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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/cleanup.h>
10#include <linux/slab.h>
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/device.h>
14#include <linux/etherdevice.h>
15
16#include "u_ether.h"
17#include "u_ether_configfs.h"
18#include "u_gether.h"
19
20/*
21 * This function packages a simple "CDC Subset" Ethernet port with no real
22 * control mechanisms; just raw data transfer over two bulk endpoints.
23 * The data transfer model is exactly that of CDC Ethernet, which is
24 * why we call it the "CDC Subset".
25 *
26 * Because it's not standardized, this has some interoperability issues.
27 * They mostly relate to driver binding, since the data transfer model is
28 * so simple (CDC Ethernet). The original versions of this protocol used
29 * specific product/vendor IDs: byteswapped IDs for Digital Equipment's
30 * SA-1100 "Itsy" board, which could run Linux 2.4 kernels and supported
31 * daughtercards with USB peripheral connectors. (It was used more often
32 * with other boards, using the Itsy identifiers.) Linux hosts recognized
33 * this with CONFIG_USB_ARMLINUX; these devices have only one configuration
34 * and one interface.
35 *
36 * At some point, MCCI defined a (nonconformant) CDC MDLM variant called
37 * "SAFE", which happens to have a mode which is identical to the "CDC
38 * Subset" in terms of data transfer and lack of control model. This was
39 * adopted by later Sharp Zaurus models, and by some other software which
40 * Linux hosts recognize with CONFIG_USB_NET_ZAURUS.
41 *
42 * Because Microsoft's RNDIS drivers are far from robust, we added a few
43 * descriptors to the CDC Subset code, making this code look like a SAFE
44 * implementation. This lets you use MCCI's host side MS-Windows drivers
45 * if you get fed up with RNDIS. It also makes it easier for composite
46 * drivers to work, since they can use class based binding instead of
47 * caring about specific product and vendor IDs.
48 */
49
50struct f_gether {
51 struct gether port;
52
53 char ethaddr[14];
54};
55
56static inline struct f_gether *func_to_geth(struct usb_function *f)
57{
58 return container_of(f, struct f_gether, port.func);
59}
60
61/*-------------------------------------------------------------------------*/
62
63/*
64 * "Simple" CDC-subset option is a simple vendor-neutral model that most
65 * full speed controllers can handle: one interface, two bulk endpoints.
66 * To assist host side drivers, we fancy it up a bit, and add descriptors so
67 * some host side drivers will understand it as a "SAFE" variant.
68 *
69 * "SAFE" loosely follows CDC WMC MDLM, violating the spec in various ways.
70 * Data endpoints live in the control interface, there's no data interface.
71 * And it's not used to talk to a cell phone radio.
72 */
73
74/* interface descriptor: */
75
76static struct usb_interface_descriptor subset_data_intf = {
77 .bLength = sizeof subset_data_intf,
78 .bDescriptorType = USB_DT_INTERFACE,
79
80 /* .bInterfaceNumber = DYNAMIC */
81 .bAlternateSetting = 0,
82 .bNumEndpoints = 2,
83 .bInterfaceClass = USB_CLASS_COMM,
84 .bInterfaceSubClass = USB_CDC_SUBCLASS_MDLM,
85 .bInterfaceProtocol = 0,
86 /* .iInterface = DYNAMIC */
87};
88
89static struct usb_cdc_header_desc mdlm_header_desc = {
90 .bLength = sizeof mdlm_header_desc,
91 .bDescriptorType = USB_DT_CS_INTERFACE,
92 .bDescriptorSubType = USB_CDC_HEADER_TYPE,
93
94 .bcdCDC = cpu_to_le16(0x0110),
95};
96
97static struct usb_cdc_mdlm_desc mdlm_desc = {
98 .bLength = sizeof mdlm_desc,
99 .bDescriptorType = USB_DT_CS_INTERFACE,
100 .bDescriptorSubType = USB_CDC_MDLM_TYPE,
101
102 .bcdVersion = cpu_to_le16(0x0100),
103 .bGUID = {
104 0x5d, 0x34, 0xcf, 0x66, 0x11, 0x18, 0x11, 0xd6,
105 0xa2, 0x1a, 0x00, 0x01, 0x02, 0xca, 0x9a, 0x7f,
106 },
107};
108
109/* since "usb_cdc_mdlm_detail_desc" is a variable length structure, we
110 * can't really use its struct. All we do here is say that we're using
111 * the submode of "SAFE" which directly matches the CDC Subset.
