MIPS, ttyFDC: Add early FDC console support

Add support for early console of MIPS Fast Debug Channel (FDC) on
channel 1 with a call very early from the MIPS setup_arch().

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9145/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index 39469ca4231c..e0c18e5b7057 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -437,4 +437,17 @@ config MIPS_EJTAG_FDC_TTY
 
           If unsure, say N.
 
+config MIPS_EJTAG_FDC_EARLYCON
+        bool "Early FDC console"
+        depends on MIPS_EJTAG_FDC_TTY
+        help
+          This registers a console on FDC channel 1 very early during boot (from
+          MIPS arch code). This is useful for bring-up and debugging early boot
+          issues.
+
+          Do not enable unless there is a debug probe attached to drain the FDC
+          TX FIFO.
+
+          If unsure, say N.
+
 endif # TTY