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

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 31/5/23 08:28, Cédric Le Goater wrote:
> 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.

OK. After looking at this file, I suppose people would expect
a "bmc-console" property name:

   -M ast2500-evb,bmc-console=uart3