Change in coreboot[master]: superio/aspeed/common: add workaround for serial routing delay quirk

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/36591 )

Change subject: superio/aspeed/common: add workaround for serial routing delay quirk
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superio/aspeed/common: add workaround for serial routing delay quirk

Some mainboards with an ASPEED BMC do the serial routing setup in the
BMC boot phase on cold boot. This results in scrambled console output
when this is not finished fast enough.

This adds a delay of 500ms as workaround in the BMCs uart setup that
can be selected at mainboard level.

A user may disable the workaround when using another BMC firmware like
OpenBMC, u-bmc or some custom BMC bootloader with fast serial setup.

Change-Id: I7d6599b76384fc94a00a9cfc1794ebfe34863ff9
Signed-off-by: Michael Niewöhner 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36591
Reviewed-by: Arthur Heymans 
Tested-by: build bot (Jenkins) 
---
M src/superio/aspeed/common/Kconfig
M src/superio/aspeed/common/early_serial.c
2 files changed, 21 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Arthur Heymans: Looks good to me, approved

diff --git a/src/superio/aspeed/common/Kconfig b/src/superio/aspeed/common/Kconfig
index 3f0dabb..f310f3e 100644
--- a/src/superio/aspeed/common/Kconfig
+++ b/src/superio/aspeed/common/Kconfig
@@ -20,3 +20,20 @@
 config SUPERIO_ASPEED_COMMON_PRE_RAM
    bool
    default n
+
+config SUPERIO_ASPEED_HAS_UART_DELAY_WORKAROUND
+	bool
+	default n
+
+config SUPERIO_ASPEED_USE_UART_DELAY_WORKAROUND
+	bool "Workaround for BMC serial console setup bug"
+	depends on CONSOLE_SERIAL && SUPERIO_ASPEED_HAS_UART_DELAY_WORKAROUND
+	default y
+	help
+	  Some mainboards with an ASPEED BMC have scrambled console output in early boot phases
+	  because the serial output routing is not set up fast enough by the BMC. By enabling
+	  this a delay of 500ms gets added before setting up the console and before any console
+	  output gets printed.
+
+	  Note: this problem may disappear with future BMC firmware versions. Another approach
+	  is using a different BMC firmware like OpenBMC, u-bmc, ...
diff --git a/src/superio/aspeed/common/early_serial.c b/src/superio/aspeed/common/early_serial.c
index 7ac9474..d2de8ed 100644
--- a/src/superio/aspeed/common/early_serial.c
+++ b/src/superio/aspeed/common/early_serial.c
@@ -35,6 +35,7 @@
  */

#include <arch/io.h>
+#include <delay.h>
 #include <device/pnp_def.h>
 #include <device/pnp_ops.h>
 #include <stdint.h>
@@ -67,4 +68,7 @@
    pnp_set_iobase(dev, PNP_IDX_IO0, iobase);
    pnp_set_enable(dev, 1);
    pnp_exit_conf_state(dev);
+
+	if (CONFIG(SUPERIO_ASPEED_USE_UART_DELAY_WORKAROUND))
+		mdelay(500);
 }