xref: /linux/drivers/memstick/core/ms_block.c (revision fab183d632628381b466a41479489541ac0e29a0)

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  ms_block.c - Sony MemoryStick (legacy) storage support

 *  Copyright (C) 2013 Maxim Levitsky <maximlevitsky@gmail.com>
 *
 * Minor portions of the driver were copied from mspro_block.c which is
 * Copyright (C) 2007 Alex Dubov <oakad@yahoo.com>
 */
#define DRIVER_NAME "ms_block"
#define pr_fmt(fmt) DRIVER_NAME ": " fmt

#include <linux/module.h>
#include <linux/blk-mq.h>
#include <linux/memstick.h>
#include <linux/idr.h>
#include <linux/hdreg.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/bitmap.h>
#include <linux/scatterlist.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include "ms_block.h"

static int debug;
static int cache_flush_timeout = 1000;
static bool verify_writes;

/*
 * Copies section of 'sg_from' starting from offset 'offset' and with length
 * 'len' To another scatterlist of to_nents enties
 */
static size_t msb_sg_copy(struct scatterlist *sg_from,
	struct scatterlist *sg_to, int to_nents, size_t offset, size_t len)
{
	size_t copied = 0;

	while (offset > 0) {
		if (offset >= sg_from->length) {
			if (sg_is_last(sg_from))
				return 0;

			offset -= sg_from->length;
			sg_from = sg_next(sg_from);
			continue;
		}

		copied = min(len, sg_from->length - offset);
		sg_set_page(sg_to, sg_page(sg_from),
			copied, sg_from->offset + offset);

		len -= copied;
		offset = 0;

		if (sg_is_last(sg_from) || !len)
			goto out;

		sg_to = sg_next(sg_to);
		to_nents--;
		sg_from = sg_next(sg_from);
	}

	while (len > sg_from->length && to_nents--) {
		len -= sg_from->length;
		copied += sg_from->length;

		sg_set_page(sg_to, sg_page(sg_from),
				sg_from->length, sg_from->offset);

		if (sg_is_last(sg_from) || !len)
			goto out;

		sg_from = sg_next(sg_from);
		sg_to = sg_next(sg_to);
	}

	if (len && to_nents) {
		sg_set_page(sg_to, sg_page(sg_from), len, sg_from->offset);
		copied += len;
	}
out:
	sg_mark_end(sg_to);
	return copied;
}

/*
 * Compares section of 'sg' starting from offset 'offset' and with length 'len'
 * to linear buffer of length 'len' at address 'buffer'
 * Returns 0 if equal and  -1 otherwice
 */
static int msb_sg_compare_to_buffer(struct scatterlist *sg,
					size_t offset, u8 *buffer, size_t len)
{
	int retval = 0, cmplen;
	struct sg_mapping_iter miter;

	sg_miter_start(&miter, sg, sg_nents(sg),
					SG_MITER_ATOMIC | SG_MITER_FROM_SG);

	while (sg_miter_next(&miter) && len > 0) {
		if (offset >= miter.length) {
			offset -= miter.length;
			continue;
		}

		cmplen = min(miter.length - offset, len);
		retval = memcmp(miter.addr + offset, buffer, cmplen) ? -1 : 0;
		if (retval)
			break;

		buffer += cmplen;
		len -= cmplen;
		offset = 0;
	}

	if (!retval && len)
		retval = -1;

	sg_miter_stop(&miter);
	return retval;
}


/* Get zone at which block with logical address 'lba' lives
 * Flash is broken into zones.
 * Each zone consists of 512 eraseblocks, out of which in first
 * zone 494 are used and 496 are for all following zones.
 * Therefore zone #0 hosts blocks 0-493, zone #1 blocks 494-988, etc...
 */
static int msb_get_zone_from_lba(int lba)
{
	if (lba < 494)
		return 0;
	return ((lba - 494) / 496) + 1;
}

/* Get zone of physical block. Trivial */
static int msb_get_zone_from_pba(int pba)
{
	return pba / MS_BLOCKS_IN_ZONE;
}

/* Debug test to validate free block counts */
static int msb_validate_used_block_bitmap(struct msb_data *msb)
{
	int total_free_blocks = 0;
	int i;

	if (!debug)
		return 0;

	for (i = 0; i < msb->zone_count; i++)
		total_free_blocks += msb->free_block_count[i];

	if (msb->block_count - bitmap_weight(msb->used_blocks_bitmap,
					msb->block_count) == total_free_blocks)
		return 0;

	pr_err("BUG: free block counts don't match the bitmap");
	msb->read_only = true;
	return -EINVAL;
}

/* Mark physical block as used */
static void msb_mark_block_used(struct msb_data *msb, int pba)
{
	int zone = msb_get_zone_from_pba(pba);

	if (test_bit(pba, msb->used_blocks_bitmap)) {
		pr_err(
		"BUG: attempt to mark already used pba %d as used", pba);
		msb->read_only = true;
		return;
	}

	if (msb_validate_used_block_bitmap(msb))
		return;

	/* No races because all IO is single threaded */
	__set_bit(pba, msb->used_blocks_bitmap);
	msb->free_block_count[zone]--;
}

/* Mark physical block as free */
static void msb_mark_block_unused(struct msb_data *msb, int pba)
{
	int zone = msb_get_zone_from_pba(pba);

	if (!test_bit(pba, msb->used_blocks_bitmap)) {
		pr_err("BUG: attempt to mark already unused pba %d as unused" , pba);
		msb->read_only = true;
		return;
	}

	if (msb_validate_used_block_bitmap(msb))
		return;

	/* No races because all IO is single threaded */
	__clear_bit(pba, msb->used_blocks_bitmap);
	msb->free_block_count[zone]++;
}

/* Invalidate current register window */
static void msb_invalidate_reg_window(struct msb_data *msb)
{
	msb->reg_addr.w_offset = offsetof(struct ms_register, id);
	msb->reg_addr.w_length = sizeof(struct ms_id_register);
	msb->reg_addr.r_offset = offsetof(struct ms_register, id);
	msb->reg_addr.r_length = sizeof(struct ms_id_register);
	msb->addr_valid = false;
}

/* Start a state machine */
static int msb_run_state_machine(struct msb_data *msb, int   (*state_func)
		(struct memstick_dev *card, struct memstick_request **req))
{
	struct memstick_dev *card = msb->card;

	WARN_ON(msb->state != -1);
	msb->int_polling = false;
	msb->state = 0;
	msb->exit_error = 0;

	memset(&card->current_mrq, 0, sizeof(card->current_mrq));

	card->next_request = state_func;
	memstick_new_req(card->host);
	wait_for_completion(&card->mrq_complete);

	WARN_ON(msb->state != -1);
	return msb->exit_error;
}

/* State machines call that to exit */
static int msb_exit_state_machine(struct msb_data *msb, int error)
{
	WARN_ON(msb->state == -1);

	msb->state = -1;
	msb->exit_error = error;
	msb->card->next_request = h_msb_default_bad;

	/* Invalidate reg window on errors */
	if (error)
		msb_invalidate_reg_window(msb);

	complete(&msb->card->mrq_complete);
	return -ENXIO;
}

/* read INT register */
static int msb_read_int_reg(struct msb_data *msb, long timeout)
{
	struct memstick_request *mrq = &msb->card->current_mrq;

	WARN_ON(msb->state == -1);

	if (!msb->int_polling) {
		msb->int_timeout = jiffies +
			msecs_to_jiffies(timeout == -1 ? 500 : timeout);
		msb->int_polling = true;
	} else if (time_after(jiffies, msb->int_timeout)) {
		mrq->data[0] = MEMSTICK_INT_CMDNAK;
		return 0;
	}

	if ((msb->caps & MEMSTICK_CAP_AUTO_GET_INT) &&
				mrq->need_card_int && !mrq->error) {
		mrq->data[0] = mrq->int_reg;
		mrq->need_card_int = false;
		return 0;
	} else {
		memstick_init_req(mrq, MS_TPC_GET_INT, NULL, 1);
		return 1;
	}
}

/* Read a register */
static int msb_read_regs(struct msb_data *msb, int offset, int len)
{
	struct memstick_request *req = &msb->card->current_mrq;

	if (msb->reg_addr.r_offset != offset ||
	    msb->reg_addr.r_length != len || !msb->addr_valid) {

		msb->reg_addr.r_offset = offset;
		msb->reg_addr.r_length = len;
		msb->addr_valid = true;

		memstick_init_req(req, MS_TPC_SET_RW_REG_ADRS,
			&msb->reg_addr, sizeof(msb->reg_addr));
		return 0;
	}

	memstick_init_req(req, MS_TPC_READ_REG, NULL, len);
	return 1;
}

/* Write a card register */
static int msb_write_regs(struct msb_data *msb, int offset, int len, void *buf)
{
	struct memstick_request *req = &msb->card->current_mrq;

	if (msb->reg_addr.w_offset != offset ||
		msb->reg_addr.w_length != len  || !msb->addr_valid) {

		msb->reg_addr.w_offset = offset;
		msb->reg_addr.w_length = len;
		msb->addr_valid = true;

		memstick_init_req(req, MS_TPC_SET_RW_REG_ADRS,
			&msb->reg_addr, sizeof(msb->reg_addr));
		return 0;
	}

	memstick_init_req(req, MS_TPC_WRITE_REG, buf, len);
	return 1;
}

/* Handler for absence of IO */
static int h_msb_default_bad(struct memstick_dev *card,
						struct memstick_request **mrq)
{
	return -ENXIO;
}