112 */
113static u8 mdlm_detail_desc[] = {
114 6,
115 USB_DT_CS_INTERFACE,
116 USB_CDC_MDLM_DETAIL_TYPE,
117
118 0, /* "SAFE" */
119 0, /* network control capabilities (none) */
120 0, /* network data capabilities ("raw" encapsulation) */
121};
122
123static struct usb_cdc_ether_desc ether_desc = {
124 .bLength = sizeof ether_desc,
125 .bDescriptorType = USB_DT_CS_INTERFACE,
126 .bDescriptorSubType = USB_CDC_ETHERNET_TYPE,
127
128 /* this descriptor actually adds value, surprise! */
129 /* .iMACAddress = DYNAMIC */
130 .bmEthernetStatistics = cpu_to_le32(0), /* no statistics */
131 .wMaxSegmentSize = cpu_to_le16(ETH_FRAME_LEN),
132 .wNumberMCFilters = cpu_to_le16(0),
133 .bNumberPowerFilters = 0,
134};
135
136/* full speed support: */
137
138static struct usb_endpoint_descriptor fs_subset_in_desc = {
139 .bLength = USB_DT_ENDPOINT_SIZE,
140 .bDescriptorType = USB_DT_ENDPOINT,
141
142 .bEndpointAddress = USB_DIR_IN,
143 .bmAttributes = USB_ENDPOINT_XFER_BULK,
144};
145
146static struct usb_endpoint_descriptor fs_subset_out_desc = {
147 .bLength = USB_DT_ENDPOINT_SIZE,
148 .bDescriptorType = USB_DT_ENDPOINT,
149
150 .bEndpointAddress = USB_DIR_OUT,
151 .bmAttributes = USB_ENDPOINT_XFER_BULK,
152};
153
154static struct usb_descriptor_header *fs_eth_function[] = {
155 (struct usb_descriptor_header *) &subset_data_intf,
156 (struct usb_descriptor_header *) &mdlm_header_desc,
157 (struct usb_descriptor_header *) &mdlm_desc,
158 (struct usb_descriptor_header *) &mdlm_detail_desc,
159 (struct usb_descriptor_header *) &ether_desc,
160 (struct usb_descriptor_header *) &fs_subset_in_desc,
161 (struct usb_descriptor_header *) &fs_subset_out_desc,
162 NULL,
163};
164
165/* high speed support: */
166
167static struct usb_endpoint_descriptor hs_subset_in_desc = {
168 .bLength = USB_DT_ENDPOINT_SIZE,
169 .bDescriptorType = USB_DT_ENDPOINT,
170
171 .bmAttributes = USB_ENDPOINT_XFER_BULK,
172 .wMaxPacketSize = cpu_to_le16(512),
173};
174
175static struct usb_endpoint_descriptor hs_subset_out_desc = {
176 .bLength = USB_DT_ENDPOINT_SIZE,
177 .bDescriptorType = USB_DT_ENDPOINT,
178
179 .bmAttributes = USB_ENDPOINT_XFER_BULK,
180 .wMaxPacketSize = cpu_to_le16(512),
181};
182
183static struct usb_descriptor_header *hs_eth_function[] = {
184 (struct usb_descriptor_header *) &subset_data_intf,
185 (struct usb_descriptor_header *) &mdlm_header_desc,
186 (struct usb_descriptor_header *) &mdlm_desc,
187 (struct usb_descriptor_header *) &mdlm_detail_desc,
188 (struct usb_descriptor_header *) &ether_desc,
189 (struct usb_descriptor_header *) &hs_subset_in_desc,
190 (struct usb_descriptor_header *) &hs_subset_out_desc,
191 NULL,
192};
193
194/* super speed support: */
