BroadcomGPIO.cpp

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/*
 * Copyright (C) 2015 Niek Linnenbank
 *
 * 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <Log.h>
#include "BroadcomGPIO.h"
 
BroadcomGPIO::BroadcomGPIO()
{
}
 
BroadcomGPIO::Result BroadcomGPIO::initialize()
{
    if (m_io.map(IO_BASE + GPIOBase, PAGESIZE,
                 Memory::User|Memory::Readable|Memory::Writable|Memory::Device)
        != IO::Success)
        return IOError;
 
    return Success;
}
 
BroadcomGPIO::Result BroadcomGPIO::setAltFunction(Size pin, uint function)
{
    // pin is a BCM2835 GPIO pin number NOT RPi pin number
    //
    // There are 6 control registers, each control the functions of a block
    // of 10 pins.
    // Each control register has 10 sets of 3 bits per GPIO pin:
    //
    //    000 = GPIO Pin X is an input
    //    001 = GPIO Pin X is an output
    //    100 = GPIO Pin X takes alternate function 0
    //    101 = GPIO Pin X takes alternate function 1
    //    110 = GPIO Pin X takes alternate function 2
    //    111 = GPIO Pin X takes alternate function 3
    //    011 = GPIO Pin X takes alternate function 4
    //    010 = GPIO Pin X takes alternate function 5
    //
    uint shift = (pin % 10) * 3;
    m_io.set(FunctionSelect0 + (pin / 10),
             function << shift);
    return Success;
}