#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mutex.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_devinfo.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>

#include "usb.h"
#include "scsiglue.h"
#include "transport.h"

/* Host functions */
/*
 * host_info()
 */
static const char *host_info(struct Scsi_Host *host)
{
	/* pr_info("scsiglue --- host_info\n"); */
	return "SCSI emulation for USB Mass Storage devices";
}

/*
 * slave_alloc()
 */
static int slave_alloc(struct scsi_device *sdev)
{
	struct us_data *us = host_to_us(sdev->host);

	/* pr_info("scsiglue --- slave_alloc\n"); */
	sdev->inquiry_len = 36;

	blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));

	if (us->subclass == USB_SC_UFI)
		sdev->sdev_target->pdt_1f_for_no_lun = 1;

	return 0;
}

/*
 * slave_configure()
 */
static int slave_configure(struct scsi_device *sdev)
{
	struct us_data *us = host_to_us(sdev->host);

	/* pr_info("scsiglue --- slave_configure\n"); */
	if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
		unsigned int max_sectors = 64;

		if (us->fflags & US_FL_MAX_SECTORS_MIN)
			max_sectors = PAGE_CACHE_SIZE >> 9;
		if (queue_max_sectors(sdev->request_queue) > max_sectors)
			blk_queue_max_hw_sectors(sdev->request_queue,
					      max_sectors);
	}

	if (sdev->type == TYPE_DISK) {
		if (us->subclass != USB_SC_SCSI &&
			us->subclass != USB_SC_CYP_ATACB)
			sdev->use_10_for_ms = 1;
		sdev->use_192_bytes_for_3f = 1;
		if (us->fflags & US_FL_NO_WP_DETECT)
			sdev->skip_ms_page_3f = 1;
		sdev->skip_ms_page_8 = 1;
		if (us->fflags & US_FL_FIX_CAPACITY)
			sdev->fix_capacity = 1;
		if (us->fflags & US_FL_CAPACITY_HEURISTICS)
			sdev->guess_capacity = 1;
		if (sdev->scsi_level > SCSI_2)
			sdev->sdev_target->scsi_level = sdev->scsi_level
								= SCSI_2;
		sdev->retry_hwerror = 1;
		sdev->allow_restart = 1;
		sdev->last_sector_bug = 1;
	} else {
		sdev->use_10_for_ms = 1;
	}

	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
					sdev->scsi_level == SCSI_UNKNOWN)
		us->max_lun = 0;

	if (us->fflags & US_FL_NOT_LOCKABLE)
		sdev->lockable = 0;

	return 0;
}

/* This is always called with scsi_lock(host) held */
/*
 * queuecommand()
 */
static int queuecommand_lck(struct scsi_cmnd *srb,
				void (*done)(struct scsi_cmnd *))
{
	struct us_data *us = host_to_us(srb->device->host);

	/* pr_info("scsiglue --- queuecommand\n"); */

	/* check for state-transition errors */
	if (us->srb != NULL) {
		/* pr_info("Error in %s: us->srb = %p\n"
				 __FUNCTION__, us->srb); */
		return SCSI_MLQUEUE_HOST_BUSY;
	}

	/* fail the command if we are disconnecting */
	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
		pr_info("Fail command during disconnect\n");
		srb->result = DID_NO_CONNECT << 16;
		done(srb);
		return 0;
	}

	/* enqueue the command and wake up the control thread */
	srb->scsi_done = done;
	us->srb = srb;
	complete(&us->cmnd_ready);

	return 0;
}

static DEF_SCSI_QCMD(queuecommand)

/***********************************************************************
 * Error handling functions
 ***********************************************************************/

/* Command timeout and abort */
/*
 * command_abort()
 */
static int command_abort(struct scsi_cmnd *srb)
{
	struct us_data *us = host_to_us(srb->device->host);

	/* pr_info("scsiglue --- command_abort\n"); */

	scsi_lock(us_to_host(us));
	if (us->srb != srb) {
		scsi_unlock(us_to_host(us));
		dev_info(&us->pusb_dev->dev, "-- nothing to abort\n");
		return FAILED;
	}

	set_bit(US_FLIDX_TIMED_OUT, &us->dflags);
	if (!test_bit(US_FLIDX_RESETTING, &us->dflags)) {
		set_bit(US_FLIDX_ABORTING, &us->dflags);
		usb_stor_stop_transport(us);
	}
	scsi_unlock(us_to_host(us));

	/* Wait for the aborted command to finish */
	wait_for_completion(&us->notify);
	return SUCCESS;
}

