/*
 * The Mass Storage protocol state machine in this file is based on mbed's
 * implementation. We augment it by adding Zephyr's USB transport and Storage
 * APIs.
 *
 * Copyright (c) 2010-2011 mbed.org, MIT License
 * Copyright (c) 2016 Intel Corporation.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */


/**
 * @file
 * @brief Mass Storage device class driver
 *
 * Driver for USB Mass Storage device class driver
 */

#include <zephyr/init.h>
#include <errno.h>
#include <string.h>
#include <zephyr/sys/byteorder.h>
#include <zephyr/sys/__assert.h>
#include <zephyr/storage/disk_access.h>
#include <zephyr/usb/usb_device.h>
#include <usb_descriptor.h>

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(usb_msc, CONFIG_USB_MASS_STORAGE_LOG_LEVEL);

/* MSC Subclass and Protocol Codes */
#define SCSI_TRANSPARENT_SUBCLASS	0x06
#define BULK_ONLY_TRANSPORT_PROTOCOL	0x50

/* MSC Request Codes for Bulk-Only Transport */
#define MSC_REQUEST_GET_MAX_LUN		0xFE
#define MSC_REQUEST_RESET		0xFF

/* MSC Command Block Wrapper (CBW) Signature */
#define CBW_Signature			0x43425355

/* MSC Command Block Wrapper Flags */
#define CBW_DIRECTION_DATA_IN		0x80

/* MSC Bulk-Only Command Block Wrapper (CBW) */
struct CBW {
	uint32_t Signature;
	uint32_t Tag;
	uint32_t DataLength;
	uint8_t  Flags;
	uint8_t  LUN;
	uint8_t  CBLength;
	uint8_t  CB[16];
} __packed;

/* MSC Command Status Wrapper (CBW) Signature */
#define CSW_Signature			0x53425355

/* MSC Command Block Status Values */
#define CSW_STATUS_CMD_PASSED		0x00
#define CSW_STATUS_CMD_FAILED		0x01
#define CSW_STATUS_PHASE_ERROR		0x02

/* MSC Bulk-Only Command Status Wrapper (CSW) */
struct CSW {
	uint32_t Signature;
	uint32_t Tag;
	uint32_t DataResidue;
	uint8_t  Status;
} __packed;

/* SCSI transparent command set used by MSC */
#define TEST_UNIT_READY			0x00
#define REQUEST_SENSE			0x03
#define FORMAT_UNIT			0x04
#define INQUIRY				0x12
#define MODE_SELECT6			0x15
#define MODE_SENSE6			0x1A
#define START_STOP_UNIT			0x1B
#define MEDIA_REMOVAL			0x1E
#define READ_FORMAT_CAPACITIES		0x23
#define READ_CAPACITY			0x25
#define READ10				0x28
#define WRITE10				0x2A
#define VERIFY10			0x2F
#define READ12				0xA8
#define WRITE12				0xAA
#define MODE_SELECT10			0x55
#define MODE_SENSE10			0x5A

/* max USB packet size */
#define MAX_PACKET	CONFIG_MASS_STORAGE_BULK_EP_MPS

#define BLOCK_SIZE	512
#define DISK_THREAD_PRIO	-5

BUILD_ASSERT(MAX_PACKET <= BLOCK_SIZE);

#define THREAD_OP_READ_QUEUED		1
#define THREAD_OP_WRITE_QUEUED		3
#define THREAD_OP_WRITE_DONE		4

#define MASS_STORAGE_IN_EP_ADDR		0x82
#define MASS_STORAGE_OUT_EP_ADDR	0x01

struct usb_mass_config {
	struct usb_if_descriptor if0;
	struct usb_ep_descriptor if0_in_ep;
	struct usb_ep_descriptor if0_out_ep;
} __packed;

