sound/firewire/cmp.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Connection Management Procedures (IEC 61883-1) helper functions
  *
  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
  */

 #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);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Connection Management Procedures (IEC 61883-1) helper functions
	*
	* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
	*/

	#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);