[PATCH v2 2/2] ACPI: SPCR: Support UART clock frequency field

[Markus Probst]

The Microsoft Serial Port Console Redirection (SPCR) specification
revision 1.08 comprises additional field: UART Clock Frequency [1].

It contains a non-zero value indicating the UART clock frequency in Hz.

Link: https://learn.microsoft.com/en-us/windows-hardware/drivers/serports/serial-port-console-redirection-table [1]
Signed-off-by: Markus Probst <markus.probst@xxxxxxxxx>
---
 drivers/acpi/spcr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index cfacbe53f279..16f94073fde6 100644
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c
@@ -228,7 +228,7 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
 	pr_info("console: %s\n", opts);
 
 	if (enable_earlycon)
-		setup_earlycon(opts, 0);
+		setup_earlycon(opts, table->header.revision >= 3 ? table->uart_clk_freq : 0);
 
 	if (enable_console)
 		err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);

-- 
2.53.0