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  • /*
     * USB HOST XHCI Controller stack
     *
     * Based on xHCI host controller driver in linux-kernel
     * by Sarah Sharp.
     *
     * Copyright (C) 2008 Intel Corp.
     * Author: Sarah Sharp
     *
     * Copyright (C) 2013 Samsung Electronics Co.Ltd
     * Authors: Vivek Gautam <gautam.vivek@samsung.com>
     *	    Vikas Sajjan <vikas.sajjan@samsung.com>
     *
     * SPDX-License-Identifier:	GPL-2.0+
     */
    
    /**
     * This file gives the xhci stack for usb3.0 looking into
     * xhci specification Rev1.0 (5/21/10).
     * The quirk devices support hasn't been given yet.
     */
    
    #include <common.h>
    
    #include <dm.h>
    
    #include <asm/byteorder.h>
    #include <usb.h>
    #include <malloc.h>
    #include <watchdog.h>
    #include <asm/cache.h>
    #include <asm/unaligned.h>
    #include <asm-generic/errno.h>
    #include "xhci.h"
    
    #ifndef CONFIG_USB_MAX_CONTROLLER_COUNT
    #define CONFIG_USB_MAX_CONTROLLER_COUNT 1
    #endif
    
    static struct descriptor {
    	struct usb_hub_descriptor hub;
    	struct usb_device_descriptor device;
    	struct usb_config_descriptor config;
    	struct usb_interface_descriptor interface;
    	struct usb_endpoint_descriptor endpoint;
    	struct usb_ss_ep_comp_descriptor ep_companion;
    } __attribute__ ((packed)) descriptor = {
    	{
    		0xc,		/* bDescLength */
    		0x2a,		/* bDescriptorType: hub descriptor */
    		2,		/* bNrPorts -- runtime modified */
    		cpu_to_le16(0x8), /* wHubCharacteristics */
    		10,		/* bPwrOn2PwrGood */
    		0,		/* bHubCntrCurrent */
    		{},		/* Device removable */
    		{}		/* at most 7 ports! XXX */
    	},
    	{
    		0x12,		/* bLength */
    		1,		/* bDescriptorType: UDESC_DEVICE */
    		cpu_to_le16(0x0300), /* bcdUSB: v3.0 */
    		9,		/* bDeviceClass: UDCLASS_HUB */
    		0,		/* bDeviceSubClass: UDSUBCLASS_HUB */
    		3,		/* bDeviceProtocol: UDPROTO_SSHUBSTT */
    		9,		/* bMaxPacketSize: 512 bytes  2^9 */
    		0x0000,		/* idVendor */
    		0x0000,		/* idProduct */
    		cpu_to_le16(0x0100), /* bcdDevice */
    		1,		/* iManufacturer */
    		2,		/* iProduct */
    		0,		/* iSerialNumber */
    		1		/* bNumConfigurations: 1 */
    	},
    	{
    		0x9,
    		2,		/* bDescriptorType: UDESC_CONFIG */
    		cpu_to_le16(0x1f), /* includes SS endpoint descriptor */
    		1,		/* bNumInterface */
    		1,		/* bConfigurationValue */
    		0,		/* iConfiguration */
    		0x40,		/* bmAttributes: UC_SELF_POWER */
    		0		/* bMaxPower */
    	},
    	{
    		0x9,		/* bLength */
    		4,		/* bDescriptorType: UDESC_INTERFACE */
    		0,		/* bInterfaceNumber */
    		0,		/* bAlternateSetting */
    		1,		/* bNumEndpoints */
    		9,		/* bInterfaceClass: UICLASS_HUB */
    		0,		/* bInterfaceSubClass: UISUBCLASS_HUB */
    		0,		/* bInterfaceProtocol: UIPROTO_HSHUBSTT */
    		0		/* iInterface */
    	},
    	{
    		0x7,		/* bLength */
    		5,		/* bDescriptorType: UDESC_ENDPOINT */
    		0x81,		/* bEndpointAddress: IN endpoint 1 */
    		3,		/* bmAttributes: UE_INTERRUPT */
    		8,		/* wMaxPacketSize */
    		255		/* bInterval */
    	},
    	{
    		0x06,		/* ss_bLength */
    		0x30,		/* ss_bDescriptorType: SS EP Companion */
    		0x00,		/* ss_bMaxBurst: allows 1 TX between ACKs */
    		/* ss_bmAttributes: 1 packet per service interval */
    		0x00,
    		/* ss_wBytesPerInterval: 15 bits for max 15 ports */
    		cpu_to_le16(0x02),
    	},
    };
    
    
    #ifndef CONFIG_DM_USB
    
    static struct xhci_ctrl xhcic[CONFIG_USB_MAX_CONTROLLER_COUNT];
    
    struct xhci_ctrl *xhci_get_ctrl(struct usb_device *udev)
    {
    
    #ifdef CONFIG_DM_USB
    	struct udevice *dev;
    
