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/*

 * Atmel AT45xxx DataFlash MTD driver for lightweight SPI framework

 *

 * Largely derived from at91_dataflash.c:

 *  Copyright (C) 2003-2005 SAN People (Pty) Ltd

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

*/

#include <linux/module.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/delay.h>

#include <linux/device.h>

#include <linux/mutex.h>

#include <linux/spi/spi.h>

#include <linux/spi/flash.h>

#include <linux/mtd/mtd.h>

#include <linux/mtd/partitions.h>

/*

 * DataFlash is a kind of SPI flash.  Most AT45 chips have two buffers in

 * each chip, which may be used for double buffered I/O; but this driver

 * doesn't (yet) use these for any kind of i/o overlap or prefetching.

 *

 * Sometimes DataFlash is packaged in MMC-format cards, although the

 * MMC stack can't use SPI (yet), or distinguish between MMC and DataFlash

 * protocols during enumeration.

 */

#define CONFIG_DATAFLASH_WRITE_VERIFY

/* reads can bypass the buffers */

#define OP_READ_CONTINUOUS      0xE8

#define OP_READ_PAGE            0xD2

/* group B requests can run even while status reports "busy" */

#define OP_READ_STATUS          0xD7    /* group B */

/* move data between host and buffer */

#define OP_READ_BUFFER1         0xD4    /* group B */

#define OP_READ_BUFFER2         0xD6    /* group B */

#define OP_WRITE_BUFFER1        0x84    /* group B */

#define OP_WRITE_BUFFER2        0x87    /* group B */

/* erasing flash */

#define OP_ERASE_PAGE           0x81

#define OP_ERASE_BLOCK          0x50

/* move data between buffer and flash */

#define OP_TRANSFER_BUF1        0x53

#define OP_TRANSFER_BUF2        0x55

#define OP_MREAD_BUFFER1        0xD4

#define OP_MREAD_BUFFER2        0xD6

#define OP_MWERASE_BUFFER1      0x83

#define OP_MWERASE_BUFFER2      0x86

#define OP_MWRITE_BUFFER1       0x88    /* sector must be pre-erased */

#define OP_MWRITE_BUFFER2       0x89    /* sector must be pre-erased */

/* write to buffer, then write-erase to flash */

#define OP_PROGRAM_VIA_BUF1     0x82

#define OP_PROGRAM_VIA_BUF2     0x85

/* compare buffer to flash */

#define OP_COMPARE_BUF1         0x60

#define OP_COMPARE_BUF2         0x61

/* read flash to buffer, then write-erase to flash */

#define OP_REWRITE_VIA_BUF1     0x58

#define OP_REWRITE_VIA_BUF2     0x59

/* newer chips report JEDEC manufacturer and device IDs; chip

 * serial number and OTP bits; and per-sector writeprotect.

 */

#define OP_READ_ID              0x9F

#define OP_READ_SECURITY        0x77

#define OP_WRITE_SECURITY       0x9A    /* OTP bits */

struct dataflash {

        u8                      command[4];

        char                    name[24];

        unsigned                partitioned:1;

        unsigned short          page_offset;    /* offset in flash address */

        unsigned int            page_size;      /* of bytes per page */

        struct mutex            lock;

        struct spi_device       *spi;

        struct mtd_info         mtd;

};

#ifdef CONFIG_MTD_PARTITIONS

#define mtd_has_partitions()    (1)

#else

#define mtd_has_partitions()    (0)

#endif

/* ......................................................................... */

/*

 * Return the status of the DataFlash device.

 */

static inline int dataflash_status(struct spi_device *spi)

{

        /* NOTE:  at45db321c over 25 MHz wants to write

         * a dummy byte after the opcode...

         */

        return spi_w8r8(spi, OP_READ_STATUS);

}

/*

 * Poll the DataFlash device until it is READY.

 * This usually takes 5-20 msec or so; more for sector erase.

 */

static int dataflash_waitready(struct spi_device *spi)

{

        int     status;

        for (;;) {

                status = dataflash_status(spi);

                if (status < 0) {

                        DEBUG(MTD_DEBUG_LEVEL1, "%s: status %d?\n",

                                        spi->dev.bus_id, status);

                        status = 0;

                }

                if (status & (1 << 7))  /* RDY/nBSY */

                        return status;

                msleep(3);

        }

}

/* ......................................................................... */

/*

 * Erase pages of flash.

