1 /*
2  *  Copyright (c) 2013, Microsoft Corporation.
3  *
4  *  This program is free software; you can redistribute it and/or modify it
5  *  under the terms and conditions of the GNU General Public License,
6  *  version 2, as published by the Free Software Foundation.
7  *
8  *  This program is distributed in the hope it will be useful, but WITHOUT
9  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  *  more details.
12  */
13 
14 #include <linux/init.h>
15 #include <linux/module.h>
16 #include <linux/device.h>
17 #include <linux/completion.h>
18 #include <linux/hyperv.h>
19 #include <linux/serio.h>
20 #include <linux/slab.h>
21 
22 /*
23  * Current version 1.0
24  *
25  */
26 #define SYNTH_KBD_VERSION_MAJOR 1
27 #define SYNTH_KBD_VERSION_MINOR	0
28 #define SYNTH_KBD_VERSION		(SYNTH_KBD_VERSION_MINOR | \
29 					 (SYNTH_KBD_VERSION_MAJOR << 16))
30 
31 
32 /*
33  * Message types in the synthetic input protocol
34  */
35 enum synth_kbd_msg_type {
36 	SYNTH_KBD_PROTOCOL_REQUEST = 1,
37 	SYNTH_KBD_PROTOCOL_RESPONSE = 2,
38 	SYNTH_KBD_EVENT = 3,
39 	SYNTH_KBD_LED_INDICATORS = 4,
40 };
41 
42 /*
43  * Basic message structures.
44  */
45 struct synth_kbd_msg_hdr {
46 	__le32 type;
47 };
48 
49 struct synth_kbd_msg {
50 	struct synth_kbd_msg_hdr header;
51 	char data[]; /* Enclosed message */
52 };
53 
54 union synth_kbd_version {
55 	__le32 version;
56 };
57 
58 /*
59  * Protocol messages
60  */
61 struct synth_kbd_protocol_request {
62 	struct synth_kbd_msg_hdr header;
63 	union synth_kbd_version version_requested;
64 };
65 
66 #define PROTOCOL_ACCEPTED	BIT(0)
67 struct synth_kbd_protocol_response {
68 	struct synth_kbd_msg_hdr header;
69 	__le32 proto_status;
70 };
71 
72 #define IS_UNICODE	BIT(0)
73 #define IS_BREAK	BIT(1)
74 #define IS_E0		BIT(2)
75 #define IS_E1		BIT(3)
76 struct synth_kbd_keystroke {
77 	struct synth_kbd_msg_hdr header;
78 	__le16 make_code;
79 	__le16 reserved0;
80 	__le32 info; /* Additional information */
81 };
82 
83 
84 #define HK_MAXIMUM_MESSAGE_SIZE 256
85 
86 #define KBD_VSC_SEND_RING_BUFFER_SIZE		(10 * PAGE_SIZE)
87 #define KBD_VSC_RECV_RING_BUFFER_SIZE		(10 * PAGE_SIZE)
88 
89 #define XTKBD_EMUL0     0xe0
90 #define XTKBD_EMUL1     0xe1
91 #define XTKBD_RELEASE   0x80
92 
93 
94 /*
95  * Represents a keyboard device
96  */
97 struct hv_kbd_dev {
98 	struct hv_device *hv_dev;
99 	struct serio *hv_serio;
100 	struct synth_kbd_protocol_request protocol_req;
101 	struct synth_kbd_protocol_response protocol_resp;
102 	/* Synchronize the request/response if needed */
103 	struct completion wait_event;
104 	spinlock_t lock; /* protects 'started' field */
105 	bool started;
106 };
107 
108 static void hv_kbd_on_receive(struct hv_device *hv_dev,
109 			      struct synth_kbd_msg *msg, u32 msg_length)
110 {
111 	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
112 	struct synth_kbd_keystroke *ks_msg;
113 	unsigned long flags;
114 	u32 msg_type = __le32_to_cpu(msg->header.type);
115 	u32 info;
116 	u16 scan_code;
117 
118 	switch (msg_type) {
119 	case SYNTH_KBD_PROTOCOL_RESPONSE:
120 		/*
121 		 * Validate the information provided by the host.
