1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *   serial-generic.c
4  *   Copyright (c) by Daniel Kaehn <kaehndan@gmail.com
5  *   Based on serial-u16550.c by Jaroslav Kysela <perex@perex.cz>,
6  *		                 Isaku Yamahata <yamahata@private.email.ne.jp>,
7  *		                 George Hansper <ghansper@apana.org.au>,
8  *		                 Hannu Savolainen
9  *
10  * Generic serial MIDI driver using the serdev serial bus API for hardware interaction
11  */
12 
13 #include <linux/err.h>
14 #include <linux/init.h>
15 #include <linux/interrupt.h>
16 #include <linux/io.h>
17 #include <linux/ioport.h>
18 #include <linux/module.h>
19 #include <linux/of_device.h>
20 #include <linux/serdev.h>
21 #include <linux/serial_reg.h>
22 #include <linux/slab.h>
23 #include <linux/dev_printk.h>
24 
25 #include <sound/core.h>
26 #include <sound/rawmidi.h>
27 #include <sound/initval.h>
28 
29 MODULE_DESCRIPTION("Generic serial MIDI driver");
30 MODULE_LICENSE("GPL");
31 
32 #define SERIAL_MODE_INPUT_OPEN		1
33 #define SERIAL_MODE_OUTPUT_OPEN	2
34 #define SERIAL_MODE_INPUT_TRIGGERED	3
35 #define SERIAL_MODE_OUTPUT_TRIGGERED	4
36 
37 #define SERIAL_TX_STATE_ACTIVE	1
38 #define SERIAL_TX_STATE_WAKEUP	2
39 
40 struct snd_serial_generic {
41 	struct serdev_device *serdev;
42 
43 	struct snd_card *card;
44 	struct snd_rawmidi *rmidi;
45 	struct snd_rawmidi_substream *midi_output;
46 	struct snd_rawmidi_substream *midi_input;
47 
48 	unsigned int baudrate;
49 
50 	unsigned long filemode;		/* open status of file */
51 	struct work_struct tx_work;
52 	unsigned long tx_state;
53 
54 };
55 
snd_serial_generic_tx_wakeup(struct snd_serial_generic * drvdata)56 static void snd_serial_generic_tx_wakeup(struct snd_serial_generic *drvdata)
57 {
58 	if (test_and_set_bit(SERIAL_TX_STATE_ACTIVE, &drvdata->tx_state))
59 		set_bit(SERIAL_TX_STATE_WAKEUP, &drvdata->tx_state);
60 
61 	schedule_work(&drvdata->tx_work);
62 }
63 
64 #define INTERNAL_BUF_SIZE 256
65 
snd_serial_generic_tx_work(struct work_struct * work)66 static void snd_serial_generic_tx_work(struct work_struct *work)
67 {
68 	static char buf[INTERNAL_BUF_SIZE];
69 	int num_bytes;
70 	struct snd_serial_generic *drvdata = container_of(work, struct snd_serial_generic,
71 						   tx_work);
72 	struct snd_rawmidi_substream *substream = drvdata->midi_output;
73 
74 	clear_bit(SERIAL_TX_STATE_WAKEUP, &drvdata->tx_state);
75 
76 	while (!snd_rawmidi_transmit_empty(substream)) {
77 
78 		if (!test_bit(SERIAL_MODE_OUTPUT_OPEN, &drvdata->filemode))
79 			break;
80 
81 		num_bytes = snd_rawmidi_transmit_peek(substream, buf, INTERNAL_BUF_SIZE);
82 		num_bytes = serdev_device_write_buf(drvdata->serdev, buf, num_bytes);
83 
84 		if (!num_bytes)
85 			break;
86 
87 		snd_rawmidi_transmit_ack(substream, num_bytes);
88 
89 		if (!test_bit(SERIAL_TX_STATE_WAKEUP, &drvdata->tx_state))
90 			break;
91 	}
92 
93 	clear_bit(SERIAL_TX_STATE_ACTIVE, &drvdata->tx_state);
94 }
95 
snd_serial_generic_write_wakeup(struct serdev_device * serdev)96 static void snd_serial_generic_write_wakeup(struct serdev_device *serdev)
97 {
98 	struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev);
99 
