/*
 * Copyright © 2009 - Maxim Levitsky
 * driver for Ricoh xD readers
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <asm/byteorder.h>
#include <linux/sched.h>
#include "sm_common.h"
#include "r852.h"


static int r852_enable_dma = 1;
module_param(r852_enable_dma, bool, S_IRUGO);
MODULE_PARM_DESC(r852_enable_dma, "Enable usage of the DMA (default)");

static int debug;
module_param(debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug level (0-2)");

/* read register */
static inline uint8_t r852_read_reg(struct r852_device *dev, int address)
{
        uint8_t reg = readb(dev->mmio + address);
        return reg;
}

/* write register */
static inline void r852_write_reg(struct r852_device *dev,
                                                int address, uint8_t value)
{
        writeb(value, dev->mmio + address);
        mmiowb();
}


/* read dword sized register */
static inline uint32_t r852_read_reg_dword(struct r852_device *dev, int address)
{
        uint32_t reg = le32_to_cpu(readl(dev->mmio + address));
        return reg;
}

/* write dword sized register */
static inline void r852_write_reg_dword(struct r852_device *dev,
                                                        int address, uint32_t value)
{
        writel(cpu_to_le32(value), dev->mmio + address);
        mmiowb();
}

/* returns pointer to our private structure */
static inline struct r852_device *r852_get_dev(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd->priv;
        return chip->priv;
}


/* check if controller supports dma */
static void r852_dma_test(struct r852_device *dev)
{
        dev->dma_usable = (r852_read_reg(dev, R852_DMA_CAP) &
                (R852_DMA1 | R852_DMA2)) == (R852_DMA1 | R852_DMA2);

        if (!dev->dma_usable)
                message("Non dma capable device detected, dma disabled");

        if (!r852_enable_dma) {
                message("disabling dma on user request");
                dev->dma_usable = 0;
        }
}

/*
 * Enable dma. Enables ether first or second stage of the DMA,
 * Expects dev->dma_dir and dev->dma_state be set
 */
static void r852_dma_enable(struct r852_device *dev)
{
        uint8_t dma_reg, dma_irq_reg;

        /* Set up dma settings */
        dma_reg = r852_read_reg_dword(dev, R852_DMA_SETTINGS);
        dma_reg &= ~(R852_DMA_READ | R852_DMA_INTERNAL | R852_DMA_MEMORY);

        if (dev->dma_dir)
                dma_reg |= R852_DMA_READ;

        if (dev->dma_state == DMA_INTERNAL) {
                dma_reg |= R852_DMA_INTERNAL;
                /* Precaution to make sure HW doesn't write */
                        /* to random kernel memory */
                r852_write_reg_dword(dev, R852_DMA_ADDR,
                        cpu_to_le32(dev->phys_bounce_buffer));
        } else {
                dma_reg |= R852_DMA_MEMORY;
                r852_write_reg_dword(dev, R852_DMA_ADDR,
                        cpu_to_le32(dev->phys_dma_addr));
        }

        /* Precaution: make sure write reached the device */
        r852_read_reg_dword(dev, R852_DMA_ADDR);

        r852_write_reg_dword(dev, R852_DMA_SETTINGS, dma_reg);

        /* Set dma irq */
        dma_irq_reg = r852_read_reg_dword(dev, R852_DMA_IRQ_ENABLE);
        r852_write_reg_dword(dev, R852_DMA_IRQ_ENABLE,
                dma_irq_reg |
                R852_DMA_IRQ_INTERNAL |
                R852_DMA_IRQ_ERROR |
                R852_DMA_IRQ_MEMORY);
}

/*
 * Disable dma, called from the interrupt handler, which specifies
 * success of the operation via 'error' argument
 */
static void r852_dma_done(struct r852_device *dev, int error)
{
        WARN_ON(dev->dma_stage == 0);

        r852_write_reg_dword(dev, R852_DMA_IRQ_STA,
                        r852_read_reg_dword(dev, R852_DMA_IRQ_STA));

        r852_write_reg_dword(dev, R852_DMA_SETTINGS, 0);
        r852_write_reg_dword(dev, R852_DMA_IRQ_ENABLE, 0);

