Re: [PATCH v4] mtd: parsers: bcm63xx: simplify CFE detection

From: Guenter Roeck <linux@roeck-us.net>
To: "Álvaro Fernández Rojas" <noltari@gmail.com>
Cc: tsbogend@alpha.franken.de, f.fainelli@gmail.com,
	bcm-kernel-feedback-list@broadcom.com, miquel.raynal@bootlin.com,
	richard@nod.at, vigneshr@ti.com, jonas.gorski@gmail.com,
	linus.walleij@linaro.org, linux-mips@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org
Subject: Re: [PATCH v4] mtd: parsers: bcm63xx: simplify CFE detection
Date: Fri, 14 Aug 2020 01:56:17 -0700	[thread overview]
Message-ID: <20200814085617.GA129183@roeck-us.net> (raw)
In-Reply-To: <20200615091740.2958303-1-noltari@gmail.com>

On Mon, Jun 15, 2020 at 11:17:40AM +0200, Álvaro Fernández Rojas wrote:
> 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@gmail.com>
> Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

mips:allmodconfig:

ERROR: modpost: "fw_arg3" [drivers/mtd/parsers/bcm63xxpart.ko] undefined!

This is not surprising, since fw_arg3 is not exported.

Guenter

> ---
>  v4: shorten conditional compilation part as suggested by Miquèl.
>  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 | 32 ++++++++++++-------------------
>  1 file changed, 12 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/mtd/parsers/bcm63xxpart.c b/drivers/mtd/parsers/bcm63xxpart.c
> index 78f90c6c18fd..b15bdadaedb5 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 +37,15 @@
>  #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;
> +	int ret = 0;
>  
> -	ret = mtd_read(master, BCM963XX_CFE_VERSION_OFFSET, 5, &retlen,
> -		       (void *)buf);
> -	buf[retlen] = 0;
> +#ifdef CONFIG_MIPS
> +	ret = (fw_arg3 == CFE_EPTSEAL);
> +#endif /* CONFIG_MIPS */
>  
> -	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);
> +	return ret;
>  }
>  
>  static int bcm63xx_read_nvram(struct mtd_info *master,
> @@ -138,7 +130,7 @@ 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));