USBD_CLASS_DESCR_DEFINE(primary, 0) struct usb_mass_config mass_cfg = {
	/* Interface descriptor */
	.if0 = {
		.bLength = sizeof(struct usb_if_descriptor),
		.bDescriptorType = USB_DESC_INTERFACE,
		.bInterfaceNumber = 0,
		.bAlternateSetting = 0,
		.bNumEndpoints = 2,
		.bInterfaceClass = USB_BCC_MASS_STORAGE,
		.bInterfaceSubClass = SCSI_TRANSPARENT_SUBCLASS,
		.bInterfaceProtocol = BULK_ONLY_TRANSPORT_PROTOCOL,
		.iInterface = 0,
	},
	/* First Endpoint IN */
	.if0_in_ep = {
		.bLength = sizeof(struct usb_ep_descriptor),
		.bDescriptorType = USB_DESC_ENDPOINT,
		.bEndpointAddress = MASS_STORAGE_IN_EP_ADDR,
		.bmAttributes = USB_DC_EP_BULK,
		.wMaxPacketSize =
			sys_cpu_to_le16(CONFIG_MASS_STORAGE_BULK_EP_MPS),
		.bInterval = 0x00,
	},
	/* Second Endpoint OUT */
	.if0_out_ep = {
		.bLength = sizeof(struct usb_ep_descriptor),
		.bDescriptorType = USB_DESC_ENDPOINT,
		.bEndpointAddress = MASS_STORAGE_OUT_EP_ADDR,
		.bmAttributes = USB_DC_EP_BULK,
		.wMaxPacketSize =
			sys_cpu_to_le16(CONFIG_MASS_STORAGE_BULK_EP_MPS),
		.bInterval = 0x00,
	},
};

static volatile int thread_op;
static K_KERNEL_STACK_DEFINE(mass_thread_stack, CONFIG_MASS_STORAGE_STACK_SIZE);
static struct k_thread mass_thread_data;
static struct k_sem disk_wait_sem;
static volatile uint32_t defered_wr_sz;

/*
 * Keep block buffer larger than BLOCK_SIZE for the case
 * the dCBWDataTransferLength is multiple of the BLOCK_SIZE and
 * the length of the transferred data is not aligned to the BLOCK_SIZE.
 *
 * Align for cases where the underlying disk access requires word-aligned
 * addresses.
 */
static uint8_t __aligned(4) page[BLOCK_SIZE + CONFIG_MASS_STORAGE_BULK_EP_MPS];

/* Initialized during mass_storage_init() */
static uint32_t block_count;
static const char *disk_pdrv = CONFIG_MASS_STORAGE_DISK_NAME;

#define MSD_OUT_EP_IDX			0
#define MSD_IN_EP_IDX			1

static void mass_storage_bulk_out(uint8_t ep,
				  enum usb_dc_ep_cb_status_code ep_status);
static void mass_storage_bulk_in(uint8_t ep,
				 enum usb_dc_ep_cb_status_code ep_status);

/* Describe EndPoints configuration */
static struct usb_ep_cfg_data mass_ep_data[] = {
	{
		.ep_cb	= mass_storage_bulk_out,
		.ep_addr = MASS_STORAGE_OUT_EP_ADDR
	},
	{
		.ep_cb = mass_storage_bulk_in,
		.ep_addr = MASS_STORAGE_IN_EP_ADDR
	}
};

/* CSW Status */
enum Status {
	CSW_PASSED,
	CSW_FAILED,
	CSW_ERROR,
};

/* MSC Bulk-only Stage */
enum Stage {
	MSC_READ_CBW,     /* wait a CBW */
	MSC_ERROR,        /* error */
	MSC_PROCESS_CBW,  /* process a CBW request */
	MSC_SEND_CSW,     /* send a CSW */
	MSC_WAIT_CSW      /* wait that a CSW has been effectively sent */
};

/* state of the bulk-only state machine */
static enum Stage stage;

/*current CBW*/
static struct CBW cbw;

/*CSW which will be sent*/
static struct CSW csw;

/*addr where will be read or written data*/
static uint32_t curr_lba;

/*length of a reading or writing*/
static uint32_t length;

/*offset into curr_lba for read/write*/
static uint16_t curr_offset;

static uint8_t max_lun_count;

/*memory OK (after a memoryVerify)*/
static bool memOK;

