drivers/mtd/nand/raw/cs553x_nand.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * (C) 2005, 2006 Red Hat Inc.
  *
  * Author: David Woodhouse <dwmw2@infradead.org>
  *	   Tom Sylla <tom.sylla@amd.com>
  *
  *  Overview:
  *   This is a device driver for the NAND flash controller found on
  *   the AMD CS5535/CS5536 companion chipsets for the Geode processor.
  *   mtd-id for command line partitioning is cs553x_nand_cs[0-3]
  *   where 0-3 reflects the chip select for NAND.
  */

 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/rawnand.h>
 #include <linux/mtd/partitions.h>
 #include <linux/iopoll.h>

 #include <asm/msr.h>

 #define NR_CS553X_CONTROLLERS	4

 #define MSR_DIVIL_GLD_CAP	0x51400000	/* DIVIL capabilities */
 #define CAP_CS5535		0x2df000ULL
 #define CAP_CS5536		0x5df500ULL

 /* 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)

 struct cs553x_nand_controller {
 	struct nand_controller base;
 	struct nand_chip chip;
 	void __iomem *mmio;
 };

 static struct cs553x_nand_controller *
 to_cs553x(struct nand_controller *controller)
 {
 	return container_of(controller, struct cs553x_nand_controller, base);
 }

 static int cs553x_write_ctrl_byte(struct cs553x_nand_controller *cs553x,
 				  u32 ctl, u8 data)
 {
 	u8 status;

 	writeb(ctl, cs553x->mmio + MM_NAND_CTL);
 	writeb(data, cs553x->mmio + MM_NAND_IO);
 	return readb_poll_timeout_atomic(cs553x->mmio + MM_NAND_STS, status,
 					!(status & CS_NAND_CTLR_BUSY), 1,
 					100000);
 }

 static void cs553x_data_in(struct cs553x_nand_controller *cs553x, void *buf,
 			   unsigned int len)
 {
 	writeb(0, cs553x->mmio + MM_NAND_CTL);
 	while (unlikely(len > 0x800)) {
 		memcpy_fromio(buf, cs553x->mmio, 0x800);
 		buf += 0x800;
 		len -= 0x800;
 	}
 	memcpy_fromio(buf, cs553x->mmio, len);
 }

 static void cs553x_data_out(struct cs553x_nand_controller *cs553x,
 			    const void *buf, unsigned int len)
 {
 	writeb(0, cs553x->mmio + MM_NAND_CTL);
 	while (unlikely(len > 0x800)) {
 		memcpy_toio(cs553x->mmio, buf, 0x800);
 		buf += 0x800;
 		len -= 0x800;
 	}
 	memcpy_toio(cs553x->mmio, buf, len);
 }

 static int cs553x_wait_ready(struct cs553x_nand_controller *cs553x,
 			     unsigned int timeout_ms)
 {
 	u8 mask = CS_NAND_CTLR_BUSY | CS_NAND_STS_FLASH_RDY;
 	u8 status;

 	return readb_poll_timeout(cs553x->mmio + MM_NAND_STS, status,
 				  (status & mask) == CS_NAND_STS_FLASH_RDY, 100,
 				  timeout_ms * 1000);
 }

 static int cs553x_exec_instr(struct cs553x_nand_controller *cs553x,
 			     const struct nand_op_instr *instr)
 {
 	unsigned int i;
 	int ret = 0;

 	switch (instr->type) {
 	case NAND_OP_CMD_INSTR:
 		ret = cs553x_write_ctrl_byte(cs553x, CS_NAND_CTL_CLE,
 					     instr->ctx.cmd.opcode);
 		break;

 	case NAND_OP_ADDR_INSTR:
 		for (i = 0; i < instr->ctx.addr.naddrs; i++) {
 			ret = cs553x_write_ctrl_byte(cs553x, CS_NAND_CTL_ALE,
 						     instr->ctx.addr.addrs[i]);
 			if (ret)
 				break;
 		}
 		break;

