mirror of
https://github.com/DCC-EX/CommandStation-EX.git
synced 2024-11-26 09:36:13 +01:00
265 lines
9.3 KiB
C
265 lines
9.3 KiB
C
/*
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* © 2022 Paul M Antoine
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* © 2021, Neil McKechnie
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* All rights reserved.
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*
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* This file is part of CommandStation-EX
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the 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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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* 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
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef I2CMANAGER_NONBLOCKING_H
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#define I2CMANAGER_NONBLOCKING_H
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#include <Arduino.h>
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#include "I2CManager.h"
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#if defined(I2C_USE_INTERRUPTS)
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// atomic.h isn't available on SAMD, and likely others too...
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#if defined(__AVR__)
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#include <util/atomic.h>
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#elif defined(__arm__)
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// Helper assembly language functions
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static __inline__ uint8_t my_iSeiRetVal(void)
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{
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__asm__ __volatile__ ("cpsie i" ::);
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return 1;
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}
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static __inline__ uint8_t my_iCliRetVal(void)
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{
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__asm__ __volatile__ ("cpsid i" ::);
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return 1;
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}
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static __inline__ void my_iRestore(const uint32_t *__s)
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{
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uint32_t res = *__s;
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__asm__ __volatile__ ("MSR primask, %0" : : "r" (res) );
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}
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static __inline__ uint32_t my_iGetIReg( void )
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{
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uint32_t reg;
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__asm__ __volatile__ ("MRS %0, primask" : "=r" (reg) );
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return reg;
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}
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// Macros for atomic isolation
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#define MY_ATOMIC_RESTORESTATE uint32_t _sa_saved \
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__attribute__((__cleanup__(my_iRestore))) = my_iGetIReg()
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#define ATOMIC() \
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for ( MY_ATOMIC_RESTORESTATE, _done = my_iCliRetVal(); \
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_done; _done = 0 )
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#define ATOMIC_BLOCK(x) ATOMIC()
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#define ATOMIC_RESTORESTATE
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#endif
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#else
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#define ATOMIC_BLOCK(x)
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#define ATOMIC_RESTORESTATE
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#endif
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// This module is only compiled if I2C_USE_WIRE is not defined, so undefine it here
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// to get intellisense to work correctly.
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#if defined(I2C_USE_WIRE)
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#undef I2C_USE_WIRE
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#endif
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/***************************************************************************
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* Initialise the I2CManagerAsync class.
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***************************************************************************/
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void I2CManagerClass::_initialise()
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{
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queueHead = queueTail = NULL;
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state = I2C_STATE_FREE;
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I2C_init();
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}
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/***************************************************************************
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* Set I2C clock speed. Normally 100000 (Standard) or 400000 (Fast)
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* on Arduino. Mega4809 supports 1000000 (Fast+) too.
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***************************************************************************/
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void I2CManagerClass::_setClock(unsigned long i2cClockSpeed) {
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I2C_setClock(i2cClockSpeed);
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}
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/***************************************************************************
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* Helper function to start operations, if the I2C interface is free and
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* there is a queued request to be processed.
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***************************************************************************/
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void I2CManagerClass::startTransaction() {
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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if ((state == I2C_STATE_FREE) && (queueHead != NULL)) {
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state = I2C_STATE_ACTIVE;
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currentRequest = queueHead;
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rxCount = txCount = 0;
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// Copy key fields to static data for speed.
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operation = currentRequest->operation;
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// Start the I2C process going.
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I2C_sendStart();
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startTime = micros();
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}
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}
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}
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/***************************************************************************
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* Function to queue a request block and initiate operations.
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***************************************************************************/
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void I2CManagerClass::queueRequest(I2CRB *req) {
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req->status = I2C_STATUS_PENDING;
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req->nextRequest = NULL;
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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if (!queueTail)
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queueHead = queueTail = req; // Only item on queue
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else
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queueTail = queueTail->nextRequest = req; // Add to end
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startTransaction();
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}
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}
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/***************************************************************************
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* Initiate a write to an I2C device (non-blocking operation)
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***************************************************************************/
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uint8_t I2CManagerClass::write(uint8_t i2cAddress, const uint8_t *writeBuffer, uint8_t writeLen, I2CRB *req) {
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// Make sure previous request has completed.
