Re: [PATCH v4 1/6] mtd: nand: vf610_nfc: Freescale NFC for VF610, MPC5125 and others

Brian Norris
2015-06-02T01:32:41Z

Hi Stefan,

Late review...

On Wed, Mar 25, 2015 at 05:28:24PM +0100, Stefan Agner wrote:
> This driver supports Freescale NFC (NAND flash controller) found on
> Vybrid (VF610), MPC5125, MCF54418 and Kinetis K70.
>
> Limitations:
> - DMA and pipelining not used
> - Pages larger than 2k are not supported
> - No hardware ECC
>
> The driver has only been tested on Vybrid (VF610).
>
> Signed-off-by: Bill Pringlemeir <bpringlemeir@nbsps.com>
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
> MAINTAINERS | 6 +
> drivers/mtd/nand/Kconfig | 12 +
> drivers/mtd/nand/Makefile | 1 +
> drivers/mtd/nand/vf610_nfc.c | 686 +++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 705 insertions(+)
> create mode 100644 drivers/mtd/nand/vf610_nfc.c
>
...
> diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
> new file mode 100644
> index 0000000..23c1510
> --- /dev/null
> +++ b/drivers/mtd/nand/vf610_nfc.c
> @@ -0,0 +1,686 @@
> +/*
> + * Copyright 2009-2015 Freescale Semiconductor, Inc. and others
> + *
> + * Description: MPC5125, VF610, MCF54418 and Kinetis K70 Nand driver.
> + * Jason ported to M54418TWR and MVFA5 (VF610).
> + * Authors: Stefan Agner <stefan.agner@toradex.com>
> + * Bill Pringlemeir <bpringlemeir@nbsps.com>
> + * Shaohui Xie <b21989@freescale.com>
> + * Jason Jin <Jason.jin@freescale.com>
> + *
> + * Based on original driver mpc5121_nfc.c.

It's not supremely obvious to me: what's the relationship between these
drivers? How similar is the IP, if at all?

