224 lines
6.0 KiB
C
224 lines
6.0 KiB
C
/*
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* Function Control Protocol (IEC 61883-1) helper functions
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*
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* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
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* Licensed under the terms of the GNU General Public License, version 2.
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*/
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#include <linux/device.h>
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#include <linux/firewire.h>
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#include <linux/firewire-constants.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/wait.h>
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#include "fcp.h"
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#include "lib.h"
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#define CTS_AVC 0x00
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#define ERROR_RETRIES 3
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#define ERROR_DELAY_MS 5
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#define FCP_TIMEOUT_MS 125
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static DEFINE_SPINLOCK(transactions_lock);
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static LIST_HEAD(transactions);
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enum fcp_state {
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STATE_PENDING,
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STATE_BUS_RESET,
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STATE_COMPLETE,
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};
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struct fcp_transaction {
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struct list_head list;
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struct fw_unit *unit;
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void *response_buffer;
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unsigned int response_size;
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unsigned int response_match_bytes;
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enum fcp_state state;
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wait_queue_head_t wait;
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};
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/**
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* fcp_avc_transaction - send an AV/C command and wait for its response
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* @unit: a unit on the target device
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* @command: a buffer containing the command frame; must be DMA-able
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* @command_size: the size of @command
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* @response: a buffer for the response frame
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* @response_size: the maximum size of @response
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* @response_match_bytes: a bitmap specifying the bytes used to detect the
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* correct response frame
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*
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* This function sends a FCP command frame to the target and waits for the
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* corresponding response frame to be returned.
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*
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* Because it is possible for multiple FCP transactions to be active at the
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* same time, the correct response frame is detected by the value of certain
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* bytes. These bytes must be set in @response before calling this function,
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* and the corresponding bits must be set in @response_match_bytes.
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*
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* @command and @response can point to the same buffer.
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*
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* Asynchronous operation (INTERIM, NOTIFY) is not supported at the moment.
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*
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* Returns the actual size of the response frame, or a negative error code.
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*/
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int fcp_avc_transaction(struct fw_unit *unit,
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const void *command, unsigned int command_size,
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void *response, unsigned int response_size,
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unsigned int response_match_bytes)
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{
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struct fcp_transaction t;
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int tcode, ret, tries = 0;
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t.unit = unit;
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t.response_buffer = response;
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t.response_size = response_size;
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t.response_match_bytes = response_match_bytes;
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t.state = STATE_PENDING;
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init_waitqueue_head(&t.wait);
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spin_lock_irq(&transactions_lock);
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list_add_tail(&t.list, &transactions);
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spin_unlock_irq(&transactions_lock);
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for (;;) {
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tcode = command_size == 4 ? TCODE_WRITE_QUADLET_REQUEST
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: TCODE_WRITE_BLOCK_REQUEST;
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ret = snd_fw_transaction(t.unit, tcode,
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CSR_REGISTER_BASE + CSR_FCP_COMMAND,
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(void *)command, command_size);
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if (ret < 0)
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break;
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wait_event_timeout(t.wait, t.state != STATE_PENDING,
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msecs_to_jiffies(FCP_TIMEOUT_MS));
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if (t.state == STATE_COMPLETE) {
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ret = t.response_size;
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break;
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} else if (t.state == STATE_BUS_RESET) {
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msleep(ERROR_DELAY_MS);
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} else if (++tries >= ERROR_RETRIES) {
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dev_err(&t.unit->device, "FCP command timed out\n");
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ret = -EIO;
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break;
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}
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}
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spin_lock_irq(&transactions_lock);
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list_del(&t.list);
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spin_unlock_irq(&transactions_lock);
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return ret;
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}
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EXPORT_SYMBOL(fcp_avc_transaction);
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/**
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* fcp_bus_reset - inform the target handler about a bus reset
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* @unit: the unit that might be used by fcp_avc_transaction()
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*
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* This function must be called from the driver's .update handler to inform
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* the FCP transaction handler that a bus reset has happened. Any pending FCP
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* transactions are retried.
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*/
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void fcp_bus_reset(struct fw_unit *unit)
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{
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struct fcp_transaction *t;
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spin_lock_irq(&transactions_lock);
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list_for_each_entry(t, &transactions, list) {
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if (t->unit == unit &&
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t->state == STATE_PENDING) {
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t->state = STATE_BUS_RESET;
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wake_up(&t->wait);
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}
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}
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spin_unlock_irq(&transactions_lock);
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}
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EXPORT_SYMBOL(fcp_bus_reset);
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/* checks whether the response matches the masked bytes in response_buffer */
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static bool is_matching_response(struct fcp_transaction *transaction,
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const void *response, size_t length)
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{
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const u8 *p1, *p2;
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unsigned int mask, i;
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p1 = response;
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p2 = transaction->response_buffer;
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mask = transaction->response_match_bytes;
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for (i = 0; ; ++i) {
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if ((mask & 1) && p1[i] != p2[i])
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return false;
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mask >>= 1;
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if (!mask)
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return true;
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if (--length == 0)
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return false;
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}
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}
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static void fcp_response(struct fw_card *card, struct fw_request *request,
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int tcode, int destination, int source,
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int generation, unsigned long long offset,
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void *data, size_t length, void *callback_data)
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{
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struct fcp_transaction *t;
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unsigned long flags;
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if (length < 1 || (*(const u8 *)data & 0xf0) != CTS_AVC)
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return;
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spin_lock_irqsave(&transactions_lock, flags);
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list_for_each_entry(t, &transactions, list) {
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struct fw_device *device = fw_parent_device(t->unit);
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if (device->card != card ||
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device->generation != generation)
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continue;
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smp_rmb(); /* node_id vs. generation */
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if (device->node_id != source)
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continue;
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if (t->state == STATE_PENDING &&
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is_matching_response(t, data, length)) {
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t->state = STATE_COMPLETE;
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t->response_size = min((unsigned int)length,
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t->response_size);
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memcpy(t->response_buffer, data, t->response_size);
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wake_up(&t->wait);
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}
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}
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spin_unlock_irqrestore(&transactions_lock, flags);
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}
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static struct fw_address_handler response_register_handler = {
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.length = 0x200,
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.address_callback = fcp_response,
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};
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static int __init fcp_module_init(void)
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{
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static const struct fw_address_region response_register_region = {
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.start = CSR_REGISTER_BASE + CSR_FCP_RESPONSE,
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.end = CSR_REGISTER_BASE + CSR_FCP_END,
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};
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fw_core_add_address_handler(&response_register_handler,
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&response_register_region);
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return 0;
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}
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static void __exit fcp_module_exit(void)
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{
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WARN_ON(!list_empty(&transactions));
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fw_core_remove_address_handler(&response_register_handler);
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}
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module_init(fcp_module_init);
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module_exit(fcp_module_exit);
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