linux/sound/firewire/fcp.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Function Control Protocol (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/list.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include "fcp.h"
#include "lib.h"
#include "amdtp-stream.h"

#define CTS_AVC …

#define ERROR_RETRIES …
#define ERROR_DELAY_MS …
#define FCP_TIMEOUT_MS …

int avc_general_set_sig_fmt(struct fw_unit *unit, unsigned int rate,
			    enum avc_general_plug_dir dir,
			    unsigned short pid)
{ … }
EXPORT_SYMBOL(…);

int avc_general_get_sig_fmt(struct fw_unit *unit, unsigned int *rate,
			    enum avc_general_plug_dir dir,
			    unsigned short pid)
{ … }
EXPORT_SYMBOL(…);

int avc_general_get_plug_info(struct fw_unit *unit, unsigned int subunit_type,
			      unsigned int subunit_id, unsigned int subfunction,
			      u8 info[AVC_PLUG_INFO_BUF_BYTES])
{ … }
EXPORT_SYMBOL(…);

static DEFINE_SPINLOCK(transactions_lock);
static LIST_HEAD(transactions);

enum fcp_state { … };

struct fcp_transaction { … };

/**
 * fcp_avc_transaction - send an AV/C command and wait for its response
 * @unit: a unit on the target device
 * @command: a buffer containing the command frame; must be DMA-able
 * @command_size: the size of @command
 * @response: a buffer for the response frame
 * @response_size: the maximum size of @response
 * @response_match_bytes: a bitmap specifying the bytes used to detect the
 *                        correct response frame
 *
 * This function sends a FCP command frame to the target and waits for the
 * corresponding response frame to be returned.
 *
 * Because it is possible for multiple FCP transactions to be active at the
 * same time, the correct response frame is detected by the value of certain
 * bytes.  These bytes must be set in @response before calling this function,
 * and the corresponding bits must be set in @response_match_bytes.
 *
 * @command and @response can point to the same buffer.
 *
 * Returns the actual size of the response frame, or a negative error code.
 */
int fcp_avc_transaction(struct fw_unit *unit,
			const void *command, unsigned int command_size,
			void *response, unsigned int response_size,
			unsigned int response_match_bytes)
{ … }
EXPORT_SYMBOL(…);

/**
 * fcp_bus_reset - inform the target handler about a bus reset
 * @unit: the unit that might be used by fcp_avc_transaction()
 *
 * This function must be called from the driver's .update handler to inform
 * the FCP transaction handler that a bus reset has happened.  Any pending FCP
 * transactions are retried.
 */
void fcp_bus_reset(struct fw_unit *unit)
{ … }
EXPORT_SYMBOL(…);

/* checks whether the response matches the masked bytes in response_buffer */
static bool is_matching_response(struct fcp_transaction *transaction,
				 const void *response, size_t length)
{ … }

static void fcp_response(struct fw_card *card, struct fw_request *request,
			 int tcode, int destination, int source,
			 int generation, unsigned long long offset,
			 void *data, size_t length, void *callback_data)
{ … }

static struct fw_address_handler response_register_handler = …;

static int __init fcp_module_init(void)
{ … }

static void __exit fcp_module_exit(void)
{ … }

module_init(…) …;
module_exit(fcp_module_exit);