MIPS: SEAD3: Probe UARTs using DT

Probe the UARTs on SEAD3 boards using device tree rather than platform
code, in order to reduce the amount of the latter. This requires that
CONFIG_SERIAL_OF_PLATFORM be enabled, so enable it in sead3_defconfig.
The SEAD3 DT shim code is extended to read bootloader environment
variables to determine the appropriate UART & mode for kernel console
output & set the stdout-path property of the chosen node accordingly.

In contrast to the old platform code, which appears to have only ever
set "console=ttyS0,38400n8r" with the code in console_config never
having an effect, this will honor the "yamontty" environment variable to
select between the 2 UARTs on the board and then check the "modetty0" or
"modetty1" variable as appropriate to determine the UART configuration.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14048/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/arch/mips/boot/dts/mti/sead3.dts b/arch/mips/boot/dts/mti/sead3.dts
index 051b3a9e5a9e..3f681c530082 100644
--- a/arch/mips/boot/dts/mti/sead3.dts
+++ b/arch/mips/boot/dts/mti/sead3.dts
@@ -12,6 +12,15 @@
         compatible = "mti,sead-3";
         interrupt-parent = <&gic>;
 
+        chosen {
+                stdout-path = "uart1:115200";
+        };
+
+        aliases {
+                uart0 = &uart0;
+                uart1 = &uart1;
+        };
+
         cpus {
                 cpu@0 {
                         compatible = "mti,mips14KEc", "mti,mips14Kc";
@@ -50,4 +59,32 @@
                         interrupts = <GIC_LOCAL 1 IRQ_TYPE_NONE>;
                 };
         };
+
+        /* UART connected to FTDI & miniUSB socket */
+        uart0: uart@1f000900 {
+                compatible = "ns16550a";
+                reg = <0x1f000900 0x20>;
+                reg-io-width = <4>;
+                reg-shift = <2>;
+
+                clock-frequency = <14745600>;
+
+                interrupts = <3>; /* GIC 3 or CPU 4 */
+
+                no-loopback-test;
+        };
+
+        /* UART connected to RS232 socket */
+        uart1: uart@1f000800 {
+                compatible = "ns16550a";
+                reg = <0x1f000800 0x20>;
+                reg-io-width = <4>;
+                reg-shift = <2>;
+
+                clock-frequency = <14745600>;
+
+                interrupts = <2>; /* GIC 2 or CPU 4 */
+
+                no-loopback-test;
+        };
 };