Re: [PATCH v2 2/5] mtd: spinand: add OTP support

From: Miquel Raynal
Date: Tue Oct 01 2024 - 05:12:56 EST

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Hi Martin,

mmkurbanov@xxxxxxxxxxxxxxxxx wrote on Tue, 27 Aug 2024 20:49:00 +0300:

> The MTD subsystem already supports accessing two OTP areas: user and
> factory. User areas can be written by the user. This patch only adds
> support for the user areas.
>
> In this patch the OTP_INFO macro is provided to add parameters to
> spinand_info.
> To implement OTP operations, the client (flash driver) is provided with
> 5 callbacks: .read(), .write(), .info(), .lock(), .erase().

Overall this looks good, I have minor changes to request. I'm not yet
done down to the last patch, but I think the implementation is neat.

> Signed-off-by: Martin Kurbanov <mmkurbanov@xxxxxxxxxxxxxxxxx>
> ---
> drivers/mtd/nand/spi/Makefile | 3 +-
> drivers/mtd/nand/spi/core.c | 3 +
> drivers/mtd/nand/spi/otp.c | 232 ++++++++++++++++++++++++++++++++++
> include/linux/mtd/spinand.h | 56 ++++++++
> 4 files changed, 293 insertions(+), 1 deletion(-)
> create mode 100644 drivers/mtd/nand/spi/otp.c
>
> diff --git a/drivers/mtd/nand/spi/Makefile b/drivers/mtd/nand/spi/Makefile
> index 19cc77288ebbc..60d2e830ffc6b 100644
> --- a/drivers/mtd/nand/spi/Makefile
> +++ b/drivers/mtd/nand/spi/Makefile
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0
> -spinand-objs := core.o alliancememory.o ato.o esmt.o foresee.o gigadevice.o macronix.o
> +spinand-objs := core.o otp.o
> +spinand-objs += alliancememory.o ato.o esmt.o foresee.o gigadevice.o macronix.o
> spinand-objs += micron.o paragon.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 807c24b0c7c4f..2cb825edd49d0 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1111,6 +1111,7 @@ int spinand_match_and_init(struct spinand_device *spinand,
> spinand->flags = table[i].flags;
> spinand->id.len = 1 + table[i].devid.len;
> spinand->select_target = table[i].select_target;
> + spinand->otp = &table[i].otp;
>
> op = spinand_select_op_variant(spinand,
> info->op_variants.read_cache);
> @@ -1292,6 +1293,8 @@ static int spinand_init(struct spinand_device *spinand)
> mtd->_max_bad_blocks = nanddev_mtd_max_bad_blocks;
> mtd->_resume = spinand_mtd_resume;
>
> + spinand_set_mtd_otp_ops(spinand);
> +
> if (nand->ecc.engine) {
> ret = mtd_ooblayout_count_freebytes(mtd);
> if (ret < 0)
> diff --git a/drivers/mtd/nand/spi/otp.c b/drivers/mtd/nand/spi/otp.c
> new file mode 100644
> index 0000000000000..d459f811f9c04
> --- /dev/null
> +++ b/drivers/mtd/nand/spi/otp.c
> @@ -0,0 +1,232 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2024, SaluteDevices. All Rights Reserved.
> + *
> + * Author: Martin Kurbanov <mmkurbanov@xxxxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/spinand.h>
> +
> +static unsigned int spinand_otp_npages(const struct spinand_device *spinand)
> +{
> + return spinand->otp->layout.npages;
> +}
> +
> +static size_t spinand_otp_size(struct spinand_device *spinand)
> +{
> + struct nand_device *nand = spinand_to_nand(spinand);
> + size_t otp_pagesize = nanddev_page_size(nand) +
> + nanddev_per_page_oobsize(nand);
> +
> + return spinand_otp_npages(spinand) * otp_pagesize;
> +}
> +
> +static int spinand_otp_rw(struct spinand_device *spinand, loff_t ofs,
> + size_t len, u8 *buf, size_t *retlen, bool is_write)
> +{
> + struct nand_device *nand = spinand_to_nand(spinand);
> + struct nand_page_io_req req = { 0 };