/*
 * This function is a handler for reads of one page from device.
 * Writes output to msb->current_sg, takes sector address from msb->reg.param
 * Can also be used to read extra data only. Set params accordintly.
 */
static int h_msb_read_page(struct memstick_dev *card,
					struct memstick_request **out_mrq)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct memstick_request *mrq = *out_mrq = &card->current_mrq;
	struct scatterlist sg[2];
	u8 command, intreg;

	if (mrq->error) {
		dbg("read_page, unknown error");
		return msb_exit_state_machine(msb, mrq->error);
	}
again:
	switch (msb->state) {
	case MSB_RP_SEND_BLOCK_ADDRESS:
		/* msb_write_regs sometimes "fails" because it needs to update
		 * the reg window, and thus it returns request for that.
		 * Then we stay in this state and retry
		 */
		if (!msb_write_regs(msb,
			offsetof(struct ms_register, param),
			sizeof(struct ms_param_register),
			(unsigned char *)&msb->regs.param))
			return 0;

		msb->state = MSB_RP_SEND_READ_COMMAND;
		return 0;

	case MSB_RP_SEND_READ_COMMAND:
		command = MS_CMD_BLOCK_READ;
		memstick_init_req(mrq, MS_TPC_SET_CMD, &command, 1);
		msb->state = MSB_RP_SEND_INT_REQ;
		return 0;

	case MSB_RP_SEND_INT_REQ:
		msb->state = MSB_RP_RECEIVE_INT_REQ_RESULT;
		/* If dont actually need to send the int read request (only in
		 * serial mode), then just fall through
		 */
		if (msb_read_int_reg(msb, -1))
			return 0;
		fallthrough;

	case MSB_RP_RECEIVE_INT_REQ_RESULT:
		intreg = mrq->data[0];
		msb->regs.status.interrupt = intreg;

		if (intreg & MEMSTICK_INT_CMDNAK)
			return msb_exit_state_machine(msb, -EIO);

		if (!(intreg & MEMSTICK_INT_CED)) {
			msb->state = MSB_RP_SEND_INT_REQ;
			goto again;
		}

		msb->int_polling = false;
		msb->state = (intreg & MEMSTICK_INT_ERR) ?
			MSB_RP_SEND_READ_STATUS_REG : MSB_RP_SEND_OOB_READ;
		goto again;

	case MSB_RP_SEND_READ_STATUS_REG:
		 /* read the status register to understand source of the INT_ERR */
		if (!msb_read_regs(msb,
			offsetof(struct ms_register, status),
			sizeof(struct ms_status_register)))
			return 0;

		msb->state = MSB_RP_RECEIVE_STATUS_REG;
		return 0;

	case MSB_RP_RECEIVE_STATUS_REG:
		msb->regs.status = *(struct ms_status_register *)mrq->data;
		msb->state = MSB_RP_SEND_OOB_READ;
		fallthrough;

	case MSB_RP_SEND_OOB_READ:
		if (!msb_read_regs(msb,
			offsetof(struct ms_register, extra_data),
			sizeof(struct ms_extra_data_register)))
			return 0;

		msb->state = MSB_RP_RECEIVE_OOB_READ;
		return 0;

	case MSB_RP_RECEIVE_OOB_READ:
		msb->regs.extra_data =
			*(struct ms_extra_data_register *) mrq->data;
		msb->state = MSB_RP_SEND_READ_DATA;
		fallthrough;

	case MSB_RP_SEND_READ_DATA:
		/* Skip that state if we only read the oob */
		if (msb->regs.param.cp == MEMSTICK_CP_EXTRA) {
			msb->state = MSB_RP_RECEIVE_READ_DATA;
			goto again;
		}

		sg_init_table(sg, ARRAY_SIZE(sg));
		msb_sg_copy(msb->current_sg, sg, ARRAY_SIZE(sg),
			msb->current_sg_offset,
			msb->page_size);

		memstick_init_req_sg(mrq, MS_TPC_READ_LONG_DATA, sg);
		msb->state = MSB_RP_RECEIVE_READ_DATA;
		return 0;

	case MSB_RP_RECEIVE_READ_DATA:
		if (!(msb->regs.status.interrupt & MEMSTICK_INT_ERR)) {
			msb->current_sg_offset += msb->page_size;
			return msb_exit_state_machine(msb, 0);
		}

		if (msb->regs.status.status1 & MEMSTICK_UNCORR_ERROR) {
			dbg("read_page: uncorrectable error");
			return msb_exit_state_machine(msb, -EBADMSG);
		}

		if (msb->regs.status.status1 & MEMSTICK_CORR_ERROR) {
			dbg("read_page: correctable error");
			msb->current_sg_offset += msb->page_size;
			return msb_exit_state_machine(msb, -EUCLEAN);
		} else {
			dbg("read_page: INT error, but no status error bits");
			return msb_exit_state_machine(msb, -EIO);
		}
	}

	BUG();
}

/*
 * Handler of writes of exactly one block.
 * Takes address from msb->regs.param.
 * Writes same extra data to blocks, also taken
 * from msb->regs.extra
 * Returns -EBADMSG if write fails due to uncorrectable error, or -EIO if
 * device refuses to take the command or something else
 */
static int h_msb_write_block(struct memstick_dev *card,
					struct memstick_request **out_mrq)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct memstick_request *mrq = *out_mrq = &card->current_mrq;
	struct scatterlist sg[2];
	u8 intreg, command;

	if (mrq->error)
		return msb_exit_state_machine(msb, mrq->error);

again:
	switch (msb->state) {

	/* HACK: Jmicon handling of TPCs between 8 and
	 *	sizeof(memstick_request.data) is broken due to hardware
	 *	bug in PIO mode that is used for these TPCs
	 *	Therefore split the write
	 */

	case MSB_WB_SEND_WRITE_PARAMS:
		if (!msb_write_regs(msb,
			offsetof(struct ms_register, param),
			sizeof(struct ms_param_register),
			&msb->regs.param))
			return 0;

		msb->state = MSB_WB_SEND_WRITE_OOB;
		return 0;

	case MSB_WB_SEND_WRITE_OOB:
		if (!msb_write_regs(msb,
			offsetof(struct ms_register, extra_data),
			sizeof(struct ms_extra_data_register),
			&msb->regs.extra_data))
			return 0;
		msb->state = MSB_WB_SEND_WRITE_COMMAND;
		return 0;


	case MSB_WB_SEND_WRITE_COMMAND:
		command = MS_CMD_BLOCK_WRITE;
		memstick_init_req(mrq, MS_TPC_SET_CMD, &command, 1);
		msb->state = MSB_WB_SEND_INT_REQ;
		return 0;

	case MSB_WB_SEND_INT_REQ:
		msb->state = MSB_WB_RECEIVE_INT_REQ;
		if (msb_read_int_reg(msb, -1))
			return 0;
		fallthrough;

	case MSB_WB_RECEIVE_INT_REQ:
		intreg = mrq->data[0];
		msb->regs.status.interrupt = intreg;

		/* errors mean out of here, and fast... */
		if (intreg & (MEMSTICK_INT_CMDNAK))
			return msb_exit_state_machine(msb, -EIO);

		if (intreg & MEMSTICK_INT_ERR)
			return msb_exit_state_machine(msb, -EBADMSG);


		/* for last page we need to poll CED */
		if (msb->current_page == msb->pages_in_block) {
			if (intreg & MEMSTICK_INT_CED)
				return msb_exit_state_machine(msb, 0);
			msb->state = MSB_WB_SEND_INT_REQ;
			goto again;

		}

		/* for non-last page we need BREQ before writing next chunk */
		if (!(intreg & MEMSTICK_INT_BREQ)) {
			msb->state = MSB_WB_SEND_INT_REQ;
			goto again;
		}

		msb->int_polling = false;
		msb->state = MSB_WB_SEND_WRITE_DATA;
		fallthrough;

	case MSB_WB_SEND_WRITE_DATA:
		sg_init_table(sg, ARRAY_SIZE(sg));

		if (msb_sg_copy(msb->current_sg, sg, ARRAY_SIZE(sg),
			msb->current_sg_offset,
			msb->page_size) < msb->page_size)
			return msb_exit_state_machine(msb, -EIO);

		memstick_init_req_sg(mrq, MS_TPC_WRITE_LONG_DATA, sg);
		mrq->need_card_int = 1;
		msb->state = MSB_WB_RECEIVE_WRITE_CONFIRMATION;
		return 0;

	case MSB_WB_RECEIVE_WRITE_CONFIRMATION:
		msb->current_page++;
		msb->current_sg_offset += msb->page_size;
		msb->state = MSB_WB_SEND_INT_REQ;
		goto again;
	default:
		BUG();
	}

	return 0;
}

/*
 * This function is used to send simple IO requests to device that consist
 * of register write + command
 */
static int h_msb_send_command(struct memstick_dev *card,
					struct memstick_request **out_mrq)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct memstick_request *mrq = *out_mrq = &card->current_mrq;
	u8 intreg;

	if (mrq->error) {
		dbg("send_command: unknown error");
		return msb_exit_state_machine(msb, mrq->error);
	}
again:
	switch (msb->state) {

