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
40 enum bus_reset_handling {
41 ABORT_ON_BUS_RESET,
42 SUCCEED_ON_BUS_RESET,
43 };
44
45 static __printf(2, 3)
46 void 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
57 static 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
65 static 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
73 static 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 */
120 int 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 }
153 EXPORT_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 */
160 int 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 }
174 EXPORT_SYMBOL(cmp_connection_check_used);
175
176 /**
177 * cmp_connection_destroy - free connection manager resources
178 * @c: the connection manager
179 */
180 void 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 }
186 EXPORT_SYMBOL(cmp_connection_destroy);
187
188 int 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);
205 end:
206 mutex_unlock(&c->mutex);
207
208 return err;
209 }
210 EXPORT_SYMBOL(cmp_connection_reserve);
211
212 void 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 }
218 EXPORT_SYMBOL(cmp_connection_release);
219
220 static __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
231 static 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
250 static __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
278 static 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 */
303 int 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
314 retry_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 }
334 EXPORT_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 */
346 int 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
375 err_unconnect:
376 c->connected = false;
377 mutex_unlock(&c->mutex);
378
379 return err;
380 }
381 EXPORT_SYMBOL(cmp_connection_update);
382
383 static __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 */
396 void 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 }
415 EXPORT_SYMBOL(cmp_connection_break);
416
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