= {}; is enough

> + unsigned long long page;
> + size_t copied = 0;
> + size_t otp_pagesize = nanddev_page_size(nand) +
> + nanddev_per_page_oobsize(nand);
> + int ret = 0;
> +
> + page = ofs;
> + req.dataoffs = do_div(page, otp_pagesize);
> + req.pos.page = page;
> + req.type = is_write ? NAND_PAGE_WRITE : NAND_PAGE_READ;
> + req.mode = MTD_OPS_RAW;
> + req.databuf.in = buf;
> +
> + while (copied < len && req.pos.page < spinand_otp_npages(spinand)) {
> + req.datalen = min_t(unsigned int,
> + otp_pagesize - req.dataoffs,
> + len - copied);
> +
> + if (is_write)
> + ret = spinand_write_page(spinand, &req);
> + else
> + ret = spinand_read_page(spinand, &req);
> +
> + if (ret < 0)
> + break;
> +
> + req.dataoffs = 0;
> + copied += req.datalen;
> + req.pos.page++;
> + }
> +
> + *retlen = copied;
> +
> + return ret;
> +}
> +
> +/**
> + * spinand_otp_read() - Read from OTP area
> + * @spinand: the spinand device
> + * @ofs: the offset to read
> + * @len: the number of data bytes to read
> + * @buf: the buffer to store the read data
> + * @retlen: the pointer to variable to store the number of read bytes
> + *
> + * Return: 0 on success, an error code otherwise.
> + */
> +int spinand_otp_read(struct spinand_device *spinand, loff_t ofs, size_t len,
> + u8 *buf, size_t *retlen)
> +{
> + return spinand_otp_rw(spinand, ofs, len, buf, retlen, false);
> +}
> +
> +/**
> + * spinand_otp_write() - Write to OTP area
> + * @spinand: the spinand device
> + * @ofs: the offset to write to
> + * @len: the number of bytes to write
> + * @buf: the buffer with data to write
> + * @retlen: the pointer to variable to store the number of written bytes
> + *
> + * Return: 0 on success, an error code otherwise.
> + */
> +int spinand_otp_write(struct spinand_device *spinand, loff_t ofs, size_t len,
> + const u8 *buf, size_t *retlen)
> +{
> + return spinand_otp_rw(spinand, ofs, len, (u8 *)buf, retlen, true);
> +}

These spinand_otp_xxx() helpers are not yet used, and thus should be
introduced later, when they are useful.

> +
> +static int spinand_otp_check_bounds(struct spinand_device *spinand, loff_t ofs,
> + size_t len)
> +{
> + if (ofs < 0 || ofs + len > spinand_otp_size(spinand))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int spinand_mtd_otp_info(struct mtd_info *mtd, size_t len,
> + size_t *retlen, struct otp_info *buf)
> +{
> + struct spinand_device *spinand = mtd_to_spinand(mtd);
> + const struct spinand_otp_ops *ops = spinand->otp->ops;
> + int ret;
> +
> + mutex_lock(&spinand->lock);
> + ret = ops->info(spinand, len, buf, retlen);
> + mutex_unlock(&spinand->lock);
> +
> + return ret;
> +}
> +
> +static int spinand_mtd_otp_rw(struct mtd_info *mtd, loff_t ofs, size_t len,
> + size_t *retlen, u8 *buf, bool is_write)
> +{
> + struct spinand_device *spinand = mtd_to_spinand(mtd);
> + const struct spinand_otp_ops *ops = spinand->otp->ops;
> + int ret;
> +
> + if (!len)
> + return 0;
> +
> + ret = spinand_otp_check_bounds(spinand, ofs, len);
> + if (ret)
> + return ret;
> +
> + mutex_lock(&spinand->lock);
> +
> + ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, CFG_OTP_ENABLE);
> + if (ret)
> + goto out_unlock;
> +
> + if (is_write)
> + ret = ops->write(spinand, ofs, len, buf, retlen);
> + else
> + ret = ops->read(spinand, ofs, len, buf, retlen);
> +
> + if (spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0)) {
> + pr_warn(1, "Can not disable OTP mode\n");

dev_warn?