	/* HACK: see h_msb_write_block */
	case MSB_SC_SEND_WRITE_PARAMS: /* write param register*/
		if (!msb_write_regs(msb,
			offsetof(struct ms_register, param),
			sizeof(struct ms_param_register),
			&msb->regs.param))
			return 0;
		msb->state = MSB_SC_SEND_WRITE_OOB;
		return 0;

	case MSB_SC_SEND_WRITE_OOB:
		if (!msb->command_need_oob) {
			msb->state = MSB_SC_SEND_COMMAND;
			goto again;
		}

		if (!msb_write_regs(msb,
			offsetof(struct ms_register, extra_data),
			sizeof(struct ms_extra_data_register),
			&msb->regs.extra_data))
			return 0;

		msb->state = MSB_SC_SEND_COMMAND;
		return 0;

	case MSB_SC_SEND_COMMAND:
		memstick_init_req(mrq, MS_TPC_SET_CMD, &msb->command_value, 1);
		msb->state = MSB_SC_SEND_INT_REQ;
		return 0;

	case MSB_SC_SEND_INT_REQ:
		msb->state = MSB_SC_RECEIVE_INT_REQ;
		if (msb_read_int_reg(msb, -1))
			return 0;
		fallthrough;

	case MSB_SC_RECEIVE_INT_REQ:
		intreg = mrq->data[0];

		if (intreg & MEMSTICK_INT_CMDNAK)
			return msb_exit_state_machine(msb, -EIO);
		if (intreg & MEMSTICK_INT_ERR)
			return msb_exit_state_machine(msb, -EBADMSG);

		if (!(intreg & MEMSTICK_INT_CED)) {
			msb->state = MSB_SC_SEND_INT_REQ;
			goto again;
		}

		return msb_exit_state_machine(msb, 0);
	}

	BUG();
}

/* Small handler for card reset */
static int h_msb_reset(struct memstick_dev *card,
					struct memstick_request **out_mrq)
{
	u8 command = MS_CMD_RESET;
	struct msb_data *msb = memstick_get_drvdata(card);
	struct memstick_request *mrq = *out_mrq = &card->current_mrq;

	if (mrq->error)
		return msb_exit_state_machine(msb, mrq->error);

	switch (msb->state) {
	case MSB_RS_SEND:
		memstick_init_req(mrq, MS_TPC_SET_CMD, &command, 1);
		mrq->need_card_int = 0;
		msb->state = MSB_RS_CONFIRM;
		return 0;
	case MSB_RS_CONFIRM:
		return msb_exit_state_machine(msb, 0);
	}
	BUG();
}

/* This handler is used to do serial->parallel switch */
static int h_msb_parallel_switch(struct memstick_dev *card,
					struct memstick_request **out_mrq)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct memstick_request *mrq = *out_mrq = &card->current_mrq;
	struct memstick_host *host = card->host;

	if (mrq->error) {
		dbg("parallel_switch: error");
		msb->regs.param.system &= ~MEMSTICK_SYS_PAM;
		return msb_exit_state_machine(msb, mrq->error);
	}

	switch (msb->state) {
	case MSB_PS_SEND_SWITCH_COMMAND:
		/* Set the parallel interface on memstick side */
		msb->regs.param.system |= MEMSTICK_SYS_PAM;

		if (!msb_write_regs(msb,
			offsetof(struct ms_register, param),
			1,
			(unsigned char *)&msb->regs.param))
			return 0;

		msb->state = MSB_PS_SWICH_HOST;
		return 0;

	case MSB_PS_SWICH_HOST:
		 /* Set parallel interface on our side + send a dummy request
		  * to see if card responds
		  */
		host->set_param(host, MEMSTICK_INTERFACE, MEMSTICK_PAR4);
		memstick_init_req(mrq, MS_TPC_GET_INT, NULL, 1);
		msb->state = MSB_PS_CONFIRM;
		return 0;

	case MSB_PS_CONFIRM:
		return msb_exit_state_machine(msb, 0);
	}

	BUG();
}

static int msb_switch_to_parallel(struct msb_data *msb);

/* Reset the card, to guard against hw errors beeing treated as bad blocks */
static int msb_reset(struct msb_data *msb, bool full)
{

	bool was_parallel = msb->regs.param.system & MEMSTICK_SYS_PAM;
	struct memstick_dev *card = msb->card;
	struct memstick_host *host = card->host;
	int error;

	/* Reset the card */
	msb->regs.param.system = MEMSTICK_SYS_BAMD;

	if (full) {
		error =  host->set_param(host,
					MEMSTICK_POWER, MEMSTICK_POWER_OFF);
		if (error)
			goto out_error;

		msb_invalidate_reg_window(msb);

		error = host->set_param(host,
					MEMSTICK_POWER, MEMSTICK_POWER_ON);
		if (error)
			goto out_error;

		error = host->set_param(host,
					MEMSTICK_INTERFACE, MEMSTICK_SERIAL);
		if (error) {
out_error:
			dbg("Failed to reset the host controller");
			msb->read_only = true;
			return -EFAULT;
		}
	}

	error = msb_run_state_machine(msb, h_msb_reset);
	if (error) {
		dbg("Failed to reset the card");
		msb->read_only = true;
		return -ENODEV;
	}

	/* Set parallel mode */
	if (was_parallel)
		msb_switch_to_parallel(msb);
	return 0;
}

/* Attempts to switch interface to parallel mode */
static int msb_switch_to_parallel(struct msb_data *msb)
{
	int error;

	error = msb_run_state_machine(msb, h_msb_parallel_switch);
	if (error) {
		pr_err("Switch to parallel failed");
		msb->regs.param.system &= ~MEMSTICK_SYS_PAM;
		msb_reset(msb, true);
		return -EFAULT;
	}

	msb->caps |= MEMSTICK_CAP_AUTO_GET_INT;
	return 0;
}

/* Changes overwrite flag on a page */
static int msb_set_overwrite_flag(struct msb_data *msb,
						u16 pba, u8 page, u8 flag)
{
	if (msb->read_only)
		return -EROFS;

	msb->regs.param.block_address = cpu_to_be16(pba);
	msb->regs.param.page_address = page;
	msb->regs.param.cp = MEMSTICK_CP_OVERWRITE;
	msb->regs.extra_data.overwrite_flag = flag;
	msb->command_value = MS_CMD_BLOCK_WRITE;
	msb->command_need_oob = true;

	dbg_verbose("changing overwrite flag to %02x for sector %d, page %d",
							flag, pba, page);
	return msb_run_state_machine(msb, h_msb_send_command);
}

static int msb_mark_bad(struct msb_data *msb, int pba)
{
	pr_notice("marking pba %d as bad", pba);
	msb_reset(msb, true);
	return msb_set_overwrite_flag(
			msb, pba, 0, 0xFF & ~MEMSTICK_OVERWRITE_BKST);
}

static int msb_mark_page_bad(struct msb_data *msb, int pba, int page)
{
	dbg("marking page %d of pba %d as bad", page, pba);
	msb_reset(msb, true);
	return msb_set_overwrite_flag(msb,
		pba, page, ~MEMSTICK_OVERWRITE_PGST0);
}

/* Erases one physical block */
static int msb_erase_block(struct msb_data *msb, u16 pba)
{
	int error, try;

	if (msb->read_only)
		return -EROFS;

	dbg_verbose("erasing pba %d", pba);

	for (try = 1; try < 3; try++) {
		msb->regs.param.block_address = cpu_to_be16(pba);
		msb->regs.param.page_address = 0;
		msb->regs.param.cp = MEMSTICK_CP_BLOCK;
		msb->command_value = MS_CMD_BLOCK_ERASE;
		msb->command_need_oob = false;


		error = msb_run_state_machine(msb, h_msb_send_command);
		if (!error || msb_reset(msb, true))
			break;
	}

	if (error) {
		pr_err("erase failed, marking pba %d as bad", pba);
		msb_mark_bad(msb, pba);
	}

	dbg_verbose("erase success, marking pba %d as unused", pba);
	msb_mark_block_unused(msb, pba);
	__set_bit(pba, msb->erased_blocks_bitmap);
	return error;
}