> + *
> + * This 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.
> + *
> + * Limitations:
> + * - Untested on MPC5125 and M54418.
> + * - DMA not used.
> + * - 2K pages or less.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/nand.h>
> +#include <linux/mtd/partitions.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/of_mtd.h>
> +
> +#define DRV_NAME "vf610_nfc"
> +
> +/* Register Offsets */
> +#define NFC_FLASH_CMD1 0x3F00
> +#define NFC_FLASH_CMD2 0x3F04
> +#define NFC_COL_ADDR 0x3F08
> +#define NFC_ROW_ADDR 0x3F0c
> +#define NFC_ROW_ADDR_INC 0x3F14
> +#define NFC_FLASH_STATUS1 0x3F18
> +#define NFC_FLASH_STATUS2 0x3F1c
> +#define NFC_CACHE_SWAP 0x3F28
> +#define NFC_SECTOR_SIZE 0x3F2c
> +#define NFC_FLASH_CONFIG 0x3F30
> +#define NFC_IRQ_STATUS 0x3F38
> +
> +/* Addresses for NFC MAIN RAM BUFFER areas */
> +#define NFC_MAIN_AREA(n) ((n) * 0x1000)
> +
> +#define PAGE_2K 0x0800
> +#define OOB_64 0x0040
> +
> +/*
> + * NFC_CMD2[CODE] values. See section:
> + * - 31.4.7 Flash Command Code Description, Vybrid manual
> + * - 23.8.6 Flash Command Sequencer, MPC5125 manual
> + *
> + * Briefly these are bitmasks of controller cycles.
> + */
> +#define READ_PAGE_CMD_CODE 0x7EE0
> +#define PROGRAM_PAGE_CMD_CODE 0x7FC0
> +#define ERASE_CMD_CODE 0x4EC0
> +#define READ_ID_CMD_CODE 0x4804
> +#define RESET_CMD_CODE 0x4040
> +#define STATUS_READ_CMD_CODE 0x4068
> +
> +/* NFC ECC mode define */
> +#define ECC_BYPASS 0
> +
> +/*** Register Mask and bit definitions */
> +
> +/* NFC_FLASH_CMD1 Field */
> +#define CMD_BYTE2_MASK 0xFF000000
> +#define CMD_BYTE2_SHIFT 24
> +
> +/* NFC_FLASH_CM2 Field */
> +#define CMD_BYTE1_MASK 0xFF000000
> +#define CMD_BYTE1_SHIFT 24
> +#define CMD_CODE_MASK 0x00FFFF00
> +#define CMD_CODE_SHIFT 8
> +#define BUFNO_MASK 0x00000006
> +#define BUFNO_SHIFT 1
> +#define START_BIT (1<<0)
> +
> +/* NFC_COL_ADDR Field */
> +#define COL_ADDR_MASK 0x0000FFFF
> +#define COL_ADDR_SHIFT 0
> +
> +/* NFC_ROW_ADDR Field */
> +#define ROW_ADDR_MASK 0x00FFFFFF
> +#define ROW_ADDR_SHIFT 0
> +#define ROW_ADDR_CHIP_SEL_RB_MASK 0xF0000000
> +#define ROW_ADDR_CHIP_SEL_RB_SHIFT 28
> +#define ROW_ADDR_CHIP_SEL_MASK 0x0F000000
> +#define ROW_ADDR_CHIP_SEL_SHIFT 24
> +
> +/* NFC_FLASH_STATUS2 Field */
> +#define STATUS_BYTE1_MASK 0x000000FF
> +
> +/* NFC_FLASH_CONFIG Field */
> +#define CONFIG_ECC_SRAM_REQ_BIT (1<<21)
> +#define CONFIG_DMA_REQ_BIT (1<<20)
> +#define CONFIG_ECC_MODE_MASK 0x000E0000
> +#define CONFIG_ECC_MODE_SHIFT 17
> +#define CONFIG_FAST_FLASH_BIT (1<<16)
> +#define CONFIG_16BIT (1<<7)
> +#define CONFIG_BOOT_MODE_BIT (1<<6)
> +#define CONFIG_ADDR_AUTO_INCR_BIT (1<<5)
> +#define CONFIG_BUFNO_AUTO_INCR_BIT (1<<4)
> +#define CONFIG_PAGE_CNT_MASK 0xF
> +#define CONFIG_PAGE_CNT_SHIFT 0
> +
> +/* NFC_IRQ_STATUS Field */
> +#define IDLE_IRQ_BIT (1<<29)
> +#define IDLE_EN_BIT (1<<20)
> +#define CMD_DONE_CLEAR_BIT (1<<18)
> +#define IDLE_CLEAR_BIT (1<<17)
> +
> +#define NFC_TIMEOUT (HZ)
> +
> +struct vf610_nfc_config {
> + int width;
> + int flash_bbt;
> +};
> +
> +struct vf610_nfc {
> + struct mtd_info mtd;
> + struct nand_chip chip;
> + struct device *dev;
> + void __iomem *regs;
> + wait_queue_head_t irq_waitq;
> + uint column;
> + int spareonly;
> + int page_sz;
> + int page;
> + /* Status and ID are in alternate locations. */
> + int alt_buf;
> +#define ALT_BUF_ID 1
> +#define ALT_BUF_STAT 2
> + struct clk *clk;
> +
> + struct vf610_nfc_config cfg;
> +};
> +
> +#define mtd_to_nfc(_mtd) container_of(_mtd, struct vf610_nfc, mtd)
> +
> +static inline u32 vf610_nfc_read(struct vf610_nfc *nfc, uint reg)
> +{
> + return readl(nfc->regs + reg);
> +}
> +
> +static inline void vf610_nfc_write(struct vf610_nfc *nfc, uint reg, u32 val)
> +{
> + writel(val, nfc->regs + reg);
> +}
> +
> +static inline void vf610_nfc_set(struct vf610_nfc *nfc, uint reg, u32 bits)
> +{
> + vf610_nfc_write(nfc, reg, vf610_nfc_read(nfc, reg) | bits);
> +}
> +
> +static inline void vf610_nfc_clear(struct vf610_nfc *nfc, uint reg, u32 bits)
> +{
> + vf610_nfc_write(nfc, reg, vf610_nfc_read(nfc, reg) & ~bits);
> +}
> +
> +static inline void vf610_nfc_set_field(struct vf610_nfc *nfc, u32 reg,
> + u32 mask, u32 shift, u32 val)
> +{
> + vf610_nfc_write(nfc, reg,
> + (vf610_nfc_read(nfc, reg) & (~mask)) | val << shift);
> +}
> +
> +static inline void vf610_nfc_memcpy(void *dst, const void *src, size_t n)
> +{
> + /*
> + * Use this accessor for the interal SRAM buffers. On ARM we can
> + * treat the SRAM buffer as if its memory, hence use memcpy

s/its/it's/
or
s/its/it is/

> + */
> + memcpy(dst, src, n);

I'm not clear on all the reasoning in your comment. Is this really
specific to ARM, that you can treat SRAM like memory? If so, should this
driver have some dependency on ARM?

