socrates_nand.c

Go to the documentation of this file.

/*
 * drivers/mtd/nand/socrates_nand.c
 *
 *  Copyright © 2008 Ilya Yanok, Emcraft Systems
 *
 *
 * 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/slab.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
#include <linux/of_platform.h>
#include <linux/io.h>

#define FPGA_NAND_CMD_MASK      (0x7 << 28)
#define FPGA_NAND_CMD_COMMAND       (0x0 << 28)
#define FPGA_NAND_CMD_ADDR      (0x1 << 28)
#define FPGA_NAND_CMD_READ      (0x2 << 28)
#define FPGA_NAND_CMD_WRITE     (0x3 << 28)
#define FPGA_NAND_BUSY          (0x1 << 15)
#define FPGA_NAND_ENABLE        (0x1 << 31)
#define FPGA_NAND_DATA_SHIFT        16

struct socrates_nand_host {
    struct nand_chip    nand_chip;
    struct mtd_info     mtd;
    void __iomem        *io_base;
    struct device       *dev;
};

static void socrates_nand_write_buf(struct mtd_info *mtd,
        const uint8_t *buf, int len)
{
    int i;
    struct nand_chip *this = mtd->priv;
    struct socrates_nand_host *host = this->priv;

    for (i = 0; i < len; i++) {
        out_be32(host->io_base, FPGA_NAND_ENABLE |
                FPGA_NAND_CMD_WRITE |
                (buf[i] << FPGA_NAND_DATA_SHIFT));
    }
}

static void socrates_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
    int i;
    struct nand_chip *this = mtd->priv;
    struct socrates_nand_host *host = this->priv;
    uint32_t val;

    val = FPGA_NAND_ENABLE | FPGA_NAND_CMD_READ;

    out_be32(host->io_base, val);
    for (i = 0; i < len; i++) {
        buf[i] = (in_be32(host->io_base) >>
                FPGA_NAND_DATA_SHIFT) & 0xff;
    }
}

static uint8_t socrates_nand_read_byte(struct mtd_info *mtd)
{
    uint8_t byte;
    socrates_nand_read_buf(mtd, &byte, sizeof(byte));
    return byte;
}

static uint16_t socrates_nand_read_word(struct mtd_info *mtd)
{
    uint16_t word;
    socrates_nand_read_buf(mtd, (uint8_t *)&word, sizeof(word));
    return word;
}

/*
 * Hardware specific access to control-lines
 */
static void socrates_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
        unsigned int ctrl)
{
    struct nand_chip *nand_chip = mtd->priv;
    struct socrates_nand_host *host = nand_chip->priv;
    uint32_t val;

    if (cmd == NAND_CMD_NONE)
        return;

    if (ctrl & NAND_CLE)
        val = FPGA_NAND_CMD_COMMAND;
    else
        val = FPGA_NAND_CMD_ADDR;

    if (ctrl & NAND_NCE)
        val |= FPGA_NAND_ENABLE;

    val |= (cmd & 0xff) << FPGA_NAND_DATA_SHIFT;

    out_be32(host->io_base, val);
}

/*
 * Read the Device Ready pin.
 */
static int socrates_nand_device_ready(struct mtd_info *mtd)
{
    struct nand_chip *nand_chip = mtd->priv;
    struct socrates_nand_host *host = nand_chip->priv;

    if (in_be32(host->io_base) & FPGA_NAND_BUSY)
        return 0; /* busy */
    return 1;
}

/*
 * Probe for the NAND device.
 */
static int __devinit socrates_nand_probe(struct platform_device *ofdev)
{
    struct socrates_nand_host *host;
    struct mtd_info *mtd;
    struct nand_chip *nand_chip;
    int res;
    struct mtd_part_parser_data ppdata;

    /* Allocate memory for the device structure (and zero it) */
    host = kzalloc(sizeof(struct socrates_nand_host), GFP_KERNEL);
    if (!host) {
        printk(KERN_ERR
               "socrates_nand: failed to allocate device structure.\n");
        return -ENOMEM;
    }

    host->io_base = of_iomap(ofdev->dev.of_node, 0);
    if (host->io_base == NULL) {
        printk(KERN_ERR "socrates_nand: ioremap failed\n");
        kfree(host);
        return -EIO;
    }

    mtd = &host->mtd;
    nand_chip = &host->nand_chip;
    host->dev = &ofdev->dev;

    nand_chip->priv = host;     /* link the private data structures */
    mtd->priv = nand_chip;
    mtd->name = "socrates_nand";
    mtd->owner = THIS_MODULE;
    mtd->dev.parent = &ofdev->dev;
    ppdata.of_node = ofdev->dev.of_node;

    /*should never be accessed directly */
    nand_chip->IO_ADDR_R = (void *)0xdeadbeef;
    nand_chip->IO_ADDR_W = (void *)0xdeadbeef;

    nand_chip->cmd_ctrl = socrates_nand_cmd_ctrl;
    nand_chip->read_byte = socrates_nand_read_byte;
    nand_chip->read_word = socrates_nand_read_word;
    nand_chip->write_buf = socrates_nand_write_buf;
    nand_chip->read_buf = socrates_nand_read_buf;
    nand_chip->dev_ready = socrates_nand_device_ready;

    nand_chip->ecc.mode = NAND_ECC_SOFT;    /* enable ECC */

    /* TODO: I have no idea what real delay is. */
    nand_chip->chip_delay = 20;     /* 20us command delay time */

    dev_set_drvdata(&ofdev->dev, host);

    /* first scan to find the device and get the page size */
    if (nand_scan_ident(mtd, 1, NULL)) {
        res = -ENXIO;
        goto out;
    }

    /* second phase scan */
    if (nand_scan_tail(mtd)) {
        res = -ENXIO;
        goto out;
    }

    res = mtd_device_parse_register(mtd, NULL, &ppdata, NULL, 0);
    if (!res)
        return res;

    nand_release(mtd);

out:
    dev_set_drvdata(&ofdev->dev, NULL);
    iounmap(host->io_base);
    kfree(host);
    return res;
}

/*
 * Remove a NAND device.
 */
static int __devexit socrates_nand_remove(struct platform_device *ofdev)
{
    struct socrates_nand_host *host = dev_get_drvdata(&ofdev->dev);
    struct mtd_info *mtd = &host->mtd;

    nand_release(mtd);

    dev_set_drvdata(&ofdev->dev, NULL);
    iounmap(host->io_base);
    kfree(host);

    return 0;
}

static const struct of_device_id socrates_nand_match[] =
{
    {
        .compatible   = "abb,socrates-nand",
    },
    {},
};

MODULE_DEVICE_TABLE(of, socrates_nand_match);

static struct platform_driver socrates_nand_driver = {
    .driver = {
        .name = "socrates_nand",
        .owner = THIS_MODULE,
        .of_match_table = socrates_nand_match,
    },
    .probe      = socrates_nand_probe,
    .remove     = __devexit_p(socrates_nand_remove),
};

module_platform_driver(socrates_nand_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ilya Yanok");
MODULE_DESCRIPTION("NAND driver for Socrates board");