100 	snd_serial_generic_tx_wakeup(drvdata);
101 }
102 
snd_serial_generic_receive_buf(struct serdev_device * serdev,const unsigned char * buf,size_t count)103 static int snd_serial_generic_receive_buf(struct serdev_device *serdev,
104 				const unsigned char *buf, size_t count)
105 {
106 	int ret;
107 	struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev);
108 
109 	if (!test_bit(SERIAL_MODE_INPUT_OPEN, &drvdata->filemode))
110 		return 0;
111 
112 	ret = snd_rawmidi_receive(drvdata->midi_input, buf, count);
113 	return ret < 0 ? 0 : ret;
114 }
115 
116 static const struct serdev_device_ops snd_serial_generic_serdev_device_ops = {
117 	.receive_buf = snd_serial_generic_receive_buf,
118 	.write_wakeup = snd_serial_generic_write_wakeup
119 };
120 
snd_serial_generic_ensure_serdev_open(struct snd_serial_generic * drvdata)121 static int snd_serial_generic_ensure_serdev_open(struct snd_serial_generic *drvdata)
122 {
123 	int err;
124 	unsigned int actual_baud;
125 
126 	if (drvdata->filemode)
127 		return 0;
128 
129 	dev_dbg(drvdata->card->dev, "Opening serial port for card %s\n",
130 		drvdata->card->shortname);
131 	err = serdev_device_open(drvdata->serdev);
132 	if (err < 0)
133 		return err;
134 
135 	actual_baud = serdev_device_set_baudrate(drvdata->serdev,
136 		drvdata->baudrate);
137 	if (actual_baud != drvdata->baudrate) {
138 		dev_warn(drvdata->card->dev, "requested %d baud for card %s but it was actually set to %d\n",
139 			drvdata->baudrate, drvdata->card->shortname, actual_baud);
140 	}
141 
142 	return 0;
143 }
144 
snd_serial_generic_input_open(struct snd_rawmidi_substream * substream)145 static int snd_serial_generic_input_open(struct snd_rawmidi_substream *substream)
146 {
147 	int err;
148 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
149 
150 	dev_dbg(drvdata->card->dev, "Opening input for card %s\n",
151 		drvdata->card->shortname);
152 
153 	err = snd_serial_generic_ensure_serdev_open(drvdata);
154 	if (err < 0)
155 		return err;
156 
157 	set_bit(SERIAL_MODE_INPUT_OPEN, &drvdata->filemode);
158 	drvdata->midi_input = substream;
159 	return 0;
160 }
161 
snd_serial_generic_input_close(struct snd_rawmidi_substream * substream)162 static int snd_serial_generic_input_close(struct snd_rawmidi_substream *substream)
163 {
164 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
165 
166 	dev_dbg(drvdata->card->dev, "Closing input for card %s\n",
167 		drvdata->card->shortname);
168 
169 	clear_bit(SERIAL_MODE_INPUT_OPEN, &drvdata->filemode);
170 	clear_bit(SERIAL_MODE_INPUT_TRIGGERED, &drvdata->filemode);
171 
172 	drvdata->midi_input = NULL;
173 
174 	if (!drvdata->filemode)
175 		serdev_device_close(drvdata->serdev);
176 	return 0;
177 }
178 
snd_serial_generic_input_trigger(struct snd_rawmidi_substream * substream,int up)179 static void snd_serial_generic_input_trigger(struct snd_rawmidi_substream *substream,
180 					int up)
181 {
182 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
183 
184 	if (up)
185 		set_bit(SERIAL_MODE_INPUT_TRIGGERED, &drvdata->filemode);
186 	else
187 		clear_bit(SERIAL_MODE_INPUT_TRIGGERED, &drvdata->filemode);
188 }
189 