195
196static struct usb_endpoint_descriptor ss_subset_in_desc = {
197 .bLength = USB_DT_ENDPOINT_SIZE,
198 .bDescriptorType = USB_DT_ENDPOINT,
199
200 .bmAttributes = USB_ENDPOINT_XFER_BULK,
201 .wMaxPacketSize = cpu_to_le16(1024),
202};
203
204static struct usb_endpoint_descriptor ss_subset_out_desc = {
205 .bLength = USB_DT_ENDPOINT_SIZE,
206 .bDescriptorType = USB_DT_ENDPOINT,
207
208 .bmAttributes = USB_ENDPOINT_XFER_BULK,
209 .wMaxPacketSize = cpu_to_le16(1024),
210};
211
212static struct usb_ss_ep_comp_descriptor ss_subset_bulk_comp_desc = {
213 .bLength = sizeof ss_subset_bulk_comp_desc,
214 .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
215
216 /* the following 2 values can be tweaked if necessary */
217 /* .bMaxBurst = 0, */
218 /* .bmAttributes = 0, */
219};
220
221static struct usb_descriptor_header *ss_eth_function[] = {
222 (struct usb_descriptor_header *) &subset_data_intf,
223 (struct usb_descriptor_header *) &mdlm_header_desc,
224 (struct usb_descriptor_header *) &mdlm_desc,
225 (struct usb_descriptor_header *) &mdlm_detail_desc,
226 (struct usb_descriptor_header *) &ether_desc,
227 (struct usb_descriptor_header *) &ss_subset_in_desc,
228 (struct usb_descriptor_header *) &ss_subset_bulk_comp_desc,
229 (struct usb_descriptor_header *) &ss_subset_out_desc,
230 (struct usb_descriptor_header *) &ss_subset_bulk_comp_desc,
231 NULL,
232};
233
234/* string descriptors: */
235
236static struct usb_string geth_string_defs[] = {
237 [0].s = "CDC Ethernet Subset/SAFE",
238 [1].s = "",
239 { } /* end of list */
240};
241
242static struct usb_gadget_strings geth_string_table = {
243 .language = 0x0409, /* en-us */
244 .strings = geth_string_defs,
245};
246
247static struct usb_gadget_strings *geth_strings[] = {
248 &geth_string_table,
249 NULL,
250};
251
252/*-------------------------------------------------------------------------*/
253
254static int geth_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
255{
256 struct f_gether *geth = func_to_geth(f);
257 struct usb_composite_dev *cdev = f->config->cdev;
258 struct net_device *net;
259
260 /* we know alt == 0, so this is an activation or a reset */
261
262 if (geth->port.in_ep->enabled) {
263 DBG(cdev, "reset cdc subset\n");
264 gether_disconnect(&geth->port);
265 }
266
267 DBG(cdev, "init + activate cdc subset\n");
268 if (config_ep_by_speed(cdev->gadget, f, geth->port.in_ep) ||
269 config_ep_by_speed(cdev->gadget, f, geth->port.out_ep)) {
270 geth->port.in_ep->desc = NULL;
271 geth->port.out_ep->desc = NULL;
272 return -EINVAL;
273 }
274
275 net = gether_connect(&geth->port);
276 return PTR_ERR_OR_ZERO(net);
277}
278
279static void geth_disable(struct usb_function *f)
