1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * WUSB Wire Adapter: Control/Data Streaming Interface (WUSB[8])
4 * Notification EndPoint support
5 *
6 * Copyright (C) 2006 Intel Corporation
7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
8 *
9 * This part takes care of getting the notification from the hw
10 * only and dispatching through wusbwad into
11 * wa_notif_dispatch. Handling is done there.
12 *
13 * WA notifications are limited in size; most of them are three or
14 * four bytes long, and the longest is the HWA Device Notification,
15 * which would not exceed 38 bytes (DNs are limited in payload to 32
16 * bytes plus 3 bytes header (WUSB1.0[7.6p2]), plus 3 bytes HWA
17 * header (WUSB1.0[8.5.4.2]).
18 *
19 * It is not clear if more than one Device Notification can be packed
20 * in a HWA Notification, I assume no because of the wording in
21 * WUSB1.0[8.5.4.2]. In any case, the bigger any notification could
22 * get is 256 bytes (as the bLength field is a byte).
23 *
24 * So what we do is we have this buffer and read into it; when a
25 * notification arrives we schedule work to a specific, single thread
26 * workqueue (so notifications are serialized) and copy the
27 * notification data. After scheduling the work, we rearm the read from
28 * the notification endpoint.
29 *
30 * Entry points here are:
31 *
32 * wa_nep_[create|destroy]() To initialize/release this subsystem
33 *
34 * wa_nep_cb() Callback for the notification
35 * endpoint; when data is ready, this
36 * does the dispatching.
37 */
38 #include <linux/workqueue.h>
39 #include <linux/ctype.h>
40 #include <linux/slab.h>
41
42 #include "wa-hc.h"
43 #include "wusbhc.h"
44
45 /* Structure for queueing notifications to the workqueue */
46 struct wa_notif_work {
47 struct work_struct work;
48 struct wahc *wa;
49 size_t size;
50 u8 data[];
51 };
52
53 /*
54 * Process incoming notifications from the WA's Notification EndPoint
55 * [the wuswad daemon, basically]
56 *
57 * @_nw: Pointer to a descriptor which has the pointer to the
58 * @wa, the size of the buffer and the work queue
59 * structure (so we can free all when done).
60 * @returns 0 if ok, < 0 errno code on error.
61 *
62 * All notifications follow the same format; they need to start with a
63 * 'struct wa_notif_hdr' header, so it is easy to parse through
64 * them. We just break the buffer in individual notifications (the
65 * standard doesn't say if it can be done or is forbidden, so we are
66 * cautious) and dispatch each.
67 *
68 * So the handling layers are is:
69 *
70 * WA specific notification (from NEP)
71 * Device Notification Received -> wa_handle_notif_dn()
72 * WUSB Device notification generic handling
73 * BPST Adjustment -> wa_handle_notif_bpst_adj()
74 * ... -> ...
75 *
76 * @wa has to be referenced
77 */
78 static void wa_notif_dispatch(struct work_struct *ws)
79 {
80 void *itr;
81 u8 missing = 0;
82 struct wa_notif_work *nw = container_of(ws, struct wa_notif_work,
83 work);
84 struct wahc *wa = nw->wa;
85 struct wa_notif_hdr *notif_hdr;
86 size_t size;
87
88 struct device *dev = &wa->usb_iface->dev;
89
90 #if 0
91 /* FIXME: need to check for this??? */
92 if (usb_hcd->state == HC_STATE_QUIESCING) /* Going down? */
93 goto out; /* screw it */
94 #endif
95 atomic_dec(&wa->notifs_queued); /* Throttling ctl */
96 size = nw->size;
97 itr = nw->data;
98
99 while (size) {
100 if (size < sizeof(*notif_hdr)) {
101 missing = sizeof(*notif_hdr) - size;
102 goto exhausted_buffer;
103 }
104 notif_hdr = itr;
105 if (size < notif_hdr->bLength)
106 goto exhausted_buffer;
107 itr += notif_hdr->bLength;
108 size -= notif_hdr->bLength;
109 /* Dispatch the notification [don't use itr or size!] */
110 switch (notif_hdr->bNotifyType) {
111 case HWA_NOTIF_DN: {
112 struct hwa_notif_dn *hwa_dn;
113 hwa_dn = container_of(notif_hdr, struct hwa_notif_dn,
114 hdr);
115 wusbhc_handle_dn(wa->wusb, hwa_dn->bSourceDeviceAddr,
116 hwa_dn->dndata,
117 notif_hdr->bLength - sizeof(*hwa_dn));
118 break;
119 }
120 case WA_NOTIF_TRANSFER:
121 wa_handle_notif_xfer(wa, notif_hdr);
122 break;
123 case HWA_NOTIF_BPST_ADJ:
124 break; /* no action needed for BPST ADJ. */
125 case DWA_NOTIF_RWAKE:
126 case DWA_NOTIF_PORTSTATUS:
127 /* FIXME: unimplemented WA NOTIFs */
128 /* fallthru */
129 default:
130 dev_err(dev, "HWA: unknown notification 0x%x, "
131 "%zu bytes; discarding\n",
132 notif_hdr->bNotifyType,
133 (size_t)notif_hdr->bLength);
134 break;
135 }
136 }
137 out:
138 wa_put(wa);
139 kfree(nw);
140 return;
141
142 /* THIS SHOULD NOT HAPPEN
143 *
144 * Buffer exahusted with partial data remaining; just warn and
145 * discard the data, as this should not happen.