snd_serial_generic_output_open(struct snd_rawmidi_substream * substream)190 static int snd_serial_generic_output_open(struct snd_rawmidi_substream *substream)
191 {
192 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
193 	int err;
194 
195 	dev_dbg(drvdata->card->dev, "Opening output for card %s\n",
196 		drvdata->card->shortname);
197 
198 	err = snd_serial_generic_ensure_serdev_open(drvdata);
199 	if (err < 0)
200 		return err;
201 
202 	set_bit(SERIAL_MODE_OUTPUT_OPEN, &drvdata->filemode);
203 
204 	drvdata->midi_output = substream;
205 	return 0;
206 };
207 
snd_serial_generic_output_close(struct snd_rawmidi_substream * substream)208 static int snd_serial_generic_output_close(struct snd_rawmidi_substream *substream)
209 {
210 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
211 
212 	dev_dbg(drvdata->card->dev, "Closing output for card %s\n",
213 		drvdata->card->shortname);
214 
215 	clear_bit(SERIAL_MODE_OUTPUT_OPEN, &drvdata->filemode);
216 	clear_bit(SERIAL_MODE_OUTPUT_TRIGGERED, &drvdata->filemode);
217 
218 	if (!drvdata->filemode)
219 		serdev_device_close(drvdata->serdev);
220 
221 	drvdata->midi_output = NULL;
222 
223 	return 0;
224 };
225 
snd_serial_generic_output_trigger(struct snd_rawmidi_substream * substream,int up)226 static void snd_serial_generic_output_trigger(struct snd_rawmidi_substream *substream,
227 					 int up)
228 {
229 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
230 
231 	if (up)
232 		set_bit(SERIAL_MODE_OUTPUT_TRIGGERED, &drvdata->filemode);
233 	else
234 		clear_bit(SERIAL_MODE_OUTPUT_TRIGGERED, &drvdata->filemode);
235 
236 	if (up)
237 		snd_serial_generic_tx_wakeup(drvdata);
238 }
239 
snd_serial_generic_output_drain(struct snd_rawmidi_substream * substream)240 static void snd_serial_generic_output_drain(struct snd_rawmidi_substream *substream)
241 {
242 	struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
243 
244 	/* Flush any pending characters */
245 	serdev_device_write_flush(drvdata->serdev);
246 	cancel_work_sync(&drvdata->tx_work);
247 }
248 
249 static const struct snd_rawmidi_ops snd_serial_generic_output = {
250 	.open =		snd_serial_generic_output_open,
251 	.close =	snd_serial_generic_output_close,
252 	.trigger =	snd_serial_generic_output_trigger,
253 	.drain =	snd_serial_generic_output_drain,
254 };
255 
256 static const struct snd_rawmidi_ops snd_serial_generic_input = {
257 	.open =		snd_serial_generic_input_open,
258 	.close =	snd_serial_generic_input_close,
259 	.trigger =	snd_serial_generic_input_trigger,
260 };
261 
snd_serial_generic_parse_dt(struct serdev_device * serdev,struct snd_serial_generic * drvdata)262 static void snd_serial_generic_parse_dt(struct serdev_device *serdev,
263 				struct snd_serial_generic *drvdata)
264 {
265 	int err;
266 
267 	err = of_property_read_u32(serdev->dev.of_node, "current-speed",
268 		&drvdata->baudrate);
269 	if (err < 0) {
270 		dev_dbg(drvdata->card->dev,
271 			"MIDI device reading of current-speed DT param failed with error %d, using default of 38400\n",
272 			err);
273 		drvdata->baudrate = 38400;
274 	}
275 
276 }
277 
