Re: [PATCH] mtd: spinand: add support for ISSI SPI NAND flash

[Miquel Raynal]

Hello Han,

Mostly style fixes.

On 25/08/2026 at 17:30:48 -05, han.xu@xxxxxxxxxxx wrote:

> From: Bill Lee <blee@xxxxxxxx>
>
> Add a new manufacturer driver for ISSI SPI NAND devices (manufacturer
> ID 0x9d). The driver supports the IS37/IS38SMW01/02G8B family (1Gb and
> 2Gb, 1.8V) including the 4Gb 2-die stacked variants.

Can you please reword a bit, perhaps make the list of supported devices
a bullet point list for clarity.

The chip list contains a 3.3V chip, is this an error or a lack in the
commit log?

> Register the new driver by adding issi.o to the spinand Makefile,
> declaring issi_spinand_manufacturer in spinand.h, and adding it to the
> spinand_manufacturers[] table in core.c.

This paragraph is not particularly useful, I would suggest to drop it.

> Signed-off-by: Bill Lee <blee@xxxxxxxx>
> Signed-off-by: Jeff Kim <jekim@xxxxxxxx>
> Signed-off-by: Han Xu <han.xu@xxxxxxx>
> ---
>  drivers/mtd/nand/spi/Makefile |   2 +-
>  drivers/mtd/nand/spi/core.c   |   1 +
>  drivers/mtd/nand/spi/issi.c   | 272 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mtd/spinand.h   |   1 +
>  4 files changed, 275 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/nand/spi/Makefile b/drivers/mtd/nand/spi/Makefile
> index b5ccb44860df..f6b2a094fafc 100644
> --- a/drivers/mtd/nand/spi/Makefile
> +++ b/drivers/mtd/nand/spi/Makefile
> @@ -1,5 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
>  spinand-objs := core.o otp.o
>  spinand-objs += alliancememory.o ato.o dosilicon.o esmt.o fmsh.o foresee.o gigadevice.o heyangtek.o
> -spinand-objs += macronix.o micron.o paragon.o skyhigh.o toshiba.o winbond.o xtx.o
> +spinand-objs += issi.o macronix.o micron.o paragon.o skyhigh.o toshiba.o winbond.o xtx.o
>  obj-$(CONFIG_MTD_SPI_NAND) += spinand.o
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 35365b67dd8e..c11d74450257 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1360,6 +1360,7 @@ static const struct spinand_manufacturer *spinand_manufacturers[] = {
>  	&foresee_spinand_manufacturer,
>  	&gigadevice_spinand_manufacturer,
>  	&heyangtek_spinand_manufacturer,
> +	&issi_spinand_manufacturer,
>  	&macronix_spinand_manufacturer,
>  	&micron_spinand_manufacturer,
>  	&paragon_spinand_manufacturer,
> diff --git a/drivers/mtd/nand/spi/issi.c b/drivers/mtd/nand/spi/issi.c
> new file mode 100644
> index 000000000000..ddcbb6aae72e
> --- /dev/null
> +++ b/drivers/mtd/nand/spi/issi.c
> @@ -0,0 +1,272 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2026 ISSI
> + *
> + * Authors:
> + *	Bill Lee <blee@xxxxxxxx>
> + *	Jeff Kim <jekim@xxxxxxxx>
> + * Co-Author:
> + *	Han Xu <han.xu@xxxxxxx>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/mtd/spinand.h>
> +
> +#define SPINAND_MFR_ISSI 0x9d
> +
> +/*
> + * ___________________________________________________________________________________________
> + * |       ISSI SPI NAND Flash ECC Status Register Bit Descriptions(Refer status register)     |
> + * |------|------|------|----------------------------------------------------------------------|
> + * | Bit6 | Bit5 | Bit4 | ECC Status                                                           |
> + * |------|------|------|----------------------------------------------------------------------|
> + * | 0    | 0    | 0    | No bit error detected during the previous read algorithm.            |
> + * | 0    | 0    | 1    | 1-3 bit errors detected and corrected; no data refreshment required. |
> + * | 0    | 1    | 0    | >8 bit errors detected and NOT corrected.                            |
> + * | 0    | 1    | 1    | 4-6 bit errors detected and corrected; refresh recommended.          |
> + * | 1    | 0    | 0    | Reserved                                                             |
> + * | 1    | 0    | 1    | 7-8 bit errors detected and corrected; refresh must be done.         |
> + * | 1    | 1    | 0    | Reserved                                                             |
> + * | 1    | 1    | 1    | Invalid state                                                        |
> + * |------|------|------|----------------------------------------------------------------------|
> + */
> +#define ISSI_STATUS_ECC_MASK GENMASK(6, 4)

This one is a candidate for a FIELD_GET() based macro.

