kernel: implement tty driver system

kernel/tty/device.c

@@ -0,0 +1,42 @@
+#include <socks/tty.h>
+#include <socks/device.h>
+#include <socks/libc/stdio.h>
+
+struct device *tty_device_create(void)
+{
+	struct char_device *cdev = char_device_create();
+	if (!cdev) {
+		return NULL;
+	}
+
+	struct tty_device *tty_dev = kmalloc(sizeof *tty_dev, VM_NORMAL);
+	if (!tty_dev) {
+		/* TODO destroy cdev */
+		return NULL;
+	}
+
+	cdev->c_tty = tty_dev;
+	return char_device_base(cdev);
+}
+
+static kern_status_t generate_name(struct tty_driver *owner, struct device *dev, char out[DEV_NAME_MAX])
+{
+	/* minor numbers start at 1. subtract 1 to start at 0 instead */
+	snprintf(out, DEV_NAME_MAX, "%s%u", owner->tty_name, dev->dev_minor - 1);
+	return KERN_OK;
+}
+
+kern_status_t tty_device_register(struct device *dev, struct tty_driver *owner, struct device *parent)
+{
+	kern_status_t status = device_register(dev, tty_driver_base(owner), parent);
+	if (status != KERN_OK) {
+		return status;
+	}
+
+	char link_name[DEV_NAME_MAX];
+	generate_name(owner, dev, link_name);
+	char link_path[OBJECT_PATH_MAX];
+	snprintf(link_path, sizeof link_path, "/dev/tty/%s", link_name);
+
+	return object_namespace_create_link(global_namespace(), link_path, &dev->dev_base);
+}