#define INQ_VENDOR_ID_LEN 8
#define INQ_PRODUCT_ID_LEN 16
#define INQ_REVISION_LEN 4

struct dabc_inquiry_data {
	uint8_t head[8];
	uint8_t t10_vid[INQ_VENDOR_ID_LEN];
	uint8_t product_id[INQ_PRODUCT_ID_LEN];
	uint8_t product_rev[INQ_REVISION_LEN];
} __packed;

static const struct dabc_inquiry_data inq_rsp = {
	.head = {0x00, 0x80, 0x00, 0x01, 36 - 4, 0x80, 0x00, 0x00},
	.t10_vid = CONFIG_MASS_STORAGE_INQ_VENDOR_ID,
	.product_id = CONFIG_MASS_STORAGE_INQ_PRODUCT_ID,
	.product_rev = CONFIG_MASS_STORAGE_INQ_REVISION,
};

BUILD_ASSERT(sizeof(CONFIG_MASS_STORAGE_INQ_VENDOR_ID) == (INQ_VENDOR_ID_LEN + 1),
	"CONFIG_MASS_STORAGE_INQ_VENDOR_ID must be 8 characters (pad with spaces)");

BUILD_ASSERT(sizeof(CONFIG_MASS_STORAGE_INQ_PRODUCT_ID) == (INQ_PRODUCT_ID_LEN + 1),
	"CONFIG_MASS_STORAGE_INQ_PRODUCT_ID must be 16 characters (pad with spaces)");

BUILD_ASSERT(sizeof(CONFIG_MASS_STORAGE_INQ_REVISION) == (INQ_REVISION_LEN + 1),
	"CONFIG_MASS_STORAGE_INQ_REVISION must be 4 characters (pad with spaces)");

static void msd_state_machine_reset(void)
{
	stage = MSC_READ_CBW;
}

static void msd_init(void)
{
	(void)memset((void *)&cbw, 0, sizeof(struct CBW));
	(void)memset((void *)&csw, 0, sizeof(struct CSW));
	(void)memset(page, 0, sizeof(page));
	curr_lba = 0U;
	length = 0U;
	curr_offset = 0U;
}

static void sendCSW(void)
{
	csw.Signature = CSW_Signature;
	if (usb_write(mass_ep_data[MSD_IN_EP_IDX].ep_addr, (uint8_t *)&csw,
		      sizeof(struct CSW), NULL) != 0) {
		LOG_ERR("usb write failure");
	}
	stage = MSC_WAIT_CSW;
}

static void fail(void)
{
	if (cbw.DataLength) {
		/* Stall data stage */
		if ((cbw.Flags & 0x80) != 0U) {
			usb_ep_set_stall(mass_ep_data[MSD_IN_EP_IDX].ep_addr);
		} else {
			usb_ep_set_stall(mass_ep_data[MSD_OUT_EP_IDX].ep_addr);
		}
	}

	csw.Status = CSW_FAILED;
	sendCSW();
}

static bool write(uint8_t *buf, uint16_t size)
{
	if (size >= cbw.DataLength) {
		size = cbw.DataLength;
	}

	/* updating the State Machine , so that we send CSW when this
	 * transfer is complete, ie when we get a bulk in callback
	 */
	stage = MSC_SEND_CSW;

	if (usb_write(mass_ep_data[MSD_IN_EP_IDX].ep_addr, buf, size, NULL)) {
		LOG_ERR("USB write failed");
		return false;
	}

	csw.DataResidue -= size;
	csw.Status = CSW_PASSED;
	return true;
}

/**
 * @brief Handler called for Class requests not handled by the USB stack.
 *
 * @param pSetup    Information about the request to execute.
 * @param len       Size of the buffer.
 * @param data      Buffer containing the request result.
 *
 * @return  0 on success, negative errno code on fail.
 */
static int mass_storage_class_handle_req(struct usb_setup_packet *setup,
					 int32_t *len, uint8_t **data)
{
	if (setup->wIndex != mass_cfg.if0.bInterfaceNumber ||
	    setup->wValue != 0) {
		LOG_ERR("Invalid setup parameters");
		return -EINVAL;
	}

	if (usb_reqtype_is_to_device(setup)) {
		if (setup->bRequest == MSC_REQUEST_RESET &&
		    setup->wLength == 0) {
			LOG_DBG("MSC_REQUEST_RESET");
			msd_state_machine_reset();
			return 0;
		}
	} else {
		if (setup->bRequest == MSC_REQUEST_GET_MAX_LUN &&
		    setup->wLength == 1) {
			LOG_DBG("MSC_REQUEST_GET_MAX_LUN");
			max_lun_count = 0U;
			*data = (uint8_t *)(&max_lun_count);
			*len = 1;
			return 0;
		}
	}