 */

static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)

{

        struct dataflash        *priv = (struct dataflash *)mtd->priv;

        struct spi_device       *spi = priv->spi;

        struct spi_transfer     x = { .tx_dma = 0, };

        struct spi_message      msg;

        unsigned                blocksize = priv->page_size << 3;

        u8                      *command;

        DEBUG(MTD_DEBUG_LEVEL2, "%s: erase addr=0x%x len 0x%x\n",

                        spi->dev.bus_id,

                        instr->addr, instr->len);

        /* Sanity checks */

        if ((instr->addr + instr->len) > mtd->size

                        || (instr->len % priv->page_size) != 0

                        || (instr->addr % priv->page_size) != 0)

                return -EINVAL;

        spi_message_init(&msg);

        x.tx_buf = command = priv->command;

        x.len = 4;

        spi_message_add_tail(&x, &msg);

        mutex_lock(&priv->lock);

        while (instr->len > 0) {

                unsigned int    pageaddr;

                int             status;

                int             do_block;

                /* Calculate flash page address; use block erase (for speed) if

                 * we're at a block boundary and need to erase the whole block.

                 */

                pageaddr = instr->addr / priv->page_size;

                do_block = (pageaddr & 0x7) == 0 && instr->len >= blocksize;

                pageaddr = pageaddr << priv->page_offset;

                command[0] = do_block ? OP_ERASE_BLOCK : OP_ERASE_PAGE;

                command[1] = (u8)(pageaddr >> 16);

                command[2] = (u8)(pageaddr >> 8);

                command[3] = 0;

                DEBUG(MTD_DEBUG_LEVEL3, "ERASE %s: (%x) %x %x %x [%i]\n",

                        do_block ? "block" : "page",

                        command[0], command[1], command[2], command[3],

                        pageaddr);

                status = spi_sync(spi, &msg);

                (void) dataflash_waitready(spi);

                if (status < 0) {

                        printk(KERN_ERR "%s: erase %x, err %d\n",

                                spi->dev.bus_id, pageaddr, status);

                        /* REVISIT:  can retry instr->retries times; or

                         * giveup and instr->fail_addr = instr->addr;

                         */

                        continue;

                }

                if (do_block) {

                        instr->addr += blocksize;

                        instr->len -= blocksize;

                } else {

                        instr->addr += priv->page_size;

                        instr->len -= priv->page_size;

                }

        }

        mutex_unlock(&priv->lock);

        /* Inform MTD subsystem that erase is complete */

        instr->state = MTD_ERASE_DONE;

        mtd_erase_callback(instr);

        return 0;

}

/*

 * Read from the DataFlash device.

 *   from   : Start offset in flash device

 *   len    : Amount to read

 *   retlen : About of data actually read

 *   buf    : Buffer containing the data

 */

static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,

                               size_t *retlen, u_char *buf)

{

        struct dataflash        *priv = (struct dataflash *)mtd->priv;

        struct spi_transfer     x[2] = { { .tx_dma = 0, }, };

        struct spi_message      msg;

        unsigned int            addr;

        u8                      *command;

        int                     status;

        DEBUG(MTD_DEBUG_LEVEL2, "%s: read 0x%x..0x%x\n",

                priv->spi->dev.bus_id, (unsigned)from, (unsigned)(from + len));

        *retlen = 0;

        /* Sanity checks */

        if (!len)

                return 0;

        if (from + len > mtd->size)

                return -EINVAL;

        /* Calculate flash page/byte address */

        addr = (((unsigned)from / priv->page_size) << priv->page_offset)

                + ((unsigned)from % priv->page_size);

        command = priv->command;

        DEBUG(MTD_DEBUG_LEVEL3, "READ: (%x) %x %x %x\n",

                command[0], command[1], command[2], command[3]);

        spi_message_init(&msg);

        x[0].tx_buf = command;

        x[0].len = 8;

        spi_message_add_tail(&x[0], &msg);

        x[1].rx_buf = buf;

        x[1].len = len;

        spi_message_add_tail(&x[1], &msg);

        mutex_lock(&priv->lock);

        /* Continuous read, max clock = f(car) which may be less than

         * the peak rate available.  Some chips support commands with

         * fewer "don't care" bytes.  Both buffers stay unchanged.