        /* Precaution to make sure HW doesn't write to random kernel memory */
        r852_write_reg_dword(dev, R852_DMA_ADDR,
                cpu_to_le32(dev->phys_bounce_buffer));
        r852_read_reg_dword(dev, R852_DMA_ADDR);

        dev->dma_error = error;
        dev->dma_stage = 0;

        if (dev->phys_dma_addr && dev->phys_dma_addr != dev->phys_bounce_buffer)
                pci_unmap_single(dev->pci_dev, dev->phys_dma_addr, R852_DMA_LEN,
                        dev->dma_dir ? PCI_DMA_FROMDEVICE : PCI_DMA_TODEVICE);
}

/*
 * Wait, till dma is done, which includes both phases of it
 */
static int r852_dma_wait(struct r852_device *dev)
{
        long timeout = wait_for_completion_timeout(&dev->dma_done,
                                msecs_to_jiffies(1000));
        if (!timeout) {
                dbg("timeout waiting for DMA interrupt");
                return -ETIMEDOUT;
        }

        return 0;
}

/*
 * Read/Write one page using dma. Only pages can be read (512 bytes)
*/
static void r852_do_dma(struct r852_device *dev, uint8_t *buf, int do_read)
{
        int bounce = 0;
        unsigned long flags;
        int error;

        dev->dma_error = 0;

        /* Set dma direction */
        dev->dma_dir = do_read;
        dev->dma_stage = 1;
        INIT_COMPLETION(dev->dma_done);

        dbg_verbose("doing dma %s ", do_read ? "read" : "write");

        /* Set intial dma state: for reading first fill on board buffer,
          from device, for writes first fill the buffer  from memory*/
        dev->dma_state = do_read ? DMA_INTERNAL : DMA_MEMORY;

        /* if incoming buffer is not page aligned, we should do bounce */
        if ((unsigned long)buf & (R852_DMA_LEN-1))
                bounce = 1;

        if (!bounce) {
                dev->phys_dma_addr = pci_map_single(dev->pci_dev, (void *)buf,
                        R852_DMA_LEN,
                        (do_read ? PCI_DMA_FROMDEVICE : PCI_DMA_TODEVICE));

                if (pci_dma_mapping_error(dev->pci_dev, dev->phys_dma_addr))
                        bounce = 1;
        }

        if (bounce) {
                dbg_verbose("dma: using bounce buffer");
                dev->phys_dma_addr = dev->phys_bounce_buffer;
                if (!do_read)
                        memcpy(dev->bounce_buffer, buf, R852_DMA_LEN);
        }

        /* Enable DMA */
        spin_lock_irqsave(&dev->irqlock, flags);
        r852_dma_enable(dev);
        spin_unlock_irqrestore(&dev->irqlock, flags);

        /* Wait till complete */
        error = r852_dma_wait(dev);

        if (error) {
                r852_dma_done(dev, error);
                return;
        }

        if (do_read && bounce)
                memcpy((void *)buf, dev->bounce_buffer, R852_DMA_LEN);
}

/*
 * Program data lines of the nand chip to send data to it
 */
void r852_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
{
        struct r852_device *dev = r852_get_dev(mtd);
        uint32_t reg;

        /* Don't allow any access to hardware if we suspect card removal */
        if (dev->card_unstable)
                return;

        /* Special case for whole sector read */
        if (len == R852_DMA_LEN && dev->dma_usable) {
                r852_do_dma(dev, (uint8_t *)buf, 0);
                return;
        }

        /* write DWORD chinks - faster */
        while (len) {
                reg = buf[0] | buf[1] << 8 | buf[2] << 16 | buf[3] << 24;
                r852_write_reg_dword(dev, R852_DATALINE, reg);
                buf += 4;
                len -= 4;

        }

        /* write rest */
        while (len)
                r852_write_reg(dev, R852_DATALINE, *buf++);
}

/*
 * Read data lines of the nand chip to retrieve data
 */
void r852_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
        struct r852_device *dev = r852_get_dev(mtd);
        uint32_t reg;

        if (dev->card_unstable) {
                /* since we can't signal error here, at least, return
                        predictable buffer */
                memset(buf, 0, len);
                return;
        }

        /* special case for whole sector read */
        if (len == R852_DMA_LEN && dev->dma_usable) {
                r852_do_dma(dev, buf, 1);
                return;
        }

