/*
 *  drivers/mtd/nand/au1550nd.c
 *
 *  Copyright (C) 2004 Embedded Edge, LLC
 *
 * 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/gpio.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
#include <linux/platform_device.h>
#include <asm/io.h>
#include <asm/mach-au1x00/au1000.h>
#include <asm/mach-au1x00/au1550nd.h>


struct au1550nd_ctx {
        struct nand_chip chip;

        int cs;
        void __iomem *base;
        void (*write_byte)(struct mtd_info *, u_char);
};

/**
 * au_read_byte -  read one byte from the chip
 * @mtd:        MTD device structure
 *
 * read function for 8bit buswidth
 */
static u_char au_read_byte(struct mtd_info *mtd)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        u_char ret = readb(this->IO_ADDR_R);
        wmb(); /* drain writebuffer */
        return ret;
}

/**
 * au_write_byte -  write one byte to the chip
 * @mtd:        MTD device structure
 * @byte:       pointer to data byte to write
 *
 * write function for 8it buswidth
 */
static void au_write_byte(struct mtd_info *mtd, u_char byte)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        writeb(byte, this->IO_ADDR_W);
        wmb(); /* drain writebuffer */
}

/**
 * au_read_byte16 -  read one byte endianness aware from the chip
 * @mtd:        MTD device structure
 *
 * read function for 16bit buswidth with endianness conversion
 */
static u_char au_read_byte16(struct mtd_info *mtd)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        u_char ret = (u_char) cpu_to_le16(readw(this->IO_ADDR_R));
        wmb(); /* drain writebuffer */
        return ret;
}

/**
 * au_write_byte16 -  write one byte endianness aware to the chip
 * @mtd:        MTD device structure
 * @byte:       pointer to data byte to write
 *
 * write function for 16bit buswidth with endianness conversion
 */
static void au_write_byte16(struct mtd_info *mtd, u_char byte)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        writew(le16_to_cpu((u16) byte), this->IO_ADDR_W);
        wmb(); /* drain writebuffer */
}

/**
 * au_read_word -  read one word from the chip
 * @mtd:        MTD device structure
 *
 * read function for 16bit buswidth without endianness conversion
 */
static u16 au_read_word(struct mtd_info *mtd)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        u16 ret = readw(this->IO_ADDR_R);
        wmb(); /* drain writebuffer */
        return ret;
}

/**
 * au_write_buf -  write buffer to chip
 * @mtd:        MTD device structure
 * @buf:        data buffer
 * @len:        number of bytes to write
 *
 * write function for 8bit buswidth
 */
static void au_write_buf(struct mtd_info *mtd, const u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd_to_nand(mtd);

        for (i = 0; i < len; i++) {
                writeb(buf[i], this->IO_ADDR_W);
                wmb(); /* drain writebuffer */
        }
}

/**
 * au_read_buf -  read chip data into buffer
 * @mtd:        MTD device structure
 * @buf:        buffer to store date
 * @len:        number of bytes to read
 *
 * read function for 8bit buswidth
 */
static void au_read_buf(struct mtd_info *mtd, u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd_to_nand(mtd);

        for (i = 0; i < len; i++) {
                buf[i] = readb(this->IO_ADDR_R);
                wmb(); /* drain writebuffer */
        }
}

/**
 * au_write_buf16 -  write buffer to chip
 * @mtd:        MTD device structure
 * @buf:        data buffer
 * @len:        number of bytes to write
 *
 * write function for 16bit buswidth
 */
static void au_write_buf16(struct mtd_info *mtd, const u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd_to_nand(mtd);
        u16 *p = (u16 *) buf;
        len >>= 1;

        for (i = 0; i < len; i++) {
                writew(p[i], this->IO_ADDR_W);
                wmb(); /* drain writebuffer */
        }

}

/**
 * au_read_buf16 -  read chip data into buffer
 * @mtd:        MTD device structure
 * @buf:        buffer to store date
 * @len:        number of bytes to read
 *
 * read function for 16bit buswidth
 */
static void au_read_buf16(struct mtd_info *mtd, u_char *buf, int len)
{
        int i;
        struct nand_chip *this = mtd_to_nand(mtd);
        u16 *p = (u16 *) buf;
        len >>= 1;

        for (i = 0; i < len; i++) {
                p[i] = readw(this->IO_ADDR_R);
                wmb(); /* drain writebuffer */
        }
}

