linux-kernel - Re: [PATCH 6/7] mtd: spi-nor: Rework the SPI NOR lock/unlock logic

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Date:   Sun, 4 Aug 2019 20:06:05 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     <Tudor.Ambarus@...rochip.com>, <boris.brezillon@...labora.com>,
        <marek.vasut@...il.com>
CC:     <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <miquel.raynal@...tlin.com>, <richard@....at>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <boris.brezillon@...tlin.com>
Subject: Re: [PATCH 6/7] mtd: spi-nor: Rework the SPI NOR lock/unlock logic

Hi Tudor,

On 31-Jul-19 2:33 PM, Tudor.Ambarus@...rochip.com wrote:
> From: Boris Brezillon <boris.brezillon@...tlin.com>
> 
> Move the locking hooks in a separate struct so that we have just
> one field to update when we change the locking implementation.
> 
> stm_locking_ops, the legacy locking operations, can be overwritten
> later on by implementing manufacturer specific default_init() hooks.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...tlin.com>
> [tudor.ambarus@...rochip.com: use ->default_init() hook]
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>

[...]

> @@ -1782,7 +1788,7 @@ static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
>  	if (ret)
>  		return ret;
>  
> -	ret = nor->flash_is_locked(nor, ofs, len);
> +	ret = nor->locking_ops->is_locked(nor, ofs, len);
>  
>  	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_LOCK);
>  	return ret;
> @@ -4805,6 +4811,10 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>  	nor->quad_enable = spansion_quad_enable;
>  	nor->set_4byte = spansion_set_4byte;
>  
> +	/* Default locking operations. */
> +	if (info->flags & SPI_NOR_HAS_LOCK)
> +		nor->locking_ops = &stm_locking_ops;
> +

This condition is different than how lock/unlock ops are populated
today. We would need to add SPI_NOR_HAS_LOCK to all SNOR_MFR_ST and
SNOR_MFR_MICRON entries to be backward compatible or keep the condition
as is.

>  	/* Init flash parameters based on flash_info struct and SFDP */
>  	spi_nor_init_params(nor, &params);
>  
> @@ -4819,21 +4829,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>  	mtd->_read = spi_nor_read;
>  	mtd->_resume = spi_nor_resume;
>  
> -	/* NOR protection support for STmicro/Micron chips and similar */
> -	if (JEDEC_MFR(info) == SNOR_MFR_ST ||
> -	    JEDEC_MFR(info) == SNOR_MFR_MICRON ||
> -	    info->flags & SPI_NOR_HAS_LOCK) {
> -		nor->flash_lock = stm_lock;
> -		nor->flash_unlock = stm_unlock;
> -		nor->flash_is_locked = stm_is_locked;
> -	}
> -

[...]

> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index a434ab7a53e6..bd68ec5a10e7 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -425,9 +425,23 @@ struct spi_nor {
>  	int (*set_4byte)(struct spi_nor *nor, bool enable);
>  	int (*clear_sr_bp)(struct spi_nor *nor);
>  
> +	const struct spi_nor_locking_ops *locking_ops;
> +

Also, to be consistent, document this new member.


>  	void *priv;
>  };
>  
> +/**
> + * struct spi_nor_locking_ops - SPI NOR locking methods
> + * @lock: lock a region of the SPI NOR
> + * @unlock: unlock a region of the SPI NOR
> + * @is_locked: check if a region of the SPI NOR is completely locked
> + */
> +struct spi_nor_locking_ops {
> +	int (*lock)(struct spi_nor *nor, loff_t ofs, uint64_t len);
> +	int (*unlock)(struct spi_nor *nor, loff_t ofs, uint64_t len);
> +	int (*is_locked)(struct spi_nor *nor, loff_t ofs, uint64_t len);

checkpatch does not like uint64_t. Please changes these to size_t

Regards
Vignesh


> +};
> +
>  static u64 __maybe_unused
>  spi_nor_region_is_last(const struct spi_nor_erase_region *region)
>  {
>