1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Connection Management Procedures (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/module.h>
12#include <linux/sched.h>
13#include "lib.h"
14#include "iso-resources.h"
15#include "cmp.h"
16
17/* MPR common fields */
18#define MPR_SPEED_MASK		0xc0000000
19#define MPR_SPEED_SHIFT		30
20#define MPR_XSPEED_MASK		0x00000060
21#define MPR_XSPEED_SHIFT	5
22#define MPR_PLUGS_MASK		0x0000001f
23
24/* PCR common fields */
25#define PCR_ONLINE		0x80000000
26#define PCR_BCAST_CONN		0x40000000
27#define PCR_P2P_CONN_MASK	0x3f000000
28#define PCR_P2P_CONN_SHIFT	24
29#define PCR_CHANNEL_MASK	0x003f0000
30#define PCR_CHANNEL_SHIFT	16
31
32/* oPCR specific fields */
33#define OPCR_XSPEED_MASK	0x00C00000
34#define OPCR_XSPEED_SHIFT	22
35#define OPCR_SPEED_MASK		0x0000C000
36#define OPCR_SPEED_SHIFT	14
37#define OPCR_OVERHEAD_ID_MASK	0x00003C00
38#define OPCR_OVERHEAD_ID_SHIFT	10
39
40enum bus_reset_handling {
41	ABORT_ON_BUS_RESET,
42	SUCCEED_ON_BUS_RESET,
43};
44
45static __printf(2, 3)
46void cmp_error(struct cmp_connection *c, const char *fmt, ...)
47{
48	va_list va;
49
50	va_start(va, fmt);
51	dev_err(&c->resources.unit->device, "%cPCR%u: %pV",
52		(c->direction == CMP_INPUT) ? 'i' : 'o',
53		c->pcr_index, &(struct va_format){ fmt, &va });
54	va_end(va);
55}
56
57static u64 mpr_address(struct cmp_connection *c)
58{
59	if (c->direction == CMP_INPUT)
60		return CSR_REGISTER_BASE + CSR_IMPR;
61	else
62		return CSR_REGISTER_BASE + CSR_OMPR;
63}
64
65static u64 pcr_address(struct cmp_connection *c)
66{
67	if (c->direction == CMP_INPUT)
68		return CSR_REGISTER_BASE + CSR_IPCR(c->pcr_index);
69	else
70		return CSR_REGISTER_BASE + CSR_OPCR(c->pcr_index);
71}
72
73static int pcr_modify(struct cmp_connection *c,
74		      __be32 (*modify)(struct cmp_connection *c, __be32 old),
75		      int (*check)(struct cmp_connection *c, __be32 pcr),
76		      enum bus_reset_handling bus_reset_handling)
77{
78	__be32 old_arg, buffer[2];
79	int err;
80
81	buffer[0] = c->last_pcr_value;
82	for (;;) {
83		old_arg = buffer[0];
84		buffer[1] = modify(c, buffer[0]);
85
86		err = snd_fw_transaction(
87				c->resources.unit, TCODE_LOCK_COMPARE_SWAP,
88				pcr_address(c), buffer, 8,
89				FW_FIXED_GENERATION | c->resources.generation);
90
91		if (err < 0) {
92			if (err == -EAGAIN &&
93			    bus_reset_handling == SUCCEED_ON_BUS_RESET)
94				err = 0;
95			return err;
96		}
97
98		if (buffer[0] == old_arg) /* success? */
99			break;
100
101		if (check) {
102			err = check(c, buffer[0]);
103			if (err < 0)
104				return err;
105		}
106	}
107	c->last_pcr_value = buffer[1];
108
109	return 0;
110}
111
112
113/**
114 * cmp_connection_init - initializes a connection manager
115 * @c: the connection manager to initialize
116 * @unit: a unit of the target device
117 * @direction: input or output
118 * @pcr_index: the index of the iPCR/oPCR on the target device
119 */
120int cmp_connection_init(struct cmp_connection *c,
121			struct fw_unit *unit,
122			enum cmp_direction direction,