        /* read in dword sized chunks */
        while (len >= 4) {

                reg = r852_read_reg_dword(dev, R852_DATALINE);
                *buf++ = reg & 0xFF;
                *buf++ = (reg >> 8) & 0xFF;
                *buf++ = (reg >> 16) & 0xFF;
                *buf++ = (reg >> 24) & 0xFF;
                len -= 4;
        }

        /* read the reset by bytes */
        while (len--)
                *buf++ = r852_read_reg(dev, R852_DATALINE);
}

/*
 * Read one byte from nand chip
 */
static uint8_t r852_read_byte(struct mtd_info *mtd)
{
        struct r852_device *dev = r852_get_dev(mtd);

        /* Same problem as in r852_read_buf.... */
        if (dev->card_unstable)
                return 0;

        return r852_read_reg(dev, R852_DATALINE);
}


/*
 * Readback the buffer to verify it
 */
int r852_verify_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
{
        struct r852_device *dev = r852_get_dev(mtd);

        /* We can't be sure about anything here... */
        if (dev->card_unstable)
                return -1;

        /* This will never happen, unless you wired up a nand chip
                with > 512 bytes page size to the reader */
        if (len > SM_SECTOR_SIZE)
                return 0;

        r852_read_buf(mtd, dev->tmp_buffer, len);
        return memcmp(buf, dev->tmp_buffer, len);
}

/*
 * Control several chip lines & send commands
 */
void r852_cmdctl(struct mtd_info *mtd, int dat, unsigned int ctrl)
{
        struct r852_device *dev = r852_get_dev(mtd);

        if (dev->card_unstable)
                return;

        if (ctrl & NAND_CTRL_CHANGE) {

                dev->ctlreg &= ~(R852_CTL_DATA | R852_CTL_COMMAND |
                                 R852_CTL_ON | R852_CTL_CARDENABLE);

                if (ctrl & NAND_ALE)
                        dev->ctlreg |= R852_CTL_DATA;

                if (ctrl & NAND_CLE)
                        dev->ctlreg |= R852_CTL_COMMAND;

                if (ctrl & NAND_NCE)
                        dev->ctlreg |= (R852_CTL_CARDENABLE | R852_CTL_ON);
                else
                        dev->ctlreg &= ~R852_CTL_WRITE;

                /* when write is stareted, enable write access */
                if (dat == NAND_CMD_ERASE1)
                        dev->ctlreg |= R852_CTL_WRITE;

                r852_write_reg(dev, R852_CTL, dev->ctlreg);
        }

         /* HACK: NAND_CMD_SEQIN is called without NAND_CTRL_CHANGE, but we need
                to set write mode */
        if (dat == NAND_CMD_SEQIN && (dev->ctlreg & R852_CTL_COMMAND)) {
                dev->ctlreg |= R852_CTL_WRITE;
                r852_write_reg(dev, R852_CTL, dev->ctlreg);
        }

        if (dat != NAND_CMD_NONE)
                r852_write_reg(dev, R852_DATALINE, dat);
}

/*
 * Wait till card is ready.
 * based on nand_wait, but returns errors on DMA error
 */
int r852_wait(struct mtd_info *mtd, struct nand_chip *chip)
{
        struct r852_device *dev = chip->priv;

        unsigned long timeout;
        int status;

        timeout = jiffies + (chip->state == FL_ERASING ?
                msecs_to_jiffies(400) : msecs_to_jiffies(20));

        while (time_before(jiffies, timeout))
                if (chip->dev_ready(mtd))
                        break;

        chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
        status = (int)chip->read_byte(mtd);

        /* Unfortunelly, no way to send detailed error status... */
        if (dev->dma_error) {
                status |= NAND_STATUS_FAIL;
                dev->dma_error = 0;
        }
        return status;
}

/*
 * Check if card is ready
 */

int r852_ready(struct mtd_info *mtd)
{
        struct r852_device *dev = r852_get_dev(mtd);
        return !(r852_read_reg(dev, R852_CARD_STA) & R852_CARD_STA_BUSY);
}


/*
 * Set ECC engine mode
*/

void r852_ecc_hwctl(struct mtd_info *mtd, int mode)
{
        struct r852_device *dev = r852_get_dev(mtd);

        if (dev->card_unstable)
                return;

        switch (mode) {
        case NAND_ECC_READ:
        case NAND_ECC_WRITE:
                /* enable ecc generation/check*/
                dev->ctlreg |= R852_CTL_ECC_ENABLE;

