Re: [PATCH 11/12] aspeed: Introduce a "uart" machine option - Philippe Mathieu-Daudé

From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: "Cédric Le Goater" <clg@kaod.org>, qemu-arm@nongnu.org
Cc: qemu-devel@nongnu.org, Peter Maydell <peter.maydell@linaro.org>,
	Joel Stanley <joel@jms.id.au>, Andrew Jeffery <andrew@aj.id.au>,
	Abhishek Singh Dagur <abhishek@drut.io>
Subject: Re: [PATCH 11/12] aspeed: Introduce a "uart" machine option
Date: Tue, 30 May 2023 23:22:44 +0200	[thread overview]
Message-ID: <d0dedd1a-e2b7-5db9-d710-595e94b084a0@linaro.org> (raw)
In-Reply-To: <20230508075859.3326566-12-clg@kaod.org>

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'.

> +.. 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?

> +        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",