/* Select the chip by setting nCE to low */
#define NAND_CTL_SETNCE         1
/* Deselect the chip by setting nCE to high */
#define NAND_CTL_CLRNCE         2
/* Select the command latch by setting CLE to high */
#define NAND_CTL_SETCLE         3
/* Deselect the command latch by setting CLE to low */
#define NAND_CTL_CLRCLE         4
/* Select the address latch by setting ALE to high */
#define NAND_CTL_SETALE         5
/* Deselect the address latch by setting ALE to low */
#define NAND_CTL_CLRALE         6

static void au1550_hwcontrol(struct mtd_info *mtd, int cmd)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        struct au1550nd_ctx *ctx = container_of(this, struct au1550nd_ctx,
                                                chip);

        switch (cmd) {

        case NAND_CTL_SETCLE:
                this->IO_ADDR_W = ctx->base + MEM_STNAND_CMD;
                break;

        case NAND_CTL_CLRCLE:
                this->IO_ADDR_W = ctx->base + MEM_STNAND_DATA;
                break;

        case NAND_CTL_SETALE:
                this->IO_ADDR_W = ctx->base + MEM_STNAND_ADDR;
                break;

        case NAND_CTL_CLRALE:
                this->IO_ADDR_W = ctx->base + MEM_STNAND_DATA;
                /* FIXME: Nobody knows why this is necessary,
                 * but it works only that way */
                udelay(1);
                break;

        case NAND_CTL_SETNCE:
                /* assert (force assert) chip enable */
                alchemy_wrsmem((1 << (4 + ctx->cs)), AU1000_MEM_STNDCTL);
                break;

        case NAND_CTL_CLRNCE:
                /* deassert chip enable */
                alchemy_wrsmem(0, AU1000_MEM_STNDCTL);
                break;
        }

        this->IO_ADDR_R = this->IO_ADDR_W;

        wmb(); /* Drain the writebuffer */
}

int au1550_device_ready(struct mtd_info *mtd)
{
        return (alchemy_rdsmem(AU1000_MEM_STSTAT) & 0x1) ? 1 : 0;
}

/**
 * au1550_select_chip - control -CE line
 *      Forbid driving -CE manually permitting the NAND controller to do this.
 *      Keeping -CE asserted during the whole sector reads interferes with the
 *      NOR flash and PCMCIA drivers as it causes contention on the static bus.
 *      We only have to hold -CE low for the NAND read commands since the flash
 *      chip needs it to be asserted during chip not ready time but the NAND
 *      controller keeps it released.
 *
 * @mtd:        MTD device structure
 * @chip:       chipnumber to select, -1 for deselect
 */
static void au1550_select_chip(struct mtd_info *mtd, int chip)
{
}

/**
 * au1550_command - Send command to NAND device
 * @mtd:        MTD device structure
 * @command:    the command to be sent
 * @column:     the column address for this command, -1 if none
 * @page_addr:  the page address for this command, -1 if none
 */
static void au1550_command(struct mtd_info *mtd, unsigned command, int column, int page_addr)
{
        struct nand_chip *this = mtd_to_nand(mtd);
        struct au1550nd_ctx *ctx = container_of(this, struct au1550nd_ctx,
                                                chip);
        int ce_override = 0, i;
        unsigned long flags = 0;

        /* Begin command latch cycle */
        au1550_hwcontrol(mtd, NAND_CTL_SETCLE);
        /*
         * Write out the command to the device.
         */
        if (command == NAND_CMD_SEQIN) {
                int readcmd;

                if (column >= mtd->writesize) {
                        /* OOB area */
                        column -= mtd->writesize;
                        readcmd = NAND_CMD_READOOB;
                } else if (column < 256) {
                        /* First 256 bytes --> READ0 */
                        readcmd = NAND_CMD_READ0;
                } else {
                        column -= 256;
                        readcmd = NAND_CMD_READ1;
                }
                ctx->write_byte(mtd, readcmd);
        }
        ctx->write_byte(mtd, command);

        /* Set ALE and clear CLE to start address cycle */
        au1550_hwcontrol(mtd, NAND_CTL_CLRCLE);

        if (column != -1 || page_addr != -1) {
                au1550_hwcontrol(mtd, NAND_CTL_SETALE);

                /* Serially input address */
                if (column != -1) {
                        /* Adjust columns for 16 bit buswidth */
                        if (this->options & NAND_BUSWIDTH_16 &&
                                        !nand_opcode_8bits(command))
                                column >>= 1;
                        ctx->write_byte(mtd, column);
                }
                if (page_addr != -1) {
                        ctx->write_byte(mtd, (u8)(page_addr & 0xff));

                        if (command == NAND_CMD_READ0 ||
                            command == NAND_CMD_READ1 ||
                            command == NAND_CMD_READOOB) {
                                /*
                                 * NAND controller will release -CE after
                                 * the last address byte is written, so we'll
                                 * have to forcibly assert it. No interrupts
                                 * are allowed while we do this as we don't
                                 * want the NOR flash or PCMCIA drivers to
                                 * steal our precious bytes of data...
                                 */
                                ce_override = 1;
                                local_irq_save(flags);
                                au1550_hwcontrol(mtd, NAND_CTL_SETNCE);
                        }

                        ctx->write_byte(mtd, (u8)(page_addr >> 8));

                        /* One more address cycle for devices > 32MiB */
                        if (this->chipsize > (32 << 20))
                                ctx->write_byte(mtd,
                                                ((page_addr >> 16) & 0x0f));
                }
                /* Latch in address */
                au1550_hwcontrol(mtd, NAND_CTL_CLRALE);
        }

