[linux.git] / sound / firewire / cmp.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Connection Management Procedures (IEC 61883-1) helper functions
 *
 * Copyright (c) Clemens Ladisch <[email protected]>
 */

#include <linux/device.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/module.h>
#include <linux/sched.h>
#include "lib.h"
#include "iso-resources.h"
#include "cmp.h"

/* MPR common fields */
#define MPR_SPEED_MASK		0xc0000000
#define MPR_SPEED_SHIFT		30
#define MPR_XSPEED_MASK		0x00000060
#define MPR_XSPEED_SHIFT	5
#define MPR_PLUGS_MASK		0x0000001f

/* PCR common fields */
#define PCR_ONLINE		0x80000000
#define PCR_BCAST_CONN		0x40000000
#define PCR_P2P_CONN_MASK	0x3f000000
#define PCR_P2P_CONN_SHIFT	24
#define PCR_CHANNEL_MASK	0x003f0000
#define PCR_CHANNEL_SHIFT	16

/* oPCR specific fields */
#define OPCR_XSPEED_MASK	0x00C00000
#define OPCR_XSPEED_SHIFT	22
#define OPCR_SPEED_MASK		0x0000C000
#define OPCR_SPEED_SHIFT	14
#define OPCR_OVERHEAD_ID_MASK	0x00003C00
#define OPCR_OVERHEAD_ID_SHIFT	10

enum bus_reset_handling {
	ABORT_ON_BUS_RESET,
	SUCCEED_ON_BUS_RESET,
};

static __printf(2, 3)
void cmp_error(struct cmp_connection *c, const char *fmt, ...)
{
	va_list va;

	va_start(va, fmt);
	dev_err(&c->resources.unit->device, "%cPCR%u: %pV",
		(c->direction == CMP_INPUT) ? 'i' : 'o',
		c->pcr_index, &(struct va_format){ fmt, &va });
	va_end(va);
}

static u64 mpr_address(struct cmp_connection *c)
{
	if (c->direction == CMP_INPUT)
		return CSR_REGISTER_BASE + CSR_IMPR;
	else
		return CSR_REGISTER_BASE + CSR_OMPR;
}

static u64 pcr_address(struct cmp_connection *c)
{
	if (c->direction == CMP_INPUT)
		return CSR_REGISTER_BASE + CSR_IPCR(c->pcr_index);
	else
		return CSR_REGISTER_BASE + CSR_OPCR(c->pcr_index);
}

static int pcr_modify(struct cmp_connection *c,
		      __be32 (*modify)(struct cmp_connection *c, __be32 old),
		      int (*check)(struct cmp_connection *c, __be32 pcr),
		      enum bus_reset_handling bus_reset_handling)
{
	__be32 old_arg, buffer[2];
	int err;

	buffer[0] = c->last_pcr_value;
	for (;;) {
		old_arg = buffer[0];
		buffer[1] = modify(c, buffer[0]);

		err = snd_fw_transaction(
				c->resources.unit, TCODE_LOCK_COMPARE_SWAP,
				pcr_address(c), buffer, 8,
				FW_FIXED_GENERATION | c->resources.generation);

		if (err < 0) {
			if (err == -EAGAIN &&
			    bus_reset_handling == SUCCEED_ON_BUS_RESET)
				err = 0;
			return err;
		}

		if (buffer[0] == old_arg) /* success? */
			break;

		if (check) {
			err = check(c, buffer[0]);
			if (err < 0)
				return err;
		}
	}
	c->last_pcr_value = buffer[1];

	return 0;
}


/**
 * cmp_connection_init - initializes a connection manager
 * @c: the connection manager to initialize
 * @unit: a unit of the target device
 * @direction: input or output
 * @pcr_index: the index of the iPCR/oPCR on the target device
 */
int cmp_connection_init(struct cmp_connection *c,
			struct fw_unit *unit,
			enum cmp_direction direction,
			unsigned int pcr_index)
{
	__be32 mpr_be;
	u32 mpr;
	int err;

	c->direction = direction;
	err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
				 mpr_address(c), &mpr_be, 4, 0);
	if (err < 0)
		return err;
	mpr = be32_to_cpu(mpr_be);

	if (pcr_index >= (mpr & MPR_PLUGS_MASK))
		return -EINVAL;

	err = fw_iso_resources_init(&c->resources, unit);
	if (err < 0)
		return err;

	c->connected = false;
	mutex_init(&c->mutex);
	c->last_pcr_value = cpu_to_be32(0x80000000);
	c->pcr_index = pcr_index;
	c->max_speed = (mpr & MPR_SPEED_MASK) >> MPR_SPEED_SHIFT;
	if (c->max_speed == SCODE_BETA)
		c->max_speed += (mpr & MPR_XSPEED_MASK) >> MPR_XSPEED_SHIFT;

	return 0;
}
EXPORT_SYMBOL(cmp_connection_init);