 	case NAND_OP_DATA_IN_INSTR:
 		cs553x_data_in(cs553x, instr->ctx.data.buf.in,
 			       instr->ctx.data.len);
 		break;

 	case NAND_OP_DATA_OUT_INSTR:
 		cs553x_data_out(cs553x, instr->ctx.data.buf.out,
 				instr->ctx.data.len);
 		break;

 	case NAND_OP_WAITRDY_INSTR:
 		ret = cs553x_wait_ready(cs553x, instr->ctx.waitrdy.timeout_ms);
 		break;
 	}

 	if (instr->delay_ns)
 		ndelay(instr->delay_ns);

 	return ret;
 }

 static int cs553x_exec_op(struct nand_chip *this,
 			  const struct nand_operation *op,
 			  bool check_only)
 {
 	struct cs553x_nand_controller *cs553x = to_cs553x(this->controller);
 	unsigned int i;
 	int ret;

 	if (check_only)
 		return true;

 	/* De-assert the CE pin */
 	writeb(0, cs553x->mmio + MM_NAND_CTL);
 	for (i = 0; i < op->ninstrs; i++) {
 		ret = cs553x_exec_instr(cs553x, &op->instrs[i]);
 		if (ret)
 			break;
 	}

 	/* Re-assert the CE pin. */
 	writeb(CS_NAND_CTL_CE, cs553x->mmio + MM_NAND_CTL);

 	return ret;
 }

 static void cs_enable_hwecc(struct nand_chip *this, int mode)
 {
 	struct cs553x_nand_controller *cs553x = to_cs553x(this->controller);

 	writeb(0x07, cs553x->mmio + MM_NAND_ECC_CTL);
 }

 static int cs_calculate_ecc(struct nand_chip *this, const u_char *dat,
 			    u_char *ecc_code)
 {
 	struct cs553x_nand_controller *cs553x = to_cs553x(this->controller);
 	uint32_t ecc;

 	ecc = readl(cs553x->mmio + MM_NAND_STS);

 	ecc_code[1] = ecc >> 8;
 	ecc_code[0] = ecc >> 16;
 	ecc_code[2] = ecc >> 24;
 	return 0;
 }

 static struct cs553x_nand_controller *controllers[4];

 static int cs553x_attach_chip(struct nand_chip *chip)
 {
 	if (chip->ecc.engine_type != NAND_ECC_ENGINE_TYPE_ON_HOST)
 		return 0;

 	chip->ecc.size = 256;
 	chip->ecc.bytes = 3;
 	chip->ecc.hwctl  = cs_enable_hwecc;
 	chip->ecc.calculate = cs_calculate_ecc;
 	chip->ecc.correct  = rawnand_sw_hamming_correct;
 	chip->ecc.strength = 1;

 	return 0;
 }

 static const struct nand_controller_ops cs553x_nand_controller_ops = {
 	.exec_op = cs553x_exec_op,
 	.attach_chip = cs553x_attach_chip,
 };

 static int __init cs553x_init_one(int cs, int mmio, unsigned long adr)
 {
 	struct cs553x_nand_controller *controller;
 	int err = 0;
 	struct nand_chip *this;
 	struct mtd_info *new_mtd;

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

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

 	/* Allocate memory for MTD device structure and private data */
 	controller = kzalloc(sizeof(*controller), GFP_KERNEL);
 	if (!controller) {
 		err = -ENOMEM;
 		goto out;
 	}

 	this = &controller->chip;
 	nand_controller_init(&controller->base);
 	controller->base.ops = &cs553x_nand_controller_ops;
 	this->controller = &controller->base;
 	new_mtd = nand_to_mtd(this);

 	/* Link the private data with the MTD structure */
 	new_mtd->owner = THIS_MODULE;

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

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

 	new_mtd->name = kasprintf(GFP_KERNEL, "cs553x_nand_cs%d", cs);
 	if (!new_mtd->name) {
 		err = -ENOMEM;
 		goto out_ior;
 	}

