diff options
| -rw-r--r-- | arch/powerpc/Kconfig.debug | 23 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/udbg.h | 1 | ||||
| -rw-r--r-- | arch/powerpc/kernel/udbg.c | 3 | ||||
| -rw-r--r-- | arch/powerpc/sysdev/Makefile | 2 | ||||
| -rw-r--r-- | arch/powerpc/sysdev/udbg_memcons.c | 105 |
5 files changed, 134 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 5416e28a753..863d877e0b5 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -262,8 +262,31 @@ config PPC_EARLY_DEBUG_OPAL_HVSI Select this to enable early debugging for the PowerNV platform using an "hvsi" console +config PPC_EARLY_DEBUG_MEMCONS + bool "In memory console" + help + Select this to enable early debugging using an in memory console. + This console provides input and output buffers stored within the + kernel BSS and should be safe to select on any system. A debugger + can then be used to read kernel output or send input to the console. endchoice +config PPC_MEMCONS_OUTPUT_SIZE + int "In memory console output buffer size" + depends on PPC_EARLY_DEBUG_MEMCONS + default 4096 + help + Selects the size of the output buffer (in bytes) of the in memory + console. + +config PPC_MEMCONS_INPUT_SIZE + int "In memory console input buffer size" + depends on PPC_EARLY_DEBUG_MEMCONS + default 128 + help + Selects the size of the input buffer (in bytes) of the in memory + console. + config PPC_EARLY_DEBUG_OPAL def_bool y depends on PPC_EARLY_DEBUG_OPAL_RAW || PPC_EARLY_DEBUG_OPAL_HVSI diff --git a/arch/powerpc/include/asm/udbg.h b/arch/powerpc/include/asm/udbg.h index 5a7510e9d09..dc590919f8e 100644 --- a/arch/powerpc/include/asm/udbg.h +++ b/arch/powerpc/include/asm/udbg.h @@ -52,6 +52,7 @@ extern void __init udbg_init_40x_realmode(void); extern void __init udbg_init_cpm(void); extern void __init udbg_init_usbgecko(void); extern void __init udbg_init_wsp(void); +extern void __init udbg_init_memcons(void); extern void __init udbg_init_ehv_bc(void); extern void __init udbg_init_ps3gelic(void); extern void __init udbg_init_debug_opal_raw(void); diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c index 13b86709349..9d3fdcd6629 100644 --- a/arch/powerpc/kernel/udbg.c +++ b/arch/powerpc/kernel/udbg.c @@ -64,6 +64,9 @@ void __init udbg_early_init(void) udbg_init_usbgecko(); #elif defined(CONFIG_PPC_EARLY_DEBUG_WSP) udbg_init_wsp(); +#elif defined(CONFIG_PPC_EARLY_DEBUG_MEMCONS) + /* In memory console */ + udbg_init_memcons(); #elif defined(CONFIG_PPC_EARLY_DEBUG_EHV_BC) udbg_init_ehv_bc(); #elif defined(CONFIG_PPC_EARLY_DEBUG_PS3GELIC) diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile index b0a518e9759..99464a7bdb3 100644 --- a/arch/powerpc/sysdev/Makefile +++ b/arch/powerpc/sysdev/Makefile @@ -64,6 +64,8 @@ endif obj-$(CONFIG_PPC_SCOM) += scom.o +obj-$(CONFIG_PPC_EARLY_DEBUG_MEMCONS) += udbg_memcons.o + subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror obj-$(CONFIG_PPC_XICS) += xics/ diff --git a/arch/powerpc/sysdev/udbg_memcons.c b/arch/powerpc/sysdev/udbg_memcons.c new file mode 100644 index 00000000000..ce5a7b489e4 --- /dev/null +++ b/arch/powerpc/sysdev/udbg_memcons.c @@ -0,0 +1,105 @@ +/* + * A udbg backend which logs messages and reads input from in memory + * buffers. + * + * The console output can be read from memcons_output which is a + * circular buffer whose next write position is stored in memcons.output_pos. + * + * Input may be passed by writing into the memcons_input buffer when it is + * empty. The input buffer is empty when both input_pos == input_start and + * *input_start == '\0'. + * + * Copyright (C) 2003-2005 Anton Blanchard and Milton Miller, IBM Corp + * Copyright (C) 2013 Alistair Popple, IBM Corp + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <asm/barrier.h> +#include <asm/page.h> +#include <asm/processor.h> +#include <asm/udbg.h> + +struct memcons { + char *output_start; + char *output_pos; + char *output_end; + char *input_start; + char *input_pos; + char *input_end; +}; + +static char memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE]; +static char memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE]; + +struct memcons memcons = { + .output_start = memcons_output, + .output_pos = memcons_output, + .output_end = &memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE], + .input_start = memcons_input, + .input_pos = memcons_input, + .input_end = &memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE], +}; + +void memcons_putc(char c) +{ + char *new_output_pos; + + *memcons.output_pos = c; + wmb(); + new_output_pos = memcons.output_pos + 1; + if (new_output_pos >= memcons.output_end) + new_output_pos = memcons.output_start; + + memcons.output_pos = new_output_pos; +} + +int memcons_getc_poll(void) +{ + char c; + char *new_input_pos; + + if (*memcons.input_pos) { + c = *memcons.input_pos; + + new_input_pos = memcons.input_pos + 1; + if (new_input_pos >= memcons.input_end) + new_input_pos = memcons.input_start; + else if (*new_input_pos == '\0') + new_input_pos = memcons.input_start; + + *memcons.input_pos = '\0'; + wmb(); + memcons.input_pos = new_input_pos; + return c; + } + + return -1; +} + +int memcons_getc(void) +{ + int c; + + while (1) { + c = memcons_getc_poll(); + if (c == -1) + cpu_relax(); + else + break; + } + + return c; +} + +void udbg_init_memcons(void) +{ + udbg_putc = memcons_putc; + udbg_getc = memcons_getc; + udbg_getc_poll = memcons_getc_poll; +} |