1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Bluetooth HCI serdev driver lib
4  *
5  *  Copyright (C) 2017  Linaro, Ltd., Rob Herring <robh@kernel.org>
6  *
7  *  Based on hci_ldisc.c:
8  *
9  *  Copyright (C) 2000-2001  Qualcomm Incorporated
10  *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
11  *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/types.h>
16 #include <linux/serdev.h>
17 #include <linux/skbuff.h>
18 
19 #include <net/bluetooth/bluetooth.h>
20 #include <net/bluetooth/hci_core.h>
21 
22 #include "hci_uart.h"
23 
24 static inline void hci_uart_tx_complete(struct hci_uart *hu, int pkt_type)
25 {
26 	struct hci_dev *hdev = hu->hdev;
27 
28 	/* Update HCI stat counters */
29 	switch (pkt_type) {
30 	case HCI_COMMAND_PKT:
31 		hdev->stat.cmd_tx++;
32 		break;
33 
34 	case HCI_ACLDATA_PKT:
35 		hdev->stat.acl_tx++;
36 		break;
37 
38 	case HCI_SCODATA_PKT:
39 		hdev->stat.sco_tx++;
40 		break;
41 	}
42 }
43 
44 static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
45 {
46 	struct sk_buff *skb = hu->tx_skb;
47 
48 	if (!skb) {
49 		if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
50 			skb = hu->proto->dequeue(hu);
51 	} else
52 		hu->tx_skb = NULL;
53 
54 	return skb;
55 }
56 
57 static void hci_uart_write_work(struct work_struct *work)
58 {
59 	struct hci_uart *hu = container_of(work, struct hci_uart, write_work);
60 	struct serdev_device *serdev = hu->serdev;
61 	struct hci_dev *hdev = hu->hdev;
62 	struct sk_buff *skb;
63 
64 	/* REVISIT:
65 	 * should we cope with bad skbs or ->write() returning an error value?
66 	 */
67 	do {
68 		clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
69 
70 		while ((skb = hci_uart_dequeue(hu))) {
71 			int len;
72 
73 			len = serdev_device_write_buf(serdev,
74 						      skb->data, skb->len);
75 			hdev->stat.byte_tx += len;
76 
77 			skb_pull(skb, len);
78 			if (skb->len) {
79 				hu->tx_skb = skb;
80 				break;
81 			}
82 
83 			hci_uart_tx_complete(hu, hci_skb_pkt_type(skb));
84 			kfree_skb(skb);
85 		}
86 
87 		clear_bit(HCI_UART_SENDING, &hu->tx_state);
88 	} while (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state));
89 }
90 
91 /* ------- Interface to HCI layer ------ */
92 
93 /* Reset device */
94 static int hci_uart_flush(struct hci_dev *hdev)
95 {
96 	struct hci_uart *hu  = hci_get_drvdata(hdev);
97 
98 	BT_DBG("hdev %p serdev %p", hdev, hu->serdev);
99 
100 	if (hu->tx_skb) {
101 		kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
102 	}
103 
104 	/* Flush any pending characters in the driver and discipline. */
105 	serdev_device_write_flush(hu->serdev);
106 
107 	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
108 		hu->proto->flush(hu);
109 
110 	return 0;
111 }
112 
113 /* Initialize device */
114 static int hci_uart_open(struct hci_dev *hdev)
115 {
116 	struct hci_uart *hu = hci_get_drvdata(hdev);
117 	int err;
118 
119 	BT_DBG("%s %p", hdev->name, hdev);
120 
121 	/* When Quirk HCI_QUIRK_NON_PERSISTENT_SETUP is set by
122 	 * driver, BT SoC is completely turned OFF during
123 	 * BT OFF. Upon next BT ON UART port should be opened.
124 	 */
125 	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
126 		err = serdev_device_open(hu->serdev);
127 		if (err)
128 			return err;
129 		set_bit(HCI_UART_PROTO_READY, &hu->flags);
130 	}
131 
132 	/* Undo clearing this from hci_uart_close() */
133 	hdev->flush = hci_uart_flush;
134 
135 	return 0;
136 }
137 
138 /* Close device */
139 static int hci_uart_close(struct hci_dev *hdev)
140 {
141 	struct hci_uart *hu = hci_get_drvdata(hdev);
142 
143 	BT_DBG("hdev %p", hdev);
144 
145 	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
146 		return 0;
147 
148 	hci_uart_flush(hdev);
149 	hdev->flush = NULL;
150 
151 	/* When QUIRK HCI_QUIRK_NON_PERSISTENT_SETUP is set by driver,
152 	 * BT SOC is completely powered OFF during BT OFF, holding port
153 	 * open may drain the battery.