 	/* Scan to find existence of the device */
 	err = nand_scan(this, 1);
 	if (err)
 		goto out_free;

 	controllers[cs] = controller;
 	goto out;

 out_free:
 	kfree(new_mtd->name);
 out_ior:
 	iounmap(controller->mmio);
 out_mtd:
 	kfree(controller);
 out:
 	return err;
 }

 static int is_geode(void)
 {
 	/* These are the CPUs which will have a CS553[56] companion chip */
 	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
 	    boot_cpu_data.x86 == 5 &&
 	    boot_cpu_data.x86_model == 10)
 		return 1; /* Geode LX */

 	if ((boot_cpu_data.x86_vendor == X86_VENDOR_NSC ||
 	     boot_cpu_data.x86_vendor == X86_VENDOR_CYRIX) &&
 	    boot_cpu_data.x86 == 5 &&
 	    boot_cpu_data.x86_model == 5)
 		return 1; /* Geode GX (née GX2) */

 	return 0;
 }

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

 	/* If the CPU isn't a Geode GX or LX, abort */
 	if (!is_geode())
 		return -ENXIO;

 	/* If it doesn't have the CS553[56], abort */
 	rdmsrl(MSR_DIVIL_GLD_CAP, val);
 	val &= ~0xFFULL;
 	if (val != CAP_CS5535 && val != CAP_CS5536)
 		return -ENXIO;

 	/* If it doesn't have the NAND controller enabled, abort */
 	rdmsrl(MSR_DIVIL_BALL_OPTS, val);
 	if (val & PIN_OPT_IDE) {
 		pr_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 (controllers[i]) {
 			/* If any devices registered, return success. Else the last error. */
 			mtd_device_register(nand_to_mtd(&controllers[i]->chip),
 					    NULL, 0);
 			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 cs553x_nand_controller *controller = controllers[i];
 		struct nand_chip *this = &controller->chip;
 		struct mtd_info *mtd = nand_to_mtd(this);
 		int ret;

 		if (!mtd)
 			continue;

 		/* Release resources, unregister device */
 		ret = mtd_device_unregister(mtd);
 		WARN_ON(ret);
 		nand_cleanup(this);
 		kfree(mtd->name);
 		controllers[i] = NULL;

 		/* unmap physical address */
 		iounmap(controller->mmio);

 		/* Free the MTD device structure */
 		kfree(controller);
 	}
 }

 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");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* (C) 2005, 2006 Red Hat Inc.
	*
	* Author: David Woodhouse <dwmw2@infradead.org>
	* Tom Sylla <tom.sylla@amd.com>
	*
	* Overview:
	* This is a device driver for the NAND flash controller found on
	* the AMD CS5535/CS5536 companion chipsets for the Geode processor.
	* mtd-id for command line partitioning is cs553x_nand_cs[0-3]
	* where 0-3 reflects the chip select for NAND.
	*/

	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/delay.h>
	#include <linux/mtd/mtd.h>
	#include <linux/mtd/rawnand.h>
	#include <linux/mtd/partitions.h>
	#include <linux/iopoll.h>

	#include <asm/msr.h>

	#define NR_CS553X_CONTROLLERS 4

	#define MSR_DIVIL_GLD_CAP 0x51400000 /* DIVIL capabilities */
	#define CAP_CS5535 0x2df000ULL
	#define CAP_CS5536 0x5df500ULL

	/* 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)

	struct cs553x_nand_controller {
	struct nand_controller base;
	struct nand_chip chip;
	void __iomem *mmio;
	};

	static struct cs553x_nand_controller *
	to_cs553x(struct nand_controller *controller)
	{
	return container_of(controller, struct cs553x_nand_controller, base);
	}

	static int cs553x_write_ctrl_byte(struct cs553x_nand_controller *cs553x,
	u32 ctl, u8 data)
	{
	u8 status;

	writeb(ctl, cs553x->mmio + MM_NAND_CTL);
	writeb(data, cs553x->mmio + MM_NAND_IO);
	return readb_poll_timeout_atomic(cs553x->mmio + MM_NAND_STS, status,
	!(status & CS_NAND_CTLR_BUSY), 1,
	100000);
	}

