138 lines
3.9 KiB
C
138 lines
3.9 KiB
C
/*
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* wiringPiSPI.c:
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* Simplified SPI access routines
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* Copyright (c) 2012-2015 Gordon Henderson
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* wiringPi 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with wiringPi.
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* If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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#include <stdint.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <asm/ioctl.h>
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#include <linux/spi/spidev.h>
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#include "wiringPi.h"
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#include "wiringPiSPI.h"
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// The SPI bus parameters
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// Variables as they need to be passed as pointers later on
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static const char *spiDev0 = "/dev/spidev0.0" ;
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static const char *spiDev1 = "/dev/spidev0.1" ;
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static const uint8_t spiBPW = 8 ;
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static const uint16_t spiDelay = 0 ;
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static uint32_t spiSpeeds [2] ;
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static int spiFds [2] ;
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/*
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* wiringPiSPIGetFd:
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* Return the file-descriptor for the given channel
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*********************************************************************************
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*/
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int wiringPiSPIGetFd (int channel)
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{
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return spiFds [channel & 1] ;
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}
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/*
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* wiringPiSPIDataRW:
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* Write and Read a block of data over the SPI bus.
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* Note the data ia being read into the transmit buffer, so will
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* overwrite it!
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* This is also a full-duplex operation.
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*********************************************************************************
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*/
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int wiringPiSPIDataRW (int channel, unsigned char *data, int len)
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{
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struct spi_ioc_transfer spi ;
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channel &= 1 ;
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// Mentioned in spidev.h but not used in the original kernel documentation
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// test program )-:
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memset (&spi, 0, sizeof (spi)) ;
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spi.tx_buf = (unsigned long)data ;
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spi.rx_buf = (unsigned long)data ;
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spi.len = len ;
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spi.delay_usecs = spiDelay ;
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spi.speed_hz = spiSpeeds [channel] ;
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spi.bits_per_word = spiBPW ;
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return ioctl (spiFds [channel], SPI_IOC_MESSAGE(1), &spi) ;
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}
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/*
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* wiringPiSPISetupMode:
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* Open the SPI device, and set it up, with the mode, etc.
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*********************************************************************************
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*/
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int wiringPiSPISetupMode (int channel, int speed, int mode)
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{
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int fd ;
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mode &= 3 ; // Mode is 0, 1, 2 or 3
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channel &= 1 ; // Channel is 0 or 1
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if ((fd = open (channel == 0 ? spiDev0 : spiDev1, O_RDWR)) < 0)
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return wiringPiFailure (WPI_ALMOST, "Unable to open SPI device: %s\n", strerror (errno)) ;
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spiSpeeds [channel] = speed ;
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spiFds [channel] = fd ;
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// Set SPI parameters.
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if (ioctl (fd, SPI_IOC_WR_MODE, &mode) < 0)
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return wiringPiFailure (WPI_ALMOST, "SPI Mode Change failure: %s\n", strerror (errno)) ;
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if (ioctl (fd, SPI_IOC_WR_BITS_PER_WORD, &spiBPW) < 0)
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return wiringPiFailure (WPI_ALMOST, "SPI BPW Change failure: %s\n", strerror (errno)) ;
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if (ioctl (fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed) < 0)
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return wiringPiFailure (WPI_ALMOST, "SPI Speed Change failure: %s\n", strerror (errno)) ;
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return fd ;
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}
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/*
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* wiringPiSPISetup:
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* Open the SPI device, and set it up, etc. in the default MODE 0
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*********************************************************************************
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*/
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int wiringPiSPISetup (int channel, int speed)
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{
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return wiringPiSPISetupMode (channel, speed, 0) ;
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}
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