linux-kernel - Re: [PATCH v2] mtd: slram: use memremap() instead of ioremap()

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Message-ID: <CAKWsp+zhqHZaUjbzeutxqE81f5orOLMd6uNVoYifjeYibhAD5w@mail.gmail.com>
Date:   Mon, 6 Nov 2017 14:29:02 -0800
From:   Roy Franz <rfranz@...ium.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        boris.brezillon@...e-electrons.com,
        Marek Vašut <marek.vasut@...il.com>,
        richard@....at, cyrille.pitchen@...ev4u.fr
Cc:     "Roy Franz (roy.franz@...ium.com) (roy.franz@...ium.com)" 
        <roy.franz@...ium.com>, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        David Daney <ddaney@...ium.com>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v2] mtd: slram: use memremap() instead of ioremap()

ping - is this suitable for 4.15?

Thanks,
Roy


On Thu, Oct 19, 2017 at 3:55 PM, Roy Franz <rfranz@...ium.com> wrote:
> Convert slram to use memremap() to map the memory it uses to back an MTD
> device, as this is the proper interface for mapping memory. This change
> enables normal memory to be used to back an MTD device on arm64, as arm64
> prevents ioremap() being used on normal memory.
>
> Signed-off-by: Roy Franz <roy.franz@...ium.com>
> Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Tested-by: David Daney <david.daney@...ium.com>
> ---
> Tested on arm64 simulation, using simulator to preload filesystem image into RAM,
> and also tested on x86_64 using video card memory.  This is useful for speeding
> up booting on (very slow) emulation environments by avoiding any processing of
> an initramfs.
> David Daney tested on MIPS64.
>
> v2: Fix typo in subject line, s/mdt/mtd/
>     added acked-by/tested-by
>
>  drivers/mtd/devices/slram.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/devices/slram.c b/drivers/mtd/devices/slram.c
> index 8087c36dc693..0ec85f316d24 100644
> --- a/drivers/mtd/devices/slram.c
> +++ b/drivers/mtd/devices/slram.c
> @@ -163,8 +163,9 @@ static int register_device(char *name, unsigned long start, unsigned long length
>         }
>
>         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
> -                               ioremap(start, length))) {
> -               E("slram: ioremap failed\n");
> +               memremap(start, length,
> +                        MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC))) {
> +               E("slram: memremap failed\n");
>                 return -EIO;
>         }
>         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
> @@ -186,7 +187,7 @@ static int register_device(char *name, unsigned long start, unsigned long length
>
>         if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0))   {
>                 E("slram: Failed to register new device\n");
> -               iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
> +               memunmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
>                 kfree((*curmtd)->mtdinfo->priv);
>                 kfree((*curmtd)->mtdinfo);
>                 return(-EAGAIN);
> @@ -206,7 +207,7 @@ static void unregister_devices(void)
>         while (slram_mtdlist) {
>                 nextitem = slram_mtdlist->next;
>                 mtd_device_unregister(slram_mtdlist->mtdinfo);
> -               iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
> +               memunmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
>                 kfree(slram_mtdlist->mtdinfo->priv);
>                 kfree(slram_mtdlist->mtdinfo);
>                 kfree(slram_mtdlist);
> --
> 2.11.0
>