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req->wait();
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req->setWriteParams(i2cAddress, writeBuffer, writeLen);
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queueRequest(req);
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return I2C_STATUS_OK;
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}
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/***************************************************************************
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* Initiate a write from PROGMEM (flash) to an I2C device (non-blocking operation)
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***************************************************************************/
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uint8_t I2CManagerClass::write_P(uint8_t i2cAddress, const uint8_t * writeBuffer, uint8_t writeLen, I2CRB *req) {
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// Make sure previous request has completed.
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req->wait();
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req->setWriteParams(i2cAddress, writeBuffer, writeLen);
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req->operation = OPERATION_SEND_P;
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queueRequest(req);
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return I2C_STATUS_OK;
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}
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/***************************************************************************
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* Initiate a read from the I2C device, optionally preceded by a write
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* (non-blocking operation)
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***************************************************************************/
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uint8_t I2CManagerClass::read(uint8_t i2cAddress, uint8_t *readBuffer, uint8_t readLen,
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const uint8_t *writeBuffer, uint8_t writeLen, I2CRB *req)
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{
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// Make sure previous request has completed.
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req->wait();
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req->setRequestParams(i2cAddress, readBuffer, readLen, writeBuffer, writeLen);
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queueRequest(req);
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return I2C_STATUS_OK;
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}
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/***************************************************************************
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* checkForTimeout() function, called from isBusy() and wait() to cancel
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* requests that are taking too long to complete.
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* This function doesn't fully work as intended so is not currently called.
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* Instead we check for an I2C hang-up and report an error from
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* I2CRB::wait(), but we aren't able to recover from the hang-up. Such faults
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* may be caused by an I2C wire short for example.
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***************************************************************************/
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void I2CManagerClass::checkForTimeout() {
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unsigned long currentMicros = micros();
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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I2CRB *t = queueHead;
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if (state==I2C_STATE_ACTIVE && t!=0 && t==currentRequest && timeout > 0) {
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// Check for timeout
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if (currentMicros - startTime > timeout) {
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// Excessive time. Dequeue request
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queueHead = t->nextRequest;
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if (!queueHead) queueTail = NULL;
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currentRequest = NULL;
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// Post request as timed out.
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t->status = I2C_STATUS_TIMEOUT;
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// Reset TWI interface so it is able to continue
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// Try close and init, not entirely satisfactory but sort of works...
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I2C_close(); // Shutdown and restart twi interface
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I2C_init();
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state = I2C_STATE_FREE;
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// Initiate next queued request if any.
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startTransaction();
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}
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}
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}
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}
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/***************************************************************************
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* Loop function, for general background work
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***************************************************************************/
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void I2CManagerClass::loop() {
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#if !defined(I2C_USE_INTERRUPTS)
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handleInterrupt();
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#endif
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// Timeout is now reported in I2CRB::wait(), not here.
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// I've left the code, commented out, as a reminder to look at this again
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// in the future.
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//checkForTimeout();
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}
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/***************************************************************************
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* Interupt handler. Call I2C state machine, and dequeue request
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* if completed.
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***************************************************************************/
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void I2CManagerClass::handleInterrupt() {
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// Update hardware state machine
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I2C_handleInterrupt();
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// Enable interrupts to minimise effect on other interrupt code
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interrupts();
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// Check if current request has completed. If there's a current request
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// and state isn't active then state contains the completion status of the request.
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if (state != I2C_STATE_ACTIVE && currentRequest != NULL) {
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// Remove completed request from head of queue
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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I2CRB * t = queueHead;
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if (t == queueHead) {
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queueHead = t->nextRequest;
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if (!queueHead) queueTail = queueHead;
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t->nBytes = rxCount;
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t->status = state;
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// I2C state machine is now free for next request
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currentRequest = NULL;
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state = I2C_STATE_FREE;
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// Start next request (if any)
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I2CManager.startTransaction();
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}
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}
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}
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}
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// Fields in I2CManager class specific to Non-blocking implementation.
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I2CRB * volatile I2CManagerClass::queueHead = NULL;
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I2CRB * volatile I2CManagerClass::queueTail = NULL;
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I2CRB * volatile I2CManagerClass::currentRequest = NULL;
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volatile uint8_t I2CManagerClass::state = I2C_STATE_FREE;
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volatile uint8_t I2CManagerClass::txCount;
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volatile uint8_t I2CManagerClass::rxCount;
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volatile uint8_t I2CManagerClass::operation;
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volatile uint8_t I2CManagerClass::bytesToSend;
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volatile uint8_t I2CManagerClass::bytesToReceive;
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volatile unsigned long I2CManagerClass::startTime;
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unsigned long I2CManagerClass::timeout = 0;
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#endif |