	static void cs553x_data_in(struct cs553x_nand_controller cs553x, void buf,
	unsigned int len)
	{
	writeb(0, cs553x->mmio + MM_NAND_CTL);
	while (unlikely(len > 0x800)) {
	memcpy_fromio(buf, cs553x->mmio, 0x800);
	buf += 0x800;
	len -= 0x800;
	}
	memcpy_fromio(buf, cs553x->mmio, len);
	}

	static void cs553x_data_out(struct cs553x_nand_controller *cs553x,
	const void *buf, unsigned int len)
	{
	writeb(0, cs553x->mmio + MM_NAND_CTL);
	while (unlikely(len > 0x800)) {
	memcpy_toio(cs553x->mmio, buf, 0x800);
	buf += 0x800;
	len -= 0x800;
	}
	memcpy_toio(cs553x->mmio, buf, len);
	}

	static int cs553x_wait_ready(struct cs553x_nand_controller *cs553x,
	unsigned int timeout_ms)
	{
	u8 mask = CS_NAND_CTLR_BUSY \| CS_NAND_STS_FLASH_RDY;
	u8 status;

	return readb_poll_timeout(cs553x->mmio + MM_NAND_STS, status,
	(status & mask) == CS_NAND_STS_FLASH_RDY, 100,
	timeout_ms * 1000);
	}

	static int cs553x_exec_instr(struct cs553x_nand_controller *cs553x,
	const struct nand_op_instr *instr)
	{
	unsigned int i;
	int ret = 0;

	switch (instr->type) {
	case NAND_OP_CMD_INSTR:
	ret = cs553x_write_ctrl_byte(cs553x, CS_NAND_CTL_CLE,
	instr->ctx.cmd.opcode);
	break;

	case NAND_OP_ADDR_INSTR:
	for (i = 0; i < instr->ctx.addr.naddrs; i++) {
	ret = cs553x_write_ctrl_byte(cs553x, CS_NAND_CTL_ALE,
	instr->ctx.addr.addrs[i]);
	if (ret)
	break;
	}
	break;

	case NAND_OP_DATA_IN_INSTR:
	cs553x_data_in(cs553x, instr->ctx.data.buf.in,
	instr->ctx.data.len);
	break;

	case NAND_OP_DATA_OUT_INSTR:
	cs553x_data_out(cs553x, instr->ctx.data.buf.out,
	instr->ctx.data.len);
	break;

	case NAND_OP_WAITRDY_INSTR:
	ret = cs553x_wait_ready(cs553x, instr->ctx.waitrdy.timeout_ms);
	break;
	}

	if (instr->delay_ns)
	ndelay(instr->delay_ns);

	return ret;
	}

	static int cs553x_exec_op(struct nand_chip *this,
	const struct nand_operation *op,
	bool check_only)
	{
	struct cs553x_nand_controller *cs553x = to_cs553x(this->controller);
	unsigned int i;
	int ret;

	if (check_only)
	return true;

	/* De-assert the CE pin */
	writeb(0, cs553x->mmio + MM_NAND_CTL);
	for (i = 0; i < op->ninstrs; i++) {
	ret = cs553x_exec_instr(cs553x, &op->instrs[i]);
	if (ret)
	break;
	}

	/* Re-assert the CE pin. */
	writeb(CS_NAND_CTL_CE, cs553x->mmio + MM_NAND_CTL);

	return ret;
	}

	static void cs_enable_hwecc(struct nand_chip *this, int mode)
	{
	struct cs553x_nand_controller *cs553x = to_cs553x(this->controller);

	writeb(0x07, cs553x->mmio + MM_NAND_ECC_CTL);
	}

	static int cs_calculate_ecc(struct nand_chip this, const u_char dat,
	u_char *ecc_code)
	{
	struct cs553x_nand_controller *cs553x = to_cs553x(this->controller);
	uint32_t ecc;

	ecc = readl(cs553x->mmio + MM_NAND_STS);

	ecc_code[1] = ecc >> 8;
	ecc_code[0] = ecc >> 16;
	ecc_code[2] = ecc >> 24;
	return 0;
	}