> + ret = -EIO;
> + }
> +
> +out_unlock:
> + mutex_unlock(&spinand->lock);
> + return ret;
> +}
> +
> +static int spinand_mtd_otp_read(struct mtd_info *mtd, loff_t ofs, size_t len,
> + size_t *retlen, u8 *buf)
> +{
> + return spinand_mtd_otp_rw(mtd, ofs, len, retlen, buf, false);
> +}
> +
> +static int spinand_mtd_otp_write(struct mtd_info *mtd, loff_t ofs, size_t len,
> + size_t *retlen, const u8 *buf)
> +{
> + return spinand_mtd_otp_rw(mtd, ofs, len, retlen, (u8 *)buf, true);
> +}
> +
> +static int spinand_mtd_otp_erase(struct mtd_info *mtd, loff_t ofs, size_t len)
> +{
> + struct spinand_device *spinand = mtd_to_spinand(mtd);
> + const struct spinand_otp_ops *ops = spinand->otp->ops;
> + int ret;
> +
> + if (!ops->erase)
> + return -EOPNOTSUPP;
> +
> + if (!len)
> + return 0;
> +
> + ret = spinand_otp_check_bounds(spinand, ofs, len);
> + if (ret)
> + return ret;
> +
> + mutex_lock(&spinand->lock);
> + ret = ops->erase(spinand, ofs, len);
> + mutex_unlock(&spinand->lock);
> +
> + return ret;
> +}
> +
> +static int spinand_mtd_otp_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
> +{
> + struct spinand_device *spinand = mtd_to_spinand(mtd);
> + const struct spinand_otp_ops *ops = spinand->otp->ops;
> + int ret;
> +
> + if (!ops->lock)
> + return -EOPNOTSUPP;
> +
> + if (!len)
> + return 0;
> +
> + ret = spinand_otp_check_bounds(spinand, ofs, len);
> + if (ret)
> + return ret;
> +
> + mutex_lock(&spinand->lock);
> + ret = ops->lock(spinand, ofs, len);
> + mutex_unlock(&spinand->lock);
> +
> + return ret;
> +}
> +
> +/**
> + * spinand_set_mtd_otp_ops() - Set up OTP methods
> + * @spinand: the spinand device
> + *
> + * Set up OTP methods.
> + */
> +void spinand_set_mtd_otp_ops(struct spinand_device *spinand)
> +{
> + struct mtd_info *mtd = spinand_to_mtd(spinand);
> +
> + if (!spinand->otp->ops)

Could we use something else as check? It feels odd to check for otp ops
and then just ignore the fact that they are here. Maybe check npages or
otp_size() ?

> + return;
> +
> + mtd->_get_user_prot_info = spinand_mtd_otp_info;
> + mtd->_read_user_prot_reg = spinand_mtd_otp_read;
> + mtd->_write_user_prot_reg = spinand_mtd_otp_write;
> + mtd->_lock_user_prot_reg = spinand_mtd_otp_lock;
> + mtd->_erase_user_prot_reg = spinand_mtd_otp_erase;
> +}
> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
> index 555846517faf6..8099f35f0e051 100644
> --- a/include/linux/mtd/spinand.h
> +++ b/include/linux/mtd/spinand.h
> @@ -322,6 +322,43 @@ struct spinand_ondie_ecc_conf {
> u8 status;
> };

Thanks,
Miquèl

Next message: Miquel Raynal: "Re: [PATCH v2 1/5] mtd: spinand: make spinand_{read,write}_page global"
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