> +#define ISSI_STATUS_ECC_NO_BITFLIPS (0 << 4)
> +#define ISSI_STATUS_ECC_1TO3_BITFLIPS (1 << 4)
> +#define ISSI_STATUS_ECC_UNCOR_ERROR (2 << 4)
> +#define ISSI_STATUS_ECC_4TO6_BITFLIPS (3 << 4)
> +#define ISSI_STATUS_ECC_7TO8_BITFLIPS (5 << 4)

So these become single integer values.

> +
> +/*
> + * As per datasheet, die selection is done by the 7th bit of Drive
> + * Strength Register (Address 0xD0).
> + */
> +#define ISSI_DIE_SELECT_REG 0xD0
> +#define ISSI_SELECT_DIE_MASK BIT(7)
> +#define ISSI_SELECT_DIE(x) ((x) << 7)
> +
> +static SPINAND_OP_VARIANTS(
> +	quadio_read_cache_variants,
> +	SPINAND_PAGE_READ_FROM_CACHE_1S_1S_4S_OP(0, 1, NULL, 0, 0),
> +	SPINAND_PAGE_READ_FROM_CACHE_1S_1S_2S_OP(0, 1, NULL, 0, 0),
> +	SPINAND_PAGE_READ_FROM_CACHE_FAST_1S_1S_1S_OP(0, 1, NULL, 0, 0),
> +	SPINAND_PAGE_READ_FROM_CACHE_1S_1S_1S_OP(0, 1, NULL, 0, 0));
> +
> +static SPINAND_OP_VARIANTS(x4_write_cache_variants,
> +			   SPINAND_PROG_LOAD_1S_1S_4S_OP(true, 0, NULL,
> +							 0), // 0x32 quad io
> +			   SPINAND_PROG_LOAD_1S_1S_1S_OP(true, 0, NULL,
> +							 0)); // 0x02 single io

You can drop these comments.

> +
> +static SPINAND_OP_VARIANTS(
> +	x4_update_cache_variants,
> +	SPINAND_PROG_LOAD_1S_1S_4S_OP(false, 0, NULL, 0), // 0x34 random quad io
> +	SPINAND_PROG_LOAD_1S_1S_1S_OP(false, 0, NULL,
> +				      0)); // 0x84 random single io

Same here

> +
> +/*
> + * ISSI - 8 bit ECC per 544 - bytes Spare Area Mapping
> + *  ________________________________________________________________________
> + * |________________________________________________________________________|
> + * | Max Addr | Min Addr | ECC Prot | Area     | Description                |
> + * |----------|----------|----------|----------|----------------------------|
> + * | 0x01FF   | 0x0000   | Yes      | Main 0   | User data 0                |
> + * | 0x03FF   | 0x0200   | Yes      | Main 1   | User data 1                |
> + * | 0x05FF   | 0x0400   | Yes      | Main 2   | User data 2                |
> + * | 0x07FF   | 0x0600   | Yes      | Main 3   | User data 3                |
> + * -------------------------------------------------------------------------|
> + * | 0x080F   | 0x0800   | Yes      | Spare 0  | Spare 0                    |
> + * | 0x081F   | 0x0810   | Yes      | Spare 1  | Spare 1                    |
> + * | 0x082F   | 0x0820   | Yes      | Spare 2  | Spare 2                    |
> + * | 0x083F   | 0x0830   | Yes      | Spare 3  | Spare 3                    |
> + * -------------------------------------------------------------------------|
> + * | 0x084F   | 0x0840   | Yes      | Parity 0 | ECC for main/spare 0       |
> + * | 0x085F   | 0x0850   | Yes      | Parity 1 | ECC for main/spare 1       |
> + * | 0x086F   | 0x0860   | Yes      | Parity 2 | ECC for main/spare 2       |
> + * | 0x087F   | 0x0870   | Yes      | Parity 3 | ECC for main/spare 3       |
> + * |________________________________________________________________________|
> + */

The OOB layout looks pretty straightforward, I am not sure the table is
really useful. If you want to keep it:
- Invert columns Min addr and Max addr
- Drop the description (totally redundant with the Area field)
- Drop the ECC prot column and just mention it in the title