122 		 * If the host is giving us a bogus packet,
123 		 * drop the packet (hoping the problem
124 		 * goes away).
125 		 */
126 		if (msg_length < sizeof(struct synth_kbd_protocol_response)) {
127 			dev_err(&hv_dev->device,
128 				"Illegal protocol response packet (len: %d)\n",
129 				msg_length);
130 			break;
131 		}
132 
133 		memcpy(&kbd_dev->protocol_resp, msg,
134 			sizeof(struct synth_kbd_protocol_response));
135 		complete(&kbd_dev->wait_event);
136 		break;
137 
138 	case SYNTH_KBD_EVENT:
139 		/*
140 		 * Validate the information provided by the host.
141 		 * If the host is giving us a bogus packet,
142 		 * drop the packet (hoping the problem
143 		 * goes away).
144 		 */
145 		if (msg_length < sizeof(struct  synth_kbd_keystroke)) {
146 			dev_err(&hv_dev->device,
147 				"Illegal keyboard event packet (len: %d)\n",
148 				msg_length);
149 			break;
150 		}
151 
152 		ks_msg = (struct synth_kbd_keystroke *)msg;
153 		info = __le32_to_cpu(ks_msg->info);
154 
155 		/*
156 		 * Inject the information through the serio interrupt.
157 		 */
158 		spin_lock_irqsave(&kbd_dev->lock, flags);
159 		if (kbd_dev->started) {
160 			if (info & IS_E0)
161 				serio_interrupt(kbd_dev->hv_serio,
162 						XTKBD_EMUL0, 0);
163 			if (info & IS_E1)
164 				serio_interrupt(kbd_dev->hv_serio,
165 						XTKBD_EMUL1, 0);
166 			scan_code = __le16_to_cpu(ks_msg->make_code);
167 			if (info & IS_BREAK)
168 				scan_code |= XTKBD_RELEASE;
169 
170 			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
171 		}
172 		spin_unlock_irqrestore(&kbd_dev->lock, flags);
173 
174 		/*
175 		 * Only trigger a wakeup on key down, otherwise
176 		 * "echo freeze > /sys/power/state" can't really enter the
177 		 * state because the Enter-UP can trigger a wakeup at once.
178 		 */
179 		if (!(info & IS_BREAK))
180 			pm_wakeup_hard_event(&hv_dev->device);
181 
182 		break;
183 
184 	default:
185 		dev_err(&hv_dev->device,
186 			"unhandled message type %d\n", msg_type);
187 	}
188 }
189 
190 static void hv_kbd_handle_received_packet(struct hv_device *hv_dev,
191 					  struct vmpacket_descriptor *desc,
192 					  u32 bytes_recvd,
193 					  u64 req_id)
194 {
195 	struct synth_kbd_msg *msg;
196 	u32 msg_sz;
197 
198 	switch (desc->type) {
199 	case VM_PKT_COMP:
200 		break;
201 
202 	case VM_PKT_DATA_INBAND:
203 		/*
204 		 * We have a packet that has "inband" data. The API used
205 		 * for retrieving the packet guarantees that the complete
206 		 * packet is read. So, minimally, we should be able to
207 		 * parse the payload header safely (assuming that the host
208 		 * can be trusted.  Trusting the host seems to be a
209 		 * reasonable assumption because in a virtualized
210 		 * environment there is not whole lot you can do if you
211 		 * don't trust the host.
212 		 *
213 		 * Nonetheless, let us validate if the host can be trusted
214 		 * (in a trivial way).  The interesting aspect of this
215 		 * validation is how do you recover if we discover that the
216 		 * host is not to be trusted? Simply dropping the packet, I
217 		 * don't think is an appropriate recovery.  In the interest
218 		 * of failing fast, it may be better to crash the guest.
219 		 * For now, I will just drop the packet!
