On Thu, Sep 12, 2024 at 7:39 PM Raul E Rangel <rrangel@xxxxxxxxxxxx> wrote: > > Revision 3 supports specifying the UART input clock. This allows for > proper computation of the UART divisor when the baud rate is specified. > > The earlycon code can accept the following format (See `parse_options` > in `earlycon.c`.): > * <name>,io|mmio|mmio32|mmio32be,<addr>,<baud>,<uartclk>,<options> > > This change makes it so the uartclk is passed along if it's defined in > the SPCR table. > > Booting with `earlycon` and a SPCR v3 table that has the uartclk and > baud defined: > [ 0.028251] ACPI: SPCR: console: uart,mmio32,0xfedc9000,115200,48000000 > [ 0.028267] earlycon: uart0 at MMIO32 0x00000000fedc9000 (options '115200,48000000') > [ 0.028272] printk: legacy bootconsole [uart0] enabled > > Link: https://learn.microsoft.com/en-us/windows-hardware/drivers/serports/serial-port-console-redirection-table > > Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx> > > --- > > drivers/acpi/spcr.c | 5 ++++- > include/acpi/actbl3.h | 6 +++--- > 2 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c > index cd36a97b0ea2c7..67ae42afcc59ef 100644 > --- a/drivers/acpi/spcr.c > +++ b/drivers/acpi/spcr.c > @@ -209,9 +209,12 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console) > if (!baud_rate) { > snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype, > table->serial_port.address); > - } else { > + } else if (table->header.revision <= 2 || !table->uartclk) { > snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype, > table->serial_port.address, baud_rate); > + } else { > + snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d,%d", uart, iotype, > + table->serial_port.address, baud_rate, table->uartclk); > } > > pr_info("console: %s\n", opts); > diff --git a/include/acpi/actbl3.h b/include/acpi/actbl3.h > index 8f775e3a08fdfb..afe45a2379866a 100644 > --- a/include/acpi/actbl3.h > +++ b/include/acpi/actbl3.h The part of the patch below is outdated - SPCR v4 is supported already. Please rebase on the current mainline kernel source. > @@ -92,10 +92,10 @@ struct acpi_table_slit { > /******************************************************************************* > * > * SPCR - Serial Port Console Redirection table > - * Version 2 > + * Version 3 > * > * Conforms to "Serial Port Console Redirection Table", > - * Version 1.03, August 10, 2015 > + * Version 1.08, October 7, 2021 > * > ******************************************************************************/ > > @@ -120,7 +120,7 @@ struct acpi_table_spcr { > u8 pci_function; > u32 pci_flags; > u8 pci_segment; > - u32 reserved2; > + u32 uartclk; > }; > > /* Masks for pci_flags field above */ > -- > 2.46.0.662.g92d0881bb0-goog >