280{
281 struct f_gether *geth = func_to_geth(f);
282 struct usb_composite_dev *cdev = f->config->cdev;
283
284 DBG(cdev, "net deactivated\n");
285 gether_disconnect(&geth->port);
286}
287
288/*-------------------------------------------------------------------------*/
289
290/* serial function driver setup/binding */
291
292static int
293geth_bind(struct usb_configuration *c, struct usb_function *f)
294{
295 struct usb_composite_dev *cdev = c->cdev;
296 struct f_gether *geth = func_to_geth(f);
297 struct usb_string *us;
298 int status;
299 struct usb_ep *ep;
300
301 struct f_gether_opts *gether_opts;
302 struct net_device *net __free(detach_gadget) = NULL;
303
304 gether_opts = container_of(f->fi, struct f_gether_opts, func_inst);
305
306 scoped_guard(mutex, &gether_opts->lock)
307 if (gether_opts->bind_count == 0 && !gether_opts->bound) {
308 if (!device_is_registered(&gether_opts->net->dev)) {
309 gether_set_gadget(gether_opts->net, cdev->gadget);
310 status = gether_register_netdev(gether_opts->net);
311 } else
312 status = gether_attach_gadget(gether_opts->net, cdev->gadget);
313
314 if (status)
315 return status;
316 net = gether_opts->net;
317 }
318
319 us = usb_gstrings_attach(cdev, geth_strings,
320 ARRAY_SIZE(geth_string_defs));
321 if (IS_ERR(us))
322 return PTR_ERR(us);
323
324 subset_data_intf.iInterface = us[0].id;
325 ether_desc.iMACAddress = us[1].id;
326
327 /* allocate instance-specific interface IDs */
328 status = usb_interface_id(c, f);
329 if (status < 0)
330 return status;
331 subset_data_intf.bInterfaceNumber = status;
332
333 /* allocate instance-specific endpoints */
334 ep = usb_ep_autoconfig(cdev->gadget, &fs_subset_in_desc);
335 if (!ep)
336 return -ENODEV;
337 geth->port.in_ep = ep;
338
339 ep = usb_ep_autoconfig(cdev->gadget, &fs_subset_out_desc);
340 if (!ep)
341 return -ENODEV;
342 geth->port.out_ep = ep;
343
344 /* support all relevant hardware speeds... we expect that when
345 * hardware is dual speed, all bulk-capable endpoints work at
346 * both speeds
347 */
348 hs_subset_in_desc.bEndpointAddress = fs_subset_in_desc.bEndpointAddress;
349 hs_subset_out_desc.bEndpointAddress =
350 fs_subset_out_desc.bEndpointAddress;
351
352 ss_subset_in_desc.bEndpointAddress = fs_subset_in_desc.bEndpointAddress;
353 ss_subset_out_desc.bEndpointAddress =
354 fs_subset_out_desc.bEndpointAddress;
355
356 status = usb_assign_descriptors(f, fs_eth_function, hs_eth_function,
357 ss_eth_function, ss_eth_function);
358 if (status)
359 return status;
360
361 /* NOTE: all that is done without knowing or caring about
362 * the network link ... which is unavailable to this code
363 * until we're activated via set_alt().