/* Reads one page from device */
static int msb_read_page(struct msb_data *msb,
	u16 pba, u8 page, struct ms_extra_data_register *extra,
					struct scatterlist *sg,  int offset)
{
	int try, error;

	if (pba == MS_BLOCK_INVALID) {
		unsigned long flags;
		struct sg_mapping_iter miter;
		size_t len = msb->page_size;

		dbg_verbose("read unmapped sector. returning 0xFF");

		local_irq_save(flags);
		sg_miter_start(&miter, sg, sg_nents(sg),
				SG_MITER_ATOMIC | SG_MITER_TO_SG);

		while (sg_miter_next(&miter) && len > 0) {

			int chunklen;

			if (offset && offset >= miter.length) {
				offset -= miter.length;
				continue;
			}

			chunklen = min(miter.length - offset, len);
			memset(miter.addr + offset, 0xFF, chunklen);
			len -= chunklen;
			offset = 0;
		}

		sg_miter_stop(&miter);
		local_irq_restore(flags);

		if (offset)
			return -EFAULT;

		if (extra)
			memset(extra, 0xFF, sizeof(*extra));
		return 0;
	}

	if (pba >= msb->block_count) {
		pr_err("BUG: attempt to read beyond the end of the card at pba %d", pba);
		return -EINVAL;
	}

	for (try = 1; try < 3; try++) {
		msb->regs.param.block_address = cpu_to_be16(pba);
		msb->regs.param.page_address = page;
		msb->regs.param.cp = MEMSTICK_CP_PAGE;

		msb->current_sg = sg;
		msb->current_sg_offset = offset;
		error = msb_run_state_machine(msb, h_msb_read_page);


		if (error == -EUCLEAN) {
			pr_notice("correctable error on pba %d, page %d",
				pba, page);
			error = 0;
		}

		if (!error && extra)
			*extra = msb->regs.extra_data;

		if (!error || msb_reset(msb, true))
			break;

	}

	/* Mark bad pages */
	if (error == -EBADMSG) {
		pr_err("uncorrectable error on read of pba %d, page %d",
			pba, page);

		if (msb->regs.extra_data.overwrite_flag &
					MEMSTICK_OVERWRITE_PGST0)
			msb_mark_page_bad(msb, pba, page);
		return -EBADMSG;
	}

	if (error)
		pr_err("read of pba %d, page %d failed with error %d",
			pba, page, error);
	return error;
}

/* Reads oob of page only */
static int msb_read_oob(struct msb_data *msb, u16 pba, u16 page,
	struct ms_extra_data_register *extra)
{
	int error;

	BUG_ON(!extra);
	msb->regs.param.block_address = cpu_to_be16(pba);
	msb->regs.param.page_address = page;
	msb->regs.param.cp = MEMSTICK_CP_EXTRA;

	if (pba > msb->block_count) {
		pr_err("BUG: attempt to read beyond the end of card at pba %d", pba);
		return -EINVAL;
	}

	error = msb_run_state_machine(msb, h_msb_read_page);
	*extra = msb->regs.extra_data;

	if (error == -EUCLEAN) {
		pr_notice("correctable error on pba %d, page %d",
			pba, page);
		return 0;
	}

	return error;
}

/* Reads a block and compares it with data contained in scatterlist orig_sg */
static int msb_verify_block(struct msb_data *msb, u16 pba,
				struct scatterlist *orig_sg,  int offset)
{
	struct scatterlist sg;
	int page = 0, error;

	sg_init_one(&sg, msb->block_buffer, msb->block_size);

	while (page < msb->pages_in_block) {

		error = msb_read_page(msb, pba, page,
				NULL, &sg, page * msb->page_size);
		if (error)
			return error;
		page++;
	}

	if (msb_sg_compare_to_buffer(orig_sg, offset,
				msb->block_buffer, msb->block_size))
		return -EIO;
	return 0;
}

/* Writes exactly one block + oob */
static int msb_write_block(struct msb_data *msb,
			u16 pba, u32 lba, struct scatterlist *sg, int offset)
{
	int error, current_try = 1;

	BUG_ON(sg->length < msb->page_size);

	if (msb->read_only)
		return -EROFS;

	if (pba == MS_BLOCK_INVALID) {
		pr_err(
			"BUG: write: attempt to write MS_BLOCK_INVALID block");
		return -EINVAL;
	}

	if (pba >= msb->block_count || lba >= msb->logical_block_count) {
		pr_err(
		"BUG: write: attempt to write beyond the end of device");
		return -EINVAL;
	}

	if (msb_get_zone_from_lba(lba) != msb_get_zone_from_pba(pba)) {
		pr_err("BUG: write: lba zone mismatch");
		return -EINVAL;
	}

	if (pba == msb->boot_block_locations[0] ||
		pba == msb->boot_block_locations[1]) {
		pr_err("BUG: write: attempt to write to boot blocks!");
		return -EINVAL;
	}

	while (1) {

		if (msb->read_only)
			return -EROFS;

		msb->regs.param.cp = MEMSTICK_CP_BLOCK;
		msb->regs.param.page_address = 0;
		msb->regs.param.block_address = cpu_to_be16(pba);

		msb->regs.extra_data.management_flag = 0xFF;
		msb->regs.extra_data.overwrite_flag = 0xF8;
		msb->regs.extra_data.logical_address = cpu_to_be16(lba);

		msb->current_sg = sg;
		msb->current_sg_offset = offset;
		msb->current_page = 0;

		error = msb_run_state_machine(msb, h_msb_write_block);

		/* Sector we just wrote to is assumed erased since its pba
		 * was erased. If it wasn't erased, write will succeed
		 * and will just clear the bits that were set in the block
		 * thus test that what we have written,
		 * matches what we expect.
		 * We do trust the blocks that we erased
		 */
		if (!error && (verify_writes ||
				!test_bit(pba, msb->erased_blocks_bitmap)))
			error = msb_verify_block(msb, pba, sg, offset);

		if (!error)
			break;

		if (current_try > 1 || msb_reset(msb, true))
			break;

		pr_err("write failed, trying to erase the pba %d", pba);
		error = msb_erase_block(msb, pba);
		if (error)
			break;

		current_try++;
	}
	return error;
}

/* Finds a free block for write replacement */
static u16 msb_get_free_block(struct msb_data *msb, int zone)
{
	u16 pos;
	int pba = zone * MS_BLOCKS_IN_ZONE;
	int i;

	get_random_bytes(&pos, sizeof(pos));

	if (!msb->free_block_count[zone]) {
		pr_err("NO free blocks in the zone %d, to use for a write, (media is WORN out) switching to RO mode", zone);
		msb->read_only = true;
		return MS_BLOCK_INVALID;
	}

	pos %= msb->free_block_count[zone];

	dbg_verbose("have %d choices for a free block, selected randomly: %d",
		msb->free_block_count[zone], pos);

	pba = find_next_zero_bit(msb->used_blocks_bitmap,
							msb->block_count, pba);
	for (i = 0; i < pos; ++i)
		pba = find_next_zero_bit(msb->used_blocks_bitmap,
						msb->block_count, pba + 1);

	dbg_verbose("result of the free blocks scan: pba %d", pba);

	if (pba == msb->block_count || (msb_get_zone_from_pba(pba)) != zone) {
		pr_err("BUG: can't get a free block");
		msb->read_only = true;
		return MS_BLOCK_INVALID;
	}

	msb_mark_block_used(msb, pba);
	return pba;
}

static int msb_update_block(struct msb_data *msb, u16 lba,
	struct scatterlist *sg, int offset)
{
	u16 pba, new_pba;
	int error, try;

	pba = msb->lba_to_pba_table[lba];
	dbg_verbose("start of a block update at lba  %d, pba %d", lba, pba);

	if (pba != MS_BLOCK_INVALID) {
		dbg_verbose("setting the update flag on the block");
		msb_set_overwrite_flag(msb, pba, 0,
				0xFF & ~MEMSTICK_OVERWRITE_UDST);
	}

	for (try = 0; try < 3; try++) {
		new_pba = msb_get_free_block(msb,
			msb_get_zone_from_lba(lba));

		if (new_pba == MS_BLOCK_INVALID) {
			error = -EIO;
			goto out;
		}

		dbg_verbose("block update: writing updated block to the pba %d",
								new_pba);
		error = msb_write_block(msb, new_pba, lba, sg, offset);
		if (error == -EBADMSG) {
			msb_mark_bad(msb, new_pba);
			continue;
		}

		if (error)
			goto out;

		dbg_verbose("block update: erasing the old block");
		msb_erase_block(msb, pba);
		msb->lba_to_pba_table[lba] = new_pba;
		return 0;
	}
out:
	if (error) {
		pr_err("block update error after %d tries,  switching to r/o mode", try);
		msb->read_only = true;
	}
	return error;
}

