cmp.c

  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	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);