364 */
365
366 gether_opts->bind_count++;
367 retain_and_null_ptr(net);
368
369 DBG(cdev, "CDC Subset: IN/%s OUT/%s\n",
370 geth->port.in_ep->name, geth->port.out_ep->name);
371 return 0;
372}
373
374static inline struct f_gether_opts *to_f_gether_opts(struct config_item *item)
375{
376 return container_of(to_config_group(item), struct f_gether_opts,
377 func_inst.group);
378}
379
380/* f_gether_item_ops */
381USB_ETHERNET_CONFIGFS_ITEM(gether);
382
383/* f_gether_opts_dev_addr */
384USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(gether);
385
386/* f_gether_opts_host_addr */
387USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(gether);
388
389/* f_gether_opts_qmult */
390USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(gether);
391
392/* f_gether_opts_ifname */
393USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(gether);
394
395static struct configfs_attribute *gether_attrs[] = {
396 &gether_opts_attr_dev_addr,
397 &gether_opts_attr_host_addr,
398 &gether_opts_attr_qmult,
399 &gether_opts_attr_ifname,
400 NULL,
401};
402
403static const struct config_item_type gether_func_type = {
404 .ct_item_ops = &gether_item_ops,
405 .ct_attrs = gether_attrs,
406 .ct_owner = THIS_MODULE,
407};
408
409static void geth_free_inst(struct usb_function_instance *f)
410{
411 struct f_gether_opts *opts;
412
413 opts = container_of(f, struct f_gether_opts, func_inst);
414 if (device_is_registered(&opts->net->dev))
415 gether_cleanup(netdev_priv(opts->net));
416 else
417 free_netdev(opts->net);
418 kfree(opts);
419}
420
421static struct usb_function_instance *geth_alloc_inst(void)
422{
423 struct f_gether_opts *opts;
424
425 opts = kzalloc_obj(*opts);
426 if (!opts)
427 return ERR_PTR(-ENOMEM);
428 mutex_init(&opts->lock);
429 opts->func_inst.free_func_inst = geth_free_inst;
430 opts->net = gether_setup_default();
431 if (IS_ERR(opts->net)) {
432 struct net_device *net = opts->net;
433 kfree(opts);
434 return ERR_CAST(net);
435 }
436
437 config_group_init_type_name(&opts->func_inst.group, "",
438 &gether_func_type);
439
440 return &opts->func_inst;
441}
442
443static void geth_free(struct usb_function *f)
444{
445 struct f_gether *eth;
446 struct f_gether_opts *opts;
447
448 opts = container_of(f->fi, struct f_gether_opts, func_inst);
449
450 eth = func_to_geth(f);
451 scoped_guard(mutex, &opts->lock)
452 opts->refcnt--;
453 kfree(eth);
454}
455
456static void geth_unbind(struct usb_configuration *c, struct usb_function *f)
457{
458 struct f_gether_opts *opts;
459
460 opts = container_of(f->fi, struct f_gether_opts, func_inst);
461
462 geth_string_defs[0].id = 0;
463 usb_free_all_descriptors(f);
464
465 opts->bind_count--;
466 if (opts->bind_count == 0 && !opts->bound)
467 gether_detach_gadget(opts->net);
468}
469
470static struct usb_function *geth_alloc(struct usb_function_instance *fi)
471{
472 struct f_gether *geth;
473 struct f_gether_opts *opts;
474 int status;
475
476 /* allocate and initialize one new instance */
477 geth = kzalloc_obj(*geth);
478 if (!geth)
479 return ERR_PTR(-ENOMEM);
480
481 opts = container_of(fi, struct f_gether_opts, func_inst);
482
483 mutex_lock(&opts->lock);
484 opts->refcnt++;
485 /* export host's Ethernet address in CDC format */
486 status = gether_get_host_addr_cdc(opts->net, geth->ethaddr,
487 sizeof(geth->ethaddr));
488 if (status < 12) {
489 kfree(geth);
490 mutex_unlock(&opts->lock);
491 return ERR_PTR(-EINVAL);
492 }
493 geth_string_defs[1].s = geth->ethaddr;
494
495 geth->port.ioport = netdev_priv(opts->net);
496 mutex_unlock(&opts->lock);
497 geth->port.cdc_filter = DEFAULT_FILTER;
498
499 geth->port.func.name = "cdc_subset";
500 geth->port.func.bind = geth_bind;
501 geth->port.func.unbind = geth_unbind;
502 geth->port.func.set_alt = geth_set_alt;
503 geth->port.func.disable = geth_disable;
504 geth->port.func.free_func = geth_free;
505
506 return &geth->port.func;
507}
508
509DECLARE_USB_FUNCTION_INIT(geth, geth_alloc_inst, geth_alloc);
510MODULE_DESCRIPTION("\"CDC Subset\" Ethernet link function driver");
511MODULE_LICENSE("GPL");
512MODULE_AUTHOR("David Brownell");