Re: [Xen-devel] [PATCH v4] ns16550: Add ACPI support for ARM only

[Wei Xu <xuwei5@xxxxxxxxxxxxx>]

Hi Julien,

On 2020/2/21 22:57, Julien Grall wrote:
> 
> 
> On 21/02/2020 14:02, Jan Beulich wrote:
>> On 21.02.2020 03:22, Wei Xu wrote:
>>> --- a/xen/drivers/char/ns16550.c
>>> +++ b/xen/drivers/char/ns16550.c
>>> @@ -1620,6 +1620,85 @@ DT_DEVICE_START(ns16550, "NS16550 UART", 
>>> DEVICE_SERIAL)
>>>   DT_DEVICE_END
>>>
>>>   #endif /* HAS_DEVICE_TREE */
>>> +
>>> +#if defined(CONFIG_ACPI) && defined(CONFIG_ARM)
>>> +#include <xen/acpi.h>
>>> +
>>> +static int __init ns16550_acpi_uart_init(const void *data)
>>> +{
>>> +    struct acpi_table_header *table;
>>> +    struct acpi_table_spcr *spcr;
>>> +    acpi_status status;
>>> +    /*
>>> +     * Same as the DT part.
>>> +     * Only support one UART on ARM which happen to be ns16550_com[0].
>>> +     */
>>> +    struct ns16550 *uart = &ns16550_com[0];
>>> +
>>> +    status = acpi_get_table(ACPI_SIG_SPCR, 0, &table);
>>> +    if ( ACPI_FAILURE(status) )
>>> +    {
>>> +        printk("ns16550: Failed to get SPCR table\n");
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    spcr = container_of(table, struct acpi_table_spcr, header);
>>> +
>>> +    /*
>>> +     * The serial port address may be 0 for example
>>> +     * if the console redirection is disabled.
>>> +     */
>>> +    if ( unlikely(!spcr->serial_port.address) )
>>> +    {
>>> +        printk("ns16550: Console redirection is disabled\n");
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    if ( unlikely(spcr->serial_port.space_id != 
>>> ACPI_ADR_SPACE_SYSTEM_MEMORY) )
>>> +    {
>>> +        printk("ns16550: Address space type is not mmio\n");
>>> +        return -EINVAL;
>>> +    }
>>
>> The space_id field qualifies the address one, i.e. whether a value of
>> zero can sensibly mean "disabled" depends on the address space. Hence
>> logically the address space check should come first.
>>
>> This is the last thing I'd like to see changed. I won't give the
>> patch my ack though, as I think it should be an Arm maintainer to ack
>> it.
> 
> Acked-by: Julien Grall <julien@xxxxxxx>

Thanks!

Best Regards,
Wei

> 
> Although, a reviewed-by tag from you would be nice as you did most of the 
> review for this patch.
> 
> Cheers,
> 


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