/*
 * drivers/mtd/nand/cs553x_nand.c
 *
 * (C) 2005, 2006 Red Hat Inc.
 *
 * Author: David Woodhouse <dwmw2@infradead.org>
 *
 * 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.
 *
 *  Overview:
 *   This is a device driver for the NAND flash controller found on 
 *   the AMD CS5535/CS5536 companion chipsets for the Geode processor.
 *
 */

#include <linux/slab.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>

#include <asm/msr.h>
#include <asm/io.h>

#define NR_CS553X_CONTROLLERS	4

/* NAND Timing MSRs */
#define MSR_NANDF_DATA		0x5140001b	/* NAND Flash Data Timing MSR */
#define MSR_NANDF_CTL		0x5140001c	/* NAND Flash Control Timing */
#define MSR_NANDF_RSVD		0x5140001d	/* Reserved */

/* NAND BAR MSRs */
#define MSR_DIVIL_LBAR_FLSH0	0x51400010	/* Flash Chip Select 0 */
#define MSR_DIVIL_LBAR_FLSH1	0x51400011	/* Flash Chip Select 1 */
#define MSR_DIVIL_LBAR_FLSH2	0x51400012	/* Flash Chip Select 2 */
#define MSR_DIVIL_LBAR_FLSH3	0x51400013	/* Flash Chip Select 3 */
	/* Each made up of... */
#define FLSH_LBAR_EN		(1ULL<<32)
#define FLSH_NOR_NAND		(1ULL<<33)	/* 1 for NAND */
#define FLSH_MEM_IO		(1ULL<<34)	/* 1 for MMIO */
	/* I/O BARs have BASE_ADDR in bits 15:4, IO_MASK in 47:36 */
	/* MMIO BARs have BASE_ADDR in bits 31:12, MEM_MASK in 63:44 */

/* Pin function selection MSR (IDE vs. flash on the IDE pins) */
#define MSR_DIVIL_BALL_OPTS	0x51400015
#define PIN_OPT_IDE		(1<<0)		/* 0 for flash, 1 for IDE */

/* Registers within the NAND flash controller BAR -- memory mapped */
#define MM_NAND_DATA		0x00	/* 0 to 0x7ff, in fact */
#define MM_NAND_CTL		0x800	/* Any even address 0x800-0x80e */
#define MM_NAND_IO		0x801	/* Any odd address 0x801-0x80f */
#define MM_NAND_STS		0x810
#define MM_NAND_ECC_LSB		0x811
#define MM_NAND_ECC_MSB		0x812
#define MM_NAND_ECC_COL		0x813
#define MM_NAND_LAC		0x814
#define MM_NAND_ECC_CTL		0x815

/* Registers within the NAND flash controller BAR -- I/O mapped */
#define IO_NAND_DATA		0x00	/* 0 to 3, in fact */
#define IO_NAND_CTL		0x04
#define IO_NAND_IO		0x05
#define IO_NAND_STS		0x06
#define IO_NAND_ECC_CTL		0x08
#define IO_NAND_ECC_LSB		0x09
#define IO_NAND_ECC_MSB		0x0a
#define IO_NAND_ECC_COL		0x0b
#define IO_NAND_LAC		0x0c

#define CS_NAND_CTL_DIST_EN	(1<<4)	/* Enable NAND Distract interrupt */
#define CS_NAND_CTL_RDY_INT_MASK	(1<<3)	/* Enable RDY/BUSY# interrupt */
#define CS_NAND_CTL_ALE		(1<<2)
#define CS_NAND_CTL_CLE		(1<<1)
#define CS_NAND_CTL_CE		(1<<0)	/* Keep low; 1 to reset */

#define CS_NAND_STS_FLASH_RDY	(1<<3)
#define CS_NAND_CTLR_BUSY	(1<<2)
#define CS_NAND_CMD_COMP	(1<<1)
#define CS_NAND_DIST_ST		(1<<0)

#define CS_NAND_ECC_PARITY	(1<<2)
#define CS_NAND_ECC_CLRECC	(1<<1)
#define CS_NAND_ECC_ENECC	(1<<0)

static unsigned char cs553x_read_byte(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd->priv;
	unsigned char foo = readb(this->IO_ADDR_R);
	return foo;
}

static void cs553x_write_byte(struct mtd_info *mtd, u_char byte)
{
	struct nand_chip *this = mtd->priv;
	int i = 100000;

	while (i && readb(this->IO_ADDR_R + MM_NAND_STS) & CS_NAND_CTLR_BUSY) {
		udelay(1);
		i--;
	}
	writeb(byte, this->IO_ADDR_W+0x801);
}

static void cs553x_hwcontrol(struct mtd_info *mtd, int cmd)
{
	struct nand_chip *this = mtd->priv;
	void __iomem *mmio_base = this->IO_ADDR_R;

	uint8_t old = readb(mmio_base + MM_NAND_CTL);

	switch(cmd) {
	case NAND_CTL_SETCLE:
		old |= CS_NAND_CTL_CLE;
		break;

	case NAND_CTL_CLRCLE:
		old &= ~CS_NAND_CTL_CLE;
		break;

	case NAND_CTL_SETALE:
		old |= CS_NAND_CTL_ALE;
		break;

	case NAND_CTL_CLRALE:
		old &= ~CS_NAND_CTL_ALE;
		break;

