[PATCH 1/2 RFC v2] mtd/uclinux: support ROM and allow passing the base address
Uwe Kleine-König
u.kleine-koenig at pengutronix.de
Mon Oct 15 02:58:55 EDT 2012
Hello,
On Mon, Oct 15, 2012 at 02:14:55PM +1000, Greg Ungerer wrote:
> Hi Uwe,
>
> On 12/10/12 17:41, 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
> ^^^^
> safe
>
> >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>
>
> Unfortunately email to me goes through an exchange server and openchange,
> and it manages to often mangle anything more than 7bit ascii. Not too
> much I can do about it, sorry.
hehe, so openchange is really MS compatible now? :-)
> >Changed since (implicit) v1:
> >
> > - don't make uclinux_ram_map static as pointed out by Mike and Greg.
> >
> > drivers/mtd/maps/Kconfig | 2 +-
> > drivers/mtd/maps/uclinux.c | 28 ++++++++++++++++++++++------
> > 2 files changed, 23 insertions(+), 7 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..f5e8e9a 100644
> >--- a/drivers/mtd/maps/uclinux.c
> >+++ b/drivers/mtd/maps/uclinux.c
> >@@ -24,11 +24,12 @@
> > /****************************************************************************/
> >
> > struct map_info uclinux_ram_map = {
> >- .name = "RAM",
> >- .phys = (unsigned long)__bss_stop,
> > .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);
>
> Is there any value in saying "RAM/ROM"?
> Why don't we just drop those chars altogether.
ok.
> > 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");
>
> Do we really want this message?
> My predominate usage of this code is in RAM mappings. Network
> loading kernel+filesystem images on bare boards. Anyone who wants
> to know and is looking in the kernel boot messages will see
> something like:
>
> Creating 1 MTD partitions on "RAM":
> 0x000000000000-0x0000000d8000 : "ROMfs"
>
> So they will know what type of mapping it was loaded from.
I want it because if nobody reports it it might well be possible to drop
map_ram support.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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