    	/* Find the USB controller */
    	for (dev = udev->dev;
    	     device_get_uclass_id(dev) != UCLASS_USB;
    	     dev = dev->parent)
    		;
    	return dev_get_priv(dev);
    #else
    
    	return udev->controller;
    
    /**
     * Waits for as per specified amount of time
     * for the "result" to match with "done"
     *
     * @param ptr	pointer to the register to be read
     * @param mask	mask for the value read
     * @param done	value to be campared with result
     * @param usec	time to wait till
     * @return 0 if handshake is success else < 0 on failure
     */
    static int handshake(uint32_t volatile *ptr, uint32_t mask,
    					uint32_t done, int usec)
    {
    	uint32_t result;
    
    	do {
    		result = xhci_readl(ptr);
    		if (result == ~(uint32_t)0)
    			return -ENODEV;
    		result &= mask;
    		if (result == done)
    			return 0;
    		usec--;
    		udelay(1);
    	} while (usec > 0);
    
    	return -ETIMEDOUT;
    }
    
    /**
     * Set the run bit and wait for the host to be running.
     *
     * @param hcor	pointer to host controller operation registers
     * @return status of the Handshake
     */
    static int xhci_start(struct xhci_hcor *hcor)
    {
    	u32 temp;
    	int ret;
    
    	puts("Starting the controller\n");
    	temp = xhci_readl(&hcor->or_usbcmd);
    	temp |= (CMD_RUN);
    	xhci_writel(&hcor->or_usbcmd, temp);
    
    	/*
    	 * Wait for the HCHalted Status bit to be 0 to indicate the host is
    	 * running.
    	 */
    	ret = handshake(&hcor->or_usbsts, STS_HALT, 0, XHCI_MAX_HALT_USEC);
    	if (ret)
    		debug("Host took too long to start, "
    				"waited %u microseconds.\n",
    				XHCI_MAX_HALT_USEC);
    	return ret;
    }
    
    /**
     * Resets the XHCI Controller
     *
     * @param hcor	pointer to host controller operation registers
     * @return -EBUSY if XHCI Controller is not halted else status of handshake
     */
    int xhci_reset(struct xhci_hcor *hcor)
    {
    	u32 cmd;
    	u32 state;
    	int ret;
    
    	/* Halting the Host first */
    	debug("// Halt the HC\n");
    	state = xhci_readl(&hcor->or_usbsts) & STS_HALT;
    	if (!state) {
    		cmd = xhci_readl(&hcor->or_usbcmd);
    		cmd &= ~CMD_RUN;
    		xhci_writel(&hcor->or_usbcmd, cmd);
    	}
    
    	ret = handshake(&hcor->or_usbsts,
    			STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
    	if (ret) {
    		printf("Host not halted after %u microseconds.\n",
    				XHCI_MAX_HALT_USEC);
    		return -EBUSY;
    	}
    
    	debug("// Reset the HC\n");
    	cmd = xhci_readl(&hcor->or_usbcmd);
    	cmd |= CMD_RESET;
    	xhci_writel(&hcor->or_usbcmd, cmd);
    
    	ret = handshake(&hcor->or_usbcmd, CMD_RESET, 0, XHCI_MAX_RESET_USEC);
    	if (ret)
    		return ret;
    
    	/*
    	 * xHCI cannot write to any doorbells or operational registers other
    	 * than status until the "Controller Not Ready" flag is cleared.
    	 */
    	return handshake(&hcor->or_usbsts, STS_CNR, 0, XHCI_MAX_RESET_USEC);
    }
    
    /**
     * Used for passing endpoint bitmasks between the core and HCDs.
     * Find the index for an endpoint given its descriptor.
     * Use the return value to right shift 1 for the bitmask.
     *
     * Index  = (epnum * 2) + direction - 1,
     * where direction = 0 for OUT, 1 for IN.
     * For control endpoints, the IN index is used (OUT index is unused), so
     * index = (epnum * 2) + direction - 1 = (epnum * 2) + 1 - 1 = (epnum * 2)
     *
     * @param desc	USB enpdoint Descriptor
     * @return index of the Endpoint
     */
    static unsigned int xhci_get_ep_index(struct usb_endpoint_descriptor *desc)
    {
    	unsigned int index;
    
    	if (usb_endpoint_xfer_control(desc))
    		index = (unsigned int)(usb_endpoint_num(desc) * 2);
    	else
    		index = (unsigned int)((usb_endpoint_num(desc) * 2) -
    				(usb_endpoint_dir_in(desc) ? 0 : 1));
    
