Re: [PATCH v3 10/17] hw/arm/allwinner-h3: add Boot ROM support

[Niek Linnenbank <nieklinnenbank@gmail.com>]

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On Tue, Jan 14, 2020 at 12:28 AM Philippe Mathieu-Daudé <philmd@redhat.com>
wrote:

> On 1/8/20 9:00 PM, Niek Linnenbank wrote:
> > A real Allwinner H3 SoC contains a Boot ROM which is the
> > first code that runs right after the SoC is powered on.
> > The Boot ROM is responsible for loading user code (e.g. a bootloader)
> > from any of the supported external devices and writing the downloaded
> > code to internal SRAM. After loading the SoC begins executing the code
> > written to SRAM. This commits adds emulation of the Boot ROM firmware
> > setup functionality by loading user code from SD card.
> >
> > Signed-off-by: Niek Linnenbank <nieklinnenbank@gmail.com>
> > ---
> >   include/hw/arm/allwinner-h3.h | 23 +++++++++++++++++++++++
> >   hw/arm/allwinner-h3.c         | 28 ++++++++++++++++++++++++++++
> >   hw/arm/orangepi.c             |  3 +++
> >   3 files changed, 54 insertions(+)
> >
> > diff --git a/include/hw/arm/allwinner-h3.h
> b/include/hw/arm/allwinner-h3.h
> > index 5d74cca28e..4b66227ac4 100644
> > --- a/include/hw/arm/allwinner-h3.h
> > +++ b/include/hw/arm/allwinner-h3.h
> > @@ -50,6 +50,7 @@
> >   #include "hw/sd/allwinner-sdhost.h"
> >   #include "hw/net/allwinner-sun8i-emac.h"
> >   #include "target/arm/cpu.h"
> > +#include "sysemu/block-backend.h"
> >
> >   /**
> >    * Allwinner H3 device list
> > @@ -130,4 +131,26 @@ typedef struct AwH3State {
> >       MemoryRegion sram_c;
> >   } AwH3State;
> >
> > +/**
> > + * Emulate Boot ROM firmware setup functionality.
> > + *
> > + * A real Allwinner H3 SoC contains a Boot ROM
> > + * which is the first code that runs right after
> > + * the SoC is powered on. The Boot ROM is responsible
> > + * for loading user code (e.g. a bootloader) from any
> > + * of the supported external devices and writing the
> > + * downloaded code to internal SRAM. After loading the SoC
> > + * begins executing the code written to SRAM.
> > + *
> > + * This function emulates the Boot ROM by copying 32 KiB
> > + * of data from the given block device and writes it to
> > + * the start of the first internal SRAM memory.
> > + *
> > + * @s: Allwinner H3 state object pointer
> > + * @blk: Block backend device object pointer
> > + * @errp: Error object pointer for raising errors
> > + */
> > +void allwinner_h3_bootrom_setup(AwH3State *s, BlockBackend *blk,
> > +                                Error **errp);
> > +
> >   #endif /* HW_ARM_ALLWINNER_H3_H */
> > diff --git a/hw/arm/allwinner-h3.c b/hw/arm/allwinner-h3.c
> > index e692432b4e..e7b768ad5b 100644
> > --- a/hw/arm/allwinner-h3.c
> > +++ b/hw/arm/allwinner-h3.c
> > @@ -27,6 +27,7 @@
> >   #include "hw/char/serial.h"
> >   #include "hw/misc/unimp.h"
> >   #include "hw/usb/hcd-ehci.h"
> > +#include "hw/loader.h"
> >   #include "sysemu/sysemu.h"
> >   #include "hw/arm/allwinner-h3.h"
> >
> > @@ -168,6 +169,33 @@ enum {
> >       AW_H3_GIC_NUM_SPI       = 128
> >   };
> >
> > +void allwinner_h3_bootrom_setup(AwH3State *s, BlockBackend *blk, Error
> **errp)
> > +{
> > +    uint8_t *buffer;
> > +    int64_t rom_size = 32 * KiB;
>
> Why restrict to 32K? The A1 SRAM is 64K.
>

The reason is that the actual Boot ROM on the H3 also uses 32K:
    https://linux-sunxi.org/BROM

See the 'U-Boot SPL Limitations' table at the end of the page.

You can see the comment in the table there regarding the 32 KiB:
  "Sizes larger than 32 KiB are rejected by the BROM. Exactly 32 KiB is
fine, as verified by writing a special pattern at the end of the SPL and
checking it in the SRAM."

Probably it would not harm to increase it to the full size of the SRAM, but
I tried to model
the behavior as close to the real hardware as possible.

Regards,
Niek


> > +
> > +    int64_t blk_size = blk_getlength(blk);
> > +    if (blk_size <= 0) {
> > +        error_setg(errp, "%s: failed to get BlockBackend size",
> __func__);
> > +        return;
> > +    }
> > +
> > +    if (rom_size > blk_size) {
> > +        rom_size = blk_size;
> > +    }
> > +
> > +    buffer = g_new0(uint8_t, rom_size);
> > +    if (blk_pread(blk, 8 * KiB, buffer, rom_size) < 0) {
> > +        error_setg(errp, "%s: failed to read BlockBackend data",
> __func__);
> > +        return;
> > +    }
> > +
> > +    rom_add_blob("allwinner-h3.bootrom", buffer, rom_size,
> > +                  rom_size, s->memmap[AW_H3_SRAM_A1],
> > +                  NULL, NULL, NULL, NULL, false);
> > +    g_free(buffer);
> > +}
> > +
> >   static void allwinner_h3_init(Object *obj)
> >   {
> >       AwH3State *s = AW_H3(obj);
> > diff --git a/hw/arm/orangepi.c b/hw/arm/orangepi.c
> > index 0eb52eb813..b722f49485 100644
> > --- a/hw/arm/orangepi.c
> > +++ b/hw/arm/orangepi.c
> > @@ -93,6 +93,9 @@ static void orangepi_init(MachineState *machine)
> >       if (bios_name) {
> >           error_report("BIOS not supported for this machine");
> >           exit(1);
> > +    } else if (!machine->kernel_filename && blk_is_available(blk)) {
> > +        /* Use Boot ROM to copy data from SD card to SRAM */
> > +        allwinner_h3_bootrom_setup(s->h3, blk, &error_fatal);
> >       }
> >       orangepi_binfo.loader_start = s->h3->memmap[AW_H3_SDRAM];
> >       orangepi_binfo.ram_size = machine->ram_size;
> >
>
>

-- 
Niek Linnenbank

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