powerpc/microwatt: Use standard 16550 UART for console

This adds support to the Microwatt platform to use the standard
16550-style UART which available in the standalone Microwatt FPGA.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/YMwXGCTzedpQje7r@thinks.paulus.ozlabs.org

diff --git a/arch/powerpc/boot/dts/microwatt.dts b/arch/powerpc/boot/dts/microwatt.dts
index 04e5dd9..974abbd 100644 (file)
--- a/arch/powerpc/boot/dts/microwatt.dts
+++ b/arch/powerpc/boot/dts/microwatt.dts
@@ -6,6 +6,10 @@
        model-name = "microwatt";
        compatible = "microwatt-soc";
 
+       aliases {
+               serial0 = &UART0;
+       };
+
        reserved-memory {
                #size-cells = <0x02>;
                #address-cells = <0x02>;
@@ -89,12 +93,6 @@
                };
        };
 
-       chosen {
-               bootargs = "";
-               ibm,architecture-vec-5 = [19 00 10 00 00 00 00 00 00 00 00 00 00 00 00 00
-                                         00 00 00 00 00 00 00 00 40 00 40];
-       };
-
        soc@c0000000 {
                compatible = "simple-bus";
                #address-cells = <1>;
@@ -119,5 +117,22 @@
                        #interrupt-cells = <2>;
                };
 
+               UART0: serial@2000 {
+                       device_type = "serial";
+                       compatible = "ns16550";
+                       reg = <0x2000 0x8>;
+                       clock-frequency = <100000000>;
+                       current-speed = <115200>;
+                       reg-shift = <2>;
+                       fifo-size = <16>;
+                       interrupts = <0x10 0x1>;
+               };
+       };
+
+       chosen {
+               bootargs = "";
+               ibm,architecture-vec-5 = [19 00 10 00 00 00 00 00 00 00 00 00 00 00 00 00
+                                         00 00 00 00 00 00 00 00 40 00 40];
+               stdout-path = &UART0;
        };
 };

diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index 9356b60..8513aa4 100644 (file)
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -296,3 +296,42 @@ void __init udbg_init_40x_realmode(void)
 }
 
 #endif /* CONFIG_PPC_EARLY_DEBUG_40x */
+
+#ifdef CONFIG_PPC_EARLY_DEBUG_MICROWATT
+
+#define UDBG_UART_MW_ADDR      ((void __iomem *)0xc0002000)
+
+static u8 udbg_uart_in_isa300_rm(unsigned int reg)
+{
+       uint64_t msr = mfmsr();
+       uint8_t  c;
+
+       mtmsr(msr & ~(MSR_EE|MSR_DR));
+       isync();
+       eieio();
+       c = __raw_rm_readb(UDBG_UART_MW_ADDR + (reg << 2));
+       mtmsr(msr);
+       isync();
+       return c;
+}
+
+static void udbg_uart_out_isa300_rm(unsigned int reg, u8 val)
+{
+       uint64_t msr = mfmsr();
+
+       mtmsr(msr & ~(MSR_EE|MSR_DR));
+       isync();
+       eieio();
+       __raw_rm_writeb(val, UDBG_UART_MW_ADDR + (reg << 2));
+       mtmsr(msr);
+       isync();
+}
+
+void __init udbg_init_debug_microwatt(void)
+{
+       udbg_uart_in = udbg_uart_in_isa300_rm;
+       udbg_uart_out = udbg_uart_out_isa300_rm;
+       udbg_use_uart();
+}
+
+#endif /* CONFIG_PPC_EARLY_DEBUG_MICROWATT */

diff --git a/arch/powerpc/platforms/microwatt/Kconfig b/arch/powerpc/platforms/microwatt/Kconfig
index b52c869..50ed0ce 100644 (file)
--- a/arch/powerpc/platforms/microwatt/Kconfig
+++ b/arch/powerpc/platforms/microwatt/Kconfig
@@ -6,6 +6,7 @@ config PPC_MICROWATT
        select PPC_ICS_NATIVE
        select PPC_ICP_NATIVE
        select PPC_NATIVE
+       select PPC_UDBG_16550
        help
           This option enables support for FPGA-based Microwatt implementations.
 

diff --git a/arch/powerpc/platforms/microwatt/setup.c b/arch/powerpc/platforms/microwatt/setup.c
index 1c1b779..0b02603 100644 (file)
--- a/arch/powerpc/platforms/microwatt/setup.c
+++ b/arch/powerpc/platforms/microwatt/setup.c
@@ -14,6 +14,7 @@
 #include <asm/machdep.h>
 #include <asm/time.h>
 #include <asm/xics.h>
+#include <asm/udbg.h>
 
 static void __init microwatt_init_IRQ(void)
 {
@@ -35,5 +36,6 @@ define_machine(microwatt) {
        .name                   = "microwatt",
        .probe                  = microwatt_probe,
        .init_IRQ               = microwatt_init_IRQ,
+       .progress               = udbg_progress,
        .calibrate_decr         = generic_calibrate_decr,
 };