    	return index;
    }
    
    /**
     * Issue a configure endpoint command or evaluate context command
     * and wait for it to finish.
     *
     * @param udev	pointer to the Device Data Structure
     * @param ctx_change	flag to indicate the Context has changed or NOT
     * @return 0 on success, -1 on failure
     */
    static int xhci_configure_endpoints(struct usb_device *udev, bool ctx_change)
    {
    	struct xhci_container_ctx *in_ctx;
    	struct xhci_virt_device *virt_dev;
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	union xhci_trb *event;
    
    	virt_dev = ctrl->devs[udev->slot_id];
    	in_ctx = virt_dev->in_ctx;
    
    
    	xhci_flush_cache((uintptr_t)in_ctx->bytes, in_ctx->size);
    
    	xhci_queue_command(ctrl, in_ctx->bytes, udev->slot_id, 0,
    			   ctx_change ? TRB_EVAL_CONTEXT : TRB_CONFIG_EP);
    	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
    	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
    		!= udev->slot_id);
    
    	switch (GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))) {
    	case COMP_SUCCESS:
    		debug("Successful %s command\n",
    			ctx_change ? "Evaluate Context" : "Configure Endpoint");
    		break;
    	default:
    		printf("ERROR: %s command returned completion code %d.\n",
    			ctx_change ? "Evaluate Context" : "Configure Endpoint",
    			GET_COMP_CODE(le32_to_cpu(event->event_cmd.status)));
    		return -EINVAL;
    	}
    
    	xhci_acknowledge_event(ctrl);
    
    	return 0;
    }
    
    /**
     * Configure the endpoint, programming the device contexts.
     *
     * @param udev	pointer to the USB device structure
     * @return returns the status of the xhci_configure_endpoints
     */
    static int xhci_set_configuration(struct usb_device *udev)
    {
    	struct xhci_container_ctx *in_ctx;
    	struct xhci_container_ctx *out_ctx;
    	struct xhci_input_control_ctx *ctrl_ctx;
    	struct xhci_slot_ctx *slot_ctx;
    	struct xhci_ep_ctx *ep_ctx[MAX_EP_CTX_NUM];
    	int cur_ep;
    	int max_ep_flag = 0;
    	int ep_index;
    	unsigned int dir;
    	unsigned int ep_type;
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	int num_of_ep;
    	int ep_flag = 0;
    	u64 trb_64 = 0;
    	int slot_id = udev->slot_id;
    	struct xhci_virt_device *virt_dev = ctrl->devs[slot_id];
    	struct usb_interface *ifdesc;
    
    	out_ctx = virt_dev->out_ctx;
    	in_ctx = virt_dev->in_ctx;
    
    	num_of_ep = udev->config.if_desc[0].no_of_ep;
    	ifdesc = &udev->config.if_desc[0];
    
    	ctrl_ctx = xhci_get_input_control_ctx(in_ctx);
    	/* Zero the input context control */
    	ctrl_ctx->add_flags = 0;
    	ctrl_ctx->drop_flags = 0;
    
    	/* EP_FLAG gives values 1 & 4 for EP1OUT and EP2IN */
    	for (cur_ep = 0; cur_ep < num_of_ep; cur_ep++) {
    		ep_flag = xhci_get_ep_index(&ifdesc->ep_desc[cur_ep]);
    		ctrl_ctx->add_flags |= cpu_to_le32(1 << (ep_flag + 1));
    		if (max_ep_flag < ep_flag)
    			max_ep_flag = ep_flag;
    	}
    
    
    	xhci_inval_cache((uintptr_t)out_ctx->bytes, out_ctx->size);
    
    
    	/* slot context */
    	xhci_slot_copy(ctrl, in_ctx, out_ctx);
    	slot_ctx = xhci_get_slot_ctx(ctrl, in_ctx);
    	slot_ctx->dev_info &= ~(LAST_CTX_MASK);
    	slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(max_ep_flag + 1) | 0);
    
    	xhci_endpoint_copy(ctrl, in_ctx, out_ctx, 0);
    
    	/* filling up ep contexts */
    	for (cur_ep = 0; cur_ep < num_of_ep; cur_ep++) {
    		struct usb_endpoint_descriptor *endpt_desc = NULL;
    
    		endpt_desc = &ifdesc->ep_desc[cur_ep];
    		trb_64 = 0;
    
    		ep_index = xhci_get_ep_index(endpt_desc);
    		ep_ctx[ep_index] = xhci_get_ep_ctx(ctrl, in_ctx, ep_index);
    
    		/* Allocate the ep rings */
    		virt_dev->eps[ep_index].ring = xhci_ring_alloc(1, true);
    		if (!virt_dev->eps[ep_index].ring)
    			return -ENOMEM;
    
