Both OpenOCD and QEMU have a semihosting implementation that provides a
console suitable for low level debugging. Add a DEBUG_LL implementation
that is usable when QEMU is called with
--semihosting-config chardev=serial0
or following OpenOCD is executed:
arm semihosting enable
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
arch/arm/include/asm/debug_ll.h | 4 ++++
arch/arm/include/asm/semihosting.h | 32 ++++++++++++++++++++++++++++++
common/Kconfig.debug_ll | 13 ++++++++++++
drivers/firmware/Kconfig | 1 +
include/debug_ll/semihosting.h | 15 ++++++++++++++
5 files changed, 65 insertions(+)
create mode 100644 include/debug_ll/semihosting.h
diff --git a/arch/arm/include/asm/debug_ll.h b/arch/arm/include/asm/debug_ll.h
index 999f1cb831a8..bac0b2106936 100644
--- a/arch/arm/include/asm/debug_ll.h
+++ b/arch/arm/include/asm/debug_ll.h
@@ -35,6 +35,10 @@
#include <mach/layerscape/debug_ll.h>
#endif
+#ifdef CONFIG_DEBUG_SEMIHOSTING
+#include <debug_ll/semihosting.h>
+#endif
+
#ifdef CONFIG_DEBUG_QEMU_ARM64_VIRT
#define DEBUG_LL_UART_ADDR 0x9000000
#include <debug_ll/pl011.h>
diff --git a/arch/arm/include/asm/semihosting.h b/arch/arm/include/asm/semihosting.h
index c18aa1a5fef5..2219e858d040 100644
--- a/arch/arm/include/asm/semihosting.h
+++ b/arch/arm/include/asm/semihosting.h
@@ -4,5 +4,37 @@
#define __ASM_ARM_SEMIHOSTING_H
#include <asm-generic/semihosting.h>
+#include <asm/unified.h>
+
+static inline void semihosting_putc(void *unused, int c)
+{
+ /* We may not be relocated yet here, so we push
+ * to stack and take address of that
+ */
+#ifdef CONFIG_CPU_64
+ asm volatile (
+ "stp %0, xzr, [sp, #-16]!\n"
+ "mov x1, sp\n"
+ "mov x0, #0x03\n"
+ "hlt #0xf000\n"
+ "add sp, sp, #16\n"
+ : /* No outputs */
+ : "r" ((long)c)
+ : "x0", "x1", "x2", "x3", "x12", "memory"
+ );
+#else
+ asm volatile (
+ "push {%0}\n"
+ "mov r1, sp\n"
+ "mov r0, #0x03\n"
+ ARM( "bkpt #0x123456\n")
+ THUMB( "bkpt #0xAB\n")
+ "pop {%0}\n"
+ : /* No outputs */
+ : "r" (c)
+ : "r0", "r1", "r2", "r3", "r12", "memory"
+ );
+#endif
+}
#endif
diff --git a/common/Kconfig.debug_ll b/common/Kconfig.debug_ll
index 472048177f8b..3f6f3e7c3bdb 100644
--- a/common/Kconfig.debug_ll
+++ b/common/Kconfig.debug_ll
@@ -337,6 +337,19 @@ config DEBUG_QEMU_ARM64_VIRT
bool "QEMU ARM64 Virt PL011 console"
depends on ARCH_ARM64_VIRT
+config DEBUG_SEMIHOSTING
+ bool "Semihosting console"
+ depends on SEMIHOSTING
+ help
+ Semihosting enables code to use the I/O facilities on a
+ host debugger/emulator through a simple supervisor call.
+ The host debugger or emulator must have semihosting enabled
+ for the supervisor call to be trapped, otherwise barebox
+ will crash.
+
+ Say Y here if you want low-level debugging support
+ using semihosting writec.
+
endchoice
config DEBUG_LL_NS16550
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 89c8bdeda3f0..264f7b2a5a65 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -3,6 +3,7 @@ menu "Firmware Drivers"
config SEMIHOSTING
bool
+ select HAS_DEBUG_LL
config FIRMWARE_ALTERA_SERIAL
bool "Altera SPI programming"
diff --git a/include/debug_ll/semihosting.h b/include/debug_ll/semihosting.h
new file mode 100644
index 000000000000..125d42ee88de
--- /dev/null
+++ b/include/debug_ll/semihosting.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __DEBUG_LL_SEMIHOSTING_H
+#define __DEBUG_LL_SEMIHOSTING_H
+
+#include <asm/semihosting.h>
+#include <linux/stddef.h>
+
+#ifdef CONFIG_DEBUG_SEMIHOSTING
+static inline void PUTC_LL(char c)
+{
+ semihosting_putc(NULL, c);
+}
+#endif
+
+#endif /* __DEBUG_LL_ARM_SEMIHOSTING_H */
--
2.39.2