snd_serial_generic_substreams(struct snd_rawmidi_str * stream,int dev_num)278 static void snd_serial_generic_substreams(struct snd_rawmidi_str *stream, int dev_num)
279 {
280 	struct snd_rawmidi_substream *substream;
281 
282 	list_for_each_entry(substream, &stream->substreams, list) {
283 		sprintf(substream->name, "Serial MIDI %d-%d", dev_num, substream->number);
284 	}
285 }
286 
snd_serial_generic_rmidi(struct snd_serial_generic * drvdata,int outs,int ins,struct snd_rawmidi ** rmidi)287 static int snd_serial_generic_rmidi(struct snd_serial_generic *drvdata,
288 				int outs, int ins, struct snd_rawmidi **rmidi)
289 {
290 	struct snd_rawmidi *rrawmidi;
291 	int err;
292 
293 	err = snd_rawmidi_new(drvdata->card, drvdata->card->driver, 0,
294 				outs, ins, &rrawmidi);
295 
296 	if (err < 0)
297 		return err;
298 
299 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
300 				&snd_serial_generic_input);
301 	snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
302 				&snd_serial_generic_output);
303 	strcpy(rrawmidi->name, drvdata->card->shortname);
304 
305 	snd_serial_generic_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT],
306 					drvdata->serdev->ctrl->nr);
307 	snd_serial_generic_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT],
308 					drvdata->serdev->ctrl->nr);
309 
310 	rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
311 			       SNDRV_RAWMIDI_INFO_INPUT |
312 			       SNDRV_RAWMIDI_INFO_DUPLEX;
313 
314 	if (rmidi)
315 		*rmidi = rrawmidi;
316 	return 0;
317 }
318 
snd_serial_generic_probe(struct serdev_device * serdev)319 static int snd_serial_generic_probe(struct serdev_device *serdev)
320 {
321 	struct snd_card *card;
322 	struct snd_serial_generic *drvdata;
323 	int err;
324 
325 	err  = snd_devm_card_new(&serdev->dev, SNDRV_DEFAULT_IDX1,
326 				SNDRV_DEFAULT_STR1, THIS_MODULE,
327 				sizeof(struct snd_serial_generic), &card);
328 
329 	if (err < 0)
330 		return err;
331 
332 	strcpy(card->driver, "SerialMIDI");
333 	sprintf(card->shortname, "SerialMIDI-%d", serdev->ctrl->nr);
334 	sprintf(card->longname, "Serial MIDI device at serial%d", serdev->ctrl->nr);
335 
336 	drvdata = card->private_data;
337 
338 	drvdata->serdev = serdev;
339 	drvdata->card = card;
340 
341 	snd_serial_generic_parse_dt(serdev, drvdata);
342 
343 	INIT_WORK(&drvdata->tx_work, snd_serial_generic_tx_work);
344 
345 	err = snd_serial_generic_rmidi(drvdata, 1, 1, &drvdata->rmidi);
346 	if (err < 0)
347 		return err;
348 
349 	serdev_device_set_client_ops(serdev, &snd_serial_generic_serdev_device_ops);
350 	serdev_device_set_drvdata(drvdata->serdev, drvdata);
351 
352 	err = snd_card_register(card);
353 	if (err < 0)
354 		return err;
355 
356 	return 0;
357 }
358 
359 static const struct of_device_id snd_serial_generic_dt_ids[] = {
360 	{ .compatible = "serial-midi" },
361 	{},
362 };
363 
364 MODULE_DEVICE_TABLE(of, snd_serial_generic_dt_ids);
365 
366 static struct serdev_device_driver snd_serial_generic_driver = {
367 	.driver	= {
368 		.name		= "snd-serial-generic",
369 		.of_match_table	= of_match_ptr(snd_serial_generic_dt_ids),
370 	},
371 	.probe	= snd_serial_generic_probe,
372 };
373 
374 module_serdev_device_driver(snd_serial_generic_driver);
375