/**
 * cmp_connection_check_used - check connection is already esablished or not
 * @c: the connection manager to be checked
 * @used: the pointer to store the result of checking the connection
 */
int cmp_connection_check_used(struct cmp_connection *c, bool *used)
{
	__be32 pcr;
	int err;

	err = snd_fw_transaction(
			c->resources.unit, TCODE_READ_QUADLET_REQUEST,
			pcr_address(c), &pcr, 4, 0);
	if (err >= 0)
		*used = !!(pcr & cpu_to_be32(PCR_BCAST_CONN |
					     PCR_P2P_CONN_MASK));

	return err;
}
EXPORT_SYMBOL(cmp_connection_check_used);

/**
 * cmp_connection_destroy - free connection manager resources
 * @c: the connection manager
 */
void cmp_connection_destroy(struct cmp_connection *c)
{
	WARN_ON(c->connected);
	mutex_destroy(&c->mutex);
	fw_iso_resources_destroy(&c->resources);
}
EXPORT_SYMBOL(cmp_connection_destroy);

int cmp_connection_reserve(struct cmp_connection *c,
			   unsigned int max_payload_bytes)
{
	int err;

	mutex_lock(&c->mutex);

	if (WARN_ON(c->resources.allocated)) {
		err = -EBUSY;
		goto end;
	}

	c->speed = min(c->max_speed,
		       fw_parent_device(c->resources.unit)->max_speed);

	err = fw_iso_resources_allocate(&c->resources, max_payload_bytes,
					c->speed);
end:
	mutex_unlock(&c->mutex);

	return err;
}
EXPORT_SYMBOL(cmp_connection_reserve);

void cmp_connection_release(struct cmp_connection *c)
{
	mutex_lock(&c->mutex);
	fw_iso_resources_free(&c->resources);
	mutex_unlock(&c->mutex);
}
EXPORT_SYMBOL(cmp_connection_release);

static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
{
	ipcr &= ~cpu_to_be32(PCR_BCAST_CONN |
			     PCR_P2P_CONN_MASK |
			     PCR_CHANNEL_MASK);
	ipcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
	ipcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);

	return ipcr;
}

static int get_overhead_id(struct cmp_connection *c)
{
	int id;

	/*
	 * apply "oPCR overhead ID encoding"
	 * the encoding table can convert up to 512.
	 * here the value over 512 is converted as the same way as 512.
	 */
	for (id = 1; id < 16; id++) {
		if (c->resources.bandwidth_overhead < (id << 5))
			break;
	}
	if (id == 16)
		id = 0;

	return id;
}

static __be32 opcr_set_modify(struct cmp_connection *c, __be32 opcr)
{
	unsigned int spd, xspd;

	/* generate speed and extended speed field value */
	if (c->speed > SCODE_400) {
		spd  = SCODE_800;
		xspd = c->speed - SCODE_800;
	} else {
		spd = c->speed;
		xspd = 0;
	}

	opcr &= ~cpu_to_be32(PCR_BCAST_CONN |
			     PCR_P2P_CONN_MASK |
			     OPCR_XSPEED_MASK |
			     PCR_CHANNEL_MASK |
			     OPCR_SPEED_MASK |
			     OPCR_OVERHEAD_ID_MASK);
	opcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
	opcr |= cpu_to_be32(xspd << OPCR_XSPEED_SHIFT);
	opcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
	opcr |= cpu_to_be32(spd << OPCR_SPEED_SHIFT);
	opcr |= cpu_to_be32(get_overhead_id(c) << OPCR_OVERHEAD_ID_SHIFT);

	return opcr;
}

static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
{
	if (pcr & cpu_to_be32(PCR_BCAST_CONN |
			      PCR_P2P_CONN_MASK)) {
		cmp_error(c, "plug is already in use\n");
		return -EBUSY;
	}
	if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
		cmp_error(c, "plug is not on-line\n");
		return -ECONNREFUSED;
	}

	return 0;
}

/**
 * cmp_connection_establish - establish a connection to the target
 * @c: the connection manager
 *
 * This function establishes a point-to-point connection from the local
 * computer to the target by allocating isochronous resources (channel and
 * bandwidth) and setting the target's input/output plug control register.
 * When this function succeeds, the caller is responsible for starting
 * transmitting packets.
 */
int cmp_connection_establish(struct cmp_connection *c)
{
	int err;

	mutex_lock(&c->mutex);

	if (WARN_ON(c->connected)) {
		mutex_unlock(&c->mutex);
		return -EISCONN;
	}

retry_after_bus_reset:
	if (c->direction == CMP_OUTPUT)
		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
				 ABORT_ON_BUS_RESET);
	else
		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
				 ABORT_ON_BUS_RESET);

	if (err == -EAGAIN) {
		err = fw_iso_resources_update(&c->resources);
		if (err >= 0)
			goto retry_after_bus_reset;
	}
	if (err >= 0)
		c->connected = true;

	mutex_unlock(&c->mutex);

	return err;
}
EXPORT_SYMBOL(cmp_connection_establish);

