[PATCH v2 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 v1:
-   Moved the identical smh_* and semihosting_enabled/disable_semihosting
	code of ARM and RISC-V to lib/semihosting.c
-	Extend the handle_trap() functionality to call disable_semihosting()
	if the cause is a breakpoint (i.e. ebreak instruction)
-	Change our implementation of semihosting_enabled to be exactly the
	same as the way ARM implemented it
-	Additionally enable the CONFIG_SPL_FS_EXT4 and CONFIG_SPL_FS_FAT
	configs for qemu defconfigs so that CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
	gets automatically enabled instead of us #defining it in
	include/configs/qemu-riscv.h

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                     |   2 +
 arch/arm/lib/semihosting.c           | 179 +-------------------------
 arch/riscv/Kconfig                   |  47 +++++++
 arch/riscv/include/asm/semihosting.h |  11 ++
 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                          |   3 +
 lib/Makefile                         |   2 +
 lib/semihosting.c                    | 186 +++++++++++++++++++++++++++
 18 files changed, 331 insertions(+), 178 deletions(-)
 create mode 100644 arch/riscv/include/asm/semihosting.h
 create mode 100644 arch/riscv/lib/semihosting.c
 create mode 100644 lib/semihosting.c

-- 
2.34.1