/* This invokes the transport reset mechanism to reset the state of the
 * device.
 */
/*
 * device_reset()
 */
static int device_reset(struct scsi_cmnd *srb)
{
	struct us_data *us = host_to_us(srb->device->host);
	int result;

	/* pr_info("scsiglue --- device_reset\n"); */

	/* lock the device pointers and do the reset */
	mutex_lock(&(us->dev_mutex));
	result = us->transport_reset(us);
	mutex_unlock(&us->dev_mutex);

	return result < 0 ? FAILED : SUCCESS;
}

/*
 * bus_reset()
 */
static int bus_reset(struct scsi_cmnd *srb)
{
	struct us_data *us = host_to_us(srb->device->host);
	int result;

	/* pr_info("scsiglue --- bus_reset\n"); */
	result = usb_stor_port_reset(us);
	return result < 0 ? FAILED : SUCCESS;
}

/*
 * usb_stor_report_device_reset()
 */
void usb_stor_report_device_reset(struct us_data *us)
{
	int i;
	struct Scsi_Host *host = us_to_host(us);

	/* pr_info("scsiglue --- usb_stor_report_device_reset\n"); */
	scsi_report_device_reset(host, 0, 0);
	if (us->fflags & US_FL_SCM_MULT_TARG) {
		for (i = 1; i < host->max_id; ++i)
			scsi_report_device_reset(host, 0, i);
	}
}

/*
 * usb_stor_report_bus_reset()
 */
void usb_stor_report_bus_reset(struct us_data *us)
{
	struct Scsi_Host *host = us_to_host(us);

	/* pr_info("scsiglue --- usb_stor_report_bus_reset\n"); */
	scsi_lock(host);
	scsi_report_bus_reset(host, 0);
	scsi_unlock(host);
}

/***********************************************************************
 * /proc/scsi/ functions
 ***********************************************************************/

/* we use this macro to help us write into the buffer */
#undef SPRINTF
#define SPRINTF(args...) seq_printf(m, ##args)

static int write_info(struct Scsi_Host *host, char *buffer, int length)
{
	return length;
}

static int show_info(struct seq_file *m, struct Scsi_Host *host)
{
	struct us_data *us = host_to_us(host);
	const char *string;

	/* print the controller name */
	SPRINTF("   Host scsi%d: usb-storage\n", host->host_no);

	/* print product, vendor, and serial number strings */
	if (us->pusb_dev->manufacturer)
		string = us->pusb_dev->manufacturer;
	else if (us->unusual_dev->vendorName)
		string = us->unusual_dev->vendorName;
	else
		string = "Unknown";
	SPRINTF("       Vendor: %s\n", string);
	if (us->pusb_dev->product)
		string = us->pusb_dev->product;
	else if (us->unusual_dev->productName)
		string = us->unusual_dev->productName;
	else
		string = "Unknown";
	SPRINTF("      Product: %s\n", string);
	if (us->pusb_dev->serial)
		string = us->pusb_dev->serial;
	else
		string = "None";
	SPRINTF("Serial Number: %s\n", string);

	/* show the protocol and transport */
	SPRINTF("     Protocol: %s\n", us->protocol_name);
	SPRINTF("    Transport: %s\n", us->transport_name);

	/* show the device flags */
	SPRINTF("       Quirks:");

#define US_FLAG(name, value) \
	do { \
		if (us->fflags & value) \
			SPRINTF(" " #name); \
	} while (0);
US_DO_ALL_FLAGS
#undef US_FLAG
	seq_putc(m, '\n');
	return 0;
}

/***********************************************************************
 * Sysfs interface
 ***********************************************************************/

/* Output routine for the sysfs max_sectors file */
/*
 * show_max_sectors()
 */
static ssize_t show_max_sectors(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct scsi_device *sdev = to_scsi_device(dev);

	/* pr_info("scsiglue --- ssize_t show_max_sectors\n"); */
	return sprintf(buf, "%u\n", queue_max_sectors(sdev->request_queue));
}

/* Input routine for the sysfs max_sectors file */
/*
 * store_max_sectors()
 */
static ssize_t store_max_sectors(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t count)
{
	struct scsi_device *sdev = to_scsi_device(dev);
	unsigned short ms;

	/* pr_info("scsiglue --- ssize_t store_max_sectors\n"); */
	if (sscanf(buf, "%hu", &ms) > 0 && ms <= SCSI_DEFAULT_MAX_SECTORS) {
		blk_queue_max_hw_sectors(sdev->request_queue, ms);
		return strlen(buf);
	}
	return -EINVAL;
}

static DEVICE_ATTR(max_sectors, S_IRUGO | S_IWUSR, show_max_sectors,
							store_max_sectors);
static struct device_attribute *sysfs_device_attr_list[] = {
	&dev_attr_max_sectors, NULL,
};

