Index: uspace/drv/bus/usb/xhci/rh.c
===================================================================
--- uspace/drv/bus/usb/xhci/rh.c	(revision 7428b925cd218f639c5da7dde3d0259a1e078bc3)
+++ uspace/drv/bus/usb/xhci/rh.c	(revision 174788ffb5d406f02ffce47ca7271c2c04f1531b)
@@ -37,8 +37,84 @@
 #include <str_error.h>
 #include <usb/debug.h>
+#include <usb/host/utils/malloc32.h>
 #include "debug.h"
+#include "commands.h"
 #include "hc.h"
 #include "hw_struct/trb.h"
 #include "rh.h"
+
+// TODO: Check device deallocation, we free device_ctx in hc.c, not
+//       sure about the other structs.
+static int alloc_dev(xhci_hc_t *hc, uint8_t port)
+{
+	int err;
+
+	xhci_cmd_t *cmd = xhci_alloc_command();
+	if (!cmd)
+		return ENOMEM;
+
+	xhci_send_enable_slot_command(hc, cmd);
+	if ((err = xhci_wait_for_command(cmd, 100000)) != EOK)
+		goto err_command;
+
+	uint32_t slot_id = cmd->slot_id;
+	usb_log_debug2("Obtained slot ID: %u.\n", slot_id);
+
+	xhci_free_command(cmd);
+	cmd = NULL;
+
+	xhci_input_ctx_t *ictx = malloc32(sizeof(xhci_input_ctx_t));
+	if (!ictx) {
+		err = ENOMEM;
+		goto err_command;
+	}
+
+	memset(ictx, 0, sizeof(xhci_input_ctx_t));
+
+	XHCI_INPUT_CTRL_CTX_ADD_SET(ictx->ctrl_ctx, 0);
+	XHCI_INPUT_CTRL_CTX_ADD_SET(ictx->ctrl_ctx, 1);
+
+	// TODO: Initialize ictx->slot_ctx according to section 4.3.3
+	//       point 3. This requires setters for XHCI_SLOT_* and figuring
+	//       out how are we supposed to find the root string field, which
+	//       can be found in usb3 spec section 8.9.
+
+	// TODO: Allocated and initialize transfer ring for default
+	//       control endpoint.
+	
+	// TODO: Initialize input default control endpoint 0 context.
+	
+	// TODO: What's the alignment?
+	xhci_device_ctx_t *dctx = malloc32(sizeof(xhci_device_ctx_t));
+	if (!dctx) {
+		err = ENOMEM;
+		goto err_ctx;
+	}
+	memset(dctx, 0, sizeof(xhci_device_ctx_t));
+	
+	hc->dcbaa[slot_id] = addr_to_phys(dctx);
+	hc->dcbaa_virt[slot_id] = dctx;
+	
+	cmd = xhci_alloc_command();
+	cmd->ictx = ictx;
+	xhci_send_address_device_command(hc, cmd);
+	if ((err = xhci_wait_for_command(cmd, 100000)) != EOK)
+		goto err_ctx;
+
+	return EOK;
+
+err_ctx:
+	if (ictx) {
+		// To avoid double free.
+		if (cmd && cmd->ictx && cmd->ictx == ictx)
+			cmd->ictx = NULL;
+
+		free32(ictx);
+	}
+err_command:
+	if (cmd)
+		xhci_free_command(cmd);
+	return err;
+}
 
 static int handle_connected_device(xhci_hc_t* hc, xhci_port_regs_t* regs, uint8_t port_id)
@@ -49,5 +125,6 @@
 		uint8_t port_speed = XHCI_REG_RD(regs, XHCI_PORT_PS);
 		usb_log_debug2("Detected new device on port %u, port speed id %u.", port_id, port_speed);
-		// TODO: Assign device slot (specification 4.3.2) 
+
+		alloc_dev(hc, port_id);
 	} else if (link_state == 5) {
 		// USB 3 failed to enable