	LOG_WRN("Unsupported bmRequestType 0x%02x bRequest 0x%02x",
		setup->bmRequestType, setup->bRequest);
	return -ENOTSUP;
}

static void testUnitReady(void)
{
	if (cbw.DataLength != 0U) {
		if ((cbw.Flags & 0x80) != 0U) {
			LOG_WRN("Stall IN endpoint");
			usb_ep_set_stall(mass_ep_data[MSD_IN_EP_IDX].ep_addr);
		} else {
			LOG_WRN("Stall OUT endpoint");
			usb_ep_set_stall(mass_ep_data[MSD_OUT_EP_IDX].ep_addr);
		}
	}

	csw.Status = CSW_PASSED;
	sendCSW();
}

static bool requestSense(void)
{
	uint8_t request_sense[] = {
		0x70,
		0x00,
		0x05,   /* Sense Key: illegal request */
		0x00,
		0x00,
		0x00,
		0x00,
		0x0A,
		0x00,
		0x00,
		0x00,
		0x00,
		0x30,
		0x01,
		0x00,
		0x00,
		0x00,
		0x00,
	};

	return write(request_sense, sizeof(request_sense));
}

static bool inquiryRequest(void)
{
	return write((uint8_t *)&inq_rsp, sizeof(inq_rsp));
}

static bool modeSense6(void)
{
	uint8_t sense6[] = { 0x03, 0x00, 0x00, 0x00 };

	return write(sense6, sizeof(sense6));
}

static bool readFormatCapacity(void)
{
	uint8_t capacity[] = { 0x00, 0x00, 0x00, 0x08,
			(uint8_t)((block_count >> 24) & 0xff),
			(uint8_t)((block_count >> 16) & 0xff),
			(uint8_t)((block_count >> 8) & 0xff),
			(uint8_t)((block_count >> 0) & 0xff),

			0x02,
			(uint8_t)((BLOCK_SIZE >> 16) & 0xff),
			(uint8_t)((BLOCK_SIZE >> 8) & 0xff),
			(uint8_t)((BLOCK_SIZE >> 0) & 0xff),
	};

	return write(capacity, sizeof(capacity));
}

static bool readCapacity(void)
{
	uint8_t capacity[8];

	sys_put_be32(block_count - 1, &capacity[0]);
	sys_put_be32(BLOCK_SIZE, &capacity[4]);

	return write(capacity, sizeof(capacity));
}

static void thread_memory_read_done(void)
{
	uint32_t n = length;

	if (n > MAX_PACKET) {
		n = MAX_PACKET;
	}
	if (n > BLOCK_SIZE - curr_offset) {
		n = BLOCK_SIZE - curr_offset;
	}

	if (usb_write(mass_ep_data[MSD_IN_EP_IDX].ep_addr,
		&page[curr_offset], n, NULL) != 0) {
		LOG_ERR("Failed to write EP 0x%x",
			mass_ep_data[MSD_IN_EP_IDX].ep_addr);
	}
	curr_offset += n;
	if (curr_offset >= BLOCK_SIZE) {
		curr_offset -= BLOCK_SIZE;
		curr_lba += 1;
	}
	length -= n;
	csw.DataResidue -= n;

	if (!length || (stage != MSC_PROCESS_CBW)) {
		csw.Status = (stage == MSC_PROCESS_CBW) ?
			CSW_PASSED : CSW_FAILED;
		stage = (stage == MSC_PROCESS_CBW) ? MSC_SEND_CSW : stage;
	}
}


static void memoryRead(void)
{
	if (curr_lba >= block_count) {
		LOG_WRN("Attempt to read past end of device: lba=%u", curr_lba);
		fail();
		return;
	}

	if (!curr_offset) {
		/* we need a new block */
		thread_op = THREAD_OP_READ_QUEUED;
		LOG_DBG("Signal thread for %u", curr_lba);
		k_sem_give(&disk_wait_sem);
	} else {
		thread_memory_read_done();
	}
}

static bool check_cbw_data_length(void)
{
	if (!cbw.DataLength) {
		LOG_WRN("Zero length in CBW");
		csw.Status = CSW_FAILED;
		sendCSW();
		return false;
	}

	return true;
}

static bool infoTransfer(void)
{
	uint32_t n;

	if (!check_cbw_data_length()) {
		return false;
	}

	/* Logical Block Address of First Block */
	n = sys_get_be32(&cbw.CB[2]);

