feat(lab03): add ex1 with dev/mem

src/02-driver/main.c

@@ -7,12 +7,49 @@
 #include <sys/mman.h>
 #include <unistd.h>
 
-
 int main() {
 
-    int fd = open()
+    int fd = open("/dev/mem", O_RDWR);
+
+    if (fd < 0) {
+        printf("Failed to open /dev/mem: %s\n", strerror(errno));
+        return 1;
+    }
+
+    size_t page_size = getpagesize(); // return the number of byte in a page
+    off_t chip_id_addr = 0x01c14200; // physical address
+    off_t offset = chip_id_addr % page_size; // get the number of page until the chip is address
+    off_t start_page = chip_id_addr - offset; // align with pages
+
+    printf("page_size=0x%x offset=0x%x offset_page=0x%x\n", (unsigned int) page_size, (unsigned int) offset, (unsigned int) start_page);
+
+    // Get register virtual address from /dev/mem of the chip id
+    volatile uint32_t* regs = mmap(0, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, start_page);
+
+    if (regs == MAP_FAILED) {
+        printf("Failed to mmap: %s\n", strerror(errno));
+        return 1;
+    }
 
 
 
+    uint32_t chipid[4] = {[0] = 0,};
+
+    // Read values - Chip ID
+    chipid[0] = *(regs + (0x00 + offset) / sizeof(uint32_t));
+    chipid[1] = *(regs + (0x04 + offset) / sizeof(uint32_t));
+    chipid[2] = *(regs + (0x08 + offset) / sizeof(uint32_t));
+    chipid[3] = *(regs + (0x0c + offset) / sizeof(uint32_t));
+    printf(
+        "chipid=%08x'%08x'%08x'%08x\n",
+        chipid[0], chipid[1], chipid[2], chipid[3]
+    );
+
+    // Free space memory of the user¨
+    munmap((void*)regs, page_size);
+
+    // Close the file
+    close(fd);
+
     return 0;
 }