1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * f_subset.c -- "CDC Subset" Ethernet link function driver
4 *
5 * Copyright (C) 2003-2005,2008 David Brownell
6 * Copyright (C) 2008 Nokia Corporation
7 */
8
9 #include <linux/slab.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/etherdevice.h>
14
15 #include "u_ether.h"
16 #include "u_ether_configfs.h"
17 #include "u_gether.h"
18
19 /*
20 * This function packages a simple "CDC Subset" Ethernet port with no real
21 * control mechanisms; just raw data transfer over two bulk endpoints.
22 * The data transfer model is exactly that of CDC Ethernet, which is
23 * why we call it the "CDC Subset".
24 *
25 * Because it's not standardized, this has some interoperability issues.
26 * They mostly relate to driver binding, since the data transfer model is
27 * so simple (CDC Ethernet). The original versions of this protocol used
28 * specific product/vendor IDs: byteswapped IDs for Digital Equipment's
29 * SA-1100 "Itsy" board, which could run Linux 2.4 kernels and supported
30 * daughtercards with USB peripheral connectors. (It was used more often
31 * with other boards, using the Itsy identifiers.) Linux hosts recognized
32 * this with CONFIG_USB_ARMLINUX; these devices have only one configuration
33 * and one interface.
34 *
35 * At some point, MCCI defined a (nonconformant) CDC MDLM variant called
36 * "SAFE", which happens to have a mode which is identical to the "CDC
37 * Subset" in terms of data transfer and lack of control model. This was
38 * adopted by later Sharp Zaurus models, and by some other software which
39 * Linux hosts recognize with CONFIG_USB_NET_ZAURUS.
40 *
41 * Because Microsoft's RNDIS drivers are far from robust, we added a few
42 * descriptors to the CDC Subset code, making this code look like a SAFE
43 * implementation. This lets you use MCCI's host side MS-Windows drivers
44 * if you get fed up with RNDIS. It also makes it easier for composite
45 * drivers to work, since they can use class based binding instead of
46 * caring about specific product and vendor IDs.
47 */
48
49 struct f_gether {
50 struct gether port;
51
52 char ethaddr[14];
53 };
54
func_to_geth(struct usb_function * f)55 static inline struct f_gether *func_to_geth(struct usb_function *f)
56 {
57 return container_of(f, struct f_gether, port.func);
58 }
59
60 /*-------------------------------------------------------------------------*/
61
62 /*
63 * "Simple" CDC-subset option is a simple vendor-neutral model that most
64 * full speed controllers can handle: one interface, two bulk endpoints.
65 * To assist host side drivers, we fancy it up a bit, and add descriptors so
66 * some host side drivers will understand it as a "SAFE" variant.
67 *
68 * "SAFE" loosely follows CDC WMC MDLM, violating the spec in various ways.
69 * Data endpoints live in the control interface, there's no data interface.
70 * And it's not used to talk to a cell phone radio.
71 */
72
73 /* interface descriptor: */
74
75 static struct usb_interface_descriptor subset_data_intf = {
76 .bLength = sizeof subset_data_intf,
77 .bDescriptorType = USB_DT_INTERFACE,
78
79 /* .bInterfaceNumber = DYNAMIC */
80 .bAlternateSetting = 0,
81 .bNumEndpoints = 2,
82 .bInterfaceClass = USB_CLASS_COMM,
83 .bInterfaceSubClass = USB_CDC_SUBCLASS_MDLM,
84 .bInterfaceProtocol = 0,
85 /* .iInterface = DYNAMIC */
86 };
87
88 static struct usb_cdc_header_desc mdlm_header_desc = {
89 .bLength = sizeof mdlm_header_desc,
90 .bDescriptorType = USB_DT_CS_INTERFACE,
91 .bDescriptorSubType = USB_CDC_HEADER_TYPE,
92
93 .bcdCDC = cpu_to_le16(0x0110),
94 };
95
96 static struct usb_cdc_mdlm_desc mdlm_desc = {
97 .bLength = sizeof mdlm_desc,
98 .bDescriptorType = USB_DT_CS_INTERFACE,
99 .bDescriptorSubType = USB_CDC_MDLM_TYPE,
100
101 .bcdVersion = cpu_to_le16(0x0100),
102 .bGUID = {
103 0x5d, 0x34, 0xcf, 0x66, 0x11, 0x18, 0x11, 0xd6,
104 0xa2, 0x1a, 0x00, 0x01, 0x02, 0xca, 0x9a, 0x7f,
105 },
106 };
107
108 /* since "usb_cdc_mdlm_detail_desc" is a variable length structure, we
109 * can't really use its struct. All we do here is say that we're using
110 * the submode of "SAFE" which directly matches the CDC Subset.