    		/*NOTE: ep_desc[0] actually represents EP1 and so on */
    		dir = (((endpt_desc->bEndpointAddress) & (0x80)) >> 7);
    		ep_type = (((endpt_desc->bmAttributes) & (0x3)) | (dir << 2));
    		ep_ctx[ep_index]->ep_info2 =
    			cpu_to_le32(ep_type << EP_TYPE_SHIFT);
    		ep_ctx[ep_index]->ep_info2 |=
    			cpu_to_le32(MAX_PACKET
    			(get_unaligned(&endpt_desc->wMaxPacketSize)));
    
    		ep_ctx[ep_index]->ep_info2 |=
    			cpu_to_le32(((0 & MAX_BURST_MASK) << MAX_BURST_SHIFT) |
    			((3 & ERROR_COUNT_MASK) << ERROR_COUNT_SHIFT));
    
    		trb_64 = (uintptr_t)
    				virt_dev->eps[ep_index].ring->enqueue;
    		ep_ctx[ep_index]->deq = cpu_to_le64(trb_64 |
    				virt_dev->eps[ep_index].ring->cycle_state);
    	}
    
    	return xhci_configure_endpoints(udev, false);
    }
    
    /**
     * Issue an Address Device command (which will issue a SetAddress request to
     * the device).
     *
     * @param udev pointer to the Device Data Structure
     * @return 0 if successful else error code on failure
     */
    
    static int xhci_address_device(struct usb_device *udev, int root_portnr)
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	struct xhci_slot_ctx *slot_ctx;
    	struct xhci_input_control_ctx *ctrl_ctx;
    	struct xhci_virt_device *virt_dev;
    	int slot_id = udev->slot_id;
    	union xhci_trb *event;
    
    	virt_dev = ctrl->devs[slot_id];
    
    	/*
    	 * This is the first Set Address since device plug-in
    	 * so setting up the slot context.
    	 */
    
    	debug("Setting up addressable devices %p\n", ctrl->dcbaa);
    	xhci_setup_addressable_virt_dev(ctrl, udev->slot_id, udev->speed,
    					root_portnr);
    
    
    	ctrl_ctx = xhci_get_input_control_ctx(virt_dev->in_ctx);
    	ctrl_ctx->add_flags = cpu_to_le32(SLOT_FLAG | EP0_FLAG);
    	ctrl_ctx->drop_flags = 0;
    
    	xhci_queue_command(ctrl, (void *)ctrl_ctx, slot_id, 0, TRB_ADDR_DEV);
    	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
    	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags)) != slot_id);
    
    	switch (GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))) {
    	case COMP_CTX_STATE:
    	case COMP_EBADSLT:
    		printf("Setup ERROR: address device command for slot %d.\n",
    								slot_id);
    		ret = -EINVAL;
    		break;
    	case COMP_TX_ERR:
    		puts("Device not responding to set address.\n");
    		ret = -EPROTO;
    		break;
    	case COMP_DEV_ERR:
    		puts("ERROR: Incompatible device"
    					"for address device command.\n");
    		ret = -ENODEV;
    		break;
    	case COMP_SUCCESS:
    		debug("Successful Address Device command\n");
    		udev->status = 0;
    		break;
    	default:
    		printf("ERROR: unexpected command completion code 0x%x.\n",
    			GET_COMP_CODE(le32_to_cpu(event->event_cmd.status)));
    		ret = -EINVAL;
    		break;
    	}
    
    	xhci_acknowledge_event(ctrl);
    
    	if (ret < 0)
    		/*
    		 * TODO: Unsuccessful Address Device command shall leave the
    		 * slot in default state. So, issue Disable Slot command now.
    		 */
    		return ret;
    
    
    	xhci_inval_cache((uintptr_t)virt_dev->out_ctx->bytes,
    			 virt_dev->out_ctx->size);
    
    	slot_ctx = xhci_get_slot_ctx(ctrl, virt_dev->out_ctx);
    
    	debug("xHC internal address is: %d\n",
    		le32_to_cpu(slot_ctx->dev_state) & DEV_ADDR_MASK);
    
    	return 0;
    }
    
    /**
     * Issue Enable slot command to the controller to allocate
     * device slot and assign the slot id. It fails if the xHC
     * ran out of device slots, the Enable Slot command timed out,
     * or allocating memory failed.
     *
     * @param udev	pointer to the Device Data Structure
     * @return Returns 0 on succes else return error code on failure
     */
    
    int _xhci_alloc_device(struct usb_device *udev)
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	union xhci_trb *event;
    	int ret;
    
    	/*
    	 * Root hub will be first device to be initailized.
    	 * If this device is root-hub, don't do any xHC related
    	 * stuff.
    	 */
    	if (ctrl->rootdev == 0) {
    		udev->speed = USB_SPEED_SUPER;
    		return 0;
    	}
    
    	xhci_queue_command(ctrl, NULL, 0, 0, TRB_ENABLE_SLOT);
    	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
    	BUG_ON(GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))
    		!= COMP_SUCCESS);
    
    	udev->slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags));
    
    	xhci_acknowledge_event(ctrl);
    
    
    	ret = xhci_alloc_virt_device(ctrl, udev->slot_id);
    
    	if (ret < 0) {
    		/*
    		 * TODO: Unsuccessful Address Device command shall leave
    		 * the slot in default. So, issue Disable Slot command now.
    		 */
    		puts("Could not allocate xHCI USB device data structures\n");
    		return ret;
    	}
    
    	return 0;
    }
    
    
    #ifndef CONFIG_DM_USB
    int usb_alloc_device(struct usb_device *udev)
    {
    	return _xhci_alloc_device(udev);
    }
    #endif
    