	case NAND_CTL_SETNCE:
		old &= ~CS_NAND_CTL_CE;
		break;

	case NAND_CTL_CLRNCE:
		old |= CS_NAND_CTL_CE;
		break;
	}
	writeb(old, mmio_base + MM_NAND_CTL);
}


static int cs553x_device_ready(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd->priv;
	void __iomem *mmio_base = this->IO_ADDR_R;
	unsigned char foo = readb(mmio_base + MM_NAND_STS);

	return (foo & CS_NAND_STS_FLASH_RDY) && !(foo & CS_NAND_CTLR_BUSY); 
}

static struct mtd_info *cs553x_mtd[4];

static int __init cs553x_init_one(int cs, int mmio, unsigned long adr)
{
	int err = 0;
	struct nand_chip *this;
	struct mtd_info *new_mtd;

	printk(KERN_NOTICE "Probing CS553x NAND controller CS#%d at %sIO 0x%08lx\n", cs, mmio?"MM":"P", adr);

	if (!mmio) {
		printk(KERN_NOTICE "PIO mode not yet implemented for CS553X NAND controller\n");
		return -ENXIO;
	}

	/* Allocate memory for MTD device structure and private data */
	new_mtd = kmalloc (sizeof(struct mtd_info) + sizeof (struct nand_chip), GFP_KERNEL);
	if (!new_mtd) {
		printk(KERN_WARNING "Unable to allocate CS553X NAND MTD device structure.\n");
		err = -ENOMEM;
		goto out;
	}

	/* Get pointer to private data */
	this = (struct nand_chip *) (&new_mtd[1]);

	/* Initialize structures */
	memset((char *) new_mtd, 0, sizeof(struct mtd_info));
	memset((char *) this, 0, sizeof(struct nand_chip));

	/* Link the private data with the MTD structure */
	new_mtd->priv = this;

	/* map physical address */
	this->IO_ADDR_R = this->IO_ADDR_W = ioremap(adr, 4096);
	if (!this->IO_ADDR_R) {
		printk(KERN_WARNING "ioremap cs553x NAND @0x%08lx failed\n", adr);
		err = -EIO;
		goto out_mtd;
	}

	this->hwcontrol = cs553x_hwcontrol;
	this->dev_ready = cs553x_device_ready;
	this->read_byte = cs553x_read_byte;
	this->write_byte = cs553x_write_byte;

	/* 20 us command delay time */
	this->chip_delay = 20;
	this->eccmode = NAND_ECC_SOFT;

	/* Enable the following for a flash based bad block table */
	//	this->options = NAND_USE_FLASH_BBT;

	/* Scan to find existance of the device */
	if (nand_scan (new_mtd, 1)) {
		err = -ENXIO;
		goto out_ior;
	}

	cs553x_mtd[cs] = new_mtd;
	goto out;

out_ior:
	iounmap((void *)this->IO_ADDR_R);
out_mtd:
	kfree (new_mtd);
out:
	return err;
}

int __init cs553x_init(void)
{
	int err = -ENXIO;
	int i;
	uint64_t val;

	/* Check whether we actually have a CS5535 or CS5536 */
	if (!pci_find_device(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA, NULL) &&
	    !pci_find_device(PCI_VENDOR_ID_NS,  PCI_DEVICE_ID_NS_CS5535_ISA, NULL))
		return -ENXIO;

	rdmsrl(MSR_DIVIL_BALL_OPTS, val);
	if (val & 1) {
		printk(KERN_INFO "CS553x NAND controller: Flash I/O not enabled in MSR_DIVIL_BALL_OPTS.\n");
		return -ENXIO;
	}

	for (i=0; i<NR_CS553X_CONTROLLERS; i++) {
		rdmsrl(MSR_DIVIL_LBAR_FLSH0+i, val);

		if ((val & (FLSH_LBAR_EN|FLSH_NOR_NAND)) == (FLSH_LBAR_EN|FLSH_NOR_NAND))
			err = cs553x_init_one(i, !!(val & FLSH_MEM_IO), val & 0xFFFFFFFF);
	}
	
	/* Register all devices together here. This means we can easily hack it to 
	   do mtdconcat etc. if we want to. */
	for (i=0; i<NR_CS553X_CONTROLLERS; i++) {
		if (cs553x_mtd[i]) {
			add_mtd_device(cs553x_mtd[i]);

			/* If any devices registered, return success. Else the last error. */
			err = 0;
		}
	}

	return err;
}
module_init(cs553x_init);

static void __exit cs553x_cleanup (void)
{
	int i;

	for (i=0; i<NR_CS553X_CONTROLLERS; i++) {
		struct mtd_info *mtd = cs553x_mtd[i];
		struct nand_chip *this;
		void __iomem *mmio_base;

		if (!mtd)
			break;

		this = cs553x_mtd[i]->priv;
		mmio_base = this->IO_ADDR_R;

		/* Release resources, unregister device */
		nand_release (cs553x_mtd[i]);
		cs553x_mtd[i] = NULL;

		/* unmap physical adress */
		iounmap(mmio_base);

		/* Free the MTD device structure */
		kfree (mtd);
	}
}
module_exit(cs553x_cleanup);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("NAND controller driver for AMD CS5535/CS5536 companion chip");