Re: [PATCH 11/12] aspeed: Introduce a "uart" machine option

[Cédric Le Goater]

On 5/30/23 23:22, Philippe Mathieu-Daudé wrote:
> On 8/5/23 09:58, Cédric Le Goater wrote:
> > Most of the Aspeed machines use the UART5 device for the boot console,
> > and QEMU connects the first serial Chardev to this SoC device for this
> > purpose. See routine connect_serial_hds_to_uarts().
> >
> > Nevertheless, some machines use another boot console, such as the fuji,
> > and commit 5d63d0c76c ("hw/arm/aspeed: Allow machine to set UART
> > default") introduced a SoC class attribute 'uart_default' and property
> > to be able to change the boot console device. It was later changed by
> > commit d2b3eaefb4 ("aspeed: Refactor UART init for multi-SoC machines").
> >
> > The "uart" machine option goes a step further and lets the user define
> > the UART device from the QEMU command line without introducing a new
> > machine definition. For instance, to use device UART3 (mapped on
> > /dev/ttyS2 under Linux) instead of the default UART5, one would use :
> >
> >    -M ast2500-evb,uart=uart3
> >
> > Cc: Abhishek Singh Dagur <abhishek@drut.io>
> > Signed-off-by: Cédric Le Goater <clg@kaod.org>
> > ---
> >   docs/system/arm/aspeed.rst | 10 ++++++++++
> >   hw/arm/aspeed.c            | 39 ++++++++++++++++++++++++++++++++++++--
> >   2 files changed, 47 insertions(+), 2 deletions(-)
> >
> > diff --git a/docs/system/arm/aspeed.rst b/docs/system/arm/aspeed.rst
> > index d4e293e7f9..e70f0aeea3 100644
> > --- a/docs/system/arm/aspeed.rst
> > +++ b/docs/system/arm/aspeed.rst
> > @@ -122,6 +122,10 @@ Options specific to Aspeed machines are :
> >    * ``spi-model`` to change the SPI Flash model.
> > + * ``uart`` 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.
>
> This comment ...
>
> >   For instance, to start the ``ast2500-evb`` machine with a different
> >   FMC chip and a bigger (64M) SPI chip, use :
> > @@ -129,6 +133,12 @@ FMC chip and a bigger (64M) SPI chip, use :
> >     -M ast2500-evb,fmc-model=mx25l25635e,spi-model=mx66u51235f
> > +To change the boot console and use device ``UART3`` (``/dev/ttyS2``
> > +under Linux), use :
>
> ... and this one suggest 'boot-console' could be a better name.
>
> Or 'boot-console-index'.

you might be right. people expect to find the console messages on
this device. I will think about it.

> > +.. code-block:: bash
> > +
> > +  -M ast2500-evb,uart=uart3
> >   Aspeed minibmc family boards (``ast1030-evb``)
> >   ==================================================================
> > diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
> > index 3d5488faf7..6c32f674b9 100644
> > --- a/hw/arm/aspeed.c
> > +++ b/hw/arm/aspeed.c
> > @@ -43,6 +43,7 @@ struct AspeedMachineState {
> >       AspeedSoCState soc;
> >       MemoryRegion boot_rom;
> >       bool mmio_exec;
> > +    uint32_t uart_chosen;
> >       char *fmc_model;
> >       char *spi_model;
> >   };
> > @@ -331,10 +332,11 @@ static void 
> > connect_serial_hds_to_uarts(AspeedMachineState *bmc)
> >       AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(bmc);
> >       AspeedSoCState *s = &bmc->soc;
> >       AspeedSoCClass *sc = ASPEED_SOC_GET_CLASS(s);
> > +    int uart_chosen = bmc->uart_chosen ? bmc->uart_chosen : amc->uart_default;
> > -    aspeed_soc_uart_set_chr(s, amc->uart_default, serial_hd(0));
> > +    aspeed_soc_uart_set_chr(s, uart_chosen, serial_hd(0));
> >       for (int i = 1, uart = ASPEED_DEV_UART1; i < sc->uarts_num; i++, uart++) {
> > -        if (uart == amc->uart_default) {
> > +        if (uart == uart_chosen) {
> >               continue;
> >           }
> >           aspeed_soc_uart_set_chr(s, uart, serial_hd(i));
> > @@ -1077,6 +1079,35 @@ static void aspeed_set_spi_model(Object *obj, const char 
> > *value, Error **errp)
> >       bmc->spi_model = g_strdup(value);
> >   }
> > +static char *aspeed_get_uart(Object *obj, Error **errp)
> > +{
> > +    AspeedMachineState *bmc = ASPEED_MACHINE(obj);
> > +    AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(bmc);
> > +    int uart_chosen = bmc->uart_chosen ? bmc->uart_chosen : amc->uart_default;
> > +
> > +    return g_strdup_printf("uart%d", uart_chosen - ASPEED_DEV_UART1 + 1);
> > +}
> > +
> > +static void aspeed_set_uart(Object *obj, const char *value, Error **errp)
> > +{
> > +    AspeedMachineState *bmc = ASPEED_MACHINE(obj);
> > +    AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(bmc);
> > +    AspeedSoCClass *sc = ASPEED_SOC_CLASS(object_class_by_name(amc->soc_name));
> > +    int val;
> > +
> > +    if (sscanf(value, "uart%u", &val) != 1) {
> > +        error_setg(errp, "Bad value for \"uart\" property");
>
> Why are you asking for a string and not an index?

because the literal name is what people find in the DT. See files
arch/arm/boot/dts/aspeed-bmc-* under Linux.

Thanks,

C.

> > +        return;
> > +    }
> > +
> > +    /* The number of UART depends on the SoC */
> > +    if (val < 1 || val > sc->uarts_num) {
> > +        error_setg(errp, "\"uart\" should be in range [1 - %d]", 
> > sc->uarts_num);
> > +        return;
> > +    }
> > +    bmc->uart_chosen = ASPEED_DEV_UART1 + val - 1;
> > +}
> > +
> >   static void aspeed_machine_class_props_init(ObjectClass *oc)
> >   {
> >       object_class_property_add_bool(oc, "execute-in-place",
> > @@ -1085,6 +1116,10 @@ static void aspeed_machine_class_props_init(ObjectClass 
> > *oc)
> >       object_class_property_set_description(oc, "execute-in-place",
> >                              "boot directly from CE0 flash device");
> > +    object_class_property_add_str(oc, "uart", aspeed_get_uart, 
> > aspeed_set_uart);
> > +    object_class_property_set_description(oc, "uart",
> > +                           "Change the default UART to \"uartX\"");
> > +
> >       object_class_property_add_str(oc, "fmc-model", aspeed_get_fmc_model,
> >                                      aspeed_set_fmc_model);
> >       object_class_property_set_description(oc, "fmc-model",