    
    /*
     * Full speed devices may have a max packet size greater than 8 bytes, but the
     * USB core doesn't know that until it reads the first 8 bytes of the
     * descriptor.  If the usb_device's max packet size changes after that point,
     * we need to issue an evaluate context command and wait on it.
     *
     * @param udev	pointer to the Device Data Structure
     * @return returns the status of the xhci_configure_endpoints
     */
    int xhci_check_maxpacket(struct usb_device *udev)
    {
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	unsigned int slot_id = udev->slot_id;
    	int ep_index = 0;	/* control endpoint */
    	struct xhci_container_ctx *in_ctx;
    	struct xhci_container_ctx *out_ctx;
    	struct xhci_input_control_ctx *ctrl_ctx;
    	struct xhci_ep_ctx *ep_ctx;
    	int max_packet_size;
    	int hw_max_packet_size;
    	int ret = 0;
    	struct usb_interface *ifdesc;
    
    	ifdesc = &udev->config.if_desc[0];
    
    	out_ctx = ctrl->devs[slot_id]->out_ctx;
    
    	xhci_inval_cache((uintptr_t)out_ctx->bytes, out_ctx->size);
    
    
    	ep_ctx = xhci_get_ep_ctx(ctrl, out_ctx, ep_index);
    	hw_max_packet_size = MAX_PACKET_DECODED(le32_to_cpu(ep_ctx->ep_info2));
    	max_packet_size = usb_endpoint_maxp(&ifdesc->ep_desc[0]);
    	if (hw_max_packet_size != max_packet_size) {
    		debug("Max Packet Size for ep 0 changed.\n");
    		debug("Max packet size in usb_device = %d\n", max_packet_size);
    		debug("Max packet size in xHCI HW = %d\n", hw_max_packet_size);
    		debug("Issuing evaluate context command.\n");
    
    		/* Set up the modified control endpoint 0 */
    		xhci_endpoint_copy(ctrl, ctrl->devs[slot_id]->in_ctx,
    				ctrl->devs[slot_id]->out_ctx, ep_index);
    		in_ctx = ctrl->devs[slot_id]->in_ctx;
    		ep_ctx = xhci_get_ep_ctx(ctrl, in_ctx, ep_index);
    		ep_ctx->ep_info2 &= cpu_to_le32(~MAX_PACKET_MASK);
    		ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet_size));
    
    		/*
    		 * Set up the input context flags for the command
    		 * FIXME: This won't work if a non-default control endpoint
    		 * changes max packet sizes.
    		 */
    		ctrl_ctx = xhci_get_input_control_ctx(in_ctx);
    		ctrl_ctx->add_flags = cpu_to_le32(EP0_FLAG);
    		ctrl_ctx->drop_flags = 0;
    
    		ret = xhci_configure_endpoints(udev, true);
    	}
    	return ret;
    }
    
    /**
     * Clears the Change bits of the Port Status Register
     *
     * @param wValue	request value
     * @param wIndex	request index
     * @param addr		address of posrt status register
     * @param port_status	state of port status register
     * @return none
     */
    static void xhci_clear_port_change_bit(u16 wValue,
    		u16 wIndex, volatile uint32_t *addr, u32 port_status)
    {
    	char *port_change_bit;
    	u32 status;
    
    	switch (wValue) {
    	case USB_PORT_FEAT_C_RESET:
    		status = PORT_RC;
    		port_change_bit = "reset";
    		break;
    	case USB_PORT_FEAT_C_CONNECTION:
    		status = PORT_CSC;
    		port_change_bit = "connect";
    		break;
    	case USB_PORT_FEAT_C_OVER_CURRENT:
    		status = PORT_OCC;
    		port_change_bit = "over-current";
    		break;
    	case USB_PORT_FEAT_C_ENABLE:
    		status = PORT_PEC;
    		port_change_bit = "enable/disable";
    		break;
    	case USB_PORT_FEAT_C_SUSPEND:
    		status = PORT_PLC;
    		port_change_bit = "suspend/resume";
    		break;
    	default:
    		/* Should never happen */
    		return;
    	}
    
    	/* Change bits are all write 1 to clear */
    	xhci_writel(addr, port_status | status);
    
    	port_status = xhci_readl(addr);
    	debug("clear port %s change, actual port %d status  = 0x%x\n",
    			port_change_bit, wIndex, port_status);
    }
    