/* Converts endiannes in the boot block for easy use */
static void msb_fix_boot_page_endianness(struct ms_boot_page *p)
{
	p->header.block_id = be16_to_cpu(p->header.block_id);
	p->header.format_reserved = be16_to_cpu(p->header.format_reserved);
	p->entry.disabled_block.start_addr
		= be32_to_cpu(p->entry.disabled_block.start_addr);
	p->entry.disabled_block.data_size
		= be32_to_cpu(p->entry.disabled_block.data_size);
	p->entry.cis_idi.start_addr
		= be32_to_cpu(p->entry.cis_idi.start_addr);
	p->entry.cis_idi.data_size
		= be32_to_cpu(p->entry.cis_idi.data_size);
	p->attr.block_size = be16_to_cpu(p->attr.block_size);
	p->attr.number_of_blocks = be16_to_cpu(p->attr.number_of_blocks);
	p->attr.number_of_effective_blocks
		= be16_to_cpu(p->attr.number_of_effective_blocks);
	p->attr.page_size = be16_to_cpu(p->attr.page_size);
	p->attr.memory_manufacturer_code
		= be16_to_cpu(p->attr.memory_manufacturer_code);
	p->attr.memory_device_code = be16_to_cpu(p->attr.memory_device_code);
	p->attr.implemented_capacity
		= be16_to_cpu(p->attr.implemented_capacity);
	p->attr.controller_number = be16_to_cpu(p->attr.controller_number);
	p->attr.controller_function = be16_to_cpu(p->attr.controller_function);
}

static int msb_read_boot_blocks(struct msb_data *msb)
{
	int pba = 0;
	struct scatterlist sg;
	struct ms_extra_data_register extra;
	struct ms_boot_page *page;

	msb->boot_block_locations[0] = MS_BLOCK_INVALID;
	msb->boot_block_locations[1] = MS_BLOCK_INVALID;
	msb->boot_block_count = 0;

	dbg_verbose("Start of a scan for the boot blocks");

	if (!msb->boot_page) {
		page = kmalloc_objs(struct ms_boot_page, 2);
		if (!page)
			return -ENOMEM;

		msb->boot_page = page;
	} else
		page = msb->boot_page;

	msb->block_count = MS_BLOCK_MAX_BOOT_ADDR;

	for (pba = 0; pba < MS_BLOCK_MAX_BOOT_ADDR; pba++) {

		sg_init_one(&sg, page, sizeof(*page));
		if (msb_read_page(msb, pba, 0, &extra, &sg, 0)) {
			dbg("boot scan: can't read pba %d", pba);
			continue;
		}

		if (extra.management_flag & MEMSTICK_MANAGEMENT_SYSFLG) {
			dbg("management flag doesn't indicate boot block %d",
									pba);
			continue;
		}

		if (be16_to_cpu(page->header.block_id) != MS_BLOCK_BOOT_ID) {
			dbg("the pba at %d doesn't contain boot block ID", pba);
			continue;
		}

		msb_fix_boot_page_endianness(page);
		msb->boot_block_locations[msb->boot_block_count] = pba;

		page++;
		msb->boot_block_count++;

		if (msb->boot_block_count == 2)
			break;
	}

	if (!msb->boot_block_count) {
		pr_err("media doesn't contain master page, aborting");
		return -EIO;
	}

	dbg_verbose("End of scan for boot blocks");
	return 0;
}

static int msb_read_bad_block_table(struct msb_data *msb, int block_nr)
{
	struct ms_boot_page *boot_block;
	struct scatterlist sg;
	u16 *buffer = NULL;
	int offset = 0;
	int i, error = 0;
	int data_size, data_offset, page, page_offset, size_to_read;
	u16 pba;

	BUG_ON(block_nr > 1);
	boot_block = &msb->boot_page[block_nr];
	pba = msb->boot_block_locations[block_nr];

	if (msb->boot_block_locations[block_nr] == MS_BLOCK_INVALID)
		return -EINVAL;

	data_size = boot_block->entry.disabled_block.data_size;
	data_offset = sizeof(struct ms_boot_page) +
			boot_block->entry.disabled_block.start_addr;
	if (!data_size)
		return 0;

	page = data_offset / msb->page_size;
	page_offset = data_offset % msb->page_size;
	size_to_read =
		DIV_ROUND_UP(data_size + page_offset, msb->page_size) *
			msb->page_size;

	dbg("reading bad block of boot block at pba %d, offset %d len %d",
		pba, data_offset, data_size);

	buffer = kzalloc(size_to_read, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	/* Read the buffer */
	sg_init_one(&sg, buffer, size_to_read);

	while (offset < size_to_read) {
		error = msb_read_page(msb, pba, page, NULL, &sg, offset);
		if (error)
			goto out;

		page++;
		offset += msb->page_size;

		if (page == msb->pages_in_block) {
			pr_err(
			"bad block table extends beyond the boot block");
			break;
		}
	}

	/* Process the bad block table */
	for (i = page_offset; i < data_size / sizeof(u16); i++) {

		u16 bad_block = be16_to_cpu(buffer[i]);

		if (bad_block >= msb->block_count) {
			dbg("bad block table contains invalid block %d",
								bad_block);
			continue;
		}

		if (test_bit(bad_block, msb->used_blocks_bitmap))  {
			dbg("duplicate bad block %d in the table",
				bad_block);
			continue;
		}

		dbg("block %d is marked as factory bad", bad_block);
		msb_mark_block_used(msb, bad_block);
	}
out:
	kfree(buffer);
	return error;
}

static int msb_ftl_initialize(struct msb_data *msb)
{
	int i;

	if (msb->ftl_initialized)
		return 0;

	msb->zone_count = msb->block_count / MS_BLOCKS_IN_ZONE;
	if (msb->block_count > MS_MAX_ZONES * MS_BLOCKS_IN_ZONE) {
		pr_err("Too many blocks: %d\n", msb->block_count);
		return -EINVAL;
	}
	msb->logical_block_count = msb->zone_count * 496 - 2;

	msb->used_blocks_bitmap = bitmap_zalloc(msb->block_count, GFP_KERNEL);
	msb->erased_blocks_bitmap = bitmap_zalloc(msb->block_count, GFP_KERNEL);
	msb->lba_to_pba_table =
		kmalloc_array(msb->logical_block_count, sizeof(u16),
			      GFP_KERNEL);

	if (!msb->used_blocks_bitmap || !msb->lba_to_pba_table ||
						!msb->erased_blocks_bitmap) {
		bitmap_free(msb->used_blocks_bitmap);
		bitmap_free(msb->erased_blocks_bitmap);
		kfree(msb->lba_to_pba_table);
		return -ENOMEM;
	}

	for (i = 0; i < msb->zone_count; i++)
		msb->free_block_count[i] = MS_BLOCKS_IN_ZONE;

	memset(msb->lba_to_pba_table, MS_BLOCK_INVALID,
			msb->logical_block_count * sizeof(u16));

	dbg("initial FTL tables created. Zone count = %d, Logical block count = %d",
		msb->zone_count, msb->logical_block_count);

	msb->ftl_initialized = true;
	return 0;
}

static int msb_ftl_scan(struct msb_data *msb)
{
	u16 pba, lba, other_block;
	u8 overwrite_flag, management_flag, other_overwrite_flag;
	int error;
	struct ms_extra_data_register extra;
	u8 *overwrite_flags = kzalloc(msb->block_count, GFP_KERNEL);

	if (!overwrite_flags)
		return -ENOMEM;

	dbg("Start of media scanning");
	for (pba = 0; pba < msb->block_count; pba++) {

		if (pba == msb->boot_block_locations[0] ||
			pba == msb->boot_block_locations[1]) {
			dbg_verbose("pba %05d -> [boot block]", pba);
			msb_mark_block_used(msb, pba);
			continue;
		}

		if (test_bit(pba, msb->used_blocks_bitmap)) {
			dbg_verbose("pba %05d -> [factory bad]", pba);
			continue;
		}

		memset(&extra, 0, sizeof(extra));
		error = msb_read_oob(msb, pba, 0, &extra);

		/* can't trust the page if we can't read the oob */
		if (error == -EBADMSG) {
			pr_notice(
			"oob of pba %d damaged, will try to erase it", pba);
			msb_mark_block_used(msb, pba);
			msb_erase_block(msb, pba);
			continue;
		} else if (error) {
			pr_err("unknown error %d on read of oob of pba %d - aborting",
				error, pba);

			kfree(overwrite_flags);
			return error;
		}

		lba = be16_to_cpu(extra.logical_address);
		management_flag = extra.management_flag;
		overwrite_flag = extra.overwrite_flag;
		overwrite_flags[pba] = overwrite_flag;

		/* Skip bad blocks */
		if (!(overwrite_flag & MEMSTICK_OVERWRITE_BKST)) {
			dbg("pba %05d -> [BAD]", pba);
			msb_mark_block_used(msb, pba);
			continue;
		}

		/* Skip system/drm blocks */
		if ((management_flag & MEMSTICK_MANAGEMENT_FLAG_NORMAL) !=
			MEMSTICK_MANAGEMENT_FLAG_NORMAL) {
			dbg("pba %05d -> [reserved management flag %02x]",
							pba, management_flag);
			msb_mark_block_used(msb, pba);
			continue;
		}