	LOG_DBG("LBA (block) : 0x%x ", n);
	if (n >= block_count) {
		LOG_ERR("LBA out of range");
		fail();
		return false;
	}

	curr_lba = n;
	curr_offset = 0U;

	/* Number of Blocks to transfer */
	switch (cbw.CB[0]) {
	case READ10:
	case WRITE10:
	case VERIFY10:
		n = sys_get_be16(&cbw.CB[7]);
		break;

	case READ12:
	case WRITE12:
		n = sys_get_be32(&cbw.CB[6]);
		break;
	}

	LOG_DBG("Size (block) : 0x%x ", n);
	length = n * BLOCK_SIZE;

	if (cbw.DataLength != length) {
		LOG_ERR("DataLength mismatch");
		fail();
		return false;
	}

	return true;
}

static void CBWDecode(uint8_t *buf, uint16_t size)
{
	if (size != sizeof(cbw)) {
		LOG_ERR("size != sizeof(cbw)");
		return;
	}

	memcpy((uint8_t *)&cbw, buf, size);
	if (cbw.Signature != CBW_Signature) {
		LOG_ERR("CBW Signature Mismatch");
		return;
	}

	csw.Tag = cbw.Tag;
	csw.DataResidue = cbw.DataLength;

	if ((cbw.CBLength <  1) || (cbw.CBLength > 16) || (cbw.LUN != 0U)) {
		LOG_WRN("cbw.CBLength %d", cbw.CBLength);
		fail();
	} else {
		switch (cbw.CB[0]) {
		case TEST_UNIT_READY:
			LOG_DBG(">> TUR");
			testUnitReady();
			break;
		case REQUEST_SENSE:
			LOG_DBG(">> REQ_SENSE");
			if (check_cbw_data_length()) {
				requestSense();
			}
			break;
		case INQUIRY:
			LOG_DBG(">> INQ");
			if (check_cbw_data_length()) {
				inquiryRequest();
			}
			break;
		case MODE_SENSE6:
			LOG_DBG(">> MODE_SENSE6");
			if (check_cbw_data_length()) {
				modeSense6();
			}
			break;
		case READ_FORMAT_CAPACITIES:
			LOG_DBG(">> READ_FORMAT_CAPACITY");
			if (check_cbw_data_length()) {
				readFormatCapacity();
			}
			break;
		case READ_CAPACITY:
			LOG_DBG(">> READ_CAPACITY");
			if (check_cbw_data_length()) {
				readCapacity();
			}
			break;
		case READ10:
		case READ12:
			LOG_DBG(">> READ");
			if (infoTransfer()) {
				if ((cbw.Flags & 0x80)) {
					stage = MSC_PROCESS_CBW;
					memoryRead();
				} else {
					usb_ep_set_stall(
					  mass_ep_data[MSD_OUT_EP_IDX].ep_addr);
					LOG_WRN("Stall OUT endpoint");
					csw.Status = CSW_ERROR;
					sendCSW();
				}
			}
			break;
		case WRITE10:
		case WRITE12:
			LOG_DBG(">> WRITE");
			if (infoTransfer()) {
				if (!(cbw.Flags & 0x80)) {
					stage = MSC_PROCESS_CBW;
				} else {
					usb_ep_set_stall(
					  mass_ep_data[MSD_IN_EP_IDX].ep_addr);
					LOG_WRN("Stall IN endpoint");
					csw.Status = CSW_ERROR;
					sendCSW();
				}
			}
			break;
		case VERIFY10:
			LOG_DBG(">> VERIFY10");
			if (!(cbw.CB[1] & 0x02)) {
				csw.Status = CSW_PASSED;
				sendCSW();
				break;
			}
			if (infoTransfer()) {
				if (!(cbw.Flags & 0x80)) {
					stage = MSC_PROCESS_CBW;
					memOK = true;
				} else {
					usb_ep_set_stall(
					  mass_ep_data[MSD_IN_EP_IDX].ep_addr);
					LOG_WRN("Stall IN endpoint");
					csw.Status = CSW_ERROR;
					sendCSW();
				}
			}
			break;
		case MEDIA_REMOVAL:
			LOG_DBG(">> MEDIA_REMOVAL");
			csw.Status = CSW_PASSED;
			sendCSW();
			break;
		default:
			LOG_WRN(">> default CB[0] %x", cbw.CB[0]);
			fail();
			break;
		}		/*switch(cbw.CB[0])*/
	}		/* else */