         */

        command[0] = OP_READ_CONTINUOUS;

        command[1] = (u8)(addr >> 16);

        command[2] = (u8)(addr >> 8);

        command[3] = (u8)(addr >> 0);

        /* plus 4 "don't care" bytes */

        status = spi_sync(priv->spi, &msg);

        mutex_unlock(&priv->lock);

        if (status >= 0) {

                *retlen = msg.actual_length - 8;

                status = 0;

        } else

                DEBUG(MTD_DEBUG_LEVEL1, "%s: read %x..%x --> %d\n",

                        priv->spi->dev.bus_id,

                        (unsigned)from, (unsigned)(from + len),

                        status);

        return status;

}

/*

 * Write to the DataFlash device.

 *   to     : Start offset in flash device

 *   len    : Amount to write

 *   retlen : Amount of data actually written

 *   buf    : Buffer containing the data

 */

static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,

                                size_t * retlen, const u_char * buf)

{

        struct dataflash        *priv = (struct dataflash *)mtd->priv;

        struct spi_device       *spi = priv->spi;

        struct spi_transfer     x[2] = { { .tx_dma = 0, }, };

        struct spi_message      msg;

        unsigned int            pageaddr, addr, offset, writelen;

        size_t                  remaining = len;

        u_char                  *writebuf = (u_char *) buf;

        int                     status = -EINVAL;

        u8                      *command;

        DEBUG(MTD_DEBUG_LEVEL2, "%s: write 0x%x..0x%x\n",

                spi->dev.bus_id, (unsigned)to, (unsigned)(to + len));

        *retlen = 0;

        /* Sanity checks */

        if (!len)

                return 0;

        if ((to + len) > mtd->size)

                return -EINVAL;

        spi_message_init(&msg);

        x[0].tx_buf = command = priv->command;

        x[0].len = 4;

        spi_message_add_tail(&x[0], &msg);

        pageaddr = ((unsigned)to / priv->page_size);

        offset = ((unsigned)to % priv->page_size);

        if (offset + len > priv->page_size)

                writelen = priv->page_size - offset;

        else

                writelen = len;

        mutex_lock(&priv->lock);

        while (remaining > 0) {

                DEBUG(MTD_DEBUG_LEVEL3, "write @ %i:%i len=%i\n",

                        pageaddr, offset, writelen);

                /* REVISIT:

                 * (a) each page in a sector must be rewritten at least

                 *     once every 10K sibling erase/program operations.

                 * (b) for pages that are already erased, we could

                 *     use WRITE+MWRITE not PROGRAM for ~30% speedup.

                 * (c) WRITE to buffer could be done while waiting for

                 *     a previous MWRITE/MWERASE to complete ...

                 * (d) error handling here seems to be mostly missing.

                 *

                 * Two persistent bits per page, plus a per-sector counter,

                 * could support (a) and (b) ... we might consider using

                 * the second half of sector zero, which is just one block,

                 * to track that state.  (On AT91, that sector should also

                 * support boot-from-DataFlash.)

                 */

                addr = pageaddr << priv->page_offset;

                /* (1) Maybe transfer partial page to Buffer1 */

                if (writelen != priv->page_size) {

                        command[0] = OP_TRANSFER_BUF1;

                        command[1] = (addr & 0x00FF0000) >> 16;

                        command[2] = (addr & 0x0000FF00) >> 8;

                        command[3] = 0;

                        DEBUG(MTD_DEBUG_LEVEL3, "TRANSFER: (%x) %x %x %x\n",

                                command[0], command[1], command[2], command[3]);

                        status = spi_sync(spi, &msg);

                        if (status < 0)

                                DEBUG(MTD_DEBUG_LEVEL1, "%s: xfer %u -> %d \n",

                                        spi->dev.bus_id, addr, status);

                        (void) dataflash_waitready(priv->spi);

                }

                /* (2) Program full page via Buffer1 */

                addr += offset;

                command[0] = OP_PROGRAM_VIA_BUF1;

                command[1] = (addr & 0x00FF0000) >> 16;

                command[2] = (addr & 0x0000FF00) >> 8;

                command[3] = (addr & 0x000000FF);

