Devices: Add a new Serial device

This device permits userspace to interface with the serial port.

apps/src/init.c

@@ -47,6 +47,23 @@ int main()
         return 1;
     }
 
+    FILE* serial = fopen("/dev/serial", "r");
+    if (!serial)
+    {
+        perror("fopen");
+        return 1;
+    }
+    if (fputs("Hello from init!\n", serial) < 0)
+    {
+        perror("fputs");
+        return 1;
+    }
+    if (fclose(serial) < 0)
+    {
+        perror("fclose");
+        return 1;
+    }
+
     printf("Welcome to Luna!\n");
 
     printf("Running as tid %ld\n\n", gettid());

kernel/include/fs/devices/Serial.h

@@ -0,0 +1,9 @@
+#pragma once
+#include "fs/VFS.h"
+
+namespace SerialDevice
+{
+    VFS::Node* create_new();
+
+    ssize_t write(VFS::Node* node, size_t offset, size_t size, const char* buffer);
+}

kernel/src/fs/devices/DeviceFS.cpp

@@ -1,5 +1,6 @@
 #include "fs/devices/DeviceFS.h"
 #include "fs/devices/Console.h"
+#include "fs/devices/Serial.h"
 #include "fs/devices/Version.h"
 #include "std/stdlib.h"
 #include "std/string.h"
@@ -23,6 +24,7 @@ VFS::Node* DeviceFS::get()
 
     devfs_files[devfs_file_count++] = VersionDevice::create_new();
     devfs_files[devfs_file_count++] = ConsoleDevice::create_new();
+    devfs_files[devfs_file_count++] = SerialDevice::create_new();
     return devfs_root;
 }
 

kernel/src/fs/devices/Serial.cpp

@@ -0,0 +1,25 @@
+#include "io/Serial.h"
+#include "config.h"
+#include "fs/devices/Serial.h"
+#include "std/stdio.h"
+#include "std/stdlib.h"
+#include "std/string.h"
+
+VFS::Node* SerialDevice::create_new()
+{
+    VFS::Node* dev = new VFS::Node;
+    dev->write_func = SerialDevice::write;
+    dev->inode = 0;
+    dev->length = 0;
+    dev->type = VFS_FILE;
+    dev->flags = 0;
+    strncpy(dev->name, "serial", sizeof(dev->name));
+    return dev;
+}
+
+ssize_t SerialDevice::write(VFS::Node* node, size_t, size_t size, const char* buffer)
+{
+    if (!node) return -1;
+    Serial::write(buffer, size);
+    return (ssize_t)size;
+}