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powerpc/microwatt: Use standard 16550 UART for console

Browse source 
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
This commit is contained in:
Benjamin Herrenschmidt 2021-06-18 13:46:32 +10:00 committed by Michael Ellerman
parent aa9c5adf2f
commit 48b545b801
4 changed files with 63 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
arch/powerpc/boot/dts/microwatt.dts
View file

@ -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 @@ PowerPC,Microwatt@0 {
};
};
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 @@ ICS: interrupt-controller@5000 {
#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;
};
};

39
arch/powerpc/kernel/udbg_16550.c
View file

@ -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 */

1
arch/powerpc/platforms/microwatt/Kconfig
View file

@ -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.

2
arch/powerpc/platforms/microwatt/setup.c
View file

@ -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,
};