}

static void memoryVerify(uint8_t *buf, uint16_t size)
{
	uint32_t n;

	if (curr_lba >= block_count) {
		LOG_WRN("Attempt to read past end of device: lba=%u", curr_lba);
		fail();
		return;
	}

	/* BUG: if a packet crosses block boundaries, we will probably fail. */

	/* beginning of a new block -> load a whole block in RAM */
	if (!curr_offset) {
		LOG_DBG("Disk READ sector %u", curr_lba);
		if (disk_access_read(disk_pdrv, page, curr_lba, 1)) {
			LOG_ERR("---- Disk Read Error %u", curr_lba);
		}
	}

	/* info are in RAM -> no need to re-read memory */
	for (n = 0U; n < size; n++) {
		if (page[curr_offset + n] != buf[n]) {
			LOG_DBG("Mismatch sector %u offset %u",
				curr_lba, curr_offset + n);
			memOK = false;
			break;
		}
	}

	curr_offset += n;
	if (curr_offset >= BLOCK_SIZE) {
		curr_offset -= BLOCK_SIZE;
		curr_lba += 1;
	}
	length -= size;
	csw.DataResidue -= size;

	if (!length || (stage != MSC_PROCESS_CBW)) {
		csw.Status = (memOK && (stage == MSC_PROCESS_CBW)) ?
						CSW_PASSED : CSW_FAILED;
		sendCSW();
	}
}

static void memoryWrite(uint8_t *buf, uint16_t size)
{
	if (curr_lba >= block_count) {
		LOG_WRN("Attempt to write past end of device: lba=%u", curr_lba);
		fail();
		return;
	}

	/* we fill an array in RAM of 1 block before writing it in memory */
	for (int i = 0; i < size; i++) {
		page[curr_offset + i] = buf[i];
	}

	/* if the array is filled, write it in memory */
	if (curr_offset + size >= BLOCK_SIZE) {
		if (!(disk_access_status(disk_pdrv) &
					DISK_STATUS_WR_PROTECT)) {
			LOG_DBG("Disk WRITE Qd %u", curr_lba);
			thread_op = THREAD_OP_WRITE_QUEUED;  /* write_queued */
			defered_wr_sz = size;
			k_sem_give(&disk_wait_sem);
			return;
		}
	}

	curr_offset += size;
	length -= size;
	csw.DataResidue -= size;

	if ((!length) || (stage != MSC_PROCESS_CBW)) {
		csw.Status = (stage == MSC_ERROR) ? CSW_FAILED : CSW_PASSED;
		sendCSW();
	}
}


static void mass_storage_bulk_out(uint8_t ep,
		enum usb_dc_ep_cb_status_code ep_status)
{
	uint32_t bytes_read = 0U;
	uint8_t bo_buf[CONFIG_MASS_STORAGE_BULK_EP_MPS];

	ARG_UNUSED(ep_status);

	usb_ep_read_wait(ep, bo_buf, CONFIG_MASS_STORAGE_BULK_EP_MPS,
			 &bytes_read);

	switch (stage) {
	/*the device has to decode the CBW received*/
	case MSC_READ_CBW:
		LOG_DBG("> BO - MSC_READ_CBW");
		CBWDecode(bo_buf, bytes_read);
		break;

