[PATCH v4 0/3] Add riscv semihosting support in u-boot

[Kautuk Consul <kconsul@ventanamicro.com>]

Semihosting is a mechanism that enables code running on
a target to communicate and use the Input/Output
facilities on a host computer that is running a debugger.
This patchset adds support for semihosting in u-boot
for RISCV64 targets.

CHANGES since v2 and v3:
-	v2: Move the arch/arm/Kconfig common *SEMIHOSTING* config
	options from arch/arm/Kconfig to lib/Kconfig.
-	v2: Improve the *SEMIHOSTING_FALLBACK config options in
	lib/Kconfig to depend on RISCV or ARM64.
-	v2: Remove the arch/riscv/include/asm/semhosting.h file.
-	v2: Improve the arch/riscv/lib/semihosting.c by removing the
	jump statement and moving the .align 4 to before the 2
	.option directives.
-	v3: Additionally check for the RISCV config option in the "depends"
	of the SPL_SEMIHOSTING_FALLBACK config option in lib/Kconfig.

Compilation and test commands for SPL and S-mode configurations
=================================================================

U-Boot S-mode on QEMU virt
----------------------------
// Compilation of S-mode u-boot
ARCH=riscv
CROSS_COMPILE=riscv64-unknown-linux-gnu-
make qemu-riscv64_smode_defconfig
make
// Run riscv 64-bit u-boot with opensbi on qemu
qemu-system-riscv64 -M virt -m 256M -display none -serial stdio -bios\
opensbi/build/platform/generic/firmware/fw_jump.bin -kernel\
u-boot/u-boot.bin

U-Boot SPL on QEMU virt
------------------------
// Compilation of u-boot-spl
ARCH=riscv
CROSS_COMPILE=riscv64-unknown-linux-gnu-
make qemu-riscv64_spl_defconfig
make OPENSBI=opensbi/build/platform/generic/firmware/fw_dynamic.bin
// Run 64-bit u-boot-spl in qemu
qemu-system-riscv64 -M virt -m 256M -display none -serial stdio -bios\
u-boot/spl/u-boot-spl.bin -device\
loader,file=u-boot/u-boot.itb,addr=0x80200000

Kautuk Consul (3):
  lib: Add common semihosting library
  arch/riscv: add semihosting support for RISC-V
  board: qemu-riscv: enable semihosting

 arch/arm/Kconfig                     |  46 -------
 arch/arm/lib/semihosting.c           | 181 +-------------------------
 arch/riscv/include/asm/spl.h         |   1 +
 arch/riscv/lib/Makefile              |   2 +
 arch/riscv/lib/interrupts.c          |  11 ++
 arch/riscv/lib/semihosting.c         |  24 ++++
 configs/qemu-riscv32_defconfig       |   4 +
 configs/qemu-riscv32_smode_defconfig |   4 +
 configs/qemu-riscv32_spl_defconfig   |   7 +
 configs/qemu-riscv64_defconfig       |   4 +
 configs/qemu-riscv64_smode_defconfig |   4 +
 configs/qemu-riscv64_spl_defconfig   |   7 +
 include/semihosting.h                |  11 ++
 lib/Kconfig                          |  46 +++++++
 lib/Makefile                         |   2 +
 lib/semihosting.c                    | 186 +++++++++++++++++++++++++++
 16 files changed, 314 insertions(+), 226 deletions(-)
 create mode 100644 arch/riscv/lib/semihosting.c
 create mode 100644 lib/semihosting.c

-- 
2.34.1