Also, if you're really trying to handle iomem, it makes sense to
annotate the 2nd argument with __iomem. Then sparse will only complain
on the memcpy(), which has a proper comment explanation, rather than on
every call site for vf610_nfc_memcpy(). i.e.:

static inline void vf610_nfc_memcpy(void *dst, const void __iomem *src,
size_t n)

> +}
> +
> +/* Clear flags for upcoming command */
> +static inline void vf610_nfc_clear_status(struct vf610_nfc *nfc)
> +{
> + void __iomem *reg = nfc->regs + NFC_IRQ_STATUS;
> + u32 tmp = __raw_readl(reg);

Why are you using __raw_xxx variants here, whereas you use readl() in
others? The __raw_xxx variants do not have the normal endian awareness,
nor do they have implicit I/O barriers. I'd bet you should be using the
{read,write}l_relaxed() or {read,write}l(), depending on whether this is
performance critical and you handle the consistency issues elsewhere.

(Same comment applies to all the __raw_xxx usages in this driver, I
think.)

> +
> + tmp |= CMD_DONE_CLEAR_BIT | IDLE_CLEAR_BIT;
> + __raw_writel(tmp, reg);
> +}
> +
> +static inline void vf610_nfc_done(struct vf610_nfc *nfc)
> +{
> + int rv;
> +
> + /*
> + * Barrier is needed after this write. This write need
> + * to be done before reading the next register the first
> + * time.
> + * vf610_nfc_set implicates such a barrier by using writel
> + * to write to the register.
> + */
> + vf610_nfc_set(nfc, NFC_IRQ_STATUS, IDLE_EN_BIT);
> + vf610_nfc_set(nfc, NFC_FLASH_CMD2, START_BIT);
> +
> + if (!(vf610_nfc_read(nfc, NFC_IRQ_STATUS) & IDLE_IRQ_BIT)) {
> + rv = wait_event_timeout(nfc->irq_waitq,
> + (vf610_nfc_read(nfc, NFC_IRQ_STATUS) & IDLE_IRQ_BIT),
> + NFC_TIMEOUT);

This looks like you're doing a standard IRQ-based wait-for-completion,
except that you're also including some extra register polling. Would
this work just as well using a struct completion
(wait_for_completion_timeout() and complete())? Or is the register poll
necessary?

> + if (!rv)
> + dev_warn(nfc->dev, "Timeout while waiting for BUSY.\n");
> + }
> + vf610_nfc_clear_status(nfc);
> +}
> +
> +static u8 vf610_nfc_get_id(struct vf610_nfc *nfc, int col)
> +{
> + u32 flash_id;
> +
> + if (col < 4) {
> + flash_id = vf610_nfc_read(nfc, NFC_FLASH_STATUS1);
> + return (flash_id >> (3-col)*8) & 0xff;

Add spaces around the arithmetic, please.