                /* flush ecc buffer */
                r852_write_reg(dev, R852_CTL,
                        dev->ctlreg | R852_CTL_ECC_ACCESS);

                r852_read_reg_dword(dev, R852_DATALINE);
                r852_write_reg(dev, R852_CTL, dev->ctlreg);
                return;

        case NAND_ECC_READSYN:
                /* disable ecc generation */
                dev->ctlreg &= ~R852_CTL_ECC_ENABLE;
                r852_write_reg(dev, R852_CTL, dev->ctlreg);
        }
}

/*
 * Calculate ECC, only used for writes
 */

int r852_ecc_calculate(struct mtd_info *mtd, const uint8_t *dat,
                                                        uint8_t *ecc_code)
{
        struct r852_device *dev = r852_get_dev(mtd);
        struct sm_oob *oob = (struct sm_oob *)ecc_code;
        uint32_t ecc1, ecc2;

        if (dev->card_unstable)
                return 0;

        dev->ctlreg &= ~R852_CTL_ECC_ENABLE;
        r852_write_reg(dev, R852_CTL, dev->ctlreg | R852_CTL_ECC_ACCESS);

        ecc1 = r852_read_reg_dword(dev, R852_DATALINE);
        ecc2 = r852_read_reg_dword(dev, R852_DATALINE);

        oob->ecc1[0] = (ecc1) & 0xFF;
        oob->ecc1[1] = (ecc1 >> 8) & 0xFF;
        oob->ecc1[2] = (ecc1 >> 16) & 0xFF;

        oob->ecc2[0] = (ecc2) & 0xFF;
        oob->ecc2[1] = (ecc2 >> 8) & 0xFF;
        oob->ecc2[2] = (ecc2 >> 16) & 0xFF;

        r852_write_reg(dev, R852_CTL, dev->ctlreg);
        return 0;
}

/*
 * Correct the data using ECC, hw did almost everything for us
 */

int r852_ecc_correct(struct mtd_info *mtd, uint8_t *dat,
                                uint8_t *read_ecc, uint8_t *calc_ecc)
{
        uint16_t ecc_reg;
        uint8_t ecc_status, err_byte;
        int i, error = 0;

        struct r852_device *dev = r852_get_dev(mtd);

        if (dev->card_unstable)
                return 0;

        if (dev->dma_error) {
                dev->dma_error = 0;
                return -1;
        }

        r852_write_reg(dev, R852_CTL, dev->ctlreg | R852_CTL_ECC_ACCESS);
        ecc_reg = r852_read_reg_dword(dev, R852_DATALINE);
        r852_write_reg(dev, R852_CTL, dev->ctlreg);

        for (i = 0 ; i <= 1 ; i++) {

                ecc_status = (ecc_reg >> 8) & 0xFF;

                /* ecc uncorrectable error */
                if (ecc_status & R852_ECC_FAIL) {
                        dbg("ecc: unrecoverable error, in half %d", i);
                        error = -1;
                        goto exit;
                }

                /* correctable error */
                if (ecc_status & R852_ECC_CORRECTABLE) {

                        err_byte = ecc_reg & 0xFF;
                        dbg("ecc: recoverable error, "
                                "in half %d, byte %d, bit %d", i,
                                err_byte, ecc_status & R852_ECC_ERR_BIT_MSK);

                        dat[err_byte] ^=
                                1 << (ecc_status & R852_ECC_ERR_BIT_MSK);
                        error++;
                }

                dat += 256;
                ecc_reg >>= 16;
        }
exit:
        return error;
}

/*
 * This is copy of nand_read_oob_std
 * nand_read_oob_syndrome assumes we can send column address - we can't
 */
static int r852_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
                             int page, int sndcmd)
{
        if (sndcmd) {
                chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
                sndcmd = 0;
        }
        chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
        return sndcmd;
}