123			unsigned int pcr_index)
124{
125	__be32 mpr_be;
126	u32 mpr;
127	int err;
128
129	c->direction = direction;
130	err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
131				 mpr_address(c), &mpr_be, 4, 0);
132	if (err < 0)
133		return err;
134	mpr = be32_to_cpu(mpr_be);
135
136	if (pcr_index >= (mpr & MPR_PLUGS_MASK))
137		return -EINVAL;
138
139	err = fw_iso_resources_init(&c->resources, unit);
140	if (err < 0)
141		return err;
142
143	c->connected = false;
144	mutex_init(&c->mutex);
145	c->last_pcr_value = cpu_to_be32(0x80000000);
146	c->pcr_index = pcr_index;
147	c->max_speed = (mpr & MPR_SPEED_MASK) >> MPR_SPEED_SHIFT;
148	if (c->max_speed == SCODE_BETA)
149		c->max_speed += (mpr & MPR_XSPEED_MASK) >> MPR_XSPEED_SHIFT;
150
151	return 0;
152}
153EXPORT_SYMBOL(cmp_connection_init);
154
155/**
156 * cmp_connection_check_used - check connection is already esablished or not
157 * @c: the connection manager to be checked
158 * @used: the pointer to store the result of checking the connection
159 */
160int cmp_connection_check_used(struct cmp_connection *c, bool *used)
161{
162	__be32 pcr;
163	int err;
164
165	err = snd_fw_transaction(
166			c->resources.unit, TCODE_READ_QUADLET_REQUEST,
167			pcr_address(c), &pcr, 4, 0);
168	if (err >= 0)
169		*used = !!(pcr & cpu_to_be32(PCR_BCAST_CONN |
170					     PCR_P2P_CONN_MASK));
171
172	return err;
173}
174EXPORT_SYMBOL(cmp_connection_check_used);
175
176/**
177 * cmp_connection_destroy - free connection manager resources
178 * @c: the connection manager
179 */
180void cmp_connection_destroy(struct cmp_connection *c)
181{
182	WARN_ON(c->connected);
183	mutex_destroy(&c->mutex);
184	fw_iso_resources_destroy(&c->resources);
185}
186EXPORT_SYMBOL(cmp_connection_destroy);
187
188int cmp_connection_reserve(struct cmp_connection *c,
189			   unsigned int max_payload_bytes)
190{
191	int err;
192
193	mutex_lock(&c->mutex);
194
195	if (WARN_ON(c->resources.allocated)) {
196		err = -EBUSY;
197		goto end;
198	}
199
200	c->speed = min(c->max_speed,
201		       fw_parent_device(c->resources.unit)->max_speed);
202
203	err = fw_iso_resources_allocate(&c->resources, max_payload_bytes,
204					c->speed);
205end:
206	mutex_unlock(&c->mutex);
207
208	return err;
209}
210EXPORT_SYMBOL(cmp_connection_reserve);
211
212void cmp_connection_release(struct cmp_connection *c)
213{
214	mutex_lock(&c->mutex);
215	fw_iso_resources_free(&c->resources);
216	mutex_unlock(&c->mutex);
217}
218EXPORT_SYMBOL(cmp_connection_release);
219
220static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
221{
222	ipcr &= ~cpu_to_be32(PCR_BCAST_CONN |
223			     PCR_P2P_CONN_MASK |
224			     PCR_CHANNEL_MASK);
225	ipcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
226	ipcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
227
228	return ipcr;
229}
230
231static int get_overhead_id(struct cmp_connection *c)
232{
233	int id;
234
235	/*
236	 * apply "oPCR overhead ID encoding"
237	 * the encoding table can convert up to 512.
238	 * here the value over 512 is converted as the same way as 512.
