[PATCH] [RFC] mtd/uclinux: support ROM and allow passing the base address
Greg Ungerer
gerg at snapgear.com
Mon Oct 8 23:29:46 EDT 2012
Hi Uwe,
On 09/10/12 01:25, Uwe Kleine-König wrote:
> This allows to put the filesystem at a defined address in ROM allowing
> to save more precious RAM.
>
> I think it's save to default to ROM because the intention of using the
> uclinux map is to use a romfs and so mtd-ram doesn't give you anything
> that mtd-rom doesn't.
>
> Signed-off-by: Uwe Kleine-K÷nig <u.kleine-koenig at pengutronix.de>
Looks good to me, so:
Acked-by: Greg Ungerer <gerg at uclinux.org>
Couple of things to be aware of. Artem currently has a couple of
patches against this file (looks like at least 1 of them is currently
in linux-next). It will probably conflict with your changes, should
be easy enough to fix up.
The change to this file in linux-next changes the call to ioremap
to be a phys_to_virt - which is because it was always going to be
in real RAM. This may no longer be true with your change, it could
be in ROM. For non-MMU I expect no problems. But this could be an
issue if used on systems with MMU enabled. (And one of the other
changes that I generated for this allows this for at least one
architecture type - ColdFire/m68k). Just flagging this, I don't expect
it will cause any current users any problems.
Regards
Greg
> ---
> drivers/mtd/maps/Kconfig | 2 +-
> drivers/mtd/maps/uclinux.c | 30 +++++++++++++++++++++++-------
> 2 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
> index 5ba2458..d945950 100644
> --- a/drivers/mtd/maps/Kconfig
> +++ b/drivers/mtd/maps/Kconfig
> @@ -443,7 +443,7 @@ config MTD_GPIO_ADDR
>
> config MTD_UCLINUX
> bool "Generic uClinux RAM/ROM filesystem support"
> - depends on MTD_RAM=y && !MMU
> + depends on (MTD_RAM=y || MTD_ROM=y) && !MMU
> help
> Map driver to support image based filesystems for uClinux.
>
> diff --git a/drivers/mtd/maps/uclinux.c b/drivers/mtd/maps/uclinux.c
> index c3bb304..a8a5929 100644
> --- a/drivers/mtd/maps/uclinux.c
> +++ b/drivers/mtd/maps/uclinux.c
> @@ -23,12 +23,13 @@
>
> /****************************************************************************/
>
> -struct map_info uclinux_ram_map = {
> - .name = "RAM",
> - .phys = (unsigned long)__bss_stop,
> +static struct map_info uclinux_ram_map = {
> .size = 0,
> };
>
> +static unsigned long physaddr = -1;
> +module_param(physaddr, ulong, S_IRUGO);
> +
> static struct mtd_info *uclinux_ram_mtdinfo;
>
> /****************************************************************************/
> @@ -60,11 +61,17 @@ static int __init uclinux_mtd_init(void)
> struct map_info *mapp;
>
> mapp = &uclinux_ram_map;
> +
> + if (physaddr == -1)
> + mapp->phys = (resource_size_t)__bss_stop;
> + else
> + mapp->phys = physaddr;
> +
> if (!mapp->size)
> mapp->size = PAGE_ALIGN(ntohl(*((unsigned long *)(mapp->phys + 8))));
> mapp->bankwidth = 4;
>
> - printk("uclinux[mtd]: RAM probe address=0x%x size=0x%x\n",
> + printk("uclinux[mtd]: RAM/ROM probe address=0x%x size=0x%x\n",
> (int) mapp->phys, (int) mapp->size);
>
> mapp->virt = ioremap_nocache(mapp->phys, mapp->size);
> @@ -76,9 +83,18 @@ static int __init uclinux_mtd_init(void)
>
> simple_map_init(mapp);
>
> - mtd = do_map_probe("map_ram", mapp);
> + mapp->name = "ROM";
> + mtd = do_map_probe("map_rom", mapp);
> + if (!mtd) {
> + /* fall back to ram probing for compatibility reasons */
> + mapp->name = "RAM";
> + mtd = do_map_probe("map_ram", mapp);
> + if (mtd && IS_ENABLED(CONFIG_MTD_ROM))
> + pr_err("Failed to map rom, but ram succeeded. Please report this issue!\n");
> + }
> +
> if (!mtd) {
> - printk("uclinux[mtd]: failed to find a mapping?\n");
> + printk("uclinux[mtd]: failed to find a rom/ram mapping?\n");
> iounmap(mapp->virt);
> return(-ENXIO);
> }
> @@ -115,6 +131,6 @@ module_exit(uclinux_mtd_cleanup);
>
> MODULE_LICENSE("GPL");
> MODULE_AUTHOR("Greg Ungerer <gerg at snapgear.com>");
> -MODULE_DESCRIPTION("Generic RAM based MTD for uClinux");
> +MODULE_DESCRIPTION("Generic RAM/ROM based MTD for uClinux");
>
> /****************************************************************************/
>
--
------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg at snapgear.com
SnapGear Group, McAfee PHONE: +61 7 3435 2888
8 Gardner Close FAX: +61 7 3217 5323
Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com
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