    /**
     * Save Read Only (RO) bits and save read/write bits where
     * writing a 0 clears the bit and writing a 1 sets the bit (RWS).
     * For all other types (RW1S, RW1CS, RW, and RZ), writing a '0' has no effect.
     *
     * @param state	state of the Port Status and Control Regsiter
     * @return a value that would result in the port being in the
     *	   same state, if the value was written to the port
     *	   status control register.
     */
    static u32 xhci_port_state_to_neutral(u32 state)
    {
    	/* Save read-only status and port state */
    	return (state & XHCI_PORT_RO) | (state & XHCI_PORT_RWS);
    }
    
    /**
     * Submits the Requests to the XHCI Host Controller
     *
     * @param udev pointer to the USB device structure
     * @param pipe contains the DIR_IN or OUT , devnum
     * @param buffer buffer to be read/written based on the request
     * @return returns 0 if successful else -1 on failure
     */
    static int xhci_submit_root(struct usb_device *udev, unsigned long pipe,
    			void *buffer, struct devrequest *req)
    {
    	uint8_t tmpbuf[4];
    	u16 typeReq;
    	void *srcptr = NULL;
    	int len, srclen;
    	uint32_t reg;
    	volatile uint32_t *status_reg;
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	struct xhci_hcor *hcor = ctrl->hcor;
    
    
    	if ((req->requesttype & USB_RT_PORT) &&
    	    le16_to_cpu(req->index) > CONFIG_SYS_USB_XHCI_MAX_ROOT_PORTS) {
    
    		printf("The request port(%d) is not configured\n",
    			le16_to_cpu(req->index) - 1);
    		return -EINVAL;
    	}
    
    	status_reg = (volatile uint32_t *)
    		     (&hcor->portregs[le16_to_cpu(req->index) - 1].or_portsc);
    	srclen = 0;
    
    	typeReq = req->request | req->requesttype << 8;
    
    	switch (typeReq) {
    	case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
    		switch (le16_to_cpu(req->value) >> 8) {
    		case USB_DT_DEVICE:
    			debug("USB_DT_DEVICE request\n");
    			srcptr = &descriptor.device;
    			srclen = 0x12;
    			break;
    		case USB_DT_CONFIG:
    			debug("USB_DT_CONFIG config\n");
    			srcptr = &descriptor.config;
    			srclen = 0x19;
    			break;
    		case USB_DT_STRING:
    			debug("USB_DT_STRING config\n");
    			switch (le16_to_cpu(req->value) & 0xff) {
    			case 0:	/* Language */
    				srcptr = "\4\3\11\4";
    				srclen = 4;
    				break;
    			case 1:	/* Vendor String  */
    				srcptr = "\16\3u\0-\0b\0o\0o\0t\0";
    				srclen = 14;
    				break;
    			case 2:	/* Product Name */
    				srcptr = "\52\3X\0H\0C\0I\0 "
    					 "\0H\0o\0s\0t\0 "
    					 "\0C\0o\0n\0t\0r\0o\0l\0l\0e\0r\0";
    				srclen = 42;
    				break;
    			default:
    				printf("unknown value DT_STRING %x\n",
    					le16_to_cpu(req->value));
    				goto unknown;
    			}
    			break;
    		default:
    			printf("unknown value %x\n", le16_to_cpu(req->value));
    			goto unknown;
    		}
    		break;
    	case USB_REQ_GET_DESCRIPTOR | ((USB_DIR_IN | USB_RT_HUB) << 8):
    		switch (le16_to_cpu(req->value) >> 8) {
    		case USB_DT_HUB:
    			debug("USB_DT_HUB config\n");
    			srcptr = &descriptor.hub;
    			srclen = 0x8;
    			break;
    		default:
    			printf("unknown value %x\n", le16_to_cpu(req->value));
    			goto unknown;
    		}
    		break;
    	case USB_REQ_SET_ADDRESS | (USB_RECIP_DEVICE << 8):
    		debug("USB_REQ_SET_ADDRESS\n");
    		ctrl->rootdev = le16_to_cpu(req->value);
    		break;
    	case DeviceOutRequest | USB_REQ_SET_CONFIGURATION:
    		/* Do nothing */
    		break;
    	case USB_REQ_GET_STATUS | ((USB_DIR_IN | USB_RT_HUB) << 8):
    		tmpbuf[0] = 1;	/* USB_STATUS_SELFPOWERED */
    		tmpbuf[1] = 0;
    		srcptr = tmpbuf;
    		srclen = 2;
    		break;
    	case USB_REQ_GET_STATUS | ((USB_RT_PORT | USB_DIR_IN) << 8):
    		memset(tmpbuf, 0, 4);
    		reg = xhci_readl(status_reg);
    		if (reg & PORT_CONNECT) {
    			tmpbuf[0] |= USB_PORT_STAT_CONNECTION;
    			switch (reg & DEV_SPEED_MASK) {
    			case XDEV_FS:
    				debug("SPEED = FULLSPEED\n");
    				break;
    			case XDEV_LS:
    				debug("SPEED = LOWSPEED\n");
    				tmpbuf[1] |= USB_PORT_STAT_LOW_SPEED >> 8;
    				break;
    			case XDEV_HS:
    				debug("SPEED = HIGHSPEED\n");
    				tmpbuf[1] |= USB_PORT_STAT_HIGH_SPEED >> 8;
    				break;
    			case XDEV_SS:
    				debug("SPEED = SUPERSPEED\n");
    				tmpbuf[1] |= USB_PORT_STAT_SUPER_SPEED >> 8;
    				break;
    			}
    		}
    		if (reg & PORT_PE)
    			tmpbuf[0] |= USB_PORT_STAT_ENABLE;
    		if ((reg & PORT_PLS_MASK) == XDEV_U3)
    			tmpbuf[0] |= USB_PORT_STAT_SUSPEND;
    		if (reg & PORT_OC)
    			tmpbuf[0] |= USB_PORT_STAT_OVERCURRENT;
    		if (reg & PORT_RESET)
    			tmpbuf[0] |= USB_PORT_STAT_RESET;
    		if (reg & PORT_POWER)
    			/*
    			 * XXX: This Port power bit (for USB 3.0 hub)
    			 * we are faking in USB 2.0 hub port status;
    			 * since there's a change in bit positions in
    			 * two:
    			 * USB 2.0 port status PP is at position[8]
    			 * USB 3.0 port status PP is at position[9]
    			 * So, we are still keeping it at position [8]
    			 */
    			tmpbuf[1] |= USB_PORT_STAT_POWER >> 8;
    		if (reg & PORT_CSC)
    			tmpbuf[2] |= USB_PORT_STAT_C_CONNECTION;
    		if (reg & PORT_PEC)
    			tmpbuf[2] |= USB_PORT_STAT_C_ENABLE;
    		if (reg & PORT_OCC)
    			tmpbuf[2] |= USB_PORT_STAT_C_OVERCURRENT;
    		if (reg & PORT_RC)
    			tmpbuf[2] |= USB_PORT_STAT_C_RESET;
    
