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/*
* Function Control Protocol (IEC 61883-1) helper functions
*
* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
* Licensed under the terms of the GNU General Public License, version 2.
*/
#include <linux/device.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include "fcp.h"
#include "lib.h"
#define CTS_AVC 0x00
#define ERROR_RETRIES 3
#define ERROR_DELAY_MS 5
#define FCP_TIMEOUT_MS 125
static DEFINE_SPINLOCK(transactions_lock);
static LIST_HEAD(transactions);
enum fcp_state {
STATE_PENDING,
STATE_BUS_RESET,
STATE_COMPLETE,
};
struct fcp_transaction {
struct list_head list;
struct fw_unit *unit;
void *response_buffer;
unsigned int response_size;
unsigned int response_match_bytes;
enum fcp_state state;
wait_queue_head_t wait;
};
/**
* 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.
*
* Asynchronous operation (INTERIM, NOTIFY) is not supported at the moment.
*
* 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)
{
struct fcp_transaction t;
int tcode, ret, tries = 0;
t.unit = unit;
t.response_buffer = response;
t.response_size = response_size;
t.response_match_bytes = response_match_bytes;
t.state = STATE_PENDING;
init_waitqueue_head(&t.wait);
spin_lock_irq(&transactions_lock);
list_add_tail(&t.list, &transactions);
spin_unlock_irq(&transactions_lock);
for (;;) {
tcode = command_size == 4 ? TCODE_WRITE_QUADLET_REQUEST
: TCODE_WRITE_BLOCK_REQUEST;
ret = snd_fw_transaction(t.unit, tcode,
CSR_REGISTER_BASE + CSR_FCP_COMMAND,
(void *)command, command_size);
if (ret < 0)
break;
wait_event_timeout(t.wait, t.state != STATE_PENDING,
msecs_to_jiffies(FCP_TIMEOUT_MS));
if (t.state == STATE_COMPLETE) {
ret = t.response_size;
break;
} else if (t.state == STATE_BUS_RESET) {
msleep(ERROR_DELAY_MS);
} else if (++tries >= ERROR_RETRIES) {
dev_err(&t.unit->device, "FCP command timed out\n");
ret = -EIO;
break;
}
}
spin_lock_irq(&transactions_lock);
list_del(&t.list);
spin_unlock_irq(&transactions_lock);
return ret;
}
EXPORT_SYMBOL(fcp_avc_transaction);
/**
* 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)
{
struct fcp_transaction *t;
spin_lock_irq(&transactions_lock);
list_for_each_entry(t, &transactions, list) {
if (t->unit == unit &&
t->state == STATE_PENDING) {
t->state = STATE_BUS_RESET;
wake_up(&t->wait);
}
}
spin_unlock_irq(&transactions_lock);
}
EXPORT_SYMBOL(fcp_bus_reset);
/* 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)
{
const u8 *p1, *p2;
unsigned int mask, i;
p1 = response;
p2 = transaction->response_buffer;
mask = transaction->response_match_bytes;
for (i = 0; ; ++i) {
if ((mask & 1) && p1[i] != p2[i])
return false;
mask >>= 1;
if (!mask)
return true;
if (--length == 0)
return false;
}
}
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)
{
struct fcp_transaction *t;
unsigned long flags;
if (length < 1 || (*(const u8 *)data & 0xf0) != CTS_AVC)
return;
spin_lock_irqsave(&transactions_lock, flags);
list_for_each_entry(t, &transactions, list) {
struct fw_device *device = fw_parent_device(t->unit);
if (device->card != card ||
device->generation != generation)
continue;
smp_rmb(); /* node_id vs. generation */
if (device->node_id != source)
continue;
if (t->state == STATE_PENDING &&
is_matching_response(t, data, length)) {
t->state = STATE_COMPLETE;
t->response_size = min((unsigned int)length,
t->response_size);
memcpy(t->response_buffer, data, t->response_size);
wake_up(&t->wait);
}
}
spin_unlock_irqrestore(&transactions_lock, flags);
}
static struct fw_address_handler response_register_handler = {
.length = 0x200,
.address_callback = fcp_response,
};
static int __init fcp_module_init(void)
{
static const struct fw_address_region response_register_region = {
.start = CSR_REGISTER_BASE + CSR_FCP_RESPONSE,
.end = CSR_REGISTER_BASE + CSR_FCP_END,
};
fw_core_add_address_handler(&response_register_handler,
&response_register_region);
return 0;
}
static void __exit fcp_module_exit(void)
{
WARN_ON(!list_empty(&transactions));
fw_core_remove_address_handler(&response_register_handler);
}
module_init(fcp_module_init);
module_exit(fcp_module_exit);
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