linux-kernel - Re: [PATCH v3] mtd: parsers: bcm63xx: simplify CFE detection

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Message-ID: <20200615105433.56fb5310@xps13>
Date:   Mon, 15 Jun 2020 10:54:33 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Álvaro Fernández Rojas <noltari@...il.com>
Cc:     tsbogend@...ha.franken.de, f.fainelli@...il.com,
        bcm-kernel-feedback-list@...adcom.com, richard@....at,
        vigneshr@...com, jonas.gorski@...il.com, linus.walleij@...aro.org,
        linux-mips@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org
Subject: Re: [PATCH v3] mtd: parsers: bcm63xx: simplify CFE detection

Hi Álvaro,

Álvaro Fernández Rojas <noltari@...il.com> wrote on Fri, 12 Jun 2020
09:35:49 +0200:

> Instead of trying to parse CFE version string, which is customized by some
> vendors, let's just check that "CFE1" was passed on argument 3.
> 
> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> Signed-off-by: Jonas Gorski <jonas.gorski@...il.com>
> ---
>  v3: keep COMPILE_TEST compatibility by adding a new function that only checks
>      fw_arg3 when CONFIG_MIPS is defined.
>  v2: use CFE_EPTSEAL definition and avoid using an additional function.
> 
>  drivers/mtd/parsers/bcm63xxpart.c | 34 +++++++++++--------------------
>  1 file changed, 12 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/mtd/parsers/bcm63xxpart.c b/drivers/mtd/parsers/bcm63xxpart.c
> index 78f90c6c18fd..c514c04789af 100644
> --- a/drivers/mtd/parsers/bcm63xxpart.c
> +++ b/drivers/mtd/parsers/bcm63xxpart.c
> @@ -22,6 +22,11 @@
>  #include <linux/mtd/partitions.h>
>  #include <linux/of.h>
>  
> +#ifdef CONFIG_MIPS
> +#include <asm/bootinfo.h>
> +#include <asm/fw/cfe/cfe_api.h>
> +#endif /* CONFIG_MIPS */
> +
>  #define BCM963XX_CFE_BLOCK_SIZE		SZ_64K	/* always at least 64KiB */
>  
>  #define BCM963XX_CFE_MAGIC_OFFSET	0x4e0
> @@ -32,28 +37,13 @@
>  #define STR_NULL_TERMINATE(x) \
>  	do { char *_str = (x); _str[sizeof(x) - 1] = 0; } while (0)
>  
> -static int bcm63xx_detect_cfe(struct mtd_info *master)
> +static inline int bcm63xx_detect_cfe(void)
>  {
> -	char buf[9];
> -	int ret;
> -	size_t retlen;
> -
> -	ret = mtd_read(master, BCM963XX_CFE_VERSION_OFFSET, 5, &retlen,
> -		       (void *)buf);
> -	buf[retlen] = 0;
> -
> -	if (ret)
> -		return ret;
> -
> -	if (strncmp("cfe-v", buf, 5) == 0)
> -		return 0;
> -
> -	/* very old CFE's do not have the cfe-v string, so check for magic */
> -	ret = mtd_read(master, BCM963XX_CFE_MAGIC_OFFSET, 8, &retlen,
> -		       (void *)buf);
> -	buf[retlen] = 0;
> -
> -	return strncmp("CFE1CFE1", buf, 8);
> +#ifdef CONFIG_MIPS
> +	return (fw_arg3 == CFE_EPTSEAL);
> +#else
> +	return 0;
> +#endif /* CONFIG_MIPS */

What about:

	ret = 0;

#ifdef CONFIG_MIPS
	ret = (fw_arg3 == CFE_EPTSEAL)
#endif

	return ret;

This is for shortening the conditional part.

>  }
>  
>  static int bcm63xx_read_nvram(struct mtd_info *master,
> @@ -138,7 +128,7 @@ static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
>  	struct bcm963xx_nvram *nvram = NULL;
>  	int ret;
>  
> -	if (bcm63xx_detect_cfe(master))
> +	if (!bcm63xx_detect_cfe())
>  		return -EINVAL;
>  
>  	nvram = vzalloc(sizeof(*nvram));

Thanks,
Miquèl