    		srcptr = tmpbuf;
    		srclen = 4;
    		break;
    	case USB_REQ_SET_FEATURE | ((USB_DIR_OUT | USB_RT_PORT) << 8):
    		reg = xhci_readl(status_reg);
    		reg = xhci_port_state_to_neutral(reg);
    		switch (le16_to_cpu(req->value)) {
    		case USB_PORT_FEAT_ENABLE:
    			reg |= PORT_PE;
    			xhci_writel(status_reg, reg);
    			break;
    		case USB_PORT_FEAT_POWER:
    			reg |= PORT_POWER;
    			xhci_writel(status_reg, reg);
    			break;
    		case USB_PORT_FEAT_RESET:
    			reg |= PORT_RESET;
    			xhci_writel(status_reg, reg);
    			break;
    		default:
    			printf("unknown feature %x\n", le16_to_cpu(req->value));
    			goto unknown;
    		}
    		break;
    	case USB_REQ_CLEAR_FEATURE | ((USB_DIR_OUT | USB_RT_PORT) << 8):
    		reg = xhci_readl(status_reg);
    		reg = xhci_port_state_to_neutral(reg);
    		switch (le16_to_cpu(req->value)) {
    		case USB_PORT_FEAT_ENABLE:
    			reg &= ~PORT_PE;
    			break;
    		case USB_PORT_FEAT_POWER:
    			reg &= ~PORT_POWER;
    			break;
    		case USB_PORT_FEAT_C_RESET:
    		case USB_PORT_FEAT_C_CONNECTION:
    		case USB_PORT_FEAT_C_OVER_CURRENT:
    		case USB_PORT_FEAT_C_ENABLE:
    			xhci_clear_port_change_bit((le16_to_cpu(req->value)),
    							le16_to_cpu(req->index),
    							status_reg, reg);
    			break;
    		default:
    			printf("unknown feature %x\n", le16_to_cpu(req->value));
    			goto unknown;
    		}
    		xhci_writel(status_reg, reg);
    		break;
    	default:
    		puts("Unknown request\n");
    		goto unknown;
    	}
    
    	debug("scrlen = %d\n req->length = %d\n",
    		srclen, le16_to_cpu(req->length));
    
    
    	len = min(srclen, (int)le16_to_cpu(req->length));
    
    
    	if (srcptr != NULL && len > 0)
    		memcpy(buffer, srcptr, len);
    	else
    		debug("Len is 0\n");
    
    	udev->act_len = len;
    	udev->status = 0;
    
    	return 0;
    
    unknown:
    	udev->act_len = 0;
    	udev->status = USB_ST_STALLED;
    
    	return -ENODEV;
    }
    
    /**
     * Submits the INT request to XHCI Host cotroller
     *
     * @param udev	pointer to the USB device
     * @param pipe		contains the DIR_IN or OUT , devnum
     * @param buffer	buffer to be read/written based on the request
     * @param length	length of the buffer
     * @param interval	interval of the interrupt
     * @return 0
     */
    
    static int _xhci_submit_int_msg(struct usb_device *udev, unsigned long pipe,
    				void *buffer, int length, int interval)
    