/*
 * Start the nand engine
 */

void r852_engine_enable(struct r852_device *dev)
{
        if (r852_read_reg_dword(dev, R852_HW) & R852_HW_UNKNOWN) {
                r852_write_reg(dev, R852_CTL, R852_CTL_RESET | R852_CTL_ON);
                r852_write_reg_dword(dev, R852_HW, R852_HW_ENABLED);
        } else {
                r852_write_reg_dword(dev, R852_HW, R852_HW_ENABLED);
                r852_write_reg(dev, R852_CTL, R852_CTL_RESET | R852_CTL_ON);
        }
        msleep(300);
        r852_write_reg(dev, R852_CTL, 0);
}


/*
 * Stop the nand engine
 */

void r852_engine_disable(struct r852_device *dev)
{
        r852_write_reg_dword(dev, R852_HW, 0);
        r852_write_reg(dev, R852_CTL, R852_CTL_RESET);
}

/*
 * Test if card is present
 */

void r852_card_update_present(struct r852_device *dev)
{
        unsigned long flags;
        uint8_t reg;

        spin_lock_irqsave(&dev->irqlock, flags);
        reg = r852_read_reg(dev, R852_CARD_STA);
        dev->card_detected = !!(reg & R852_CARD_STA_PRESENT);
        spin_unlock_irqrestore(&dev->irqlock, flags);
}

/*
 * Update card detection IRQ state according to current card state
 * which is read in r852_card_update_present
 */
void r852_update_card_detect(struct r852_device *dev)
{
        int card_detect_reg = r852_read_reg(dev, R852_CARD_IRQ_ENABLE);
        dev->card_unstable = 0;

        card_detect_reg &= ~(R852_CARD_IRQ_REMOVE | R852_CARD_IRQ_INSERT);
        card_detect_reg |= R852_CARD_IRQ_GENABLE;

        card_detect_reg |= dev->card_detected ?
                R852_CARD_IRQ_REMOVE : R852_CARD_IRQ_INSERT;

        r852_write_reg(dev, R852_CARD_IRQ_ENABLE, card_detect_reg);
}

ssize_t r852_media_type_show(struct device *sys_dev,
                struct device_attribute *attr, char *buf)
{
        struct mtd_info *mtd = container_of(sys_dev, struct mtd_info, dev);
        struct r852_device *dev = r852_get_dev(mtd);
        char *data = dev->sm ? "smartmedia" : "xd";

        strcpy(buf, data);
        return strlen(data);
}

DEVICE_ATTR(media_type, S_IRUGO, r852_media_type_show, NULL);


/* Detect properties of card in slot */
void r852_update_media_status(struct r852_device *dev)
{
        uint8_t reg;
        unsigned long flags;
        int readonly;

        spin_lock_irqsave(&dev->irqlock, flags);
        if (!dev->card_detected) {
                message("card removed");
                spin_unlock_irqrestore(&dev->irqlock, flags);
                return ;
        }

        readonly  = r852_read_reg(dev, R852_CARD_STA) & R852_CARD_STA_RO;
        reg = r852_read_reg(dev, R852_DMA_CAP);
        dev->sm = (reg & (R852_DMA1 | R852_DMA2)) && (reg & R852_SMBIT);

        message("detected %s %s card in slot",
                dev->sm ? "SmartMedia" : "xD",
                readonly ? "readonly" : "writeable");

        dev->readonly = readonly;
        spin_unlock_irqrestore(&dev->irqlock, flags);
}

/*
 * Register the nand device
 * Called when the card is detected
 */
int r852_register_nand_device(struct r852_device *dev)
{
        dev->mtd = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);

        if (!dev->mtd)
                goto error1;

        WARN_ON(dev->card_registred);

        dev->mtd->owner = THIS_MODULE;
        dev->mtd->priv = dev->chip;
        dev->mtd->dev.parent = &dev->pci_dev->dev;

        if (dev->readonly)
                dev->chip->options |= NAND_ROM;

        r852_engine_enable(dev);

        if (sm_register_device(dev->mtd, dev->sm))
                goto error2;

        if (device_create_file(&dev->mtd->dev, &dev_attr_media_type))
                message("can't create media type sysfs attribute");

        dev->card_registred = 1;
        return 0;
error2:
        kfree(dev->mtd);
error1:
        /* Force card redetect */
        dev->card_detected = 0;
        return -1;
}

