1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Function Control Protocol (IEC 61883-1) helper functions
4 *
5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
6 */
7
8#include <linux/device.h>
9#include <linux/firewire.h>
10#include <linux/firewire-constants.h>
11#include <linux/list.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/sched.h>
15#include <linux/spinlock.h>
16#include <linux/wait.h>
17#include <linux/delay.h>
18#include "fcp.h"
19#include "lib.h"
20#include "amdtp-stream.h"
21
22#define CTS_AVC 0x00
23
24#define ERROR_RETRIES	3
25#define ERROR_DELAY_MS	5
26#define FCP_TIMEOUT_MS	125
27
28int avc_general_set_sig_fmt(struct fw_unit *unit, unsigned int rate,
29			    enum avc_general_plug_dir dir,
30			    unsigned short pid)
31{
32	unsigned int sfc;
33	u8 *buf;
34	bool flag;
35	int err;
36
37	flag = false;
38	for (sfc = 0; sfc < CIP_SFC_COUNT; sfc++) {
39		if (amdtp_rate_table[sfc] == rate) {
40			flag = true;
41			break;
42		}
43	}
44	if (!flag)
45		return -EINVAL;
46
47	buf = kzalloc(8, GFP_KERNEL);
48	if (buf == NULL)
49		return -ENOMEM;
50
51	buf[0] = 0x00;		/* AV/C CONTROL */
52	buf[1] = 0xff;		/* UNIT */
53	if (dir == AVC_GENERAL_PLUG_DIR_IN)
54		buf[2] = 0x19;	/* INPUT PLUG SIGNAL FORMAT */
55	else
56		buf[2] = 0x18;	/* OUTPUT PLUG SIGNAL FORMAT */
57	buf[3] = 0xff & pid;	/* plug id */
58	buf[4] = 0x90;		/* EOH_1, Form_1, FMT. AM824 */
59	buf[5] = 0x07 & sfc;	/* FDF-hi. AM824, frequency */
60	buf[6] = 0xff;		/* FDF-mid. AM824, SYT hi (not used)*/
61	buf[7] = 0xff;		/* FDF-low. AM824, SYT lo (not used) */
62
63	/* do transaction and check buf[1-5] are the same against command */
64	err = fcp_avc_transaction(unit, buf, 8, buf, 8,
65				  BIT(1) | BIT(2) | BIT(3) | BIT(4) | BIT(5));
66	if (err < 0)
67		;
68	else if (err < 8)
69		err = -EIO;
70	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
71		err = -ENOSYS;
72	else if (buf[0] == 0x0a) /* REJECTED */
73		err = -EINVAL;
74	if (err < 0)
75		goto end;
76
77	err = 0;
78end:
79	kfree(buf);
80	return err;
81}
82EXPORT_SYMBOL(avc_general_set_sig_fmt);
83
84int avc_general_get_sig_fmt(struct fw_unit *unit, unsigned int *rate,
85			    enum avc_general_plug_dir dir,
86			    unsigned short pid)
87{
88	unsigned int sfc;
89	u8 *buf;
90	int err;
91
92	buf = kzalloc(8, GFP_KERNEL);
93	if (buf == NULL)
94		return -ENOMEM;
95
96	buf[0] = 0x01;		/* AV/C STATUS */
97	buf[1] = 0xff;		/* Unit */
98	if (dir == AVC_GENERAL_PLUG_DIR_IN)
99		buf[2] = 0x19;	/* INPUT PLUG SIGNAL FORMAT */
100	else
101		buf[2] = 0x18;	/* OUTPUT PLUG SIGNAL FORMAT */
102	buf[3] = 0xff & pid;	/* plug id */
103	buf[4] = 0x90;		/* EOH_1, Form_1, FMT. AM824 */
104	buf[5] = 0xff;		/* FDF-hi. AM824, frequency */
105	buf[6] = 0xff;		/* FDF-mid. AM824, SYT hi (not used) */
106	buf[7] = 0xff;		/* FDF-low. AM824, SYT lo (not used) */
107
108	/* do transaction and check buf[1-4] are the same against command */
109	err = fcp_avc_transaction(unit, buf, 8, buf, 8,
110				  BIT(1) | BIT(2) | BIT(3) | BIT(4));
111	if (err < 0)
112		;
113	else if (err < 8)
114		err = -EIO;
115	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
116		err = -ENOSYS;
117	else if (buf[0] == 0x0a) /* REJECTED */
118		err = -EINVAL;
119	else if (buf[0] == 0x0b) /* IN TRANSITION */
120		err = -EAGAIN;
121	if (err < 0)
122		goto end;
123
124	/* check sfc field and pick up rate */
125	sfc = 0x07 & buf[5];
126	if (sfc >= CIP_SFC_COUNT) {
127		err = -EAGAIN;	/* also in transition */
128		goto end;
129	}
130
131	*rate = amdtp_rate_table[sfc];
132	err = 0;
133end:
134	kfree(buf);
135	return err;
136}
137EXPORT_SYMBOL(avc_general_get_sig_fmt);
138
139int avc_general_get_plug_info(struct fw_unit *unit, unsigned int subunit_type,
140			      unsigned int subunit_id, unsigned int subfunction,
141			      u8 info[AVC_PLUG_INFO_BUF_BYTES])
142{
143	u8 *buf;
144	int err;
145
146	/* extended subunit in spec.4.2 is not supported */
