[PATCH 4/7] Add USB booting capabilities to OMAP
vj
vicencb at gmail.com
Thu Sep 27 20:27:54 EDT 2012
Hi Sascha,
I've been playing with passing some data from first to second stage using
Jan's patches.
It worked fine, but in my case I want to store this data on a global
variable, which is cleared as it's in the BSS.
There is a clean workarround to this issue?
Thanks,
Vicente.
On Wed, Sep 26, 2012 at 9:45 AM, Sascha Hauer <s.hauer at pengutronix.de>wrote:
> On Wed, Sep 26, 2012 at 12:59:51AM +0200, vj wrote:
> > ---
> > arch/arm/cpu/cpu.c | 1 +
> > arch/arm/lib/barebox.lds.S | 10 +
> > arch/arm/mach-omap/Kconfig | 21 +
> > arch/arm/mach-omap/Makefile | 1 +
> > arch/arm/mach-omap/include/mach/omap4_rom_usb.h | 146 +++++
> > arch/arm/mach-omap/omap4_generic.c | 2 +
> > arch/arm/mach-omap/omap4_rom_usb.c | 189 ++++++
> > arch/arm/mach-omap/xload.c | 26 +
> > scripts/.gitignore | 1 +
> > scripts/Makefile | 3 +
> > scripts/usbboot.c | 797
> ++++++++++++++++++++++++
> > 11 files changed, 1197 insertions(+)
> > create mode 100644 arch/arm/mach-omap/include/mach/omap4_rom_usb.h
> > create mode 100644 arch/arm/mach-omap/omap4_rom_usb.c
> > create mode 100644 scripts/usbboot.c
> >
> > diff --git a/arch/arm/cpu/cpu.c b/arch/arm/cpu/cpu.c
> > index 71ef8c0..05343de 100644
> > --- a/arch/arm/cpu/cpu.c
> > +++ b/arch/arm/cpu/cpu.c
> > @@ -89,6 +89,7 @@ void arch_shutdown(void)
> > : "r0", "r1", "r2", "r3", "r6", "r10", "r12", "lr", "cc",
> "memory"
> > );
> > #endif
> > + __asm__ __volatile__ ("cpsid i\n");
> > }
> >
> > #ifdef CONFIG_THUMB2_BAREBOX
> > diff --git a/arch/arm/lib/barebox.lds.S b/arch/arm/lib/barebox.lds.S
> > index a69013f..ff7b63d 100644
> > --- a/arch/arm/lib/barebox.lds.S
> > +++ b/arch/arm/lib/barebox.lds.S
> > @@ -97,6 +97,16 @@ SECTIONS
> > __bss_start = .;
> > .bss : { *(.bss*) }
> > __bss_stop = .;
> > +#ifdef CONFIG_SHARE_USB_HANDLE
> > + /*
> > + * Reserve space for the USB handle
> > + */
> > + . = CONFIG_USB_HANDLE_HANDOVER;
> > + . = ALIGN(4);
> > + __usb_handle = .;
> > + /* . += sizeof(struct usb); */
> > + . += 84;
> > +#endif
>
> If I understand correctly the first stage loader puts some data here
> where a second stage barebox (configured with the same value for
> CONFIG_USB_HANDLE_HANDOVER) will pick it up.
>
> This seems to be a bit fragile. Fortunately Jan has posted a series
> that gives the control of the reset vector to the boards, which means
> that both stages do not have to agree on an addres, but instead a
> pointer can be passed from the first to the second stage.
>
> > +int usb_open(void)
>
> So this uses the OMAP4 ROM to do USB communication, right? The functions
> should have a omap_rom_* prefix then, otherwise it's not clear for a
> reader which context these functions have.
>
> The calling of the ROM code btw explains why the setting of VBAR breaks
> USB boot. The ROM probably uses the vectors.
>
> > +
> > + n = rom_get_per_driver(&pusb->io, boot->device_type);
> > + if (n)
> > + return n;
> > +
> > + pusb->dread.xfer_mode = boot->xfer_mode;
> > + pusb->dread.options = boot->options;
> > + pusb->dread.device_type = boot->device_type;
> > +
> > + pusb->dwrite.xfer_mode = boot->xfer_mode;
> > + pusb->dwrite.options = boot->options;
> > + pusb->dwrite.device_type = boot->device_type;
> > +#else
> > +#ifdef CONFIG_MMU
> > +#error USB communications not working under MMU
>
> You can add the following to CONFIG_OMAP4_USB_BOOT instead:
>
> depends on !MMU
>
> So that an invalid config is not allowed in the first place.
>
>
> > diff --git a/scripts/usbboot.c b/scripts/usbboot.c
>
> This should also be named omap4-usbboot.c, or maybe, if the works on
> other OMAPs, just omap-usboot.c
>
> Sascha
>
> --
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> Industrial Linux Solutions | http://www.pengutronix.de/ |
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