/*
 * Unregister the card
 */

void r852_unregister_nand_device(struct r852_device *dev)
{
        if (!dev->card_registred)
                return;

        device_remove_file(&dev->mtd->dev, &dev_attr_media_type);
        nand_release(dev->mtd);
        r852_engine_disable(dev);
        dev->card_registred = 0;
        kfree(dev->mtd);
        dev->mtd = NULL;
}

/* Card state updater */
void r852_card_detect_work(struct work_struct *work)
{
        struct r852_device *dev =
                container_of(work, struct r852_device, card_detect_work.work);

        r852_card_update_present(dev);
        r852_update_card_detect(dev);
        dev->card_unstable = 0;

        /* False alarm */
        if (dev->card_detected == dev->card_registred)
                goto exit;

        /* Read media properties */
        r852_update_media_status(dev);

        /* Register the card */
        if (dev->card_detected)
                r852_register_nand_device(dev);
        else
                r852_unregister_nand_device(dev);
exit:
        r852_update_card_detect(dev);
}

/* Ack + disable IRQ generation */
static void r852_disable_irqs(struct r852_device *dev)
{
        uint8_t reg;
        reg = r852_read_reg(dev, R852_CARD_IRQ_ENABLE);
        r852_write_reg(dev, R852_CARD_IRQ_ENABLE, reg & ~R852_CARD_IRQ_MASK);

        reg = r852_read_reg_dword(dev, R852_DMA_IRQ_ENABLE);
        r852_write_reg_dword(dev, R852_DMA_IRQ_ENABLE,
                                        reg & ~R852_DMA_IRQ_MASK);

        r852_write_reg(dev, R852_CARD_IRQ_STA, R852_CARD_IRQ_MASK);
        r852_write_reg_dword(dev, R852_DMA_IRQ_STA, R852_DMA_IRQ_MASK);
}

/* Interrupt handler */
static irqreturn_t r852_irq(int irq, void *data)
{
        struct r852_device *dev = (struct r852_device *)data;

        uint8_t card_status, dma_status;
        unsigned long flags;
        irqreturn_t ret = IRQ_NONE;

        spin_lock_irqsave(&dev->irqlock, flags);

        /* handle card detection interrupts first */
        card_status = r852_read_reg(dev, R852_CARD_IRQ_STA);
        r852_write_reg(dev, R852_CARD_IRQ_STA, card_status);

        if (card_status & (R852_CARD_IRQ_INSERT|R852_CARD_IRQ_REMOVE)) {

                ret = IRQ_HANDLED;
                dev->card_detected = !!(card_status & R852_CARD_IRQ_INSERT);

                /* we shouldn't recieve any interrupts if we wait for card
                        to settle */
                WARN_ON(dev->card_unstable);

                /* disable irqs while card is unstable */
                /* this will timeout DMA if active, but better that garbage */
                r852_disable_irqs(dev);

                if (dev->card_unstable)
                        goto out;

                /* let, card state to settle a bit, and then do the work */
                dev->card_unstable = 1;
                queue_delayed_work(dev->card_workqueue,
                        &dev->card_detect_work, msecs_to_jiffies(100));
                goto out;
        }


        /* Handle dma interrupts */
        dma_status = r852_read_reg_dword(dev, R852_DMA_IRQ_STA);
        r852_write_reg_dword(dev, R852_DMA_IRQ_STA, dma_status);

        if (dma_status & R852_DMA_IRQ_MASK) {

                ret = IRQ_HANDLED;

                if (dma_status & R852_DMA_IRQ_ERROR) {
                        dbg("recieved dma error IRQ");
                        r852_dma_done(dev, -EIO);
                        complete(&dev->dma_done);
                        goto out;
                }

                /* recieved DMA interrupt out of nowhere? */
                WARN_ON_ONCE(dev->dma_stage == 0);

                if (dev->dma_stage == 0)
                        goto out;

                /* done device access */
                if (dev->dma_state == DMA_INTERNAL &&
                                (dma_status & R852_DMA_IRQ_INTERNAL)) {

                        dev->dma_state = DMA_MEMORY;
                        dev->dma_stage++;
                }

                /* done memory DMA */
                if (dev->dma_state == DMA_MEMORY &&
                                (dma_status & R852_DMA_IRQ_MEMORY)) {
                        dev->dma_state = DMA_INTERNAL;
                        dev->dma_stage++;
                }

                /* Enable 2nd half of dma dance */
                if (dev->dma_stage == 2)
                        r852_dma_enable(dev);

