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Merge pull request #1517 from martinling/locking-api

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Add a shim header to support locking without ldrex/strex
This commit is contained in:
Michael Ossmann
2024-12-17 12:14:03 -05:00
committed by GitHub
parent 46f43c3a9e f3e7d10d07
commit cfdfe8a1aa
3 changed files with 66 additions and 9 deletions
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55
firmware/common/locking.h Normal file
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@ -0,0 +1,55 @@
/*
* Copyright 2024 Great Scott Gadgets <info@greatscottgadgets.com>
*
* This file is part of HackRF.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __LOCKING_H__
#define __LOCKING_H__
#include <stdint.h>
#include <libopencm3/cm3/sync.h>
/* Primitives for implementing locking.
*
* Must always be used in a pair, with a call to load_exclusive being
* followed immediately or near-immediately by a call to store_exclusive().
* Failure to observe this rule may lead to undefined results. */
// Use ldrex and strex directly if available.
// Otherwise, disable interrupts to ensure exclusivity.
#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
#define load_exclusive __ldrex
#define store_exclusive __strex
#else
static inline uint32_t load_exclusive(volatile uint32_t* addr)
{
__disable_irq();
return *addr;
}
static inline uint32_t store_exclusive(uint32_t val, volatile uint32_t* addr)
{
*addr = val;
__enable_irq();
return 0;
}
#endif
#endif /* __LOCKING_H__ */

2
firmware/common/usb.c
View File

@ -29,7 +29,7 @@
#include "usb_standard_request.h"
#include <libopencm3/lpc43xx/creg.h>
#include <libopencm3/lpc43xx/m4/nvic.h>
#include <libopencm3/dispatch/nvic.h>
#include <libopencm3/lpc43xx/rgu.h>
#include <libopencm3/lpc43xx/usb.h>

16
firmware/common/usb_queue.c
View File

@ -27,8 +27,8 @@
#include <assert.h>
#include <libopencm3/cm3/cortex.h>
#include <libopencm3/cm3/sync.h>
#include "locking.h"
#include "usb.h"
#include "usb_queue.h"
@ -73,9 +73,9 @@ static usb_transfer_t* allocate_transfer(usb_queue_t* const queue)
}
do {
transfer = (void*) __ldrex((uint32_t*) &queue->free_transfers);
aborted =
__strex((uint32_t) transfer->next,
transfer = (void*) load_exclusive((uint32_t*) &queue->free_transfers);
aborted = store_exclusive(
(uint32_t) transfer->next,
(uint32_t*) &queue->free_transfers);
} while (aborted);
transfer->next = NULL;
@ -88,9 +88,11 @@ static void free_transfer(usb_transfer_t* const transfer)
usb_queue_t* const queue = transfer->queue;
bool aborted;
do {
transfer->next = (void*) __ldrex((uint32_t*) &queue->free_transfers);
aborted =
__strex((uint32_t) transfer, (uint32_t*) &queue->free_transfers);
transfer->next =
(void*) load_exclusive((uint32_t*) &queue->free_transfers);
aborted = store_exclusive(
(uint32_t) transfer,
(uint32_t*) &queue->free_transfers);
} while (aborted);
}