    {
    	/*
    	 * TODO: Not addressing any interrupt type transfer requests
    	 * Add support for it later.
    	 */
    	return -EINVAL;
    }
    
    /**
     * submit the BULK type of request to the USB Device
     *
     * @param udev	pointer to the USB device
     * @param pipe		contains the DIR_IN or OUT , devnum
     * @param buffer	buffer to be read/written based on the request
     * @param length	length of the buffer
     * @return returns 0 if successful else -1 on failure
     */
    
    static int _xhci_submit_bulk_msg(struct usb_device *udev, unsigned long pipe,
    				 void *buffer, int length)
    
    {
    	if (usb_pipetype(pipe) != PIPE_BULK) {
    		printf("non-bulk pipe (type=%lu)", usb_pipetype(pipe));
    		return -EINVAL;
    	}
    
    	return xhci_bulk_tx(udev, pipe, length, buffer);
    }
    
    /**
     * submit the control type of request to the Root hub/Device based on the devnum
     *
     * @param udev	pointer to the USB device
     * @param pipe		contains the DIR_IN or OUT , devnum
     * @param buffer	buffer to be read/written based on the request
     * @param length	length of the buffer
     * @param setup		Request type
    
     * @param root_portnr	Root port number that this device is on
    
     * @return returns 0 if successful else -1 on failure
     */
    
    static int _xhci_submit_control_msg(struct usb_device *udev, unsigned long pipe,
    				    void *buffer, int length,
    				    struct devrequest *setup, int root_portnr)
    
    	struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
    
    	int ret = 0;
    
    	if (usb_pipetype(pipe) != PIPE_CONTROL) {
    		printf("non-control pipe (type=%lu)", usb_pipetype(pipe));
    		return -EINVAL;
    	}
    
    	if (usb_pipedevice(pipe) == ctrl->rootdev)
    		return xhci_submit_root(udev, pipe, buffer, setup);
    
    	if (setup->request == USB_REQ_SET_ADDRESS)
    
    		return xhci_address_device(udev, root_portnr);
    
    
    	if (setup->request == USB_REQ_SET_CONFIGURATION) {
    		ret = xhci_set_configuration(udev);
    		if (ret) {
    			puts("Failed to configure xHCI endpoint\n");
    			return ret;
    		}
    	}
    
    	return xhci_ctrl_tx(udev, pipe, setup, length, buffer);
    }
    
    
    static int xhci_lowlevel_init(struct xhci_ctrl *ctrl)
    
    	struct xhci_hccr *hccr;
    	struct xhci_hcor *hcor;
    
    	uint32_t val;
    	uint32_t val2;
    	uint32_t reg;
    
    
    	hccr = ctrl->hccr;
    	hcor = ctrl->hcor;
    
    	/*
    	 * Program the Number of Device Slots Enabled field in the CONFIG
    	 * register with the max value of slots the HC can handle.
    	 */
    	val = (xhci_readl(&hccr->cr_hcsparams1) & HCS_SLOTS_MASK);
    	val2 = xhci_readl(&hcor->or_config);
    	val |= (val2 & ~HCS_SLOTS_MASK);
    	xhci_writel(&hcor->or_config, val);
    
    	/* initializing xhci data structures */
    	if (xhci_mem_init(ctrl, hccr, hcor) < 0)
    		return -ENOMEM;
    
    	reg = xhci_readl(&hccr->cr_hcsparams1);
    	descriptor.hub.bNbrPorts = ((reg & HCS_MAX_PORTS_MASK) >>
    						HCS_MAX_PORTS_SHIFT);
    	printf("Register %x NbrPorts %d\n", reg, descriptor.hub.bNbrPorts);
    
    	/* Port Indicators */
    	reg = xhci_readl(&hccr->cr_hccparams);
    	if (HCS_INDICATOR(reg))
    		put_unaligned(get_unaligned(&descriptor.hub.wHubCharacteristics)
    				| 0x80, &descriptor.hub.wHubCharacteristics);
    
    	/* Port Power Control */
    	if (HCC_PPC(reg))
    		put_unaligned(get_unaligned(&descriptor.hub.wHubCharacteristics)
    				| 0x01, &descriptor.hub.wHubCharacteristics);
    
    	if (xhci_start(hcor)) {
    		xhci_reset(hcor);
    		return -ENODEV;
    	}