111 */
112 static u8 mdlm_detail_desc[] = {
113 6,
114 USB_DT_CS_INTERFACE,
115 USB_CDC_MDLM_DETAIL_TYPE,
116
117 0, /* "SAFE" */
118 0, /* network control capabilities (none) */
119 0, /* network data capabilities ("raw" encapsulation) */
120 };
121
122 static struct usb_cdc_ether_desc ether_desc = {
123 .bLength = sizeof ether_desc,
124 .bDescriptorType = USB_DT_CS_INTERFACE,
125 .bDescriptorSubType = USB_CDC_ETHERNET_TYPE,
126
127 /* this descriptor actually adds value, surprise! */
128 /* .iMACAddress = DYNAMIC */
129 .bmEthernetStatistics = cpu_to_le32(0), /* no statistics */
130 .wMaxSegmentSize = cpu_to_le16(ETH_FRAME_LEN),
131 .wNumberMCFilters = cpu_to_le16(0),
132 .bNumberPowerFilters = 0,
133 };
134
135 /* full speed support: */
136
137 static struct usb_endpoint_descriptor fs_subset_in_desc = {
138 .bLength = USB_DT_ENDPOINT_SIZE,
139 .bDescriptorType = USB_DT_ENDPOINT,
140
141 .bEndpointAddress = USB_DIR_IN,
142 .bmAttributes = USB_ENDPOINT_XFER_BULK,
143 };
144
145 static struct usb_endpoint_descriptor fs_subset_out_desc = {
146 .bLength = USB_DT_ENDPOINT_SIZE,
147 .bDescriptorType = USB_DT_ENDPOINT,
148
149 .bEndpointAddress = USB_DIR_OUT,
150 .bmAttributes = USB_ENDPOINT_XFER_BULK,
151 };
152
153 static struct usb_descriptor_header *fs_eth_function[] = {
154 (struct usb_descriptor_header *) &subset_data_intf,
155 (struct usb_descriptor_header *) &mdlm_header_desc,
156 (struct usb_descriptor_header *) &mdlm_desc,
157 (struct usb_descriptor_header *) &mdlm_detail_desc,
158 (struct usb_descriptor_header *) ðer_desc,
159 (struct usb_descriptor_header *) &fs_subset_in_desc,
160 (struct usb_descriptor_header *) &fs_subset_out_desc,
161 NULL,
162 };
163
164 /* high speed support: */
165
166 static struct usb_endpoint_descriptor hs_subset_in_desc = {
167 .bLength = USB_DT_ENDPOINT_SIZE,
168 .bDescriptorType = USB_DT_ENDPOINT,
169
170 .bmAttributes = USB_ENDPOINT_XFER_BULK,
171 .wMaxPacketSize = cpu_to_le16(512),
172 };
173
174 static struct usb_endpoint_descriptor hs_subset_out_desc = {
175 .bLength = USB_DT_ENDPOINT_SIZE,
176 .bDescriptorType = USB_DT_ENDPOINT,
177
178 .bmAttributes = USB_ENDPOINT_XFER_BULK,
179 .wMaxPacketSize = cpu_to_le16(512),
180 };
181
182 static struct usb_descriptor_header *hs_eth_function[] = {
183 (struct usb_descriptor_header *) &subset_data_intf,
184 (struct usb_descriptor_header *) &mdlm_header_desc,
185 (struct usb_descriptor_header *) &mdlm_desc,
186 (struct usb_descriptor_header *) &mdlm_detail_desc,
187 (struct usb_descriptor_header *) ðer_desc,
188 (struct usb_descriptor_header *) &hs_subset_in_desc,
189 (struct usb_descriptor_header *) &hs_subset_out_desc,
190 NULL,
191 };
192
193 /* super speed support: */
194
195 static struct usb_endpoint_descriptor ss_subset_in_desc = {
196 .bLength = USB_DT_ENDPOINT_SIZE,