239	 */
240	for (id = 1; id < 16; id++) {
241		if (c->resources.bandwidth_overhead < (id << 5))
242			break;
243	}
244	if (id == 16)
245		id = 0;
246
247	return id;
248}
249
250static __be32 opcr_set_modify(struct cmp_connection *c, __be32 opcr)
251{
252	unsigned int spd, xspd;
253
254	/* generate speed and extended speed field value */
255	if (c->speed > SCODE_400) {
256		spd  = SCODE_800;
257		xspd = c->speed - SCODE_800;
258	} else {
259		spd = c->speed;
260		xspd = 0;
261	}
262
263	opcr &= ~cpu_to_be32(PCR_BCAST_CONN |
264			     PCR_P2P_CONN_MASK |
265			     OPCR_XSPEED_MASK |
266			     PCR_CHANNEL_MASK |
267			     OPCR_SPEED_MASK |
268			     OPCR_OVERHEAD_ID_MASK);
269	opcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
270	opcr |= cpu_to_be32(xspd << OPCR_XSPEED_SHIFT);
271	opcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
272	opcr |= cpu_to_be32(spd << OPCR_SPEED_SHIFT);
273	opcr |= cpu_to_be32(get_overhead_id(c) << OPCR_OVERHEAD_ID_SHIFT);
274
275	return opcr;
276}
277
278static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
279{
280	if (pcr & cpu_to_be32(PCR_BCAST_CONN |
281			      PCR_P2P_CONN_MASK)) {
282		cmp_error(c, "plug is already in use\n");
283		return -EBUSY;
284	}
285	if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
286		cmp_error(c, "plug is not on-line\n");
287		return -ECONNREFUSED;
288	}
289
290	return 0;
291}
292
293/**
294 * cmp_connection_establish - establish a connection to the target
295 * @c: the connection manager
296 *
297 * This function establishes a point-to-point connection from the local
298 * computer to the target by allocating isochronous resources (channel and
299 * bandwidth) and setting the target's input/output plug control register.
300 * When this function succeeds, the caller is responsible for starting
301 * transmitting packets.
302 */
303int cmp_connection_establish(struct cmp_connection *c)
304{
305	int err;
306
307	mutex_lock(&c->mutex);
308
309	if (WARN_ON(c->connected)) {
310		mutex_unlock(&c->mutex);
311		return -EISCONN;
312	}
313
314retry_after_bus_reset:
315	if (c->direction == CMP_OUTPUT)
316		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
317				 ABORT_ON_BUS_RESET);
318	else
319		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
320				 ABORT_ON_BUS_RESET);
321
322	if (err == -EAGAIN) {
323		err = fw_iso_resources_update(&c->resources);
324		if (err >= 0)
325			goto retry_after_bus_reset;
326	}
327	if (err >= 0)
328		c->connected = true;
329
330	mutex_unlock(&c->mutex);
331
332	return err;
333}
334EXPORT_SYMBOL(cmp_connection_establish);
335
336/**
337 * cmp_connection_update - update the connection after a bus reset
338 * @c: the connection manager
339 *
340 * This function must be called from the driver's .update handler to
341 * reestablish any connection that might have been active.
342 *
343 * Returns zero on success, or a negative error code.  On an error, the
344 * connection is broken and the caller must stop transmitting iso packets.
345 */
346int cmp_connection_update(struct cmp_connection *c)
347{
348	int err;
349
350	mutex_lock(&c->mutex);
351
352	if (!c->connected) {
353		mutex_unlock(&c->mutex);
354		return 0;
355	}
356
357	err = fw_iso_resources_update(&c->resources);
358	if (err < 0)
359		goto err_unconnect;
360
361	if (c->direction == CMP_OUTPUT)
362		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
363				 SUCCEED_ON_BUS_RESET);
364	else
365		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
366				 SUCCEED_ON_BUS_RESET);
367
368	if (err < 0)
369		goto err_unconnect;
370
371	mutex_unlock(&c->mutex);
372
373	return 0;
374
375err_unconnect:
376	c->connected = false;
377	mutex_unlock(&c->mutex);
378
379	return err;
380}
381EXPORT_SYMBOL(cmp_connection_update);
382
383static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
384{
385	return pcr & ~cpu_to_be32(PCR_BCAST_CONN | PCR_P2P_CONN_MASK);
386}
387
388/**
389 * cmp_connection_break - break the connection to the target
390 * @c: the connection manager
391 *
392 * This function deactives the connection in the target's input/output plug
393 * control register, and frees the isochronous resources of the connection.
394 * Before calling this function, the caller should cease transmitting packets.
395 */
396void cmp_connection_break(struct cmp_connection *c)
397{
398	int err;
399
400	mutex_lock(&c->mutex);
401
402	if (!c->connected) {
403		mutex_unlock(&c->mutex);
404		return;
405	}
406
407	err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
408	if (err < 0)
409		cmp_error(c, "plug is still connected\n");
410
411	c->connected = false;
412
413	mutex_unlock(&c->mutex);
414}
415EXPORT_SYMBOL(cmp_connection_break);
416