220 		 */
221 
222 		msg_sz = bytes_recvd - (desc->offset8 << 3);
223 		if (msg_sz <= sizeof(struct synth_kbd_msg_hdr)) {
224 			/*
225 			 * Drop the packet and hope
226 			 * the problem magically goes away.
227 			 */
228 			dev_err(&hv_dev->device,
229 				"Illegal packet (type: %d, tid: %llx, size: %d)\n",
230 				desc->type, req_id, msg_sz);
231 			break;
232 		}
233 
234 		msg = (void *)desc + (desc->offset8 << 3);
235 		hv_kbd_on_receive(hv_dev, msg, msg_sz);
236 		break;
237 
238 	default:
239 		dev_err(&hv_dev->device,
240 			"unhandled packet type %d, tid %llx len %d\n",
241 			desc->type, req_id, bytes_recvd);
242 		break;
243 	}
244 }
245 
246 static void hv_kbd_on_channel_callback(void *context)
247 {
248 	struct hv_device *hv_dev = context;
249 	void *buffer;
250 	int bufferlen = 0x100; /* Start with sensible size */
251 	u32 bytes_recvd;
252 	u64 req_id;
253 	int error;
254 
255 	buffer = kmalloc(bufferlen, GFP_ATOMIC);
256 	if (!buffer)
257 		return;
258 
259 	while (1) {
260 		error = vmbus_recvpacket_raw(hv_dev->channel, buffer, bufferlen,
261 					     &bytes_recvd, &req_id);
262 		switch (error) {
263 		case 0:
264 			if (bytes_recvd == 0) {
265 				kfree(buffer);
266 				return;
267 			}
268 
269 			hv_kbd_handle_received_packet(hv_dev, buffer,
270 						      bytes_recvd, req_id);
271 			break;
272 
273 		case -ENOBUFS:
274 			kfree(buffer);
275 			/* Handle large packet */
276 			bufferlen = bytes_recvd;
277 			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
278 			if (!buffer)
279 				return;
280 			break;
281 		}
282 	}
283 }
284 
285 static int hv_kbd_connect_to_vsp(struct hv_device *hv_dev)
286 {
287 	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
288 	struct synth_kbd_protocol_request *request;
289 	struct synth_kbd_protocol_response *response;
290 	u32 proto_status;
291 	int error;
292 
293 	request = &kbd_dev->protocol_req;
294 	memset(request, 0, sizeof(struct synth_kbd_protocol_request));
295 	request->header.type = __cpu_to_le32(SYNTH_KBD_PROTOCOL_REQUEST);
296 	request->version_requested.version = __cpu_to_le32(SYNTH_KBD_VERSION);
297 
298 	error = vmbus_sendpacket(hv_dev->channel, request,
299 				 sizeof(struct synth_kbd_protocol_request),
300 				 (unsigned long)request,
301 				 VM_PKT_DATA_INBAND,
302 				 VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
303 	if (error)
304 		return error;
305 
306 	if (!wait_for_completion_timeout(&kbd_dev->wait_event, 10 * HZ))
307 		return -ETIMEDOUT;
308 
309 	response = &kbd_dev->protocol_resp;
310 	proto_status = __le32_to_cpu(response->proto_status);
311 	if (!(proto_status & PROTOCOL_ACCEPTED)) {
312 		dev_err(&hv_dev->device,
313 			"synth_kbd protocol request failed (version %d)\n",
314 		        SYNTH_KBD_VERSION);
315 		return -ENODEV;
316 	}
317 
318 	return 0;
319 }
320 
321 static int hv_kbd_start(struct serio *serio)
322 {
323 	struct hv_kbd_dev *kbd_dev = serio->port_data;
324 	unsigned long flags;
325 
326 	spin_lock_irqsave(&kbd_dev->lock, flags);
327 	kbd_dev->started = true;