/* this defines our host template, with which we'll allocate hosts */

/*
 * usb_stor_host_template()
 */
struct scsi_host_template usb_stor_host_template = {
	/* basic userland interface stuff */
	.name =				"eucr-storage",
	.proc_name =			"eucr-storage",
	.write_info =			write_info,
	.show_info =			show_info,
	.info =				host_info,

	/* command interface -- queued only */
	.queuecommand =			queuecommand,

	/* error and abort handlers */
	.eh_abort_handler =		command_abort,
	.eh_device_reset_handler =	device_reset,
	.eh_bus_reset_handler =		bus_reset,

	/* queue commands only, only one command per LUN */
	.can_queue =			1,
	.cmd_per_lun =			1,

	/* unknown initiator id */
	.this_id =			-1,

	.slave_alloc =			slave_alloc,
	.slave_configure =		slave_configure,

	/* lots of sg segments can be handled */
	.sg_tablesize =			SG_ALL,

	/* limit the total size of a transfer to 120 KB */
	.max_sectors =                  240,

	/* merge commands... this seems to help performance, but
	 * periodically someone should test to see which setting is more
	 * optimal.
	 */
	.use_clustering =		1,

	/* emulated HBA */
	.emulated =			1,

	/* we do our own delay after a device or bus reset */
	.skip_settle_delay =		1,

	/* sysfs device attributes */
	.sdev_attrs =			sysfs_device_attr_list,

	/* module management */
	.module =			THIS_MODULE
};

/* To Report "Illegal Request: Invalid Field in CDB */
unsigned char usb_stor_sense_invalidCDB[18] = {
	[0]	= 0x70,			    /* current error */
	[2]	= ILLEGAL_REQUEST,	    /* Illegal Request = 0x05 */
	[7]	= 0x0a,			    /* additional length */
	[12]	= 0x24			    /* Invalid Field in CDB */
};

/***********************************************************************
 * Scatter-gather transfer buffer access routines
 ***********************************************************************/

/*
 * usb_stor_access_xfer_buf()
 */
unsigned int usb_stor_access_xfer_buf(struct us_data *us,
	unsigned char *buffer, unsigned int buflen,
	struct scsi_cmnd *srb, struct scatterlist **sgptr,
	unsigned int *offset, enum xfer_buf_dir dir)
{
	unsigned int cnt;

	/* pr_info("transport --- usb_stor_access_xfer_buf\n"); */
	struct scatterlist *sg = *sgptr;

	if (!sg)
		sg = scsi_sglist(srb);

	cnt = 0;
	while (cnt < buflen && sg) {
		struct page *page = sg_page(sg) +
					((sg->offset + *offset) >> PAGE_SHIFT);
		unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1);
		unsigned int sglen = sg->length - *offset;

		if (sglen > buflen - cnt) {
			/* Transfer ends within this s-g entry */
			sglen = buflen - cnt;
			*offset += sglen;
		} else {
			/* Transfer continues to next s-g entry */
			*offset = 0;
			sg = sg_next(sg);
		}

		while (sglen > 0) {
			unsigned int plen = min(sglen,
					(unsigned int)PAGE_SIZE - poff);
			unsigned char *ptr = kmap(page);

			if (dir == TO_XFER_BUF)
				memcpy(ptr + poff, buffer + cnt, plen);
			else
				memcpy(buffer + cnt, ptr + poff, plen);
			kunmap(page);

			/* Start at the beginning of the next page */
			poff = 0;
			++page;
			cnt += plen;
			sglen -= plen;
		}
	}
	*sgptr = sg;

	/* Return the amount actually transferred */
	return cnt;
}

/*
 * Store the contents of buffer into srb's transfer
 * buffer and set the SCSI residue.
 */
/*
 * usb_stor_set_xfer_buf()
 */
void usb_stor_set_xfer_buf(struct us_data *us, unsigned char *buffer,
		unsigned int buflen, struct scsi_cmnd *srb, unsigned int dir)
{
	unsigned int offset = 0;
	struct scatterlist *sg = NULL;

	/* pr_info("transport --- usb_stor_set_xfer_buf\n"); */
	/* TO_XFER_BUF = 0, FROM_XFER_BUF = 1 */
	buflen = min(buflen, scsi_bufflen(srb));
	buflen = usb_stor_access_xfer_buf(us, buffer, buflen, srb,
						&sg, &offset, dir);
	if (buflen < scsi_bufflen(srb))
		scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
}