> +static int issi_8_ooblayout_ecc(struct mtd_info *mtd, int section,
> +				struct mtd_oob_region *region)
> +{
> +	if (section)
> +		return -ERANGE;
> +
> +	region->offset = mtd->oobsize / 2;
> +	region->length = mtd->oobsize / 2;
> +
> +	return 0;
> +}
> +
> +static int issi_8_ooblayout_free(struct mtd_info *mtd, int section,
> +				 struct mtd_oob_region *region)
> +{
> +	if (section)
> +		return -ERANGE;
> +
> +	/* Reserve 2 bytes for the BBM. */
> +	region->offset = 2;
> +	region->length = (mtd->oobsize / 2) - 2;
> +
> +	return 0;
> +}
> +
> +static const struct mtd_ooblayout_ops issi_8_ooblayout = {
> +	.ecc = issi_8_ooblayout_ecc,
> +	.free = issi_8_ooblayout_free,
> +};
> +
> +static int issi_select_target(struct spinand_device *spinand,
> +			      unsigned int target)
> +{
> +	int ret;
> +	u8 regval;
> +
> +	if (target > 1)
> +		return -EINVAL;
> +
> +	/* Read the current value of the register */
> +	ret = spinand_read_reg_op(spinand, ISSI_DIE_SELECT_REG, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* Update only the die select bit (bit 7) */
> +	regval &= ~ISSI_SELECT_DIE_MASK;
> +	regval |= ISSI_SELECT_DIE(target);
> +
> +	/* Write back the updated value */

I guess these 3 comments are also not so useful.

> +	return spinand_write_reg_op(spinand, ISSI_DIE_SELECT_REG, regval);
> +}
> +
> +static int issi_8_ecc_get_status(struct spinand_device *spinand, u8 status)
> +{
> +	switch (status & ISSI_STATUS_ECC_MASK) {
> +	case ISSI_STATUS_ECC_NO_BITFLIPS:
> +		return 0;
> +
> +	case ISSI_STATUS_ECC_UNCOR_ERROR:
> +		return -EBADMSG;

Please move this one...

> +	case ISSI_STATUS_ECC_1TO3_BITFLIPS:
> +		return 3;
> +
> +	case ISSI_STATUS_ECC_4TO6_BITFLIPS:
> +		return 6;
> +
> +	case ISSI_STATUS_ECC_7TO8_BITFLIPS:
> +		return 8;

Here and drop the \n before default.

> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct spinand_info issi_spinand_table[] = {
> +	/* IS37/38SMW01G8B 1Gb 1.8V */
> +	SPINAND_INFO("IS37/38SMW01G8B",
> +		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x15),
> +		     /*
> +		      * - Memory Cell: 1bit/Memory Cell
> +		      * - Page Size: 2176 bytes (2048 + 128) bytes
> +		      * - Block Size: 64 pages (128K + 8K) bytes
> +		      * - Plane Size:
> +		      *   1Gb: 1024 blocks per plane
> +		      * - Device Size:
> +		      *   1Gb: 1 plane = 1024 blocks
> +		      */
> +		     NAND_MEMORG(1, 2048, 128, 64, 1024, 40, 1, 1, 1),
> +		     NAND_ECCREQ(8, 512),
> +		     SPINAND_INFO_OP_VARIANTS(&quadio_read_cache_variants,
> +					      &x4_write_cache_variants,
> +					      &x4_update_cache_variants),
> +		     SPINAND_HAS_QE_BIT,
> +		     SPINAND_ECCINFO(&issi_8_ooblayout, issi_8_ecc_get_status),
> +		     SPINAND_SELECT_TARGET(issi_select_target)),
> +
> +	/* IS37/38SMW02G8B 2Gb 1.8V */
> +	SPINAND_INFO("IS37/38SMW02G8B",
> +		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x25),
> +		     /*
> +		      * - Memory Cell: 1bit/Memory Cell
> +		      * - Page Size: 2176 bytes (2048 + 128) bytes
> +		      * - Block Size: 64 pages (128K + 8K) bytes
> +		      * - Plane Size:
> +		      *   2Gb: 2048 blocks per plane
> +		      * - Device Size:
> +		      *   2Gb: 1 plane = 2048 blocks
> +		      */
> +		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 1, 1, 1),
> +		     NAND_ECCREQ(8, 512),
> +		     SPINAND_INFO_OP_VARIANTS(&quadio_read_cache_variants,
> +					      &x4_write_cache_variants,
> +					      &x4_update_cache_variants),
> +		     SPINAND_HAS_QE_BIT,
> +		     SPINAND_ECCINFO(&issi_8_ooblayout, issi_8_ecc_get_status),
> +		     SPINAND_SELECT_TARGET(issi_select_target)),
> +
> +	/* IS37/38SML04G8 4Gb 3.3V */
> +	SPINAND_INFO("IS37/38SML04G8",
> +		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x34),
> +		     /*
> +		      * Architecture
> +		      * - Memory Cell: 1bit/Memory Cell
> +		      * - Page Size: 2176 bytes (2048 + 128) bytes
> +		      * - Block Size: 64 pages (128K + 8K) bytes
> +		      * - Plane Size: 2048 blocks per plane
> +		      * - Die Size: 2Gb with 2048 blocks
> +		      * - Device Size: 4Gb with 2-die stacks
> +		      */
> +		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 1, 1, 2),
> +		     NAND_ECCREQ(8, 512),
> +		     SPINAND_INFO_OP_VARIANTS(&quadio_read_cache_variants,
> +					      &x4_write_cache_variants,
> +					      &x4_update_cache_variants),
> +		     SPINAND_HAS_QE_BIT,
> +		     SPINAND_ECCINFO(&issi_8_ooblayout, issi_8_ecc_get_status),
> +		     SPINAND_SELECT_TARGET(issi_select_target)),
> +
> +	/* IS37/38SMW04G8B 4Gb 1.8V */
> +	SPINAND_INFO("IS37/38SMW04G8B",
> +		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x35),
> +		     /*
> +		      * Architecture
> +		      * - Memory Cell: 1bit/Memory Cell
> +		      * - Page Size: 2176 bytes (2048 + 128) bytes
> +		      * - Block Size: 64 pages (128K + 8K) bytes
> +		      * - Plane Size: 2048 blocks per plane
> +		      * - Die Size: 2Gb with 2048 blocks
> +		      * - Device Size: 4Gb with 2-die stacks
> +		      */
> +		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 1, 1, 2),
> +		     NAND_ECCREQ(8, 512),
> +		     SPINAND_INFO_OP_VARIANTS(&quadio_read_cache_variants,
> +					      &x4_write_cache_variants,
> +					      &x4_update_cache_variants),
> +		     SPINAND_HAS_QE_BIT,
> +		     SPINAND_ECCINFO(&issi_8_ooblayout, issi_8_ecc_get_status),
> +		     SPINAND_SELECT_TARGET(issi_select_target)),
> +};
> +
> +static int issi_spinand_init(struct spinand_device *spinand)
> +{
> +	/*
> +	 * manufacturer specific initialization can be done here
> +	 */
> +

This comment is not useful either.

> +	return 0;
> +}
> +
> +static const struct spinand_manufacturer_ops issi_spinand_manuf_ops = {
> +	.init = issi_spinand_init,
> +};
> +
> +const struct spinand_manufacturer issi_spinand_manufacturer = {
> +	.id = SPINAND_MFR_ISSI,
> +	.name = "ISSI",
> +	.chips = issi_spinand_table,
> +	.nchips = ARRAY_SIZE(issi_spinand_table),
> +	.ops = &issi_spinand_manuf_ops,
> +};
> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
> index 5f4c00ae72a7..b42407b69db3 100644
> --- a/include/linux/mtd/spinand.h
> +++ b/include/linux/mtd/spinand.h
> @@ -438,6 +438,7 @@ extern const struct spinand_manufacturer fmsh_spinand_manufacturer;
>  extern const struct spinand_manufacturer foresee_spinand_manufacturer;
>  extern const struct spinand_manufacturer gigadevice_spinand_manufacturer;
>  extern const struct spinand_manufacturer heyangtek_spinand_manufacturer;
> +extern const struct spinand_manufacturer issi_spinand_manufacturer;
>  extern const struct spinand_manufacturer macronix_spinand_manufacturer;
>  extern const struct spinand_manufacturer micron_spinand_manufacturer;
>  extern const struct spinand_manufacturer paragon_spinand_manufacturer;
>
> ---
> base-commit: 15a3cbce32994141252bb4ecfe3ff3a5d22d0b4f
> change-id: 20260825-spinand_issi-d9f79ed03ce0
>
> Best regards,

Thanks,
Miquèl