mirror of https://github.com/ArduPilot/ardupilot
119 lines
3.6 KiB
C++
119 lines
3.6 KiB
C++
/*
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* This file is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Code by Andrew Tridgell and Siddharth Bharat Purohit
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*/
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#pragma once
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#include "AP_HAL_ChibiOS.h"
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#define SHARED_DMA_MAX_STREAM_ID (8*2)
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// DMA stream ID for stream_id2 when only one is needed
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#define SHARED_DMA_NONE 255
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#if AP_HAL_SHARED_DMA_ENABLED
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class ChibiOS::Shared_DMA
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{
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public:
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FUNCTOR_TYPEDEF(dma_allocate_fn_t, void, Shared_DMA *);
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FUNCTOR_TYPEDEF(dma_deallocate_fn_t, void, Shared_DMA *);
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// the use of two stream IDs is for support of peripherals that
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// need both a RX and TX DMA channel
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Shared_DMA(uint8_t stream_id1, uint8_t stream_id2,
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dma_allocate_fn_t allocate,
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dma_allocate_fn_t deallocate);
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// initialise the stream locks
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static void init(void);
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// blocking lock call
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void lock(void);
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// non-blocking lock call
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bool lock_nonblock(void);
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// unlock call. The DMA channel will not be immediately
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// deallocated. Instead it will be deallocated if another driver
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// needs it
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void unlock(bool success = true);
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//should be called inside the destructor of Shared DMA participants
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void unregister(void);
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// return true if this DMA channel is being actively contended for
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// by multiple drivers
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bool has_contention(void) const { return contention; }
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// is this DMA channel locked?
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bool is_locked(void) const { return have_lock; }
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// lock all shared DMA channels. Used on reboot
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static void lock_all(void);
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// display dma contention statistics as text buffer for @SYS/dma.txt
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static void dma_info(ExpandingString &str);
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// return true if a stream ID is shared between two peripherals
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static bool is_shared(uint8_t stream_id);
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bool is_shared();
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private:
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dma_allocate_fn_t allocate;
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dma_allocate_fn_t deallocate;
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uint8_t stream_id1;
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uint8_t stream_id2;
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bool have_lock;
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// we set the contention flag if two drivers are fighting over a DMA channel.
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// the UART driver uses this to change its max transmit size to reduce latency
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bool contention;
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// core of lock call, after semaphores gained
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void lock_core(void);
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// lock one stream
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static bool lock_stream(uint8_t stream_id);
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// unlock one stream
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void unlock_stream(uint8_t stream_id, bool success);
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// lock one stream, non-blocking
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bool lock_stream_nonblocking(uint8_t stream_id);
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static struct dma_lock {
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// semaphore to ensure only one peripheral uses a DMA channel at a time
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#if CH_CFG_USE_MUTEXES == TRUE
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mutex_t mutex;
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#endif // CH_CFG_USE_MUTEXES
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// a de-allocation function that is called to release an existing user
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dma_deallocate_fn_t deallocate;
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// point to object that holds the allocation, if allocated
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Shared_DMA *obj;
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} locks[SHARED_DMA_MAX_STREAM_ID+1];
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// contention statistics
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static volatile struct dma_stats {
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uint32_t contended_locks;
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uint32_t uncontended_locks;
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uint32_t transactions;
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} *_contention_stats;
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};
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#endif // AP_HAL_SHARED_DMA_ENABLED
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