		/* Erase temporary tables */
		if (!(management_flag & MEMSTICK_MANAGEMENT_ATFLG)) {
			dbg("pba %05d -> [temp table] - will erase", pba);

			msb_mark_block_used(msb, pba);
			msb_erase_block(msb, pba);
			continue;
		}

		if (lba == MS_BLOCK_INVALID) {
			dbg_verbose("pba %05d -> [free]", pba);
			continue;
		}

		msb_mark_block_used(msb, pba);

		/* Block has LBA not according to zoning*/
		if (msb_get_zone_from_lba(lba) != msb_get_zone_from_pba(pba)) {
			pr_notice("pba %05d -> [bad lba %05d] - will erase",
								pba, lba);
			msb_erase_block(msb, pba);
			continue;
		}

		/* No collisions - great */
		if (msb->lba_to_pba_table[lba] == MS_BLOCK_INVALID) {
			dbg_verbose("pba %05d -> [lba %05d]", pba, lba);
			msb->lba_to_pba_table[lba] = pba;
			continue;
		}

		other_block = msb->lba_to_pba_table[lba];
		other_overwrite_flag = overwrite_flags[other_block];

		pr_notice("Collision between pba %d and pba %d",
			pba, other_block);

		if (!(overwrite_flag & MEMSTICK_OVERWRITE_UDST)) {
			pr_notice("pba %d is marked as stable, use it", pba);
			msb_erase_block(msb, other_block);
			msb->lba_to_pba_table[lba] = pba;
			continue;
		}

		if (!(other_overwrite_flag & MEMSTICK_OVERWRITE_UDST)) {
			pr_notice("pba %d is marked as stable, use it",
								other_block);
			msb_erase_block(msb, pba);
			continue;
		}

		pr_notice("collision between blocks %d and %d, without stable flag set on both, erasing pba %d",
				pba, other_block, other_block);

		msb_erase_block(msb, other_block);
		msb->lba_to_pba_table[lba] = pba;
	}

	dbg("End of media scanning");
	kfree(overwrite_flags);
	return 0;
}

static void msb_cache_flush_timer(struct timer_list *t)
{
	struct msb_data *msb = timer_container_of(msb, t, cache_flush_timer);

	msb->need_flush_cache = true;
	queue_work(msb->io_queue, &msb->io_work);
}


static void msb_cache_discard(struct msb_data *msb)
{
	if (msb->cache_block_lba == MS_BLOCK_INVALID)
		return;

	timer_delete_sync(&msb->cache_flush_timer);

	dbg_verbose("Discarding the write cache");
	msb->cache_block_lba = MS_BLOCK_INVALID;
	bitmap_zero(&msb->valid_cache_bitmap, msb->pages_in_block);
}

static int msb_cache_init(struct msb_data *msb)
{
	timer_setup(&msb->cache_flush_timer, msb_cache_flush_timer, 0);

	if (!msb->cache)
		msb->cache = kzalloc(msb->block_size, GFP_KERNEL);
	if (!msb->cache)
		return -ENOMEM;

	msb_cache_discard(msb);
	return 0;
}

static int msb_cache_flush(struct msb_data *msb)
{
	struct scatterlist sg;
	struct ms_extra_data_register extra;
	int page, offset, error;
	u16 pba, lba;

	if (msb->read_only)
		return -EROFS;

	if (msb->cache_block_lba == MS_BLOCK_INVALID)
		return 0;

	lba = msb->cache_block_lba;
	pba = msb->lba_to_pba_table[lba];

	dbg_verbose("Flushing the write cache of pba %d (LBA %d)",
						pba, msb->cache_block_lba);

	sg_init_one(&sg, msb->cache , msb->block_size);

	/* Read all missing pages in cache */
	for (page = 0; page < msb->pages_in_block; page++) {

		if (test_bit(page, &msb->valid_cache_bitmap))
			continue;

		offset = page * msb->page_size;

		dbg_verbose("reading non-present sector %d of cache block %d",
			page, lba);
		error = msb_read_page(msb, pba, page, &extra, &sg, offset);

		/* Bad pages are copied with 00 page status */
		if (error == -EBADMSG) {
			pr_err("read error on sector %d, contents probably damaged", page);
			continue;
		}

		if (error)
			return error;

		if ((extra.overwrite_flag & MEMSTICK_OV_PG_NORMAL) !=
							MEMSTICK_OV_PG_NORMAL) {
			dbg("page %d is marked as bad", page);
			continue;
		}

		set_bit(page, &msb->valid_cache_bitmap);
	}

	/* Write the cache now */
	error = msb_update_block(msb, msb->cache_block_lba, &sg, 0);
	pba = msb->lba_to_pba_table[msb->cache_block_lba];

	/* Mark invalid pages */
	if (!error) {
		for (page = 0; page < msb->pages_in_block; page++) {

			if (test_bit(page, &msb->valid_cache_bitmap))
				continue;

			dbg("marking page %d as containing damaged data",
				page);
			msb_set_overwrite_flag(msb,
				pba , page, 0xFF & ~MEMSTICK_OV_PG_NORMAL);
		}
	}

	msb_cache_discard(msb);
	return error;
}

static int msb_cache_write(struct msb_data *msb, int lba,
	int page, bool add_to_cache_only, struct scatterlist *sg, int offset)
{
	int error;
	struct scatterlist sg_tmp[10];

	if (msb->read_only)
		return -EROFS;

	if (msb->cache_block_lba == MS_BLOCK_INVALID ||
						lba != msb->cache_block_lba)
		if (add_to_cache_only)
			return 0;

	/* If we need to write different block */
	if (msb->cache_block_lba != MS_BLOCK_INVALID &&
						lba != msb->cache_block_lba) {
		dbg_verbose("first flush the cache");
		error = msb_cache_flush(msb);
		if (error)
			return error;
	}

	if (msb->cache_block_lba  == MS_BLOCK_INVALID) {
		msb->cache_block_lba  = lba;
		mod_timer(&msb->cache_flush_timer,
			jiffies + msecs_to_jiffies(cache_flush_timeout));
	}

	dbg_verbose("Write of LBA %d page %d to cache ", lba, page);

	sg_init_table(sg_tmp, ARRAY_SIZE(sg_tmp));
	msb_sg_copy(sg, sg_tmp, ARRAY_SIZE(sg_tmp), offset, msb->page_size);

	sg_copy_to_buffer(sg_tmp, sg_nents(sg_tmp),
		msb->cache + page * msb->page_size, msb->page_size);

	set_bit(page, &msb->valid_cache_bitmap);
	return 0;
}

static int msb_cache_read(struct msb_data *msb, int lba,
				int page, struct scatterlist *sg, int offset)
{
	int pba = msb->lba_to_pba_table[lba];
	struct scatterlist sg_tmp[10];
	int error = 0;

	if (lba == msb->cache_block_lba &&
			test_bit(page, &msb->valid_cache_bitmap)) {

		dbg_verbose("Read of LBA %d (pba %d) sector %d from cache",
							lba, pba, page);

		sg_init_table(sg_tmp, ARRAY_SIZE(sg_tmp));
		msb_sg_copy(sg, sg_tmp, ARRAY_SIZE(sg_tmp),
			offset, msb->page_size);
		sg_copy_from_buffer(sg_tmp, sg_nents(sg_tmp),
			msb->cache + msb->page_size * page,
							msb->page_size);
	} else {
		dbg_verbose("Read of LBA %d (pba %d) sector %d from device",
							lba, pba, page);

		error = msb_read_page(msb, pba, page, NULL, sg, offset);
		if (error)
			return error;

		msb_cache_write(msb, lba, page, true, sg, offset);
	}
	return error;
}

/* Emulated geometry table
 * This table content isn't that importaint,
 * One could put here different values, providing that they still
 * cover whole disk.
 * 64 MB entry is what windows reports for my 64M memstick
 */

static const struct chs_entry chs_table[] = {
/*        size sectors cylinders heads */
	{ 4,    16,    247,       2  },
	{ 8,    16,    495,       2  },
	{ 16,   16,    495,       4  },
	{ 32,   16,    991,       4  },
	{ 64,   16,    991,       8  },
	{128,   16,    991,       16 },
	{ 0 }
};

/* Load information about the card */
static int msb_init_card(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct memstick_host *host = card->host;
	struct ms_boot_page *boot_block;
	int error = 0, i, raw_size_in_megs;

	msb->caps = 0;

	if (card->id.class >= MEMSTICK_CLASS_ROM &&
				card->id.class <= MEMSTICK_CLASS_ROM)
		msb->read_only = true;

	msb->state = -1;
	error = msb_reset(msb, false);
	if (error)
		return error;

	/* Due to a bug in Jmicron driver written by Alex Dubov,
	 * its serial mode barely works,
	 * so we switch to parallel mode right away
	 */
	if (host->caps & MEMSTICK_CAP_PAR4)
		msb_switch_to_parallel(msb);

	msb->page_size = sizeof(struct ms_boot_page);