                /* Operation done */
                if (dev->dma_stage == 3) {
                        r852_dma_done(dev, 0);
                        complete(&dev->dma_done);
                }
                goto out;
        }

        /* Handle unknown interrupts */
        if (dma_status)
                dbg("bad dma IRQ status = %x", dma_status);

        if (card_status & ~R852_CARD_STA_CD)
                dbg("strange card status = %x", card_status);

out:
        spin_unlock_irqrestore(&dev->irqlock, flags);
        return ret;
}

int  r852_probe(struct pci_dev *pci_dev, const struct pci_device_id *id)
{
        int error;
        struct nand_chip *chip;
        struct r852_device *dev;

        /* pci initialization */
        error = pci_enable_device(pci_dev);

        if (error)
                goto error1;

        pci_set_master(pci_dev);

        error = pci_set_dma_mask(pci_dev, DMA_BIT_MASK(32));
        if (error)
                goto error2;

        error = pci_request_regions(pci_dev, DRV_NAME);

        if (error)
                goto error3;

        error = -ENOMEM;

        /* init nand chip, but register it only on card insert */
        chip = kzalloc(sizeof(struct nand_chip), GFP_KERNEL);

        if (!chip)
                goto error4;

        /* commands */
        chip->cmd_ctrl = r852_cmdctl;
        chip->waitfunc = r852_wait;
        chip->dev_ready = r852_ready;

        /* I/O */
        chip->read_byte = r852_read_byte;
        chip->read_buf = r852_read_buf;
        chip->write_buf = r852_write_buf;
        chip->verify_buf = r852_verify_buf;

        /* ecc */
        chip->ecc.mode = NAND_ECC_HW_SYNDROME;
        chip->ecc.size = R852_DMA_LEN;
        chip->ecc.bytes = SM_OOB_SIZE;
        chip->ecc.hwctl = r852_ecc_hwctl;
        chip->ecc.calculate = r852_ecc_calculate;
        chip->ecc.correct = r852_ecc_correct;

        /* TODO: hack */
        chip->ecc.read_oob = r852_read_oob;

        /* init our device structure */
        dev = kzalloc(sizeof(struct r852_device), GFP_KERNEL);

        if (!dev)
                goto error5;

        chip->priv = dev;
        dev->chip = chip;
        dev->pci_dev = pci_dev;
        pci_set_drvdata(pci_dev, dev);

        dev->bounce_buffer = pci_alloc_consistent(pci_dev, R852_DMA_LEN,
                &dev->phys_bounce_buffer);

        if (!dev->bounce_buffer)
                goto error6;


        error = -ENODEV;
        dev->mmio = pci_ioremap_bar(pci_dev, 0);

        if (!dev->mmio)
                goto error7;

        error = -ENOMEM;
        dev->tmp_buffer = kzalloc(SM_SECTOR_SIZE, GFP_KERNEL);

        if (!dev->tmp_buffer)
                goto error8;

        init_completion(&dev->dma_done);

        dev->card_workqueue = create_freezable_workqueue(DRV_NAME);

        if (!dev->card_workqueue)
                goto error9;

        INIT_DELAYED_WORK(&dev->card_detect_work, r852_card_detect_work);

        /* shutdown everything - precation */
        r852_engine_disable(dev);
        r852_disable_irqs(dev);

        r852_dma_test(dev);

        dev->irq = pci_dev->irq;
        spin_lock_init(&dev->irqlock);

        dev->card_detected = 0;
        r852_card_update_present(dev);

        /*register irq handler*/
        error = -ENODEV;
        if (request_irq(pci_dev->irq, &r852_irq, IRQF_SHARED,
                          DRV_NAME, dev))
                goto error10;

        /* kick initial present test */
        queue_delayed_work(dev->card_workqueue,
                &dev->card_detect_work, 0);


        printk(KERN_NOTICE DRV_NAME ": driver loaded succesfully\n");
        return 0;

error10:
        destroy_workqueue(dev->card_workqueue);
error9:
        kfree(dev->tmp_buffer);
error8:
        pci_iounmap(pci_dev, dev->mmio);
error7:
        pci_free_consistent(pci_dev, R852_DMA_LEN,
                dev->bounce_buffer, dev->phys_bounce_buffer);
error6:
        kfree(dev);
error5:
        kfree(chip);
error4:
        pci_release_regions(pci_dev);
error3:
error2:
        pci_disable_device(pci_dev);
error1:
        return error;
}

void r852_remove(struct pci_dev *pci_dev)
{
        struct r852_device *dev = pci_get_drvdata(pci_dev);