/**
 * cmp_connection_update - update the connection after a bus reset
 * @c: the connection manager
 *
 * This function must be called from the driver's .update handler to
 * reestablish any connection that might have been active.
 *
 * Returns zero on success, or a negative error code.  On an error, the
 * connection is broken and the caller must stop transmitting iso packets.
 */
int cmp_connection_update(struct cmp_connection *c)
{
	int err;

	mutex_lock(&c->mutex);

	if (!c->connected) {
		mutex_unlock(&c->mutex);
		return 0;
	}

	err = fw_iso_resources_update(&c->resources);
	if (err < 0)
		goto err_unconnect;

	if (c->direction == CMP_OUTPUT)
		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
				 SUCCEED_ON_BUS_RESET);
	else
		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
				 SUCCEED_ON_BUS_RESET);

	if (err < 0)
		goto err_unconnect;

	mutex_unlock(&c->mutex);

	return 0;

err_unconnect:
	c->connected = false;
	mutex_unlock(&c->mutex);

	return err;
}
EXPORT_SYMBOL(cmp_connection_update);

static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
{
	return pcr & ~cpu_to_be32(PCR_BCAST_CONN | PCR_P2P_CONN_MASK);
}

/**
 * cmp_connection_break - break the connection to the target
 * @c: the connection manager
 *
 * This function deactives the connection in the target's input/output plug
 * control register, and frees the isochronous resources of the connection.
 * Before calling this function, the caller should cease transmitting packets.
 */
void cmp_connection_break(struct cmp_connection *c)
{
	int err;

	mutex_lock(&c->mutex);

	if (!c->connected) {
		mutex_unlock(&c->mutex);
		return;
	}

	err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
	if (err < 0)
		cmp_error(c, "plug is still connected\n");

	c->connected = false;