197 .bDescriptorType = USB_DT_ENDPOINT,
198
199 .bmAttributes = USB_ENDPOINT_XFER_BULK,
200 .wMaxPacketSize = cpu_to_le16(1024),
201 };
202
203 static struct usb_endpoint_descriptor ss_subset_out_desc = {
204 .bLength = USB_DT_ENDPOINT_SIZE,
205 .bDescriptorType = USB_DT_ENDPOINT,
206
207 .bmAttributes = USB_ENDPOINT_XFER_BULK,
208 .wMaxPacketSize = cpu_to_le16(1024),
209 };
210
211 static struct usb_ss_ep_comp_descriptor ss_subset_bulk_comp_desc = {
212 .bLength = sizeof ss_subset_bulk_comp_desc,
213 .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
214
215 /* the following 2 values can be tweaked if necessary */
216 /* .bMaxBurst = 0, */
217 /* .bmAttributes = 0, */
218 };
219
220 static struct usb_descriptor_header *ss_eth_function[] = {
221 (struct usb_descriptor_header *) &subset_data_intf,
222 (struct usb_descriptor_header *) &mdlm_header_desc,
223 (struct usb_descriptor_header *) &mdlm_desc,
224 (struct usb_descriptor_header *) &mdlm_detail_desc,
225 (struct usb_descriptor_header *) ðer_desc,
226 (struct usb_descriptor_header *) &ss_subset_in_desc,
227 (struct usb_descriptor_header *) &ss_subset_bulk_comp_desc,
228 (struct usb_descriptor_header *) &ss_subset_out_desc,
229 (struct usb_descriptor_header *) &ss_subset_bulk_comp_desc,
230 NULL,
231 };
232
233 /* string descriptors: */
234
235 static struct usb_string geth_string_defs[] = {
236 [0].s = "CDC Ethernet Subset/SAFE",
237 [1].s = "",
238 { } /* end of list */
239 };
240
241 static struct usb_gadget_strings geth_string_table = {
242 .language = 0x0409, /* en-us */
243 .strings = geth_string_defs,
244 };
245
246 static struct usb_gadget_strings *geth_strings[] = {
247 &geth_string_table,
248 NULL,
249 };
250
251 /*-------------------------------------------------------------------------*/
252
geth_set_alt(struct usb_function * f,unsigned intf,unsigned alt)253 static int geth_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
254 {
255 struct f_gether *geth = func_to_geth(f);
256 struct usb_composite_dev *cdev = f->config->cdev;
257 struct net_device *net;
258
259 /* we know alt == 0, so this is an activation or a reset */
260
261 if (geth->port.in_ep->enabled) {
262 DBG(cdev, "reset cdc subset\n");
263 gether_disconnect(&geth->port);
264 }
265
266 DBG(cdev, "init + activate cdc subset\n");
267 if (config_ep_by_speed(cdev->gadget, f, geth->port.in_ep) ||
268 config_ep_by_speed(cdev->gadget, f, geth->port.out_ep)) {
269 geth->port.in_ep->desc = NULL;
270 geth->port.out_ep->desc = NULL;
271 return -EINVAL;
272 }
273
274 net = gether_connect(&geth->port);
275 return PTR_ERR_OR_ZERO(net);
276 }
277
geth_disable(struct usb_function * f)278 static void geth_disable(struct usb_function *f)
279 {
280 struct f_gether *geth = func_to_geth(f);
281 struct usb_composite_dev *cdev = f->config->cdev;