154 	 */
155 	if (test_bit(HCI_QUIRK_NON_PERSISTENT_SETUP, &hdev->quirks)) {
156 		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
157 		serdev_device_close(hu->serdev);
158 	}
159 
160 	return 0;
161 }
162 
163 /* Send frames from HCI layer */
164 static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
165 {
166 	struct hci_uart *hu = hci_get_drvdata(hdev);
167 
168 	BT_DBG("%s: type %d len %d", hdev->name, hci_skb_pkt_type(skb),
169 	       skb->len);
170 
171 	hu->proto->enqueue(hu, skb);
172 
173 	hci_uart_tx_wakeup(hu);
174 
175 	return 0;
176 }
177 
178 static int hci_uart_setup(struct hci_dev *hdev)
179 {
180 	struct hci_uart *hu = hci_get_drvdata(hdev);
181 	struct hci_rp_read_local_version *ver;
182 	struct sk_buff *skb;
183 	unsigned int speed;
184 	int err;
185 
186 	/* Init speed if any */
187 	if (hu->init_speed)
188 		speed = hu->init_speed;
189 	else if (hu->proto->init_speed)
190 		speed = hu->proto->init_speed;
191 	else
192 		speed = 0;
193 
194 	if (speed)
195 		serdev_device_set_baudrate(hu->serdev, speed);
196 
197 	/* Operational speed if any */
198 	if (hu->oper_speed)
199 		speed = hu->oper_speed;
200 	else if (hu->proto->oper_speed)
201 		speed = hu->proto->oper_speed;
202 	else
203 		speed = 0;
204 
205 	if (hu->proto->set_baudrate && speed) {
206 		err = hu->proto->set_baudrate(hu, speed);
207 		if (err)
208 			bt_dev_err(hdev, "Failed to set baudrate");
209 		else
210 			serdev_device_set_baudrate(hu->serdev, speed);
211 	}
212 
213 	if (hu->proto->setup)
214 		return hu->proto->setup(hu);
215 
216 	if (!test_bit(HCI_UART_VND_DETECT, &hu->hdev_flags))
217 		return 0;
218 
219 	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0, NULL,
220 			     HCI_INIT_TIMEOUT);
221 	if (IS_ERR(skb)) {
222 		bt_dev_err(hdev, "Reading local version info failed (%ld)",
223 			   PTR_ERR(skb));
224 		return 0;
225 	}
226 
227 	if (skb->len != sizeof(*ver))
228 		bt_dev_err(hdev, "Event length mismatch for version info");
229 
230 	kfree_skb(skb);
231 	return 0;
232 }
233 
234 /* Check if the device is wakeable */
235 static bool hci_uart_wakeup(struct hci_dev *hdev)
236 {
237 	/* HCI UART devices are assumed to be wakeable by default.
238 	 * Implement wakeup callback to override this behavior.
239 	 */
240 	return true;
241 }
242 
243 /** hci_uart_write_wakeup - transmit buffer wakeup
244  * @serdev: serial device
245  *
246  * This function is called by the serdev framework when it accepts
247  * more data being sent.
248  */
249 static void hci_uart_write_wakeup(struct serdev_device *serdev)
250 {
251 	struct hci_uart *hu = serdev_device_get_drvdata(serdev);
252 
253 	BT_DBG("");
254 
255 	if (!hu || serdev != hu->serdev) {
256 		WARN_ON(1);
257 		return;
258 	}
259 
260 	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
261 		hci_uart_tx_wakeup(hu);
262 }
263 
264 /** hci_uart_receive_buf - receive buffer wakeup
265  * @serdev: serial device
266  * @data:   pointer to received data
267  * @count:  count of received data in bytes
268  *
269  * This function is called by the serdev framework when it received data
270  * in the RX buffer.