147	if ((subunit_type == 0x1E) || (subunit_id == 5))
148		return -EINVAL;
149
150	buf = kzalloc(8, GFP_KERNEL);
151	if (buf == NULL)
152		return -ENOMEM;
153
154	buf[0] = 0x01;	/* AV/C STATUS */
155	/* UNIT or Subunit, Functionblock */
156	buf[1] = ((subunit_type & 0x1f) << 3) | (subunit_id & 0x7);
157	buf[2] = 0x02;	/* PLUG INFO */
158	buf[3] = 0xff & subfunction;
159
160	err = fcp_avc_transaction(unit, buf, 8, buf, 8, BIT(1) | BIT(2));
161	if (err < 0)
162		;
163	else if (err < 8)
164		err = -EIO;
165	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
166		err = -ENOSYS;
167	else if (buf[0] == 0x0a) /* REJECTED */
168		err = -EINVAL;
169	else if (buf[0] == 0x0b) /* IN TRANSITION */
170		err = -EAGAIN;
171	if (err < 0)
172		goto end;
173
174	info[0] = buf[4];
175	info[1] = buf[5];
176	info[2] = buf[6];
177	info[3] = buf[7];
178
179	err = 0;
180end:
181	kfree(buf);
182	return err;
183}
184EXPORT_SYMBOL(avc_general_get_plug_info);
185
186static DEFINE_SPINLOCK(transactions_lock);
187static LIST_HEAD(transactions);
188
189enum fcp_state {
190	STATE_PENDING,
191	STATE_BUS_RESET,
192	STATE_COMPLETE,
193	STATE_DEFERRED,
194};
195
196struct fcp_transaction {
197	struct list_head list;
198	struct fw_unit *unit;
199	void *response_buffer;
200	unsigned int response_size;
201	unsigned int response_match_bytes;
202	enum fcp_state state;
203	wait_queue_head_t wait;
204	bool deferrable;
205};
206
207/**
208 * fcp_avc_transaction - send an AV/C command and wait for its response
209 * @unit: a unit on the target device
210 * @command: a buffer containing the command frame; must be DMA-able
211 * @command_size: the size of @command
212 * @response: a buffer for the response frame
213 * @response_size: the maximum size of @response
214 * @response_match_bytes: a bitmap specifying the bytes used to detect the
215 *                        correct response frame
216 *
217 * This function sends a FCP command frame to the target and waits for the
218 * corresponding response frame to be returned.
219 *
220 * Because it is possible for multiple FCP transactions to be active at the
221 * same time, the correct response frame is detected by the value of certain
222 * bytes.  These bytes must be set in @response before calling this function,
223 * and the corresponding bits must be set in @response_match_bytes.
224 *
225 * @command and @response can point to the same buffer.
226 *
227 * Returns the actual size of the response frame, or a negative error code.
228 */
229int fcp_avc_transaction(struct fw_unit *unit,
230			const void *command, unsigned int command_size,
231			void *response, unsigned int response_size,
232			unsigned int response_match_bytes)
233{
234	struct fcp_transaction t;
235	int tcode, ret, tries = 0;
236
237	t.unit = unit;
238	t.response_buffer = response;
239	t.response_size = response_size;
240	t.response_match_bytes = response_match_bytes;
241	t.state = STATE_PENDING;
242	init_waitqueue_head(&t.wait);
243	t.deferrable = (*(const u8 *)command == 0x00 || *(const u8 *)command == 0x03);
244
245	spin_lock_irq(&transactions_lock);
246	list_add_tail(&t.list, &transactions);
247	spin_unlock_irq(&transactions_lock);
248
249	for (;;) {
250		tcode = command_size == 4 ? TCODE_WRITE_QUADLET_REQUEST
251					  : TCODE_WRITE_BLOCK_REQUEST;
252		ret = snd_fw_transaction(t.unit, tcode,
253					 CSR_REGISTER_BASE + CSR_FCP_COMMAND,
254					 (void *)command, command_size, 0);
255		if (ret < 0)
256			break;
257deferred:
258		wait_event_timeout(t.wait, t.state != STATE_PENDING,
259				   msecs_to_jiffies(FCP_TIMEOUT_MS));
260
261		if (t.state == STATE_DEFERRED) {
262			/*
263			 * 'AV/C General Specification' define no time limit
264			 * on command completion once an INTERIM response has
265			 * been sent. but we promise to finish this function
266			 * for a caller. Here we use FCP_TIMEOUT_MS for next
267			 * interval. This is not in the specification.