> + } else {
> + flash_id = vf610_nfc_read(nfc, NFC_FLASH_STATUS2);
> + return flash_id >> 24;
> + }
> +}
> +
> +static u8 vf610_nfc_get_status(struct vf610_nfc *nfc)
> +{
> + return vf610_nfc_read(nfc, NFC_FLASH_STATUS2) & STATUS_BYTE1_MASK;
> +}
> +
> +static void vf610_nfc_send_command(struct vf610_nfc *nfc, u32 cmd_byte1,
> + u32 cmd_code)
> +{
> + void __iomem *reg = nfc->regs + NFC_FLASH_CMD2;
> + u32 tmp;
> +
> + vf610_nfc_clear_status(nfc);
> +
> + tmp = __raw_readl(reg);
> + tmp &= ~(CMD_BYTE1_MASK | CMD_CODE_MASK | BUFNO_MASK);
> + tmp |= cmd_byte1 << CMD_BYTE1_SHIFT;
> + tmp |= cmd_code << CMD_CODE_SHIFT;
> + __raw_writel(tmp, reg);
> +}
> +
> +static void vf610_nfc_send_commands(struct vf610_nfc *nfc, u32 cmd_byte1,
> + u32 cmd_byte2, u32 cmd_code)
> +{
> + void __iomem *reg = nfc->regs + NFC_FLASH_CMD1;
> + u32 tmp;
> +
> + vf610_nfc_send_command(nfc, cmd_byte1, cmd_code);
> +
> + tmp = __raw_readl(reg);
> + tmp &= ~CMD_BYTE2_MASK;
> + tmp |= cmd_byte2 << CMD_BYTE2_SHIFT;
> + __raw_writel(tmp, reg);
> +}
> +
> +static irqreturn_t vf610_nfc_irq(int irq, void *data)
> +{
> + struct mtd_info *mtd = data;
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> +
> + vf610_nfc_clear(nfc, NFC_IRQ_STATUS, IDLE_EN_BIT);
> + wake_up(&nfc->irq_waitq);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static void vf610_nfc_addr_cycle(struct vf610_nfc *nfc, int column, int page)
> +{
> + if (column != -1) {
> + if (nfc->chip.options | NAND_BUSWIDTH_16)

smatch caught a hard-to-spot one here:

drivers/mtd/nand/vf610_nfc.c:335 vf610_nfc_addr_cycle() warn: suspicious bitop condition [smatch]

You probably meant:

if (nfc->chip.options & NAND_BUSWIDTH_16)