282
283 DBG(cdev, "net deactivated\n");
284 gether_disconnect(&geth->port);
285 }
286
287 /*-------------------------------------------------------------------------*/
288
289 /* serial function driver setup/binding */
290
291 static int
geth_bind(struct usb_configuration * c,struct usb_function * f)292 geth_bind(struct usb_configuration *c, struct usb_function *f)
293 {
294 struct usb_composite_dev *cdev = c->cdev;
295 struct f_gether *geth = func_to_geth(f);
296 struct usb_string *us;
297 int status;
298 struct usb_ep *ep;
299
300 struct f_gether_opts *gether_opts;
301
302 gether_opts = container_of(f->fi, struct f_gether_opts, func_inst);
303
304 /*
305 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
306 * configurations are bound in sequence with list_for_each_entry,
307 * in each configuration its functions are bound in sequence
308 * with list_for_each_entry, so we assume no race condition
309 * with regard to gether_opts->bound access
310 */
311 if (!gether_opts->bound) {
312 mutex_lock(&gether_opts->lock);
313 gether_set_gadget(gether_opts->net, cdev->gadget);
314 status = gether_register_netdev(gether_opts->net);
315 mutex_unlock(&gether_opts->lock);
316 if (status)
317 return status;
318 gether_opts->bound = true;
319 }
320
321 us = usb_gstrings_attach(cdev, geth_strings,
322 ARRAY_SIZE(geth_string_defs));
323 if (IS_ERR(us))
324 return PTR_ERR(us);
325
326 subset_data_intf.iInterface = us[0].id;
327 ether_desc.iMACAddress = us[1].id;
328
329 /* allocate instance-specific interface IDs */
330 status = usb_interface_id(c, f);
331 if (status < 0)
332 goto fail;
333 subset_data_intf.bInterfaceNumber = status;
334
335 status = -ENODEV;
336
337 /* allocate instance-specific endpoints */
338 ep = usb_ep_autoconfig(cdev->gadget, &fs_subset_in_desc);
339 if (!ep)
340 goto fail;
341 geth->port.in_ep = ep;
342
343 ep = usb_ep_autoconfig(cdev->gadget, &fs_subset_out_desc);
344 if (!ep)
345 goto fail;
346 geth->port.out_ep = ep;
347
348 /* support all relevant hardware speeds... we expect that when
349 * hardware is dual speed, all bulk-capable endpoints work at
350 * both speeds
351 */
352 hs_subset_in_desc.bEndpointAddress = fs_subset_in_desc.bEndpointAddress;
353 hs_subset_out_desc.bEndpointAddress =
354 fs_subset_out_desc.bEndpointAddress;
355
356 ss_subset_in_desc.bEndpointAddress = fs_subset_in_desc.bEndpointAddress;
357 ss_subset_out_desc.bEndpointAddress =
358 fs_subset_out_desc.bEndpointAddress;
359
360 status = usb_assign_descriptors(f, fs_eth_function, hs_eth_function,
361 ss_eth_function, ss_eth_function);
362 if (status)
363 goto fail;
364
365 /* NOTE: all that is done without knowing or caring about
366 * the network link ... which is unavailable to this code
367 * until we're activated via set_alt().
