gpio.hpp

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  * This software can be used by students and other personal of the *
  * Bern University of Applied Sciences under the terms of the MIT  *
  * license.                                                        *
  * For other persons this software is under the terms of the GNU   *
  * General Public License version 2.                               *
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  * Copyright © 2021, Bern University of Applied Sciences.     *
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#pragma once
 
#include <cpp/common/frontend/gpio.hpp>
 
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <string>
 
namespace bsp::asg::drv {
 
    // Forward declaring
    template<u8 GPIOBaseNumber>
    struct GPIOPort;
 
    template<u8 GPIOBaseNumber, u8 Pin, bsp::drv::Active LogicActive>
    struct GPIOPin {
        GPIOPin(const GPIOPin&) = delete;
        GPIOPin(GPIOPin&&) = delete;
 
        static_assert(Pin <= 15, "Pin out of range");
 
        GPIOPin& operator=(const GPIOPin&) = delete;
 
        auto& operator=(bool state) const noexcept {
            state = LogicActive == bsp::drv::Active::High ? state : !state;
 
            int fd = open(("/sys/class/gpio/gpio" + std::to_string(GPIOBaseNumber + Pin) + "/value").c_str(), O_WRONLY);
            if (fd == -1) return *this;
 
            write(fd, state ? "1" : "0", 1);
            close(fd);
 
            return *this;
        }
 
        [[nodiscard]] operator u8() const noexcept {
            int fd = open(("/sys/class/gpio/gpio" + std::to_string(GPIOBaseNumber + Pin) + "/value").c_str(), O_RDONLY);
            if (fd == -1) return 0;
 
            char buffer[2] = { 0 };
            read(fd, buffer, sizeof(buffer));
            close(fd);
 
            bool result = buffer[0] == '1';
 
            return LogicActive == bsp::drv::Active::High ? result : !result;
        }
 
        bool init() const noexcept {
            int fd = open("/sys/class/gpio/export", O_WRONLY);
            if (fd == -1) return false;
 
            auto value = std::to_string(GPIOBaseNumber + Pin);
            write(fd, value.c_str(), value.length());
            close(fd);
 
            return true;
        }
 
        bool deinit() const noexcept {
            int fd = open("/sys/class/gpio/unexport", O_WRONLY);
            if (fd == -1) return false;
 
            auto value = std::to_string(GPIOBaseNumber + Pin);
            write(fd, value.c_str(), value.length());
            close(fd);
 
            return true;
        }
 
        void makeOutput() const noexcept {          
            int fd = open(("/sys/class/gpio/gpio" + std::to_string(GPIOBaseNumber + Pin) + "/direction").c_str(), O_WRONLY);
            if (fd == -1) return;
 
            write(fd, "out", 3);
            close(fd);
        }
 
        void makeInput() const noexcept {           
            int fd = open(("/sys/class/gpio/gpio" + std::to_string(GPIOBaseNumber + Pin) + "/direction").c_str(), O_WRONLY);
            if (fd == -1) return;
 
            write(fd, "in", 2);
            close(fd);
        }
 
    private:
        GPIOPin() = default;
        template<addr_t, template<addr_t,u8> typename>
        friend struct bsp::asg::drv::GPIOPort;
    };
 
    template<u8 GPIOBaseNumber>
    struct GPIOPort {
    private:
        GPIOPort() = default;
 
    public:
        static bool init() {
            return true;
        }
 
        static bool deinit() {
            return true;
        }
 
        GPIOPort(const GPIOPort&) = delete;
        GPIOPort(GPIOPort&&) = delete;
 
        template<u8 Pin, bsp::drv::Active LogicActive>
        static constexpr auto Pin = GPIOPin<GPIOBaseNumber, Pin, LogicActive>();
    };
 
}