> + column = column/2;
> + vf610_nfc_set_field(nfc, NFC_COL_ADDR, COL_ADDR_MASK,
> + COL_ADDR_SHIFT, column);
> + }
> + if (page != -1)
> + vf610_nfc_set_field(nfc, NFC_ROW_ADDR, ROW_ADDR_MASK,
> + ROW_ADDR_SHIFT, page);
> +}
> +
> +static inline void vf610_nfc_transfer_size(void __iomem *regbase, int size)
> +{
> + __raw_writel(size, regbase + NFC_SECTOR_SIZE);
> +}
> +
> +static void vf610_nfc_command(struct mtd_info *mtd, unsigned command,
> + int column, int page)
> +{
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> +
> + nfc->column = max(column, 0);
> + nfc->spareonly = 0;
> + nfc->alt_buf = 0;
> +
> + switch (command) {
> + case NAND_CMD_PAGEPROG:
> + nfc->page = -1;
> + vf610_nfc_transfer_size(nfc->regs, nfc->page_sz);
> + vf610_nfc_send_commands(nfc, NAND_CMD_SEQIN,
> + command, PROGRAM_PAGE_CMD_CODE);
> + vf610_nfc_addr_cycle(nfc, column, page);
> + break;
> +
> + case NAND_CMD_RESET:
> + vf610_nfc_transfer_size(nfc->regs, 0);
> + vf610_nfc_send_command(nfc, command, RESET_CMD_CODE);
> + break;
> + /*
> + * NFC does not support sub-page reads and writes,
> + * so emulate them using full page transfers.
> + */
> + case NAND_CMD_READOOB:
> + nfc->spareonly = 1;
> + case NAND_CMD_SEQIN: /* Pre-read for partial writes. */
> + case NAND_CMD_READ0:
> + column = 0;
> + /* Already read? */
> + if (nfc->page == page)
> + return;
> + nfc->page = page;
> + vf610_nfc_transfer_size(nfc->regs, nfc->page_sz);
> + vf610_nfc_send_commands(nfc, NAND_CMD_READ0,
> + NAND_CMD_READSTART, READ_PAGE_CMD_CODE);
> + vf610_nfc_addr_cycle(nfc, column, page);
> + break;
> +
> + case NAND_CMD_ERASE1:
> + nfc->page = -1;
> + vf610_nfc_transfer_size(nfc->regs, 0);
> + vf610_nfc_send_commands(nfc, command,
> + NAND_CMD_ERASE2, ERASE_CMD_CODE);
> + vf610_nfc_addr_cycle(nfc, column, page);
> + break;
> +
> + case NAND_CMD_READID:
> + nfc->alt_buf = ALT_BUF_ID;
> + vf610_nfc_transfer_size(nfc->regs, 0);
> + vf610_nfc_send_command(nfc, command, READ_ID_CMD_CODE);
> + break;
> +
> + case NAND_CMD_STATUS:
> + nfc->alt_buf = ALT_BUF_STAT;
> + vf610_nfc_transfer_size(nfc->regs, 0);
> + vf610_nfc_send_command(nfc, command, STATUS_READ_CMD_CODE);
> + break;
> + default:
> + return;
> + }
> +
> + vf610_nfc_done(nfc);
> +}
> +
> +static inline void vf610_nfc_read_spare(struct mtd_info *mtd, void *buf,
> + int len)
> +{
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> +
> + len = min_t(uint, mtd->oobsize, len);
> + if (len > 0)
> + vf610_nfc_memcpy(buf, nfc->regs + mtd->writesize, len);
> +}
> +
> +static void vf610_nfc_read_buf(struct mtd_info *mtd, u_char *buf, int len)
> +{
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> + uint c = nfc->column;
> + uint l;
> +
> + /* Handle main area */
> + if (!nfc->spareonly) {
> + l = min_t(uint, len, mtd->writesize - c);
> + nfc->column += l;
> +
> + if (!nfc->alt_buf)
> + vf610_nfc_memcpy(buf, nfc->regs + NFC_MAIN_AREA(0) + c, l);
> + else
> + if (nfc->alt_buf & ALT_BUF_ID)
> + *buf = vf610_nfc_get_id(nfc, c);
> + else
> + *buf = vf610_nfc_get_status(nfc);
> +
> + buf += l;
> + len -= l;
> + }
> +
> + /* Handle spare area access */
> + if (len) {
> + nfc->column += len;
> + vf610_nfc_read_spare(mtd, buf, len);
> + }
> +}
> +
> +static void vf610_nfc_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
> +{
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> + uint c = nfc->column;
> + uint l;
> +
> + l = min_t(uint, len, mtd->writesize + mtd->oobsize - c);
> + nfc->column += l;
> + vf610_nfc_memcpy(nfc->regs + NFC_MAIN_AREA(0) + c, buf, l);
> +}
> +
> +static uint8_t vf610_nfc_read_byte(struct mtd_info *mtd)
> +{
> + u8 tmp;
> +
> + vf610_nfc_read_buf(mtd, &tmp, sizeof(tmp));
> + return tmp;
> +}
> +
> +static u16 vf610_nfc_read_word(struct mtd_info *mtd)
> +{
> + u16 tmp;
> +
> + vf610_nfc_read_buf(mtd, (u_char *)&tmp, sizeof(tmp));
> + return tmp;
> +}
> +
> +/* If not provided, upper layers apply a fixed delay. */
> +static int vf610_nfc_dev_ready(struct mtd_info *mtd)
> +{
> + /* NFC handles R/B internally; always ready. */
> + return 1;
> +}
> +
> +/*
> + * This function supports Vybrid only (MPC5125 would have full RB and four CS)
> + */
> +static void vf610_nfc_select_chip(struct mtd_info *mtd, int chip)
> +{
> +#ifdef CONFIG_SOC_VF610
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> + u32 tmp = vf610_nfc_read(nfc, NFC_ROW_ADDR);
> +
> + tmp &= ~(ROW_ADDR_CHIP_SEL_RB_MASK | ROW_ADDR_CHIP_SEL_MASK);
> + tmp |= 1 << ROW_ADDR_CHIP_SEL_RB_SHIFT;
> +
> + if (chip == 0)
> + tmp |= 1 << ROW_ADDR_CHIP_SEL_SHIFT;
> + else if (chip == 1)
> + tmp |= 2 << ROW_ADDR_CHIP_SEL_SHIFT;
> +
> + vf610_nfc_write(nfc, NFC_ROW_ADDR, tmp);
> +#endif
> +}
> +
> +#ifdef CONFIG_OF_MTD

Don't use CONFIG_OF_MTD. Maybe CONFIG_OF, but even that doesn't seem
necessary. The table is tiny, and the code should fail gracefully (and
reduce to pretty simple / negligible code) if you don't have OF enabled.

