[v3.2,5/7] aspeed: Create flash devices only when defaults are enabled

When the -nodefaults option is set, flash devices should be created
with :

     -blockdev node-name=fmc0,driver=file,filename=./flash.img \
     -device mx66u51235f,cs=0x0,bus=ssi.0,drive=fmc0 \

To be noted that in this case, the ROM will not be installed and the
initial boot sequence (U-Boot loading) will fetch instructions using
SPI transactions which is significantly slower. That's exactly how HW
operates though.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
  docs/system/arm/aspeed.rst | 35 +++++++++++++++++++++++++++++------
  hw/arm/aspeed.c            |  6 ++++--
  2 files changed, 33 insertions(+), 8 deletions(-)

On Thu, 31 Aug 2023 at 21:13, Cédric Le Goater <clg@kaod.org> wrote:
>
> When the -nodefaults option is set, flash devices should be created
> with :
>
>      -blockdev node-name=fmc0,driver=file,filename=./flash.img \
>      -device mx66u51235f,cs=0x0,bus=ssi.0,drive=fmc0 \
>
> To be noted that in this case, the ROM will not be installed and the
> initial boot sequence (U-Boot loading) will fetch instructions using
> SPI transactions which is significantly slower. That's exactly how HW
> operates though.
>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

Reviewed-by: Joel Stanley <joel@jms.id.au>

A good addition. Thanks!

> ---
>   docs/system/arm/aspeed.rst | 35 +++++++++++++++++++++++++++++------
>   hw/arm/aspeed.c            |  6 ++++--
>   2 files changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/docs/system/arm/aspeed.rst b/docs/system/arm/aspeed.rst
> index 80538422a1a4..b2dea54eedad 100644
> --- a/docs/system/arm/aspeed.rst
> +++ b/docs/system/arm/aspeed.rst
> @@ -104,7 +104,7 @@ To boot a kernel directly from a Linux build tree:
>           -dtb arch/arm/boot/dts/aspeed-ast2600-evb.dtb \
>           -initrd rootfs.cpio
>
> -The image should be attached as an MTD drive. Run :
> +To boot the machine from the flash image, use an MTD drive :
>
>   .. code-block:: bash
>
> @@ -117,23 +117,46 @@ Options specific to Aspeed machines are :
>      device by using the FMC controller to load the instructions, and
>      not simply from RAM. This takes a little longer.
>
> - * ``fmc-model`` to change the FMC Flash model. FW needs support for
> -   the chip model to boot.
> + * ``fmc-model`` to change the default FMC Flash model. FW needs
> +   support for the chip model to boot.
>
> - * ``spi-model`` to change the SPI Flash model.
> + * ``spi-model`` to change the default SPI Flash model.
>
>    * ``bmc-console`` to change the default console device. Most of the
>      machines use the ``UART5`` device for a boot console, which is
>      mapped on ``/dev/ttyS4`` under Linux, but it is not always the
>      case.
>
> -For instance, to start the ``ast2500-evb`` machine with a different
> -FMC chip and a bigger (64M) SPI chip, use :
> +To use other flash models, for instance a different FMC chip and a
> +bigger (64M) SPI for the ``ast2500-evb`` machine, run :
>
>   .. code-block:: bash
>
>     -M ast2500-evb,fmc-model=mx25l25635e,spi-model=mx66u51235f
>
> +When more flexibility is needed to define the flash devices, to use
> +different flash models or define all flash devices (up to 8), the
> +``-nodefaults`` QEMU option can be used to avoid creating the default
> +flash devices.
> +
> +Flash devices should then be created from the command line and attached
> +to a block device :
> +
> +.. code-block:: bash
> +
> +  $ qemu-system-arm -M ast2600-evb \
> +        -blockdev node-name=fmc0,driver=file,filename=/path/to/fmc0.img \
> +       -device mx66u51235f,bus=ssi.0,cs=0x0,drive=fmc0 \
> +       -blockdev node-name=fmc1,driver=file,filename=/path/to/fmc1.img \
> +       -device mx66u51235f,bus=ssi.0,cs=0x1,drive=fmc1 \
> +       -blockdev node-name=spi1,driver=file,filename=/path/to/spi1.img \
> +       -device mx66u51235f,cs=0x0,bus=ssi.1,drive=spi1 \
> +       -nographic -nodefaults
> +
> +In that case, the machine boots fetching instructions from the FMC0
> +device. It is slower to start but closer to what HW does. Using the
> +machine option ``execute-in-place`` has a similar effect.
> +
>   To change the boot console and use device ``UART3`` (``/dev/ttyS2``
>   under Linux), use :
>
> diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
> index cd92cf9ce0bb..271512ce5ced 100644
> --- a/hw/arm/aspeed.c
> +++ b/hw/arm/aspeed.c
> @@ -396,12 +396,14 @@ static void aspeed_machine_init(MachineState *machine)
>       connect_serial_hds_to_uarts(bmc);
>       qdev_realize(DEVICE(&bmc->soc), NULL, &error_abort);
>
> -    aspeed_board_init_flashes(&bmc->soc.fmc,
> +    if (defaults_enabled()) {
> +        aspeed_board_init_flashes(&bmc->soc.fmc,
>                                 bmc->fmc_model ? bmc->fmc_model : amc->fmc_model,
>                                 amc->num_cs, 0);
> -    aspeed_board_init_flashes(&bmc->soc.spi[0],
> +        aspeed_board_init_flashes(&bmc->soc.spi[0],
>                                 bmc->spi_model ? bmc->spi_model : amc->spi_model,
>                                 1, amc->num_cs);
> +    }
>
>       if (machine->kernel_filename && sc->num_cpus > 1) {
>           /* With no u-boot we must set up a boot stub for the secondary CPU */
> --
> 2.41.0
>
>