                DEBUG(MTD_DEBUG_LEVEL3, "PROGRAM: (%x) %x %x %x\n",

                        command[0], command[1], command[2], command[3]);

                x[1].tx_buf = writebuf;

                x[1].len = writelen;

                spi_message_add_tail(x + 1, &msg);

                status = spi_sync(spi, &msg);

                spi_transfer_del(x + 1);

                if (status < 0)

                        DEBUG(MTD_DEBUG_LEVEL1, "%s: pgm %u/%u -> %d \n",

                                spi->dev.bus_id, addr, writelen, status);

                (void) dataflash_waitready(priv->spi);

#ifdef  CONFIG_DATAFLASH_WRITE_VERIFY

                /* (3) Compare to Buffer1 */

                addr = pageaddr << priv->page_offset;

                command[0] = OP_COMPARE_BUF1;

                command[1] = (addr & 0x00FF0000) >> 16;

                command[2] = (addr & 0x0000FF00) >> 8;

                command[3] = 0;

                DEBUG(MTD_DEBUG_LEVEL3, "COMPARE: (%x) %x %x %x\n",

                        command[0], command[1], command[2], command[3]);

                status = spi_sync(spi, &msg);

                if (status < 0)

                        DEBUG(MTD_DEBUG_LEVEL1, "%s: compare %u -> %d \n",

                                spi->dev.bus_id, addr, status);

                status = dataflash_waitready(priv->spi);

                /* Check result of the compare operation */

                if ((status & (1 << 6)) == 1) {

                        printk(KERN_ERR "%s: compare page %u, err %d\n",

                                spi->dev.bus_id, pageaddr, status);

                        remaining = 0;

                        status = -EIO;

                        break;

                } else

                        status = 0;

#endif  /* CONFIG_DATAFLASH_WRITE_VERIFY */

                remaining = remaining - writelen;

                pageaddr++;

                offset = 0;

                writebuf += writelen;

                *retlen += writelen;

                if (remaining > priv->page_size)

                        writelen = priv->page_size;

                else

                        writelen = remaining;

        }

        mutex_unlock(&priv->lock);

        return status;

}

/* ......................................................................... */

/*

 * Register DataFlash device with MTD subsystem.

 */

static int __devinit

add_dataflash(struct spi_device *spi, char *name,

                int nr_pages, int pagesize, int pageoffset)

{

        struct dataflash                *priv;

        struct mtd_info                 *device;

        struct flash_platform_data      *pdata = spi->dev.platform_data;

        priv = kzalloc(sizeof *priv, GFP_KERNEL);

        if (!priv)

                return -ENOMEM;

        mutex_init(&priv->lock);

        priv->spi = spi;

        priv->page_size = pagesize;

        priv->page_offset = pageoffset;

        /* name must be usable with cmdlinepart */

        sprintf(priv->name, "spi%d.%d-%s",

                        spi->master->bus_num, spi->chip_select,

                        name);

        device = &priv->mtd;

        device->name = (pdata && pdata->name) ? pdata->name : priv->name;

        device->size = nr_pages * pagesize;

        device->erasesize = pagesize;

        device->writesize = pagesize;

        device->owner = THIS_MODULE;

        device->type = MTD_DATAFLASH;

        device->flags = MTD_WRITEABLE;

        device->erase = dataflash_erase;

        device->read = dataflash_read;

        device->write = dataflash_write;

        device->priv = priv;

        dev_info(&spi->dev, "%s (%d KBytes)\n", name, device->size/1024);

        dev_set_drvdata(&spi->dev, priv);

        if (mtd_has_partitions()) {

                struct mtd_partition    *parts;

                int                     nr_parts = 0;

#ifdef CONFIG_MTD_CMDLINE_PARTS

                static const char *part_probes[] = { "cmdlinepart", NULL, };

                nr_parts = parse_mtd_partitions(device, part_probes, &parts, 0);

#endif

                if (nr_parts <= 0 && pdata && pdata->parts) {

                        parts = pdata->parts;

                        nr_parts = pdata->nr_parts;

                }

                if (nr_parts > 0) {

                        priv->partitioned = 1;

                        return add_mtd_partitions(device, parts, nr_parts);

                }

        } else if (pdata && pdata->nr_parts)

                dev_warn(&spi->dev, "ignoring %d default partitions on %s\n",

                                pdata->nr_parts, device->name);

        return add_mtd_device(device) == 1 ? -ENODEV : 0;