> +static const struct of_device_id vf610_nfc_dt_ids[] = {
> + { .compatible = "fsl,vf610-nfc" },
> + { .compatible = "fsl,mpc5125-nfc" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, vf610_nfc_dt_ids);
> +
> +static int vf610_nfc_probe_dt(struct device *dev, struct vf610_nfc_config *cfg)
> +{
> + struct device_node *np = dev->of_node;
> + int buswidth;
> +
> + if (!np)
> + return 1;

Try:

return -EINVAL;

> +
> + cfg->flash_bbt = of_get_nand_on_flash_bbt(np);
> +
> + buswidth = of_get_nand_bus_width(np);
> + if (buswidth < 0)
> + return buswidth;

This function should mostly come for free as part of this:

commit 5844feeaa4154d1c46d3462c7a4653d22356d8b4
Author: Brian Norris <computersforpeace@gmail.com>
Date: Fri Jan 23 00:22:27 2015 -0800

mtd: nand: add common DT init code

in l2-mtd.git and linux-next.git. Can you try just assigning chip->dn
instead?

> +
> + cfg->width = buswidth;
> +
> + return 0;
> +}
> +#else
> +static int vf610_nfc_probe_dt(struct device *dev, struct vf610_nfc_config *cfg)
> +{
> + return 0;

Really? I doubt you want to silently do nothing if you don't have OF
enabled. It seems to make more sense to just kill the #ifdef, and have
the registration fail on either the '!np' case or the
'of_get_nand_bus_width(np) returns -ENOSYS' case.

> +}
> +#endif
> +
> +static int vf610_nfc_init_controller(struct vf610_nfc *nfc)
> +{
> + struct vf610_nfc_config *cfg = &nfc->cfg;
> +
> + if (cfg->width == 16)
> + vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);
> + else
> + vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_16BIT);
> +
> + /* Set configuration register. */
> + vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_ADDR_AUTO_INCR_BIT);
> + vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_BUFNO_AUTO_INCR_BIT);
> + vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_BOOT_MODE_BIT);
> + vf610_nfc_clear(nfc, NFC_FLASH_CONFIG, CONFIG_DMA_REQ_BIT);
> + vf610_nfc_set(nfc, NFC_FLASH_CONFIG, CONFIG_FAST_FLASH_BIT);
> +
> + /* PAGE_CNT = 1 */
> + vf610_nfc_set_field(nfc, NFC_FLASH_CONFIG, CONFIG_PAGE_CNT_MASK,
> + CONFIG_PAGE_CNT_SHIFT, 1);
> +
> + return 0;
> +}
> +
> +static int vf610_nfc_probe(struct platform_device *pdev)
> +{
> + struct vf610_nfc *nfc;
> + struct resource *res;
> + struct mtd_info *mtd;
> + struct nand_chip *chip;
> + struct vf610_nfc_config *cfg;
> + int err = 0;
> + int irq;
> +
> + nfc = devm_kzalloc(&pdev->dev, sizeof(*nfc), GFP_KERNEL);
> + if (!nfc)
> + return -ENOMEM;
> +
> + cfg = &nfc->cfg;
> +
> + nfc->dev = &pdev->dev;
> + nfc->page = -1;
> + mtd = &nfc->mtd;
> + chip = &nfc->chip;
> +
> + mtd->priv = chip;
> + mtd->owner = THIS_MODULE;
> + mtd->dev.parent = nfc->dev;
> + mtd->name = DRV_NAME;
> +
> + err = vf610_nfc_probe_dt(nfc->dev, cfg);
> + if (err)
> + return -ENODEV;
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq <= 0)
> + return -EINVAL;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + nfc->regs = devm_ioremap_resource(nfc->dev, res);
> + if (IS_ERR(nfc->regs))
> + return PTR_ERR(nfc->regs);
> +
> + nfc->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(nfc->clk))
> + return PTR_ERR(nfc->clk);
> +
> + err = clk_prepare_enable(nfc->clk);
> + if (err) {
> + dev_err(nfc->dev, "Unable to enable clock!\n");
> + return err;
> + }
> +
> + if (cfg->width == 16)
> + chip->options |= NAND_BUSWIDTH_16;
> + else
> + chip->options &= ~NAND_BUSWIDTH_16;

Is the else clause needed? Also, you'll get the above for free with the
aforementioned commit ("mtd: nand: add common DT init code").