	/* Read the boot page */
	error = msb_read_boot_blocks(msb);
	if (error)
		return -EIO;

	boot_block = &msb->boot_page[0];

	/* Save interesting attributes from boot page */
	msb->block_count = boot_block->attr.number_of_blocks;
	msb->page_size = boot_block->attr.page_size;

	msb->pages_in_block = boot_block->attr.block_size * 2;
	msb->block_size = msb->page_size * msb->pages_in_block;

	if ((size_t)msb->page_size > PAGE_SIZE) {
		/* this isn't supported by linux at all, anyway*/
		dbg("device page %d size isn't supported", msb->page_size);
		return -EINVAL;
	}

	msb->block_buffer = kzalloc(msb->block_size, GFP_KERNEL);
	if (!msb->block_buffer)
		return -ENOMEM;

	raw_size_in_megs = (msb->block_size * msb->block_count) >> 20;

	for (i = 0; chs_table[i].size; i++) {

		if (chs_table[i].size != raw_size_in_megs)
			continue;

		msb->geometry.cylinders = chs_table[i].cyl;
		msb->geometry.heads = chs_table[i].head;
		msb->geometry.sectors = chs_table[i].sec;
		break;
	}

	if (boot_block->attr.transfer_supporting == 1)
		msb->caps |= MEMSTICK_CAP_PAR4;

	if (boot_block->attr.device_type & 0x03)
		msb->read_only = true;

	dbg("Total block count = %d", msb->block_count);
	dbg("Each block consists of %d pages", msb->pages_in_block);
	dbg("Page size = %d bytes", msb->page_size);
	dbg("Parallel mode supported: %d", !!(msb->caps & MEMSTICK_CAP_PAR4));
	dbg("Read only: %d", msb->read_only);

#if 0
	/* Now we can switch the interface */
	if (host->caps & msb->caps & MEMSTICK_CAP_PAR4)
		msb_switch_to_parallel(msb);
#endif

	error = msb_cache_init(msb);
	if (error)
		return error;

	error = msb_ftl_initialize(msb);
	if (error)
		return error;


	/* Read the bad block table */
	error = msb_read_bad_block_table(msb, 0);

	if (error && error != -ENOMEM) {
		dbg("failed to read bad block table from primary boot block, trying from backup");
		error = msb_read_bad_block_table(msb, 1);
	}

	if (error)
		return error;

	/* *drum roll* Scan the media */
	error = msb_ftl_scan(msb);
	if (error) {
		pr_err("Scan of media failed");
		return error;
	}

	return 0;

}

static int msb_do_write_request(struct msb_data *msb, int lba,
	int page, struct scatterlist *sg, size_t len, int *sucessfuly_written)
{
	int error = 0;
	off_t offset = 0;
	*sucessfuly_written = 0;

	while (offset < len) {
		if (page == 0 && len - offset >= msb->block_size) {

			if (msb->cache_block_lba == lba)
				msb_cache_discard(msb);

			dbg_verbose("Writing whole lba %d", lba);
			error = msb_update_block(msb, lba, sg, offset);
			if (error)
				return error;

			offset += msb->block_size;
			*sucessfuly_written += msb->block_size;
			lba++;
			continue;
		}

		error = msb_cache_write(msb, lba, page, false, sg, offset);
		if (error)
			return error;

		offset += msb->page_size;
		*sucessfuly_written += msb->page_size;

		page++;
		if (page == msb->pages_in_block) {
			page = 0;
			lba++;
		}
	}
	return 0;
}

static int msb_do_read_request(struct msb_data *msb, int lba,
		int page, struct scatterlist *sg, int len, int *sucessfuly_read)
{
	int error = 0;
	int offset = 0;
	*sucessfuly_read = 0;

	while (offset < len) {

		error = msb_cache_read(msb, lba, page, sg, offset);
		if (error)
			return error;

		offset += msb->page_size;
		*sucessfuly_read += msb->page_size;

		page++;
		if (page == msb->pages_in_block) {
			page = 0;
			lba++;
		}
	}
	return 0;
}

static void msb_io_work(struct work_struct *work)
{
	struct msb_data *msb = container_of(work, struct msb_data, io_work);
	int page, error, len;
	sector_t lba;
	struct scatterlist *sg = msb->prealloc_sg;
	struct request *req;

	dbg_verbose("IO: work started");

	while (1) {
		spin_lock_irq(&msb->q_lock);

		if (msb->need_flush_cache) {
			msb->need_flush_cache = false;
			spin_unlock_irq(&msb->q_lock);
			msb_cache_flush(msb);
			continue;
		}

		req = msb->req;
		if (!req) {
			dbg_verbose("IO: no more requests exiting");
			spin_unlock_irq(&msb->q_lock);
			return;
		}

		spin_unlock_irq(&msb->q_lock);

		/* process the request */
		dbg_verbose("IO: processing new request");
		blk_rq_map_sg(req, sg);

		lba = blk_rq_pos(req);

		sector_div(lba, msb->page_size / 512);
		page = sector_div(lba, msb->pages_in_block);

		if (rq_data_dir(msb->req) == READ)
			error = msb_do_read_request(msb, lba, page, sg,
				blk_rq_bytes(req), &len);
		else
			error = msb_do_write_request(msb, lba, page, sg,
				blk_rq_bytes(req), &len);

		if (len && !blk_update_request(req, BLK_STS_OK, len)) {
			__blk_mq_end_request(req, BLK_STS_OK);
			spin_lock_irq(&msb->q_lock);
			msb->req = NULL;
			spin_unlock_irq(&msb->q_lock);
		}

		if (error && msb->req) {
			blk_status_t ret = errno_to_blk_status(error);

			dbg_verbose("IO: ending one sector of the request with error");
			blk_mq_end_request(req, ret);
			spin_lock_irq(&msb->q_lock);
			msb->req = NULL;
			spin_unlock_irq(&msb->q_lock);
		}

		if (msb->req)
			dbg_verbose("IO: request still pending");
	}
}

static DEFINE_IDR(msb_disk_idr); /*set of used disk numbers */
static DEFINE_MUTEX(msb_disk_lock); /* protects against races in open/release */

static void msb_data_clear(struct msb_data *msb)
{
	kfree(msb->boot_page);
	bitmap_free(msb->used_blocks_bitmap);
	bitmap_free(msb->erased_blocks_bitmap);
	kfree(msb->lba_to_pba_table);
	kfree(msb->cache);
	msb->card = NULL;
}

static int msb_bd_getgeo(struct gendisk *disk,
				 struct hd_geometry *geo)
{
	struct msb_data *msb = disk->private_data;
	*geo = msb->geometry;
	return 0;
}

static void msb_bd_free_disk(struct gendisk *disk)
{
	struct msb_data *msb = disk->private_data;

	mutex_lock(&msb_disk_lock);
	idr_remove(&msb_disk_idr, msb->disk_id);
	mutex_unlock(&msb_disk_lock);

	kfree(msb);
}

static blk_status_t msb_queue_rq(struct blk_mq_hw_ctx *hctx,
				 const struct blk_mq_queue_data *bd)
{
	struct memstick_dev *card = hctx->queue->queuedata;
	struct msb_data *msb = memstick_get_drvdata(card);
	struct request *req = bd->rq;

	dbg_verbose("Submit request");

	spin_lock_irq(&msb->q_lock);

	if (msb->card_dead) {
		dbg("Refusing requests on removed card");

		WARN_ON(!msb->io_queue_stopped);

		spin_unlock_irq(&msb->q_lock);
		blk_mq_start_request(req);
		return BLK_STS_IOERR;
	}

	if (msb->req) {
		spin_unlock_irq(&msb->q_lock);
		return BLK_STS_DEV_RESOURCE;
	}

	blk_mq_start_request(req);
	msb->req = req;

	if (!msb->io_queue_stopped)
		queue_work(msb->io_queue, &msb->io_work);

	spin_unlock_irq(&msb->q_lock);
	return BLK_STS_OK;
}

static int msb_check_card(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);

	return (msb->card_dead == 0);
}

static void msb_stop(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	unsigned long flags;

	dbg("Stopping all msblock IO");

	blk_mq_stop_hw_queues(msb->queue);
	spin_lock_irqsave(&msb->q_lock, flags);
	msb->io_queue_stopped = true;
	spin_unlock_irqrestore(&msb->q_lock, flags);

	timer_delete_sync(&msb->cache_flush_timer);
	flush_workqueue(msb->io_queue);

	spin_lock_irqsave(&msb->q_lock, flags);
	if (msb->req) {
		blk_mq_requeue_request(msb->req, false);
		msb->req = NULL;
	}
	spin_unlock_irqrestore(&msb->q_lock, flags);
}

static void msb_start(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	unsigned long flags;

	dbg("Resuming IO from msblock");

	msb_invalidate_reg_window(msb);

	spin_lock_irqsave(&msb->q_lock, flags);
	if (!msb->io_queue_stopped || msb->card_dead) {
		spin_unlock_irqrestore(&msb->q_lock, flags);
		return;
	}
	spin_unlock_irqrestore(&msb->q_lock, flags);