271  *
272  * Return: number of processed bytes
273  */
274 static int hci_uart_receive_buf(struct serdev_device *serdev, const u8 *data,
275 				   size_t count)
276 {
277 	struct hci_uart *hu = serdev_device_get_drvdata(serdev);
278 
279 	if (!hu || serdev != hu->serdev) {
280 		WARN_ON(1);
281 		return 0;
282 	}
283 
284 	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
285 		return 0;
286 
287 	/* It does not need a lock here as it is already protected by a mutex in
288 	 * tty caller
289 	 */
290 	hu->proto->recv(hu, data, count);
291 
292 	if (hu->hdev)
293 		hu->hdev->stat.byte_rx += count;
294 
295 	return count;
296 }
297 
298 static const struct serdev_device_ops hci_serdev_client_ops = {
299 	.receive_buf = hci_uart_receive_buf,
300 	.write_wakeup = hci_uart_write_wakeup,
301 };
302 
303 int hci_uart_register_device_priv(struct hci_uart *hu,
304 			     const struct hci_uart_proto *p,
305 			     int sizeof_priv)
306 {
307 	int err;
308 	struct hci_dev *hdev;
309 
310 	BT_DBG("");
311 
312 	serdev_device_set_client_ops(hu->serdev, &hci_serdev_client_ops);
313 
314 	if (percpu_init_rwsem(&hu->proto_lock))
315 		return -ENOMEM;
316 
317 	err = serdev_device_open(hu->serdev);
318 	if (err)
319 		goto err_rwsem;
320 
321 	err = p->open(hu);
322 	if (err)
323 		goto err_open;
324 
325 	hu->proto = p;
326 	set_bit(HCI_UART_PROTO_READY, &hu->flags);
327 
328 	/* Initialize and register HCI device */
329 	hdev = hci_alloc_dev_priv(sizeof_priv);
330 	if (!hdev) {
331 		BT_ERR("Can't allocate HCI device");
332 		err = -ENOMEM;
333 		goto err_alloc;
334 	}
335 
336 	hu->hdev = hdev;
337 
338 	hdev->bus = HCI_UART;
339 	hci_set_drvdata(hdev, hu);
340 
341 	INIT_WORK(&hu->init_ready, hci_uart_init_work);
342 	INIT_WORK(&hu->write_work, hci_uart_write_work);
343 
344 	/* Only when vendor specific setup callback is provided, consider
345 	 * the manufacturer information valid. This avoids filling in the
346 	 * value for Ericsson when nothing is specified.
347 	 */
348 	if (hu->proto->setup)
349 		hdev->manufacturer = hu->proto->manufacturer;
350 
351 	hdev->open  = hci_uart_open;
352 	hdev->close = hci_uart_close;
353 	hdev->flush = hci_uart_flush;
354 	hdev->send  = hci_uart_send_frame;
355 	hdev->setup = hci_uart_setup;
356 	if (!hdev->wakeup)
357 		hdev->wakeup = hci_uart_wakeup;
358 	SET_HCIDEV_DEV(hdev, &hu->serdev->dev);
359 
360 	if (test_bit(HCI_UART_NO_SUSPEND_NOTIFIER, &hu->flags))
361 		set_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks);
362 
363 	if (test_bit(HCI_UART_RAW_DEVICE, &hu->hdev_flags))
364 		set_bit(HCI_QUIRK_RAW_DEVICE, &hdev->quirks);
365 
366 	if (test_bit(HCI_UART_EXT_CONFIG, &hu->hdev_flags))
367 		set_bit(HCI_QUIRK_EXTERNAL_CONFIG, &hdev->quirks);
368 
369 	if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
370 		return 0;
371 
372 	if (hci_register_dev(hdev) < 0) {
373 		BT_ERR("Can't register HCI device");
374 		err = -ENODEV;
375 		goto err_register;
376 	}
377 
378 	set_bit(HCI_UART_REGISTERED, &hu->flags);
379 
380 	return 0;
381 
382 err_register:
383 	hci_free_dev(hdev);
384 err_alloc:
385 	clear_bit(HCI_UART_PROTO_READY, &hu->flags);
386 	p->close(hu);
387 err_open:
388 	serdev_device_close(hu->serdev);
389 err_rwsem:
390 	percpu_free_rwsem(&hu->proto_lock);
391 	return err;
392 }
393 EXPORT_SYMBOL_GPL(hci_uart_register_device_priv);
394 
395 void hci_uart_unregister_device(struct hci_uart *hu)
396 {
397 	struct hci_dev *hdev = hu->hdev;
398 
399 	cancel_work_sync(&hu->init_ready);
400 	if (test_bit(HCI_UART_REGISTERED, &hu->flags))
401 		hci_unregister_dev(hdev);
402 	hci_free_dev(hdev);
403 
404 	cancel_work_sync(&hu->write_work);
405 
406 	hu->proto->close(hu);
407 
408 	if (test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
409 		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
410 		serdev_device_close(hu->serdev);
411 	}
412 	percpu_free_rwsem(&hu->proto_lock);
413 }
414 EXPORT_SYMBOL_GPL(hci_uart_unregister_device);
415