268			 */
269			t.state = STATE_PENDING;
270			goto deferred;
271		} else if (t.state == STATE_COMPLETE) {
272			ret = t.response_size;
273			break;
274		} else if (t.state == STATE_BUS_RESET) {
275			msleep(ERROR_DELAY_MS);
276		} else if (++tries >= ERROR_RETRIES) {
277			dev_err(&t.unit->device, "FCP command timed out\n");
278			ret = -EIO;
279			break;
280		}
281	}
282
283	spin_lock_irq(&transactions_lock);
284	list_del(&t.list);
285	spin_unlock_irq(&transactions_lock);
286
287	return ret;
288}
289EXPORT_SYMBOL(fcp_avc_transaction);
290
291/**
292 * fcp_bus_reset - inform the target handler about a bus reset
293 * @unit: the unit that might be used by fcp_avc_transaction()
294 *
295 * This function must be called from the driver's .update handler to inform
296 * the FCP transaction handler that a bus reset has happened.  Any pending FCP
297 * transactions are retried.
298 */
299void fcp_bus_reset(struct fw_unit *unit)
300{
301	struct fcp_transaction *t;
302
303	spin_lock_irq(&transactions_lock);
304	list_for_each_entry(t, &transactions, list) {
305		if (t->unit == unit &&
306		    (t->state == STATE_PENDING ||
307		     t->state == STATE_DEFERRED)) {
308			t->state = STATE_BUS_RESET;
309			wake_up(&t->wait);
310		}
311	}
312	spin_unlock_irq(&transactions_lock);
313}
314EXPORT_SYMBOL(fcp_bus_reset);
315
316/* checks whether the response matches the masked bytes in response_buffer */
317static bool is_matching_response(struct fcp_transaction *transaction,
318				 const void *response, size_t length)
319{
320	const u8 *p1, *p2;
321	unsigned int mask, i;
322
323	p1 = response;
324	p2 = transaction->response_buffer;
325	mask = transaction->response_match_bytes;
326
327	for (i = 0; ; ++i) {
328		if ((mask & 1) && p1[i] != p2[i])
329			return false;
330		mask >>= 1;
331		if (!mask)
332			return true;
333		if (--length == 0)
334			return false;
335	}
336}
337
338static void fcp_response(struct fw_card *card, struct fw_request *request,
339			 int tcode, int destination, int source,
340			 int generation, unsigned long long offset,
341			 void *data, size_t length, void *callback_data)
342{
343	struct fcp_transaction *t;
344	unsigned long flags;
345
346	if (length < 1 || (*(const u8 *)data & 0xf0) != CTS_AVC)
347		return;
348
349	spin_lock_irqsave(&transactions_lock, flags);
350	list_for_each_entry(t, &transactions, list) {
351		struct fw_device *device = fw_parent_device(t->unit);
352		if (device->card != card ||
353		    device->generation != generation)
354			continue;
355		smp_rmb(); /* node_id vs. generation */
356		if (device->node_id != source)
357			continue;
358
359		if (t->state == STATE_PENDING &&
360		    is_matching_response(t, data, length)) {
361			if (t->deferrable && *(const u8 *)data == 0x0f) {
362				t->state = STATE_DEFERRED;
363			} else {
364				t->state = STATE_COMPLETE;
365				t->response_size = min_t(unsigned int, length,
366							 t->response_size);
367				memcpy(t->response_buffer, data,
368				       t->response_size);
369			}
370			wake_up(&t->wait);
371		}
372	}
373	spin_unlock_irqrestore(&transactions_lock, flags);
374}
375
376static struct fw_address_handler response_register_handler = {
377	.length = 0x200,
378	.address_callback = fcp_response,
379};
380
381static int __init fcp_module_init(void)
382{
383	static const struct fw_address_region response_register_region = {
384		.start = CSR_REGISTER_BASE + CSR_FCP_RESPONSE,
385		.end = CSR_REGISTER_BASE + CSR_FCP_END,
386	};
387
388	fw_core_add_address_handler(&response_register_handler,
389				    &response_register_region);
390
391	return 0;
392}
393
394static void __exit fcp_module_exit(void)
395{
396	WARN_ON(!list_empty(&transactions));
397	fw_core_remove_address_handler(&response_register_handler);
398}
399
400module_init(fcp_module_init);
401module_exit(fcp_module_exit);
402