	static struct cs553x_nand_controller *controllers[4];

	static int cs553x_attach_chip(struct nand_chip *chip)
	{
	if (chip->ecc.engine_type != NAND_ECC_ENGINE_TYPE_ON_HOST)
	return 0;

	chip->ecc.size = 256;
	chip->ecc.bytes = 3;
	chip->ecc.hwctl = cs_enable_hwecc;
	chip->ecc.calculate = cs_calculate_ecc;
	chip->ecc.correct = rawnand_sw_hamming_correct;
	chip->ecc.strength = 1;

	return 0;
	}

	static const struct nand_controller_ops cs553x_nand_controller_ops = {
	.exec_op = cs553x_exec_op,
	.attach_chip = cs553x_attach_chip,
	};

	static int __init cs553x_init_one(int cs, int mmio, unsigned long adr)
	{
	struct cs553x_nand_controller *controller;
	int err = 0;
	struct nand_chip *this;
	struct mtd_info *new_mtd;

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

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

	/* Allocate memory for MTD device structure and private data */
	controller = kzalloc(sizeof(*controller), GFP_KERNEL);
	if (!controller) {
	err = -ENOMEM;
	goto out;
	}

	this = &controller->chip;
	nand_controller_init(&controller->base);
	controller->base.ops = &cs553x_nand_controller_ops;
	this->controller = &controller->base;
	new_mtd = nand_to_mtd(this);

	/* Link the private data with the MTD structure */
	new_mtd->owner = THIS_MODULE;

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

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

	new_mtd->name = kasprintf(GFP_KERNEL, "cs553x_nand_cs%d", cs);
	if (!new_mtd->name) {
	err = -ENOMEM;
	goto out_ior;
	}

	/* Scan to find existence of the device */
	err = nand_scan(this, 1);
	if (err)
	goto out_free;

	controllers[cs] = controller;
	goto out;

	out_free:
	kfree(new_mtd->name);
	out_ior:
	iounmap(controller->mmio);
	out_mtd:
	kfree(controller);
	out:
	return err;
	}

	static int is_geode(void)
	{
	/* These are the CPUs which will have a CS553[56] companion chip */
	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
	boot_cpu_data.x86 == 5 &&
	boot_cpu_data.x86_model == 10)
	return 1; /* Geode LX */

	if ((boot_cpu_data.x86_vendor == X86_VENDOR_NSC \|\|
	boot_cpu_data.x86_vendor == X86_VENDOR_CYRIX) &&
	boot_cpu_data.x86 == 5 &&
	boot_cpu_data.x86_model == 5)
	return 1; /* Geode GX (née GX2) */

	return 0;
	}

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

	/* If the CPU isn't a Geode GX or LX, abort */
	if (!is_geode())
	return -ENXIO;

	/* If it doesn't have the CS553[56], abort */
	rdmsrl(MSR_DIVIL_GLD_CAP, val);
	val &= ~0xFFULL;
	if (val != CAP_CS5535 && val != CAP_CS5536)
	return -ENXIO;

	/* If it doesn't have the NAND controller enabled, abort */
	rdmsrl(MSR_DIVIL_BALL_OPTS, val);
	if (val & PIN_OPT_IDE) {
	pr_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 (controllers[i]) {
	/* If any devices registered, return success. Else the last error. */
	mtd_device_register(nand_to_mtd(&controllers[i]->chip),
	NULL, 0);
	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 cs553x_nand_controller *controller = controllers[i];
	struct nand_chip *this = &controller->chip;
	struct mtd_info *mtd = nand_to_mtd(this);
	int ret;

	if (!mtd)
	continue;

	/* Release resources, unregister device */
	ret = mtd_device_unregister(mtd);
	WARN_ON(ret);
	nand_cleanup(this);
	kfree(mtd->name);
	controllers[i] = NULL;

	/* unmap physical address */
	iounmap(controller->mmio);

	/* Free the MTD device structure */
	kfree(controller);
	}
	}

	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");