        /* Stop detect workqueue -
                we are going to unregister the device anyway*/
        cancel_delayed_work_sync(&dev->card_detect_work);
        destroy_workqueue(dev->card_workqueue);

        /* Unregister the device, this might make more IO */
        r852_unregister_nand_device(dev);

        /* Stop interrupts */

        r852_disable_irqs(dev);
        synchronize_irq(dev->irq);
        free_irq(dev->irq, dev);

        /* Cleanup */
        kfree(dev->tmp_buffer);
        pci_iounmap(pci_dev, dev->mmio);
        pci_free_consistent(pci_dev, R852_DMA_LEN,
                dev->bounce_buffer, dev->phys_bounce_buffer);

        kfree(dev->chip);
        kfree(dev);

        /* Shutdown the PCI device */
        pci_release_regions(pci_dev);
        pci_disable_device(pci_dev);
}

void r852_shutdown(struct pci_dev *pci_dev)
{
        struct r852_device *dev = pci_get_drvdata(pci_dev);

        cancel_delayed_work_sync(&dev->card_detect_work);
        r852_disable_irqs(dev);
        synchronize_irq(dev->irq);
        pci_disable_device(pci_dev);
}

#ifdef CONFIG_PM
int r852_suspend(struct device *device)
{
        struct r852_device *dev = pci_get_drvdata(to_pci_dev(device));

        if (dev->ctlreg & R852_CTL_CARDENABLE)
                return -EBUSY;

        /* First make sure the detect work is gone */
        cancel_delayed_work_sync(&dev->card_detect_work);

        /* Turn off the interrupts and stop the device */
        r852_disable_irqs(dev);
        r852_engine_disable(dev);

        /* If card was pulled off just during the suspend, which is very
                unlikely, we will remove it on resume, it too late now
                anyway... */
        dev->card_unstable = 0;
        return 0;
}

int r852_resume(struct device *device)
{
        struct r852_device *dev = pci_get_drvdata(to_pci_dev(device));

        r852_disable_irqs(dev);
        r852_card_update_present(dev);
        r852_engine_disable(dev);


        /* If card status changed, just do the work */
        if (dev->card_detected != dev->card_registred) {
                dbg("card was %s during low power state",
                        dev->card_detected ? "added" : "removed");

                queue_delayed_work(dev->card_workqueue,
                &dev->card_detect_work, msecs_to_jiffies(1000));
                return 0;
        }

        /* Otherwise, initialize the card */
        if (dev->card_registred) {
                r852_engine_enable(dev);
                dev->chip->select_chip(dev->mtd, 0);
                dev->chip->cmdfunc(dev->mtd, NAND_CMD_RESET, -1, -1);
                dev->chip->select_chip(dev->mtd, -1);
        }

        /* Program card detection IRQ */
        r852_update_card_detect(dev);
        return 0;
}
#else
#define r852_suspend    NULL
#define r852_resume     NULL
#endif

static const struct pci_device_id r852_pci_id_tbl[] = {

        { PCI_VDEVICE(RICOH, 0x0852), },
        { },
};

MODULE_DEVICE_TABLE(pci, r852_pci_id_tbl);

SIMPLE_DEV_PM_OPS(r852_pm_ops, r852_suspend, r852_resume);

static struct pci_driver r852_pci_driver = {
        .name           = DRV_NAME,
        .id_table       = r852_pci_id_tbl,
        .probe          = r852_probe,
        .remove         = r852_remove,
        .shutdown       = r852_shutdown,
        .driver.pm      = &r852_pm_ops,
};

static __init int r852_module_init(void)
{
        return pci_register_driver(&r852_pci_driver);
}

static void __exit r852_module_exit(void)
{
        pci_unregister_driver(&r852_pci_driver);
}

module_init(r852_module_init);
module_exit(r852_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Maxim Levitsky <maximlevitsky@gmail.com>");
MODULE_DESCRIPTION("Ricoh 85xx xD/smartmedia card reader driver");