> +
> + chip->dev_ready = vf610_nfc_dev_ready;
> + chip->cmdfunc = vf610_nfc_command;
> + chip->read_byte = vf610_nfc_read_byte;
> + chip->read_word = vf610_nfc_read_word;
> + chip->read_buf = vf610_nfc_read_buf;
> + chip->write_buf = vf610_nfc_write_buf;
> + chip->select_chip = vf610_nfc_select_chip;
> +
> + /* Bad block options. */
> + if (cfg->flash_bbt)
> + chip->bbt_options = NAND_BBT_USE_FLASH | NAND_BBT_NO_OOB |
> + NAND_BBT_CREATE;

You probably don't need NAND_BBT_CREATE here. It's added automatically
to the BBT descriptors in nand_bbt.c.

You can also get the NAND_BBT_USE_FLASH part for free from the
aforementioned patch ("mtd: nand: add common DT init code").

> +
> + init_waitqueue_head(&nfc->irq_waitq);
> +
> + err = devm_request_irq(nfc->dev, irq, vf610_nfc_irq, 0, DRV_NAME, mtd);
> + if (err) {
> + dev_err(nfc->dev, "Error requesting IRQ!\n");
> + goto error;
> + }
> +
> + nfc->page_sz = PAGE_2K + OOB_64;
> + nfc->page_sz += cfg->width == 16 ? 1 : 0;
> +
> + vf610_nfc_init_controller(nfc);
> +
> + /* first scan to find the device and get the page size */
> + if (nand_scan_ident(mtd, 1, NULL)) {
> + err = -ENXIO;
> + goto error;
> + }
> +
> + chip->ecc.mode = NAND_ECC_SOFT; /* default */
> +
> + nfc->page_sz = mtd->writesize + mtd->oobsize;
> +
> + /* Single buffer only, max 256 OOB minus ECC status */
> + if (nfc->page_sz > PAGE_2K + 256 - 8) {
> + dev_err(nfc->dev, "Unsupported flash page size\n");
> + err = -ENXIO;
> + goto error;
> + }
> + nfc->page_sz += cfg->width == 16 ? 1 : 0;
> +
> + /* second phase scan */
> + if (nand_scan_tail(mtd)) {
> + err = -ENXIO;
> + goto error;
> + }
> +
> + /* Register device in MTD */
> + mtd_device_parse_register(mtd, NULL,
> + &(struct mtd_part_parser_data){
> + .of_node = pdev->dev.of_node,
> + },
> + NULL, 0);

Please check the return code of mtd_device_parse_register().

> +
> + platform_set_drvdata(pdev, mtd);

If you move this up, then you can do:

return mtd_device_parse_register(...);

> +
> + return 0;
> +
> +error:
> + clk_disable_unprepare(nfc->clk);
> + return err;
> +}
> +
> +static int vf610_nfc_remove(struct platform_device *pdev)
> +{
> + struct mtd_info *mtd = platform_get_drvdata(pdev);
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> +
> + nand_release(mtd);
> + clk_disable_unprepare(nfc->clk);
> + return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int vf610_nfc_suspend(struct device *dev)
> +{
> + struct mtd_info *mtd = dev_get_drvdata(dev);
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> +
> + clk_disable_unprepare(nfc->clk);
> + return 0;
> +}
> +
> +static int vf610_nfc_resume(struct device *dev)
> +{
> + struct mtd_info *mtd = dev_get_drvdata(dev);
> + struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> +
> + pinctrl_pm_select_default_state(dev);
> +
> + clk_prepare_enable(nfc->clk);
> +
> + vf610_nfc_init_controller(nfc);
> + return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(vf610_nfc_pm_ops, vf610_nfc_suspend, vf610_nfc_resume);
> +
> +static struct platform_driver vf610_nfc_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + .of_match_table = vf610_nfc_dt_ids,
> + .pm = &vf610_nfc_pm_ops,
> + },
> + .probe = vf610_nfc_probe,
> + .remove = vf610_nfc_remove,
> +};
> +
> +module_platform_driver(vf610_nfc_driver);
> +
> +MODULE_AUTHOR("Freescale Semiconductor, Inc.");
> +MODULE_DESCRIPTION("Freescale VF610/MPC5125 NFC MTD NAND driver");
> +MODULE_LICENSE("GPL");

Brian