	mutex_unlock(&c->mutex);
}
EXPORT_SYMBOL(cmp_connection_break);
Commit	Line	Data
da607e19	1	// SPDX-License-Identifier: GPL-2.0-only
31ef9134 CL	2	/*
	3	* Connection Management Procedures (IEC 61883-1) helper functions
	4	*
	5	* Copyright (c) Clemens Ladisch <[email protected]>
31ef9134 CL	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
a7fa0d04 TS	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
31ef9134	31
44aff698 TS	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
31ef9134 CL	40	enum bus_reset_handling {
	41	ABORT_ON_BUS_RESET,
	42	SUCCEED_ON_BUS_RESET,
	43	};
	44
b9075fa9	45	static __printf(2, 3)
31ef9134 CL	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",
44aff698 TS	52	(c->direction == CMP_INPUT) ? 'i' : 'o',
44aff698 TS	53	c->pcr_index, &(struct va_format){ fmt, &va });
31ef9134 CL	54	va_end(va);
	55	}
	56
44aff698 TS	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
31ef9134 CL	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	{
f30e6d3e	78	__be32 old_arg, buffer[2];
31ef9134 CL	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
1b70485f CL	86	err = snd_fw_transaction(
1b70485f CL	87	c->resources.unit, TCODE_LOCK_COMPARE_SWAP,
44aff698	88	pcr_address(c), buffer, 8,
1b70485f CL	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	}
31ef9134 CL	106	}
	107	c->last_pcr_value = buffer[1];
	108
	109	return 0;
31ef9134 CL	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
5f217f90	117	* @direction: input or output
a7fa0d04	118	* @pcr_index: the index of the iPCR/oPCR on the target device
31ef9134 CL	119	*/
	120	int cmp_connection_init(struct cmp_connection *c,
	121	struct fw_unit *unit,
c68a1c65	122	enum cmp_direction direction,
a7fa0d04	123	unsigned int pcr_index)
31ef9134	124	{
a7fa0d04 TS	125	__be32 mpr_be;
a7fa0d04 TS	126	u32 mpr;
31ef9134 CL	127	int err;
31ef9134 CL	128
44aff698	129	c->direction = direction;
31ef9134	130	err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
44aff698	131	mpr_address(c), &mpr_be, 4, 0);
31ef9134 CL	132	if (err < 0)
31ef9134 CL	133	return err;
a7fa0d04	134	mpr = be32_to_cpu(mpr_be);
31ef9134	135
a7fa0d04	136	if (pcr_index >= (mpr & MPR_PLUGS_MASK))
31ef9134 CL	137	return -EINVAL;
31ef9134 CL	138
5b2599a0 CL	139	err = fw_iso_resources_init(&c->resources, unit);
	140	if (err < 0)
	141	return err;
	142
31ef9134 CL	143	c->connected = false;
31ef9134 CL	144	mutex_init(&c->mutex);
31ef9134	145	c->last_pcr_value = cpu_to_be32(0x80000000);
a7fa0d04 TS	146	c->pcr_index = pcr_index;
a7fa0d04 TS	147	c->max_speed = (mpr & MPR_SPEED_MASK) >> MPR_SPEED_SHIFT;
31ef9134	148	if (c->max_speed == SCODE_BETA)
a7fa0d04	149	c->max_speed += (mpr & MPR_XSPEED_MASK) >> MPR_XSPEED_SHIFT;
31ef9134 CL	150
	151	return 0;
	152	}
	153	EXPORT_SYMBOL(cmp_connection_init);
	154
b04479fb TS	155	/**
	156	* cmp_connection_check_used - check connection is already esablished or not
	157	* @c: the connection manager to be checked
5f217f90	158	* @used: the pointer to store the result of checking the connection
b04479fb TS	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)
51212eea TS	169	*used = !!(pcr & cpu_to_be32(PCR_BCAST_CONN \|
	170	PCR_P2P_CONN_MASK));
	171
b04479fb TS	172	return err;
	173	}
	174	EXPORT_SYMBOL(cmp_connection_check_used);
	175
31ef9134 CL	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
7bc93821 TS	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);
31ef9134 CL	219
	220	static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
	221	{
a7fa0d04 TS	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);
31ef9134 CL	227
	228	return ipcr;
	229	}
	230
44aff698 TS	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
a7fa0d04	278	static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
31ef9134	279	{
a7fa0d04 TS	280	if (pcr & cpu_to_be32(PCR_BCAST_CONN \|
a7fa0d04 TS	281	PCR_P2P_CONN_MASK)) {
31ef9134 CL	282	cmp_error(c, "plug is already in use\n");
	283	return -EBUSY;
	284	}
a7fa0d04	285	if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
31ef9134 CL	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
31ef9134 CL	296	*
	297	* This function establishes a point-to-point connection from the local
	298	* computer to the target by allocating isochronous resources (channel and
a7fa0d04 TS	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.
31ef9134	302	*/
7bc93821	303	int cmp_connection_establish(struct cmp_connection *c)
31ef9134 CL	304	{
	305	int err;
	306
31ef9134 CL	307	mutex_lock(&c->mutex);
31ef9134 CL	308
7bc93821 TS	309	if (WARN_ON(c->connected)) {
	310	mutex_unlock(&c->mutex);
	311	return -EISCONN;
	312	}
31ef9134	313
7bc93821	314	retry_after_bus_reset:
44aff698 TS	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
31ef9134	322	if (err == -EAGAIN) {
7bc93821 TS	323	err = fw_iso_resources_update(&c->resources);
	324	if (err >= 0)
	325	goto retry_after_bus_reset;
31ef9134	326	}
7bc93821 TS	327	if (err >= 0)
7bc93821 TS	328	c->connected = true;
31ef9134	329
31ef9134 CL	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	*
a7fa0d04 TS	340	* This function must be called from the driver's .update handler to
a7fa0d04 TS	341	* reestablish any connection that might have been active.
31ef9134 CL	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
44aff698 TS	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
31ef9134	368	if (err < 0)
7bc93821	369	goto err_unconnect;
31ef9134 CL	370
	371	mutex_unlock(&c->mutex);
	372
	373	return 0;
	374
31ef9134 CL	375	err_unconnect:
	376	c->connected = false;
	377	mutex_unlock(&c->mutex);
	378
	379	return err;
	380	}
	381	EXPORT_SYMBOL(cmp_connection_update);
	382
a7fa0d04	383	static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
31ef9134	384	{
a7fa0d04	385	return pcr & ~cpu_to_be32(PCR_BCAST_CONN \| PCR_P2P_CONN_MASK);
31ef9134 CL	386	}
	387
	388	/**
	389	* cmp_connection_break - break the connection to the target
	390	* @c: the connection manager
	391	*
a7fa0d04 TS	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.
31ef9134 CL	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
a7fa0d04	407	err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
31ef9134 CL	408	if (err < 0)
	409	cmp_error(c, "plug is still connected\n");
	410
31ef9134 CL	411	c->connected = false;
	412
	413	mutex_unlock(&c->mutex);
	414	}
	415	EXPORT_SYMBOL(cmp_connection_break);