Initial escape library

Not working yet

darkwater/gpio.cpp

@@ -0,0 +1,160 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <err.h>
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include "gpio.h"
+
+#define LOW                 0
+#define HIGH                1
+
+/* Raspberry Pi GPIO memory */
+#define BCM2708_PERI_BASE   0x20000000
+#define BCM2709_PERI_BASE   0x3F000000
+#define GPIO_BASE(address)  (address + 0x200000)
+#define PAGE_SIZE           (4*1024)
+#define BLOCK_SIZE          (4*1024)
+
+/* GPIO setup. Always use INP_GPIO(x) before OUT_GPIO(x) or SET_GPIO_ALT(x,y) */
+#define GPIO_MODE_IN(g)     *(_gpio+((g)/10)) &= ~(7<<(((g)%10)*3))
+#define GPIO_MODE_OUT(g)    *(_gpio+((g)/10)) |=  (1<<(((g)%10)*3))
+#define GPIO_MODE_ALT(g,a)  *(_gpio+(((g)/10))) |= (((a)<=3?(a)+4:(a)==4?3:2)<<(((g)%10)*3))
+#define GPIO_SET_HIGH       *(_gpio+7)  // sets   bits which are 1
+#define GPIO_SET_LOW        *(_gpio+10) // clears bits which are 1
+#define GPIO_GET(g)         (*(_gpio+13)&(1<<g)) // 0 if LOW, (1<<g) if HIGH
+
+#define MAX_SIZE_LINE       50
+
+using namespace DarkWater;
+
+Pin::Pin(uint8_t pin):
+    _pin(pin),
+    _gpio(NULL), 
+    _mode(GpioModeInput)
+{
+}
+
+Pin::~Pin()
+{
+    if (!_deinit()) {
+        warnx("deinitialization failed");
+    }
+}
+
+bool Pin::_deinit() 
+{
+    if (munmap(const_cast<uint32_t *>(_gpio), BLOCK_SIZE) < 0) {
+        warnx("unmap failed");
+        return false;
+    }
+    return true;
+}
+
+bool Pin::init()
+{
+    int mem_fd;
+    if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
+        warn("/dev/mem cannot be opened");
+        return false;
+    }
+
+    uint32_t address = getRaspberryPiVersion() == 1? GPIO_BASE(BCM2708_PERI_BASE): GPIO_BASE(BCM2709_PERI_BASE);
+
+    void *gpio_map = mmap(
+        NULL,                 /* any adddress in our space will do */
+        BLOCK_SIZE,           /* map length */
+        PROT_READ|PROT_WRITE, /* enable reading & writting to mapped memory */
+        MAP_SHARED,           /* shared with other processes */
+        mem_fd,               /* file to map */
+        address               /* offset to GPIO peripheral */
+    );
+
+    if (gpio_map == MAP_FAILED) {
+        warn("cannot mmap memory");
+        return false;
+    }
+
+    /* No need to keep mem_fd open after mmap */
+    if (close(mem_fd) < 0) {
+        warn("cannot close mem_fd");   
+        return false;
+    } 
+
+    _gpio = reinterpret_cast<volatile uint32_t *>(gpio_map); // Always use volatile pointer!
+
+    return true;
+}
+
+void Pin::setMode(GpioMode mode)
+{
+    if (mode == GpioModeInput) {
+        GPIO_MODE_IN(_pin);
+    } else {
+        GPIO_MODE_IN(_pin);
+        GPIO_MODE_OUT(_pin);
+    }
+
+    _mode = mode;
+}
+
+uint8_t Pin::read() const
+{
+    uint32_t value = GPIO_GET(_pin);
+    return value ? 1: 0;
+}
+
+void Pin::write(uint8_t value)
+{
+    if (_mode != GpioModeOutput) {
+        warnx("no effect because mode is not set");
+    }
+
+    if (value == LOW) {
+        GPIO_SET_LOW = 1 << _pin;
+    } else {
+        GPIO_SET_HIGH = 1 << _pin;
+    }
+}
+
+void Pin::toggle()
+{
+    write(!read());
+}
+
+int Pin::getRaspberryPiVersion() const
+{
+    char buffer[MAX_SIZE_LINE];
+    const char* hardware_description_entry = "Hardware";
+    const char* v1 = "BCM2708";
+    const char* v2 = "BCM2709";
+    char* flag;
+    FILE* fd;
+
+    fd = fopen("/proc/cpuinfo", "r");
+
+    while (fgets(buffer, MAX_SIZE_LINE, fd) != NULL) {
+        flag = strstr(buffer, hardware_description_entry);
+
+        if (flag != NULL) {
+            if (strstr(buffer, v2) != NULL) {
+                fclose(fd);
+                return 2;
+            } else if (strstr(buffer, v1) != NULL) {
+                fclose(fd);
+                return 1;
+            }
+        }
+    }
+
+    /* defaults to 1 */
+    fprintf(stderr, "Could not detect RPi version, defaulting to 1\n");
+    fclose(fd);
+    return 1;
+}