368 */
369
370 DBG(cdev, "CDC Subset: IN/%s OUT/%s\n",
371 geth->port.in_ep->name, geth->port.out_ep->name);
372 return 0;
373
374 fail:
375 ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
376
377 return status;
378 }
379
to_f_gether_opts(struct config_item * item)380 static inline struct f_gether_opts *to_f_gether_opts(struct config_item *item)
381 {
382 return container_of(to_config_group(item), struct f_gether_opts,
383 func_inst.group);
384 }
385
386 /* f_gether_item_ops */
387 USB_ETHERNET_CONFIGFS_ITEM(gether);
388
389 /* f_gether_opts_dev_addr */
390 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(gether);
391
392 /* f_gether_opts_host_addr */
393 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(gether);
394
395 /* f_gether_opts_qmult */
396 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(gether);
397
398 /* f_gether_opts_ifname */
399 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(gether);
400
401 static struct configfs_attribute *gether_attrs[] = {
402 &gether_opts_attr_dev_addr,
403 &gether_opts_attr_host_addr,
404 &gether_opts_attr_qmult,
405 &gether_opts_attr_ifname,
406 NULL,
407 };
408
409 static const struct config_item_type gether_func_type = {
410 .ct_item_ops = &gether_item_ops,
411 .ct_attrs = gether_attrs,
412 .ct_owner = THIS_MODULE,
413 };
414
geth_free_inst(struct usb_function_instance * f)415 static void geth_free_inst(struct usb_function_instance *f)
416 {
417 struct f_gether_opts *opts;
418
419 opts = container_of(f, struct f_gether_opts, func_inst);
420 if (opts->bound)
421 gether_cleanup(netdev_priv(opts->net));
422 else
423 free_netdev(opts->net);
424 kfree(opts);
425 }
426
geth_alloc_inst(void)427 static struct usb_function_instance *geth_alloc_inst(void)
428 {
429 struct f_gether_opts *opts;
430
431 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
432 if (!opts)
433 return ERR_PTR(-ENOMEM);
434 mutex_init(&opts->lock);
435 opts->func_inst.free_func_inst = geth_free_inst;
436 opts->net = gether_setup_default();
437 if (IS_ERR(opts->net)) {
438 struct net_device *net = opts->net;
439 kfree(opts);
440 return ERR_CAST(net);
441 }
442
443 config_group_init_type_name(&opts->func_inst.group, "",
444 &gether_func_type);
445
446 return &opts->func_inst;
447 }
448
geth_free(struct usb_function * f)449 static void geth_free(struct usb_function *f)
450 {
451 struct f_gether *eth;
452
453 eth = func_to_geth(f);
454 kfree(eth);
455 }
456
geth_unbind(struct usb_configuration * c,struct usb_function * f)457 static void geth_unbind(struct usb_configuration *c, struct usb_function *f)
458 {
459 geth_string_defs[0].id = 0;
460 usb_free_all_descriptors(f);
461 }
462
geth_alloc(struct usb_function_instance * fi)463 static struct usb_function *geth_alloc(struct usb_function_instance *fi)
464 {
465 struct f_gether *geth;
466 struct f_gether_opts *opts;
467 int status;
468
469 /* allocate and initialize one new instance */
470 geth = kzalloc(sizeof(*geth), GFP_KERNEL);
471 if (!geth)
472 return ERR_PTR(-ENOMEM);
473
474 opts = container_of(fi, struct f_gether_opts, func_inst);
475
476 mutex_lock(&opts->lock);
477 opts->refcnt++;
478 /* export host's Ethernet address in CDC format */
479 status = gether_get_host_addr_cdc(opts->net, geth->ethaddr,
480 sizeof(geth->ethaddr));
481 if (status < 12) {
482 kfree(geth);
483 mutex_unlock(&opts->lock);
484 return ERR_PTR(-EINVAL);
485 }
486 geth_string_defs[1].s = geth->ethaddr;
487
488 geth->port.ioport = netdev_priv(opts->net);
489 mutex_unlock(&opts->lock);
490 geth->port.cdc_filter = DEFAULT_FILTER;
491
492 geth->port.func.name = "cdc_subset";
493 geth->port.func.bind = geth_bind;
494 geth->port.func.unbind = geth_unbind;
495 geth->port.func.set_alt = geth_set_alt;
496 geth->port.func.disable = geth_disable;
497 geth->port.func.free_func = geth_free;
498
499 return &geth->port.func;
500 }
501
502 DECLARE_USB_FUNCTION_INIT(geth, geth_alloc_inst, geth_alloc);
503 MODULE_DESCRIPTION("\"CDC Subset\" Ethernet link function driver");
504 MODULE_LICENSE("GPL");
505 MODULE_AUTHOR("David Brownell");
506