328 	spin_unlock_irqrestore(&kbd_dev->lock, flags);
329 
330 	return 0;
331 }
332 
333 static void hv_kbd_stop(struct serio *serio)
334 {
335 	struct hv_kbd_dev *kbd_dev = serio->port_data;
336 	unsigned long flags;
337 
338 	spin_lock_irqsave(&kbd_dev->lock, flags);
339 	kbd_dev->started = false;
340 	spin_unlock_irqrestore(&kbd_dev->lock, flags);
341 }
342 
343 static int hv_kbd_probe(struct hv_device *hv_dev,
344 			const struct hv_vmbus_device_id *dev_id)
345 {
346 	struct hv_kbd_dev *kbd_dev;
347 	struct serio *hv_serio;
348 	int error;
349 
350 	kbd_dev = kzalloc(sizeof(struct hv_kbd_dev), GFP_KERNEL);
351 	hv_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
352 	if (!kbd_dev || !hv_serio) {
353 		error = -ENOMEM;
354 		goto err_free_mem;
355 	}
356 
357 	kbd_dev->hv_dev = hv_dev;
358 	kbd_dev->hv_serio = hv_serio;
359 	spin_lock_init(&kbd_dev->lock);
360 	init_completion(&kbd_dev->wait_event);
361 	hv_set_drvdata(hv_dev, kbd_dev);
362 
363 	hv_serio->dev.parent  = &hv_dev->device;
364 	hv_serio->id.type = SERIO_8042_XL;
365 	hv_serio->port_data = kbd_dev;
366 	strlcpy(hv_serio->name, dev_name(&hv_dev->device),
367 		sizeof(hv_serio->name));
368 	strlcpy(hv_serio->phys, dev_name(&hv_dev->device),
369 		sizeof(hv_serio->phys));
370 
371 	hv_serio->start = hv_kbd_start;
372 	hv_serio->stop = hv_kbd_stop;
373 
374 	error = vmbus_open(hv_dev->channel,
375 			   KBD_VSC_SEND_RING_BUFFER_SIZE,
376 			   KBD_VSC_RECV_RING_BUFFER_SIZE,
377 			   NULL, 0,
378 			   hv_kbd_on_channel_callback,
379 			   hv_dev);
380 	if (error)
381 		goto err_free_mem;
382 
383 	error = hv_kbd_connect_to_vsp(hv_dev);
384 	if (error)
385 		goto err_close_vmbus;
386 
387 	serio_register_port(kbd_dev->hv_serio);
388 
389 	device_init_wakeup(&hv_dev->device, true);
390 
391 	return 0;
392 
393 err_close_vmbus:
394 	vmbus_close(hv_dev->channel);
395 err_free_mem:
396 	kfree(hv_serio);
397 	kfree(kbd_dev);
398 	return error;
399 }
400 
401 static int hv_kbd_remove(struct hv_device *hv_dev)
402 {
403 	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
404 
405 	serio_unregister_port(kbd_dev->hv_serio);
406 	vmbus_close(hv_dev->channel);
407 	kfree(kbd_dev);
408 
409 	hv_set_drvdata(hv_dev, NULL);
410 
411 	return 0;
412 }
413 
414 static const struct hv_vmbus_device_id id_table[] = {
415 	/* Keyboard guid */
416 	{ HV_KBD_GUID, },
417 	{ },
418 };
419 
420 MODULE_DEVICE_TABLE(vmbus, id_table);
421 
422 static struct  hv_driver hv_kbd_drv = {
423 	.name = KBUILD_MODNAME,
424 	.id_table = id_table,
425 	.probe = hv_kbd_probe,
426 	.remove = hv_kbd_remove,
427 	.driver = {
428 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
429 	},
430 };
431 
432 static int __init hv_kbd_init(void)
433 {
434 	return vmbus_driver_register(&hv_kbd_drv);
435 }
436 
437 static void __exit hv_kbd_exit(void)
438 {
439 	vmbus_driver_unregister(&hv_kbd_drv);
440 }
441 
442 MODULE_LICENSE("GPL");
443 MODULE_DESCRIPTION("Microsoft Hyper-V Synthetic Keyboard Driver");
444 
445 module_init(hv_kbd_init);
446 module_exit(hv_kbd_exit);
447