	/*the device has to receive data from the host*/
	case MSC_PROCESS_CBW:
		switch (cbw.CB[0]) {
		case WRITE10:
		case WRITE12:
			/* LOG_DBG("> BO - PROC_CBW WR");*/
			memoryWrite(bo_buf, bytes_read);
			break;
		case VERIFY10:
			LOG_DBG("> BO - PROC_CBW VER");
			memoryVerify(bo_buf, bytes_read);
			break;
		default:
			LOG_ERR("> BO - PROC_CBW default <<ERROR!!!>>");
			break;
		}
		break;

	/*an error has occurred: stall endpoint and send CSW*/
	default:
		LOG_WRN("Stall OUT endpoint, stage: %d", stage);
		usb_ep_set_stall(ep);
		csw.Status = CSW_ERROR;
		sendCSW();
		break;
	}

	if (thread_op != THREAD_OP_WRITE_QUEUED) {
		usb_ep_read_continue(ep);
	} else {
		LOG_DBG("> BO not clearing NAKs yet");
	}

}

static void thread_memory_write_done(void)
{
	uint32_t size = defered_wr_sz;
	size_t overflowed_len = (curr_offset + size) - BLOCK_SIZE;

	if (BLOCK_SIZE > (curr_offset + size)) {
		overflowed_len = 0;
	}

	if (overflowed_len > 0) {
		memmove(page, &page[BLOCK_SIZE], overflowed_len);
	}

	curr_offset = overflowed_len;
	curr_lba += 1;
	length -= size;
	csw.DataResidue -= size;

	if (!length) {
		if (disk_access_ioctl(disk_pdrv, DISK_IOCTL_CTRL_SYNC, NULL)) {
			LOG_ERR("!! Disk cache sync error !!");
		}
	}

	if ((!length) || (stage != MSC_PROCESS_CBW)) {
		csw.Status = (stage == MSC_ERROR) ? CSW_FAILED : CSW_PASSED;
		sendCSW();
	}

	thread_op = THREAD_OP_WRITE_DONE;

	usb_ep_read_continue(mass_ep_data[MSD_OUT_EP_IDX].ep_addr);
}

/**
 * @brief EP Bulk IN handler, used to send data to the Host
 *
 * @param ep        Endpoint address.
 * @param ep_status Endpoint status code.
 *
 * @return  N/A.
 */
static void mass_storage_bulk_in(uint8_t ep,
				 enum usb_dc_ep_cb_status_code ep_status)
{
	ARG_UNUSED(ep_status);
	ARG_UNUSED(ep);

	switch (stage) {
	/*the device has to send data to the host*/
	case MSC_PROCESS_CBW:
		switch (cbw.CB[0]) {
		case READ10:
		case READ12:
			/* LOG_DBG("< BI - PROC_CBW  READ"); */
			memoryRead();
			break;
		default:
			LOG_ERR("< BI-PROC_CBW default <<ERROR!!>>");
			break;
		}
		break;

	/*the device has to send a CSW*/
	case MSC_SEND_CSW:
		LOG_DBG("< BI - MSC_SEND_CSW");
		sendCSW();
		break;

	/*the host has received the CSW -> we wait a CBW*/
	case MSC_WAIT_CSW:
		LOG_DBG("< BI - MSC_WAIT_CSW");
		stage = MSC_READ_CBW;
		break;

	/*an error has occurred*/
	default:
		LOG_WRN("Stall IN endpoint, stage: %d", stage);
		usb_ep_set_stall(mass_ep_data[MSD_IN_EP_IDX].ep_addr);
		sendCSW();
		break;
	}
}


/**
 * @brief Callback used to know the USB connection status
 *
 * @param status USB device status code.
 *
 * @return  N/A.
 */
static void mass_storage_status_cb(struct usb_cfg_data *cfg,
				   enum usb_dc_status_code status,
				   const uint8_t *param)
{
	ARG_UNUSED(param);
	ARG_UNUSED(cfg);

