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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Connection Management Procedures (IEC 61883-1) helper functions
4 *
5 * Copyright (c) Clemens Ladisch <[email protected]>
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 guard(mutex)(&c->mutex);
192
193 if (WARN_ON(c->resources.allocated))
194 return -EBUSY;
195
196 c->speed = min(c->max_speed,
197 fw_parent_device(c->resources.unit)->max_speed);
198
199 return fw_iso_resources_allocate(&c->resources, max_payload_bytes,
200 c->speed);
201}
202EXPORT_SYMBOL(cmp_connection_reserve);
203
204void cmp_connection_release(struct cmp_connection *c)
205{
206 guard(mutex)(&c->mutex);
207 fw_iso_resources_free(&c->resources);
208}
209EXPORT_SYMBOL(cmp_connection_release);
210
211static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
212{
213 ipcr &= ~cpu_to_be32(PCR_BCAST_CONN |
214 PCR_P2P_CONN_MASK |
215 PCR_CHANNEL_MASK);
216 ipcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
217 ipcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
218
219 return ipcr;
220}
221
222static int get_overhead_id(struct cmp_connection *c)
223{
224 int id;
225
226 /*
227 * apply "oPCR overhead ID encoding"
228 * the encoding table can convert up to 512.
229 * here the value over 512 is converted as the same way as 512.
230 */
231 for (id = 1; id < 16; id++) {
232 if (c->resources.bandwidth_overhead < (id << 5))
233 break;
234 }
235 if (id == 16)
236 id = 0;
237
238 return id;
239}
240
241static __be32 opcr_set_modify(struct cmp_connection *c, __be32 opcr)
242{
243 unsigned int spd, xspd;
244
245 /* generate speed and extended speed field value */
246 if (c->speed > SCODE_400) {
247 spd = SCODE_800;
248 xspd = c->speed - SCODE_800;
249 } else {
250 spd = c->speed;
251 xspd = 0;
252 }
253
254 opcr &= ~cpu_to_be32(PCR_BCAST_CONN |
255 PCR_P2P_CONN_MASK |
256 OPCR_XSPEED_MASK |
257 PCR_CHANNEL_MASK |
258 OPCR_SPEED_MASK |
259 OPCR_OVERHEAD_ID_MASK);
260 opcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
261 opcr |= cpu_to_be32(xspd << OPCR_XSPEED_SHIFT);
262 opcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
263 opcr |= cpu_to_be32(spd << OPCR_SPEED_SHIFT);
264 opcr |= cpu_to_be32(get_overhead_id(c) << OPCR_OVERHEAD_ID_SHIFT);
265
266 return opcr;
267}
268
269static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
270{
271 if (pcr & cpu_to_be32(PCR_BCAST_CONN |
272 PCR_P2P_CONN_MASK)) {
273 cmp_error(c, "plug is already in use\n");
274 return -EBUSY;
275 }
276 if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
277 cmp_error(c, "plug is not on-line\n");
278 return -ECONNREFUSED;
279 }
280
281 return 0;
282}
283
284/**
285 * cmp_connection_establish - establish a connection to the target
286 * @c: the connection manager
287 *
288 * This function establishes a point-to-point connection from the local
289 * computer to the target by allocating isochronous resources (channel and
290 * bandwidth) and setting the target's input/output plug control register.
291 * When this function succeeds, the caller is responsible for starting
292 * transmitting packets.
293 */
294int cmp_connection_establish(struct cmp_connection *c)
295{
296 int err;
297
298 guard(mutex)(&c->mutex);
299
300 if (WARN_ON(c->connected))
301 return -EISCONN;
302
303retry_after_bus_reset:
304 if (c->direction == CMP_OUTPUT)
305 err = pcr_modify(c, opcr_set_modify, pcr_set_check,
306 ABORT_ON_BUS_RESET);
307 else
308 err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
309 ABORT_ON_BUS_RESET);
310
311 if (err == -EAGAIN) {
312 err = fw_iso_resources_update(&c->resources);
313 if (err >= 0)
314 goto retry_after_bus_reset;
315 }
316 if (err >= 0)
317 c->connected = true;
318
319 return err;
320}
321EXPORT_SYMBOL(cmp_connection_establish);
322
323static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
324{
325 return pcr & ~cpu_to_be32(PCR_BCAST_CONN | PCR_P2P_CONN_MASK);
326}
327
328/**
329 * cmp_connection_break - break the connection to the target
330 * @c: the connection manager
331 *
332 * This function deactives the connection in the target's input/output plug
333 * control register, and frees the isochronous resources of the connection.
334 * Before calling this function, the caller should cease transmitting packets.
335 */
336void cmp_connection_break(struct cmp_connection *c)
337{
338 int err;
339
340 guard(mutex)(&c->mutex);
341
342 if (!c->connected)
343 return;
344
345 err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
346 if (err < 0)
347 cmp_error(c, "plug is still connected\n");
348
349 c->connected = false;
350}
351EXPORT_SYMBOL(cmp_connection_break);