1/*
2 * Connection Management Procedures (IEC 61883-1) helper functions
3 *
4 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
5 * Licensed under the terms of the GNU General Public License, version 2.
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
188
189static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
190{
191	ipcr &= ~cpu_to_be32(PCR_BCAST_CONN |
192			     PCR_P2P_CONN_MASK |
193			     PCR_CHANNEL_MASK);
194	ipcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
195	ipcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
196
197	return ipcr;
198}
199
200static int get_overhead_id(struct cmp_connection *c)
201{
202	int id;
203
204	/*
205	 * apply "oPCR overhead ID encoding"
206	 * the encoding table can convert up to 512.
207	 * here the value over 512 is converted as the same way as 512.
208	 */
209	for (id = 1; id < 16; id++) {
210		if (c->resources.bandwidth_overhead < (id << 5))
211			break;
212	}
213	if (id == 16)
214		id = 0;
215
216	return id;
217}
218
219static __be32 opcr_set_modify(struct cmp_connection *c, __be32 opcr)
220{
221	unsigned int spd, xspd;
222
223	/* generate speed and extended speed field value */
224	if (c->speed > SCODE_400) {
225		spd  = SCODE_800;
226		xspd = c->speed - SCODE_800;
227	} else {
228		spd = c->speed;
229		xspd = 0;
230	}
231
232	opcr &= ~cpu_to_be32(PCR_BCAST_CONN |
233			     PCR_P2P_CONN_MASK |
234			     OPCR_XSPEED_MASK |
235			     PCR_CHANNEL_MASK |
236			     OPCR_SPEED_MASK |
237			     OPCR_OVERHEAD_ID_MASK);
238	opcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
239	opcr |= cpu_to_be32(xspd << OPCR_XSPEED_SHIFT);
240	opcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
241	opcr |= cpu_to_be32(spd << OPCR_SPEED_SHIFT);
242	opcr |= cpu_to_be32(get_overhead_id(c) << OPCR_OVERHEAD_ID_SHIFT);
243
244	return opcr;
245}
246
247static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
248{
249	if (pcr & cpu_to_be32(PCR_BCAST_CONN |
250			      PCR_P2P_CONN_MASK)) {
251		cmp_error(c, "plug is already in use\n");
252		return -EBUSY;
253	}
254	if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
255		cmp_error(c, "plug is not on-line\n");
256		return -ECONNREFUSED;
257	}
258
259	return 0;
260}
261
262/**
263 * cmp_connection_establish - establish a connection to the target
264 * @c: the connection manager
265 * @max_payload_bytes: the amount of data (including CIP headers) per packet
266 *
267 * This function establishes a point-to-point connection from the local
268 * computer to the target by allocating isochronous resources (channel and
269 * bandwidth) and setting the target's input/output plug control register.
270 * When this function succeeds, the caller is responsible for starting
271 * transmitting packets.
272 */
273int cmp_connection_establish(struct cmp_connection *c,
274			     unsigned int max_payload_bytes)
275{
276	int err;
277
278	if (WARN_ON(c->connected))
279		return -EISCONN;
280
281	c->speed = min(c->max_speed,
282		       fw_parent_device(c->resources.unit)->max_speed);
283
284	mutex_lock(&c->mutex);
285
286retry_after_bus_reset:
287	err = fw_iso_resources_allocate(&c->resources,
288					max_payload_bytes, c->speed);
289	if (err < 0)
290		goto err_mutex;
291
292	if (c->direction == CMP_OUTPUT)
293		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
294				 ABORT_ON_BUS_RESET);
295	else
296		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
297				 ABORT_ON_BUS_RESET);
298
299	if (err == -EAGAIN) {
300		fw_iso_resources_free(&c->resources);
301		goto retry_after_bus_reset;
302	}
303	if (err < 0)
304		goto err_resources;
305
306	c->connected = true;
307
308	mutex_unlock(&c->mutex);
309
310	return 0;
311
312err_resources:
313	fw_iso_resources_free(&c->resources);
314err_mutex:
315	mutex_unlock(&c->mutex);
316
317	return err;
318}
319EXPORT_SYMBOL(cmp_connection_establish);
320
321/**
322 * cmp_connection_update - update the connection after a bus reset
323 * @c: the connection manager
324 *
325 * This function must be called from the driver's .update handler to
326 * reestablish any connection that might have been active.
327 *
328 * Returns zero on success, or a negative error code.  On an error, the
329 * connection is broken and the caller must stop transmitting iso packets.
330 */
331int cmp_connection_update(struct cmp_connection *c)
332{
333	int err;
334
335	mutex_lock(&c->mutex);
336
337	if (!c->connected) {
338		mutex_unlock(&c->mutex);
339		return 0;
340	}
341
342	err = fw_iso_resources_update(&c->resources);
343	if (err < 0)
344		goto err_unconnect;
345
346	if (c->direction == CMP_OUTPUT)
347		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
348				 SUCCEED_ON_BUS_RESET);
349	else
350		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
351				 SUCCEED_ON_BUS_RESET);
352
353	if (err < 0)
354		goto err_resources;
355
356	mutex_unlock(&c->mutex);
357
358	return 0;
359
360err_resources:
361	fw_iso_resources_free(&c->resources);
362err_unconnect:
363	c->connected = false;
364	mutex_unlock(&c->mutex);
365
366	return err;
367}
368EXPORT_SYMBOL(cmp_connection_update);
369
370static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
371{
372	return pcr & ~cpu_to_be32(PCR_BCAST_CONN | PCR_P2P_CONN_MASK);
373}
374
375/**
376 * cmp_connection_break - break the connection to the target
377 * @c: the connection manager
378 *
379 * This function deactives the connection in the target's input/output plug
380 * control register, and frees the isochronous resources of the connection.
381 * Before calling this function, the caller should cease transmitting packets.
382 */
383void cmp_connection_break(struct cmp_connection *c)
384{
385	int err;
386
387	mutex_lock(&c->mutex);
388
389	if (!c->connected) {
390		mutex_unlock(&c->mutex);
391		return;
392	}
393
394	err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
395	if (err < 0)
396		cmp_error(c, "plug is still connected\n");
397
398	fw_iso_resources_free(&c->resources);
399
400	c->connected = false;
401
402	mutex_unlock(&c->mutex);
403}
404EXPORT_SYMBOL(cmp_connection_break);
405