: &request->data[0], from: data, n: len)) {
137 kfree(objp: request);
138 return -EFAULT;
139 }
140
141 request->len = cpu_to_le32(len);
142
143 retval = gb_operation_sync(connection, GB_RAW_TYPE_SEND,
144 request, request_size: len + sizeof(*request),
145 NULL, response_size: 0);
146
147 kfree(objp: request);
148 return retval;
149}
150
151static int gb_raw_probe(struct gb_bundle *bundle,
152 const struct greybus_bundle_id *id)
153{
154 struct greybus_descriptor_cport *cport_desc;
155 struct gb_connection *connection;
156 struct gb_raw *raw;
157 int retval;
158 int minor;
159
160 if (bundle->num_cports != 1)
161 return -ENODEV;
162
163 cport_desc = &bundle->cport_desc[0];
164 if (cport_desc->protocol_id != GREYBUS_PROTOCOL_RAW)
165 return -ENODEV;
166
167 raw = kzalloc(size: sizeof(*raw), GFP_KERNEL);
168 if (!raw)
169 return -ENOMEM;
170
171 connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
172 handler: gb_raw_request_handler);
173 if (IS_ERR(ptr: connection)) {
174 retval = PTR_ERR(ptr: connection);
175 goto error_free;
176 }
177
178 INIT_LIST_HEAD(list: &raw->list);
179 mutex_init(&raw->list_lock);
180
181 raw->connection = connection;
182 greybus_set_drvdata(bundle, data: raw);
183
184 minor = ida_alloc(ida: &minors, GFP_KERNEL);
185 if (minor < 0) {
186 retval = minor;
187 goto error_connection_destroy;
188 }
189
190 raw->dev = MKDEV(raw_major, minor);
191 cdev_init(&raw->cdev, &raw_fops);
192
193 retval = gb_connection_enable(connection);
194 if (retval)
195 goto error_remove_ida;
196
197 retval = cdev_add(&raw->cdev, raw->dev, 1);
198 if (retval)
199 goto error_connection_disable;
200
201 raw->device = device_create(cls: &raw_class, parent: &connection->bundle->dev,
202 devt: raw->dev, drvdata: raw, fmt: "gb!raw%d", minor);
203 if (IS_ERR(ptr: raw->device)) {
204 retval = PTR_ERR(ptr: raw->device);
205 goto error_del_cdev;
206 }
207
208 return 0;
209
210error_del_cdev:
211 cdev_del(&raw->cdev);
212
213error_connection_disable:
214 gb_connection_disable(connection);
215
216error_remove_ida:
217 ida_free(&minors, id: minor);
218
219error_connection_destroy:
220 gb_connection_destroy(connection);
221
222error_free:
223 kfree(objp: raw);
224 return retval;
225}
226
227static void gb_raw_disconnect(struct gb_bundle *bundle)
228{
229 struct gb_raw *raw = greybus_get_drvdata(bundle);
230 struct gb_connection *connection = raw->connection;
231 struct raw_data *raw_data;
232 struct raw_data *temp;
233
234 // FIXME - handle removing a connection when the char device node is open.
235 device_destroy(cls: &raw_class, devt: raw->dev);
236 cdev_del(&raw->cdev);
237 gb_connection_disable(connection);
238 ida_free(&minors, MINOR(raw->dev));
239 gb_connection_destroy(connection);
240
241 mutex_lock(&raw->list_lock);
242 list_for_each_entry_safe(raw_data, temp, &raw->list, entry) {
243 list_del(entry: &raw_data->entry);
244 kfree(objp: raw_data);
245 }
246 mutex_unlock(lock: &raw->list_lock);
247
248 kfree(objp: raw);
249}
250
251/*
252 * Character device node interfaces.
253 *
254 * Note, we are using read/write to only allow a single read/write per message.
255 * This means for read(), you have to provide a big enough buffer for the full
256 * message to be copied into. If the buffer isn't big enough, the read() will
257 * fail with -ENOSPC.
258 */
259
260static int raw_open(struct inode *inode, struct file *file)
261{
262 struct cdev *cdev = inode->i_cdev;
263 struct gb_raw *raw = container_of(cdev, struct gb_raw, cdev);
264
265 file->private_data = raw;
266 return 0;
267}
268
269static ssize_t raw_write(struct file *file, const char __user *buf,
270 size_t count, loff_t *ppos)
271{
272 struct gb_raw *raw = file->private_data;
273 int retval;
274
275 if (!count)
276 return 0;
277
278 if (count > MAX_PACKET_SIZE)
279 return -E2BIG;
280
281 retval = gb_raw_send(raw, len: count, data: buf);
282 if (retval)
283 return retval;
284
285 return count;
286}
287
288static ssize_t raw_read(struct file *file, char __user *buf, size_t count,
289 loff_t *ppos)
290{
291 struct gb_raw *raw = file->private_data;
292 int retval = 0;
293 struct raw_data *raw_data;
294
295 mutex_lock(&raw->list_lock);
296 if (list_empty(head: &raw->list))
297 goto exit;
298
299 raw_data = list_first_entry(&raw->list, struct raw_data, entry);
300 if (raw_data->len > count) {
301 retval = -ENOSPC;
302 goto exit;
303 }
304
305 if (copy_to_user(to: buf, from: &raw_data->data[0], n: raw_data->len)) {
306 retval = -EFAULT;
307 goto exit;
308 }
309
310 list_del(entry: &raw_data->entry);
311 raw->list_data -= raw_data->len;
312 retval = raw_data->len;
313 kfree(objp: raw_data);
314
315exit:
316 mutex_unlock(lock: &raw->list_lock);
317 return retval;
318}
319
320static const struct file_operations raw_fops = {
321 .owner = THIS_MODULE,
322 .write = raw_write,
323 .read = raw_read,
324 .open = raw_open,
325 .llseek = noop_llseek,
326};
327
328static const struct greybus_bundle_id gb_raw_id_table[] = {
329 { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_RAW) },
330 { }
331};
332MODULE_DEVICE_TABLE(greybus, gb_raw_id_table);
333
334static struct greybus_driver gb_raw_driver = {
335 .name = "raw",
336 .probe = gb_raw_probe,
337 .disconnect = gb_raw_disconnect,
338 .id_table = gb_raw_id_table,
339};
340
341static int raw_init(void)
342{
343 dev_t dev;
344 int retval;
345
346 retval = class_register(class: &raw_class);
347 if (retval)
348 goto error_class;
349
350 retval = alloc_chrdev_region(&dev, 0, NUM_MINORS, "gb_raw");
351 if (retval < 0)
352 goto error_chrdev;
353
354 raw_major = MAJOR(dev);
355
356 retval = greybus_register(&gb_raw_driver);
357 if (retval)
358 goto error_gb;
359
360 return 0;
361
362error_gb:
363 unregister_chrdev_region(dev, NUM_MINORS);
364error_chrdev:
365 class_unregister(class: &raw_class);
366error_class:
367 return retval;
368}
369module_init(raw_init);
370
371static void __exit raw_exit(void)
372{
373 greybus_deregister(&gb_raw_driver);
374 unregister_chrdev_region(MKDEV(raw_major, 0), NUM_MINORS);
375 class_unregister(class: &raw_class);
376 ida_destroy(ida: &minors);
377}
378module_exit(raw_exit);
379
380MODULE_LICENSE("GPL v2");
381

source code of linux/drivers/staging/greybus/raw.c