        /*
         * Program and erase have their own busy handlers.
         * Status and sequential in need no delay.
         */
        switch (command) {

        case NAND_CMD_PAGEPROG:
        case NAND_CMD_ERASE1:
        case NAND_CMD_ERASE2:
        case NAND_CMD_SEQIN:
        case NAND_CMD_STATUS:
                return;

        case NAND_CMD_RESET:
                break;

        case NAND_CMD_READ0:
        case NAND_CMD_READ1:
        case NAND_CMD_READOOB:
                /* Check if we're really driving -CE low (just in case) */
                if (unlikely(!ce_override))
                        break;

                /* Apply a short delay always to ensure that we do wait tWB. */
                ndelay(100);
                /* Wait for a chip to become ready... */
                for (i = this->chip_delay; !this->dev_ready(mtd) && i > 0; --i)
                        udelay(1);

                /* Release -CE and re-enable interrupts. */
                au1550_hwcontrol(mtd, NAND_CTL_CLRNCE);
                local_irq_restore(flags);
                return;
        }
        /* Apply this short delay always to ensure that we do wait tWB. */
        ndelay(100);

        while(!this->dev_ready(mtd));
}

static int find_nand_cs(unsigned long nand_base)
{
        void __iomem *base =
                        (void __iomem *)KSEG1ADDR(AU1000_STATIC_MEM_PHYS_ADDR);
        unsigned long addr, staddr, start, mask, end;
        int i;

        for (i = 0; i < 4; i++) {
                addr = 0x1000 + (i * 0x10);                     /* CSx */
                staddr = __raw_readl(base + addr + 0x08);       /* STADDRx */
                /* figure out the decoded range of this CS */
                start = (staddr << 4) & 0xfffc0000;
                mask = (staddr << 18) & 0xfffc0000;
                end = (start | (start - 1)) & ~(start ^ mask);
                if ((nand_base >= start) && (nand_base < end))
                        return i;
        }

        return -ENODEV;
}

static int au1550nd_probe(struct platform_device *pdev)
{
        struct au1550nd_platdata *pd;
        struct au1550nd_ctx *ctx;
        struct nand_chip *this;
        struct mtd_info *mtd;
        struct resource *r;
        int ret, cs;

        pd = dev_get_platdata(&pdev->dev);
        if (!pd) {
                dev_err(&pdev->dev, "missing platform data\n");
                return -ENODEV;
        }

        ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!r) {
                dev_err(&pdev->dev, "no NAND memory resource\n");
                ret = -ENODEV;
                goto out1;
        }
        if (request_mem_region(r->start, resource_size(r), "au1550-nand")) {
                dev_err(&pdev->dev, "cannot claim NAND memory area\n");
                ret = -ENOMEM;
                goto out1;
        }

        ctx->base = ioremap_nocache(r->start, 0x1000);
        if (!ctx->base) {
                dev_err(&pdev->dev, "cannot remap NAND memory area\n");
                ret = -ENODEV;
                goto out2;
        }

        this = &ctx->chip;
        mtd = nand_to_mtd(this);
        mtd->dev.parent = &pdev->dev;

        /* figure out which CS# r->start belongs to */
        cs = find_nand_cs(r->start);
        if (cs < 0) {
                dev_err(&pdev->dev, "cannot detect NAND chipselect\n");
                ret = -ENODEV;
                goto out3;
        }
        ctx->cs = cs;

        this->dev_ready = au1550_device_ready;
        this->select_chip = au1550_select_chip;
        this->cmdfunc = au1550_command;

        /* 30 us command delay time */
        this->chip_delay = 30;
        this->ecc.mode = NAND_ECC_SOFT;
        this->ecc.algo = NAND_ECC_HAMMING;

        if (pd->devwidth)
                this->options |= NAND_BUSWIDTH_16;

        this->read_byte = (pd->devwidth) ? au_read_byte16 : au_read_byte;
        ctx->write_byte = (pd->devwidth) ? au_write_byte16 : au_write_byte;
        this->read_word = au_read_word;
        this->write_buf = (pd->devwidth) ? au_write_buf16 : au_write_buf;
        this->read_buf = (pd->devwidth) ? au_read_buf16 : au_read_buf;

        ret = nand_scan(mtd, 1);
        if (ret) {
                dev_err(&pdev->dev, "NAND scan failed with %d\n", ret);
                goto out3;
        }

        mtd_device_register(mtd, pd->parts, pd->num_parts);

        platform_set_drvdata(pdev, ctx);

        return 0;

out3:
        iounmap(ctx->base);
out2:
        release_mem_region(r->start, resource_size(r));
out1:
        kfree(ctx);
        return ret;
}

static int au1550nd_remove(struct platform_device *pdev)
{
        struct au1550nd_ctx *ctx = platform_get_drvdata(pdev);
        struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        nand_release(nand_to_mtd(&ctx->chip));
        iounmap(ctx->base);
        release_mem_region(r->start, 0x1000);
        kfree(ctx);
        return 0;
}

static struct platform_driver au1550nd_driver = {
        .driver = {
                .name   = "au1550-nand",
        },
        .probe          = au1550nd_probe,
        .remove         = au1550nd_remove,
};

module_platform_driver(au1550nd_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Embedded Edge, LLC");
MODULE_DESCRIPTION("Board-specific glue layer for NAND flash on Pb1550 board");