	/* Kick cache flush anyway, its harmless */
	msb->need_flush_cache = true;
	msb->io_queue_stopped = false;

	blk_mq_start_hw_queues(msb->queue);

	queue_work(msb->io_queue, &msb->io_work);

}

static const struct block_device_operations msb_bdops = {
	.owner		= THIS_MODULE,
	.getgeo		= msb_bd_getgeo,
	.free_disk	= msb_bd_free_disk,
};

static const struct blk_mq_ops msb_mq_ops = {
	.queue_rq	= msb_queue_rq,
};

/* Registers the block device */
static int msb_init_disk(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct queue_limits lim = {
		.logical_block_size	= msb->page_size,
		.max_hw_sectors		= MS_BLOCK_MAX_PAGES,
		.max_segments		= MS_BLOCK_MAX_SEGS,
		.max_segment_size	= MS_BLOCK_MAX_PAGES * msb->page_size,
	};
	int rc;
	unsigned long capacity;

	mutex_lock(&msb_disk_lock);
	msb->disk_id = idr_alloc(&msb_disk_idr, card, 0, 256, GFP_KERNEL);
	mutex_unlock(&msb_disk_lock);

	if (msb->disk_id  < 0)
		return msb->disk_id;

	rc = blk_mq_alloc_sq_tag_set(&msb->tag_set, &msb_mq_ops, 2, 0);
	if (rc)
		goto out_release_id;

	msb->disk = blk_mq_alloc_disk(&msb->tag_set, &lim, card);
	if (IS_ERR(msb->disk)) {
		rc = PTR_ERR(msb->disk);
		goto out_free_tag_set;
	}
	msb->queue = msb->disk->queue;

	sprintf(msb->disk->disk_name, "msblk%d", msb->disk_id);
	msb->disk->fops = &msb_bdops;
	msb->disk->private_data = msb;

	capacity = msb->pages_in_block * msb->logical_block_count;
	capacity *= (msb->page_size / 512);
	set_capacity(msb->disk, capacity);
	dbg("Set total disk size to %lu sectors", capacity);

	msb->io_queue = alloc_ordered_workqueue("ms_block", WQ_MEM_RECLAIM);
	if (!msb->io_queue) {
		rc = -ENOMEM;
		goto out_cleanup_disk;
	}

	INIT_WORK(&msb->io_work, msb_io_work);
	sg_init_table(msb->prealloc_sg, MS_BLOCK_MAX_SEGS+1);

	if (msb->read_only)
		set_disk_ro(msb->disk, 1);

	msb_start(card);
	rc = device_add_disk(&card->dev, msb->disk, NULL);
	if (rc)
		goto out_destroy_workqueue;
	dbg("Disk added");
	return 0;

out_destroy_workqueue:
	destroy_workqueue(msb->io_queue);
out_cleanup_disk:
	put_disk(msb->disk);
out_free_tag_set:
	blk_mq_free_tag_set(&msb->tag_set);
out_release_id:
	mutex_lock(&msb_disk_lock);
	idr_remove(&msb_disk_idr, msb->disk_id);
	mutex_unlock(&msb_disk_lock);
	return rc;
}

static int msb_probe(struct memstick_dev *card)
{
	struct msb_data *msb;
	int rc = 0;

	msb = kzalloc_obj(struct msb_data);
	if (!msb)
		return -ENOMEM;
	memstick_set_drvdata(card, msb);
	msb->card = card;
	spin_lock_init(&msb->q_lock);

	rc = msb_init_card(card);
	if (rc)
		goto out_free;

	rc = msb_init_disk(card);
	if (!rc) {
		card->check = msb_check_card;
		card->stop = msb_stop;
		card->start = msb_start;
		return 0;
	}
out_free:
	memstick_set_drvdata(card, NULL);
	msb_data_clear(msb);
	kfree(msb);
	return rc;
}

static void msb_remove(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	unsigned long flags;

	if (!msb->io_queue_stopped)
		msb_stop(card);

	dbg("Removing the disk device");

	/* Take care of unhandled + new requests from now on */
	spin_lock_irqsave(&msb->q_lock, flags);
	msb->card_dead = true;
	spin_unlock_irqrestore(&msb->q_lock, flags);
	blk_mq_start_hw_queues(msb->queue);

	/* Remove the disk */
	del_gendisk(msb->disk);
	blk_mq_free_tag_set(&msb->tag_set);
	msb->queue = NULL;

	mutex_lock(&msb_disk_lock);
	msb_data_clear(msb);
	mutex_unlock(&msb_disk_lock);

	put_disk(msb->disk);
	memstick_set_drvdata(card, NULL);
}

#ifdef CONFIG_PM

static int msb_suspend(struct memstick_dev *card, pm_message_t state)
{
	msb_stop(card);
	return 0;
}

static int msb_resume(struct memstick_dev *card)
{
	struct msb_data *msb = memstick_get_drvdata(card);
	struct msb_data *new_msb = NULL;
	bool card_dead = true;

#ifndef CONFIG_MEMSTICK_UNSAFE_RESUME
	msb->card_dead = true;
	return 0;
#endif
	mutex_lock(&card->host->lock);

	new_msb = kzalloc_obj(struct msb_data);
	if (!new_msb)
		goto out;

	new_msb->card = card;
	memstick_set_drvdata(card, new_msb);
	spin_lock_init(&new_msb->q_lock);
	sg_init_table(msb->prealloc_sg, MS_BLOCK_MAX_SEGS+1);

	if (msb_init_card(card))
		goto out;

	if (msb->block_size != new_msb->block_size)
		goto out;

	if (memcmp(msb->boot_page, new_msb->boot_page,
					sizeof(struct ms_boot_page)))
		goto out;

	if (msb->logical_block_count != new_msb->logical_block_count ||
		memcmp(msb->lba_to_pba_table, new_msb->lba_to_pba_table,
						msb->logical_block_count))
		goto out;

	if (msb->block_count != new_msb->block_count ||
	    !bitmap_equal(msb->used_blocks_bitmap, new_msb->used_blocks_bitmap,
							msb->block_count))
		goto out;

	card_dead = false;
out:
	if (card_dead)
		dbg("Card was removed/replaced during suspend");

	msb->card_dead = card_dead;
	memstick_set_drvdata(card, msb);

	if (new_msb) {
		msb_data_clear(new_msb);
		kfree(new_msb);
	}

	msb_start(card);
	mutex_unlock(&card->host->lock);
	return 0;
}
#else

#define msb_suspend NULL
#define msb_resume NULL

#endif /* CONFIG_PM */

static const struct memstick_device_id msb_id_tbl[] = {
	{MEMSTICK_MATCH_ALL, MEMSTICK_TYPE_LEGACY, MEMSTICK_CATEGORY_STORAGE,
	 MEMSTICK_CLASS_FLASH},

	{MEMSTICK_MATCH_ALL, MEMSTICK_TYPE_LEGACY, MEMSTICK_CATEGORY_STORAGE,
	 MEMSTICK_CLASS_ROM},

	{MEMSTICK_MATCH_ALL, MEMSTICK_TYPE_LEGACY, MEMSTICK_CATEGORY_STORAGE,
	 MEMSTICK_CLASS_RO},

	{MEMSTICK_MATCH_ALL, MEMSTICK_TYPE_LEGACY, MEMSTICK_CATEGORY_STORAGE,
	 MEMSTICK_CLASS_WP},

	{MEMSTICK_MATCH_ALL, MEMSTICK_TYPE_DUO, MEMSTICK_CATEGORY_STORAGE_DUO,
	 MEMSTICK_CLASS_DUO},
	{}
};
MODULE_DEVICE_TABLE(memstick, msb_id_tbl);


static struct memstick_driver msb_driver = {
	.driver = {
		.name  = DRIVER_NAME,
		.owner = THIS_MODULE
	},
	.id_table = msb_id_tbl,
	.probe    = msb_probe,
	.remove   = msb_remove,
	.suspend  = msb_suspend,
	.resume   = msb_resume
};

static int __init msb_init(void)
{
	int rc = memstick_register_driver(&msb_driver);

	if (rc)
		pr_err("failed to register memstick driver (error %d)\n", rc);

	return rc;
}

static void __exit msb_exit(void)
{
	memstick_unregister_driver(&msb_driver);
	idr_destroy(&msb_disk_idr);
}

module_init(msb_init);
module_exit(msb_exit);

module_param(cache_flush_timeout, int, S_IRUGO);
MODULE_PARM_DESC(cache_flush_timeout,
				"Cache flush timeout in msec (1000 default)");
module_param(debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug level (0-2)");

module_param(verify_writes, bool, S_IRUGO);
MODULE_PARM_DESC(verify_writes, "Read back and check all data that is written");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Maxim Levitsky");
MODULE_DESCRIPTION("Sony MemoryStick block device driver");