146 */
147 exhausted_buffer:
148 dev_warn(dev, "HWA: device sent short notification, "
149 "%d bytes missing; discarding %d bytes.\n",
150 missing, (int)size);
151 goto out;
152 }
153
154 /*
155 * Deliver incoming WA notifications to the wusbwa workqueue
156 *
157 * @wa: Pointer the Wire Adapter Controller Data Streaming
158 * instance (part of an 'struct usb_hcd').
159 * @size: Size of the received buffer
160 * @returns 0 if ok, < 0 errno code on error.
161 *
162 * The input buffer is @wa->nep_buffer, with @size bytes
163 * (guaranteed to fit in the allocated space,
164 * @wa->nep_buffer_size).
165 */
166 static int wa_nep_queue(struct wahc *wa, size_t size)
167 {
168 int result = 0;
169 struct device *dev = &wa->usb_iface->dev;
170 struct wa_notif_work *nw;
171
172 /* dev_fnstart(dev, "(wa %p, size %zu)\n", wa, size); */
173 BUG_ON(size > wa->nep_buffer_size);
174 if (size == 0)
175 goto out;
176 if (atomic_read(&wa->notifs_queued) > 200) {
177 if (printk_ratelimit())
178 dev_err(dev, "Too many notifications queued, "
179 "throttling back\n");
180 goto out;
181 }
182 nw = kzalloc(sizeof(*nw) + size, GFP_ATOMIC);
183 if (nw == NULL) {
184 if (printk_ratelimit())
185 dev_err(dev, "No memory to queue notification\n");
186 result = -ENOMEM;
187 goto out;
188 }
189 INIT_WORK(&nw->work, wa_notif_dispatch);
190 nw->wa = wa_get(wa);
191 nw->size = size;
192 memcpy(nw->data, wa->nep_buffer, size);
193 atomic_inc(&wa->notifs_queued); /* Throttling ctl */
194 queue_work(wusbd, &nw->work);
195 out:
196 /* dev_fnend(dev, "(wa %p, size %zu) = result\n", wa, size, result); */
197 return result;
198 }
199
200 /*
201 * Callback for the notification event endpoint
202 *
203 * Check's that everything is fine and then passes the data to be
204 * queued to the workqueue.
205 */
206 static void wa_nep_cb(struct urb *urb)
207 {
208 int result;
209 struct wahc *wa = urb->context;
210 struct device *dev = &wa->usb_iface->dev;
211
212 switch (result = urb->status) {
213 case 0:
214 result = wa_nep_queue(wa, urb->actual_length);
215 if (result < 0)
216 dev_err(dev, "NEP: unable to process notification(s): "
217 "%d\n", result);
218 break;
219 case -ECONNRESET: /* Not an error, but a controlled situation; */
220 case -ENOENT: /* (we killed the URB)...so, no broadcast */
221 case -ESHUTDOWN:
222 dev_dbg(dev, "NEP: going down %d\n", urb->status);
223 goto out;
224 default: /* On general errors, we retry unless it gets ugly */
225 if (edc_inc(&wa->nep_edc, EDC_MAX_ERRORS,
226 EDC_ERROR_TIMEFRAME)) {
227 dev_err(dev, "NEP: URB max acceptable errors "
228 "exceeded, resetting device\n");
229 wa_reset_all(wa);
230 goto out;
231 }
232 dev_err(dev, "NEP: URB error %d\n", urb->status);
233 }
234 result = wa_nep_arm(wa, GFP_ATOMIC);
235 if (result < 0) {
236 dev_err(dev, "NEP: cannot submit URB: %d\n", result);
237 wa_reset_all(wa);
238 }
239 out:
240 return;
241 }
242
243 /*
244 * Initialize @wa's notification and event's endpoint stuff
245 *
246 * This includes the allocating the read buffer, the context ID
247 * allocation bitmap, the URB and submitting the URB.
248 */
249 int wa_nep_create(struct wahc *wa, struct usb_interface *iface)
250 {
251 int result;
252 struct usb_endpoint_descriptor *epd;
253 struct usb_device *usb_dev = interface_to_usbdev(iface);
254 struct device *dev = &iface->dev;
255
256 edc_init(&wa->nep_edc);
257 epd = &iface->cur_altsetting->endpoint[0].desc;
258 wa->nep_buffer_size = 1024;
259 wa->nep_buffer = kmalloc(wa->nep_buffer_size, GFP_KERNEL);
260 if (!wa->nep_buffer)
261 goto error_nep_buffer;
262 wa->nep_urb = usb_alloc_urb(0, GFP_KERNEL);
263 if (wa->nep_urb == NULL)
264 goto error_urb_alloc;
265 usb_fill_int_urb(wa->nep_urb, usb_dev,
266 usb_rcvintpipe(usb_dev, epd->bEndpointAddress),
267 wa->nep_buffer, wa->nep_buffer_size,
268 wa_nep_cb, wa, epd->bInterval);
269 result = wa_nep_arm(wa, GFP_KERNEL);
270 if (result < 0) {
271 dev_err(dev, "Cannot submit notification URB: %d\n", result);
272 goto error_nep_arm;
273 }
274 return 0;
275
276 error_nep_arm:
277 usb_free_urb(wa->nep_urb);
278 error_urb_alloc:
279 kfree(wa->nep_buffer);
280 error_nep_buffer:
281 return -ENOMEM;
282 }
283
284 void wa_nep_destroy(struct wahc *wa)
285 {
286 wa_nep_disarm(wa);
287 usb_free_urb(wa->nep_urb);
288 kfree(wa->nep_buffer);
289 }