[sbi] Add support for running as a RISC-V SBI payload

Add basic support for running directly on top of SBI, with no UEFI
firmware present.  Build as e.g.:

  make CROSS=riscv64-linux-gnu- bin-riscv64/ipxe.sbi

The resulting binary can be tested in QEMU using e.g.:

  qemu-system-riscv64 -M virt -cpu max -serial stdio \
                      -kernel bin-riscv64/ipxe.sbi

No drivers or executable binary formats are supported yet, but the
unit test suite may be run successfully.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

3 files changed, 51 insertions, 0 deletions

diff --git a/src/arch/riscv/include/bits/umalloc.h b/src/arch/riscv/include/bits/umalloc.h
new file mode 100644
index 000000000..a7171ca2c
--- /dev/null
+++ b/src/arch/riscv/include/bits/umalloc.h
@@ -0,0 +1,14 @@
+#ifndef _BITS_UMALLOC_H
+#define _BITS_UMALLOC_H
+
+/** @file
+ *
+ * RISCV-specific user memory allocation API implementations
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <ipxe/sbi_umalloc.h>
+
+#endif /* _BITS_UMALLOC_H */
diff --git a/src/arch/riscv/include/ipxe/errno/sbi.h b/src/arch/riscv/include/ipxe/errno/sbi.h
new file mode 100644
index 000000000..2428183d4
--- /dev/null
+++ b/src/arch/riscv/include/ipxe/errno/sbi.h
@@ -0,0 +1,19 @@
+#ifndef _IPXE_ERRNO_SBI_H
+#define _IPXE_ERRNO_SBI_H
+
+/**
+ * @file
+ *
+ * RISC-V SBI platform error codes
+ *
+ * We never need to return SBI error codes ourselves, so we
+ * arbitrarily choose to use the Linux error codes as platform error
+ * codes.
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <ipxe/errno/linux.h>
+
+#endif /* _IPXE_ERRNO_SBI_H */
diff --git a/src/arch/riscv/include/ipxe/sbi_umalloc.h b/src/arch/riscv/include/ipxe/sbi_umalloc.h
new file mode 100644
index 000000000..5763239fb
--- /dev/null
+++ b/src/arch/riscv/include/ipxe/sbi_umalloc.h
@@ -0,0 +1,18 @@
+#ifndef _IPXE_SBI_UMALLOC_H
+#define _IPXE_SBI_UMALLOC_H
+
+/** @file
+ *
+ * External memory allocation
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#ifdef UMALLOC_SBI
+#define UMALLOC_PREFIX_sbi
+#else
+#define UMALLOC_PREFIX_sbi __sbi_
+#endif
+
+#endif /* _IPXE_SBI_UMALLOC_H */