}

/*

 * Detect and initialize DataFlash device:

 *

 *   Device      Density         ID code          #Pages PageSize  Offset

 *   AT45DB011B  1Mbit   (128K)  xx0011xx (0x0c)    512    264      9

 *   AT45DB021B  2Mbit   (256K)  xx0101xx (0x14)   1025    264      9

 *   AT45DB041B  4Mbit   (512K)  xx0111xx (0x1c)   2048    264      9

 *   AT45DB081B  8Mbit   (1M)    xx1001xx (0x24)   4096    264      9

 *   AT45DB0161B 16Mbit  (2M)    xx1011xx (0x2c)   4096    528     10

 *   AT45DB0321B 32Mbit  (4M)    xx1101xx (0x34)   8192    528     10

 *   AT45DB0642  64Mbit  (8M)    xx111xxx (0x3c)   8192   1056     11

 *   AT45DB1282  128Mbit (16M)   xx0100xx (0x10)  16384   1056     11

 */

static int __devinit dataflash_probe(struct spi_device *spi)

{

        int status;

        status = dataflash_status(spi);

        if (status <= 0 || status == 0xff) {

                DEBUG(MTD_DEBUG_LEVEL1, "%s: status error %d\n",

                                spi->dev.bus_id, status);

                if (status == 0 || status == 0xff)

                        status = -ENODEV;

                return status;

        }

        /* if there's a device there, assume it's dataflash.

         * board setup should have set spi->max_speed_max to

         * match f(car) for continuous reads, mode 0 or 3.

         */

        switch (status & 0x3c) {

        case 0x0c:      /* 0 0 1 1 x x */

                status = add_dataflash(spi, "AT45DB011B", 512, 264, 9);

                break;

        case 0x14:      /* 0 1 0 1 x x */

                status = add_dataflash(spi, "AT45DB021B", 1025, 264, 9);

                break;

        case 0x1c:      /* 0 1 1 1 x x */

                status = add_dataflash(spi, "AT45DB041x", 2048, 264, 9);

                break;

        case 0x24:      /* 1 0 0 1 x x */

                status = add_dataflash(spi, "AT45DB081B", 4096, 264, 9);

                break;

        case 0x2c:      /* 1 0 1 1 x x */

                status = add_dataflash(spi, "AT45DB161x", 4096, 528, 10);

                break;

        case 0x34:      /* 1 1 0 1 x x */

                status = add_dataflash(spi, "AT45DB321x", 8192, 528, 10);

                break;

        case 0x38:      /* 1 1 1 x x x */

        case 0x3c:

                status = add_dataflash(spi, "AT45DB642x", 8192, 1056, 11);

                break;

        /* obsolete AT45DB1282 not (yet?) supported */

        default:

                DEBUG(MTD_DEBUG_LEVEL1, "%s: unsupported device (%x)\n",

                                spi->dev.bus_id, status & 0x3c);

                status = -ENODEV;

        }

        if (status < 0)

                DEBUG(MTD_DEBUG_LEVEL1, "%s: add_dataflash --> %d\n",

                                spi->dev.bus_id, status);

        return status;

}

static int __devexit dataflash_remove(struct spi_device *spi)

{

        struct dataflash        *flash = dev_get_drvdata(&spi->dev);

        int                     status;

        DEBUG(MTD_DEBUG_LEVEL1, "%s: remove\n", spi->dev.bus_id);

        if (mtd_has_partitions() && flash->partitioned)

                status = del_mtd_partitions(&flash->mtd);

        else

                status = del_mtd_device(&flash->mtd);

        if (status == 0)

                kfree(flash);

        return status;

}

static struct spi_driver dataflash_driver = {

        .driver = {

                .name           = "mtd_dataflash",

                .bus            = &spi_bus_type,

                .owner          = THIS_MODULE,

        },

        .probe          = dataflash_probe,

        .remove         = __devexit_p(dataflash_remove),

        /* FIXME:  investigate suspend and resume... */

};

static int __init dataflash_init(void)

{

        return spi_register_driver(&dataflash_driver);

}

module_init(dataflash_init);

static void __exit dataflash_exit(void)

{

        spi_unregister_driver(&dataflash_driver);

}

module_exit(dataflash_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Andrew Victor, David Brownell");

MODULE_DESCRIPTION("MTD DataFlash driver");