1 files changed, 72 insertions, 0 deletions
diff --git a/lib/sbi/sbi_ecall_dbcn.c b/lib/sbi/sbi_ecall_dbcn.c
new file mode 100644
index 0000000..fe7e175
--- /dev/null
+++ b/lib/sbi/sbi_ecall_dbcn.c
@@ -0,0 +1,72 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <apatel@ventanamicro.com>
+ */
+
+#include <sbi/sbi_console.h>
+#include <sbi/sbi_domain.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_ecall.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_trap.h>
+#include <sbi/riscv_asm.h>
+
+static int sbi_ecall_dbcn_handler(unsigned long extid, unsigned long funcid,
+				  const struct sbi_trap_regs *regs,
+				  unsigned long *out_val,
+				  struct sbi_trap_info *out_trap)
+{
+	ulong smode = (csr_read(CSR_MSTATUS) & MSTATUS_MPP) >>
+			MSTATUS_MPP_SHIFT;
+
+	switch (funcid) {
+	case SBI_EXT_DBCN_CONSOLE_WRITE:
+	case SBI_EXT_DBCN_CONSOLE_READ:
+		/*
+		 * On RV32, the M-mode can only access the first 4GB of
+		 * the physical address space because M-mode does not have
+		 * MMU to access full 34-bit physical address space.
+		 *
+		 * Based on above, we simply fail if the upper 32bits of
+		 * the physical address (i.e. a2 register) is non-zero on
+		 * RV32.
+		 */
+#if __riscv_xlen == 32
+		if (regs->a2)
+			return SBI_ERR_FAILED;
+#endif
+		if (!sbi_domain_check_addr_range(sbi_domain_thishart_ptr(),
+					regs->a1, regs->a0, smode,
+					SBI_DOMAIN_READ|SBI_DOMAIN_WRITE))
+			return SBI_ERR_INVALID_PARAM;
+		if (funcid == SBI_EXT_DBCN_CONSOLE_WRITE)
+			*out_val = sbi_nputs((const char *)regs->a1, regs->a0);
+		else
+			*out_val = sbi_ngets((char *)regs->a1, regs->a0);
+		return 0;
+	case SBI_EXT_DBCN_CONSOLE_WRITE_BYTE:
+		sbi_putc(regs->a0);
+		return 0;
+	default:
+		break;
+	}
+
+	return SBI_ENOTSUPP;
+}
+
+static int sbi_ecall_dbcn_probe(unsigned long extid, unsigned long *out_val)
+{
+	*out_val = sbi_console_get_device() ? 1 : 0;
+	return 0;
+}
+
+struct sbi_ecall_extension ecall_dbcn = {
+	.extid_start = SBI_EXT_DBCN,
+	.extid_end = SBI_EXT_DBCN,
+	.handle = sbi_ecall_dbcn_handler,
+	.probe = sbi_ecall_dbcn_probe,
+};