On Wed, Mar 14, 2018 at 2:36 AM, Daniel Kurtz <djku...@chromium.org> wrote:
> AMD Carrizo / Stoneyridge use a DesignWare 8250 UART that uses a special
> earlycon setup handler to configure its input clock in order to compute
> baud rate divisor registers.
> Detect them by examining the OEMID field in the SPCR header, and pass
> then pass uart type amdcz to earlycon.
Thanks, this is what I meant.
Reviewed-by: Andy Shevchenko <andy.shevche...@gmail.com>
> Signed-off-by: Daniel Kurtz <djku...@chromium.org>
> ---
> drivers/acpi/spcr.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> index 9d52743080a4..52d840d0e05b 100644
> --- a/drivers/acpi/spcr.c
> +++ b/drivers/acpi/spcr.c
> @@ -73,6 +73,24 @@ static bool xgene_8250_erratum_present(struct
> acpi_table_spcr *tb)
> return xgene_8250;
> }
>
> +/*
> + * AMD Carrizo / Stoneyridge use a DesignWare 8250 UART that uses a special
> + * earlycon setup handler to configure its input clock in order to compute
> + * baud rate divisor registers.
> + * Detect them by examining the OEM fields in the SPCR header.
> + */
> +static bool amdcz_present(struct acpi_table_spcr *tb)
> +{
> + if (memcmp(tb->header.oem_id, "AMDCZ ", ACPI_OEM_ID_SIZE))
> + return false;
> +
> + if (memcmp(tb->header.oem_table_id, "AMDCZ ",
> + ACPI_OEM_TABLE_ID_SIZE))
> + return false;
> +
> + return true;
> +}
> +
> /**
> * acpi_parse_spcr() - parse ACPI SPCR table and add preferred console
> *
> @@ -189,6 +207,11 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool
> enable_console)
> uart = "qdf2400_e44";
> }
>
> + if (amdcz_present(table)) {
> + if (enable_earlycon)
> + uart = "amdcz";
> + }
> +
> if (xgene_8250_erratum_present(table)) {
> iotype = "mmio32";
>
> --
> 2.16.2.804.g6dcf76e118-goog
>
--
With Best Regards,
Andy Shevchenko