	/* Check the USB status and do needed action if required */
	switch (status) {
	case USB_DC_ERROR:
		LOG_DBG("USB device error");
		break;
	case USB_DC_RESET:
		LOG_DBG("USB device reset detected");
		msd_state_machine_reset();
		msd_init();
		break;
	case USB_DC_CONNECTED:
		LOG_DBG("USB device connected");
		break;
	case USB_DC_CONFIGURED:
		LOG_DBG("USB device configured");
		break;
	case USB_DC_DISCONNECTED:
		LOG_DBG("USB device disconnected");
		break;
	case USB_DC_SUSPEND:
		LOG_DBG("USB device suspended");
		break;
	case USB_DC_RESUME:
		LOG_DBG("USB device resumed");
		break;
	case USB_DC_INTERFACE:
		LOG_DBG("USB interface selected");
		break;
	case USB_DC_SOF:
		break;
	case USB_DC_UNKNOWN:
	default:
		LOG_DBG("USB unknown state");
		break;
	}
}

static void mass_interface_config(struct usb_desc_header *head,
				  uint8_t bInterfaceNumber)
{
	ARG_UNUSED(head);

	mass_cfg.if0.bInterfaceNumber = bInterfaceNumber;
}

/* Configuration of the Mass Storage Device send to the USB Driver */
USBD_DEFINE_CFG_DATA(mass_storage_config) = {
	.usb_device_description = NULL,
	.interface_config = mass_interface_config,
	.interface_descriptor = &mass_cfg.if0,
	.cb_usb_status = mass_storage_status_cb,
	.interface = {
		.class_handler = mass_storage_class_handle_req,
		.custom_handler = NULL,
	},
	.num_endpoints = ARRAY_SIZE(mass_ep_data),
	.endpoint = mass_ep_data
};

static void mass_thread_main(void *p1, void *p2, void *p3)
{
	ARG_UNUSED(p1);
	ARG_UNUSED(p2);
	ARG_UNUSED(p3);

	while (1) {
		k_sem_take(&disk_wait_sem, K_FOREVER);
		LOG_DBG("sem %d", thread_op);

		switch (thread_op) {
		case THREAD_OP_READ_QUEUED:
			if (disk_access_read(disk_pdrv,
						page, curr_lba, 1)) {
				LOG_ERR("!! Disk Read Error %u !",
					curr_lba);
			}

			thread_memory_read_done();
			break;
		case THREAD_OP_WRITE_QUEUED:
			if (disk_access_write(disk_pdrv,
						page, curr_lba, 1)) {
				LOG_ERR("!!!!! Disk Write Error %u !!!!!",
					curr_lba);
			}
			thread_memory_write_done();
			break;
		default:
			LOG_ERR("XXXXXX thread_op  %d ! XXXXX", thread_op);
		}
	}
}

/**
 * @brief Initialize USB mass storage setup
 *
 * This routine is called to reset the USB device controller chip to a
 * quiescent state. Also it initializes the backing storage and initializes
 * the mass storage protocol state.
 *
 * @param dev device struct.
 *
 * @return negative errno code on fatal failure, 0 otherwise
 */
static int mass_storage_init(void)
{
	uint32_t block_size = 0U;


	if (disk_access_init(disk_pdrv) != 0) {
		LOG_ERR("Storage init ERROR !!!! - Aborting USB init");
		return 0;
	}

	if (disk_access_ioctl(disk_pdrv,
				DISK_IOCTL_GET_SECTOR_COUNT, &block_count)) {
		LOG_ERR("Unable to get sector count - Aborting USB init");
		return 0;
	}

	if (disk_access_ioctl(disk_pdrv,
				DISK_IOCTL_GET_SECTOR_SIZE, &block_size)) {
		LOG_ERR("Unable to get sector size - Aborting USB init");
		return 0;
	}

	if (block_size != BLOCK_SIZE) {
		LOG_ERR("Block Size reported by the storage side is "
			"different from Mass Storage Class page Buffer - "
			"Aborting");
		return 0;
	}


	LOG_INF("Sect Count %u", block_count);
	LOG_INF("Memory Size %llu", (uint64_t) block_count * BLOCK_SIZE);

	msd_state_machine_reset();
	msd_init();

	k_sem_init(&disk_wait_sem, 0, 1);

	/* Start a thread to offload disk ops */
	k_thread_create(&mass_thread_data, mass_thread_stack,
			CONFIG_MASS_STORAGE_STACK_SIZE,
			mass_thread_main, NULL, NULL, NULL,
			DISK_THREAD_PRIO, 0, K_NO_WAIT);

	k_thread_name_set(&mass_thread_data, "usb_mass");

	return 0;
}

SYS_INIT(mass_storage_init, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEVICE);