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-rw-r--r--arch/powerpc/Kconfig.debug23
-rw-r--r--arch/powerpc/include/asm/udbg.h1
-rw-r--r--arch/powerpc/kernel/udbg.c3
-rw-r--r--arch/powerpc/sysdev/Makefile2
-rw-r--r--arch/powerpc/sysdev/udbg_memcons.c105
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;
+}