riscv: add support for supervisor binary interface (SBI)

SBI is runtime service for OS. For an introduction, please refer to
https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.md

Change-Id: Ib6c1f21d2f085f02208305dc4e3a0f970d400c27
Signed-off-by: Xiang Wang <wxjstz@126.com>
Reviewed-on: https://review.coreboot.org/28096
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 121 insertions, 0 deletions

diff --git a/src/arch/riscv/sbi.c b/src/arch/riscv/sbi.c
new file mode 100644
index 0000000000..832d4d3d97
--- /dev/null
+++ b/src/arch/riscv/sbi.c
@@ -0,0 +1,121 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 HardenedLinux
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <mcall.h>
+#include <stdint.h>
+#include <commonlib/compiler.h>
+#include <arch/exception.h>
+#include <sbi.h>
+#include <vm.h>
+#include <console/uart.h>
+#include <console/console.h>
+#include <commonlib/helpers.h>
+
+static uintptr_t send_ipi(uintptr_t *pmask, intptr_t type)
+{
+	uintptr_t mask = mprv_read_uintptr_t(pmask);
+	for (int i = 0; mask; i++) {
+		if (mask & 1) {
+			OTHER_HLS(i)->ipi_pending |= type;
+			/* send soft interrupt to target hart */
+			set_msip(i, 1);
+		}
+		mask = mask >> 1;
+	}
+	return 0;
+}
+
+static uintptr_t sbi_set_timer(uint64_t when)
+{
+	clear_csr(mip, MIP_STIP);
+	set_csr(mie, MIP_MTIP);
+	*(HLS()->timecmp) = when;
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_CONSOLE_SERIAL)
+static uintptr_t sbi_console_putchar(uint8_t ch)
+{
+	uart_tx_byte(CONFIG_UART_FOR_CONSOLE, ch);
+	return 0;
+}
+
+static uintptr_t sbi_console_getchar(void)
+{
+	return uart_rx_byte(CONFIG_UART_FOR_CONSOLE);
+}
+#endif
+
+static uintptr_t sbi_clear_ipi(void)
+{
+	clear_csr(mip, MIP_SSIP);
+	return 0;
+}
+
+
+/*
+ * sbi is triggered by the s-mode ecall
+ * parameter : register a0 a1 a2
+ * function  : register a7
+ * return    : register a0
+ */
+void handle_sbi(trapframe *tf)
+{
+	uintptr_t ret = 0;
+	uintptr_t arg0 = tf->gpr[10];
+	__unused uintptr_t arg1 = tf->gpr[11];
+	uintptr_t which = tf->gpr[17];
+
+	switch (which) {
+	case SBI_SET_TIMER:
+#if __riscv_xlen == 32
+		ret = sbi_set_timer(arg0 + ((uint64_t)arg1 << 32));
+#else
+		ret = sbi_set_timer(arg0);
+#endif
+		break;
+#if IS_ENABLED(CONFIG_CONSOLE_SERIAL)
+	case SBI_CONSOLE_PUTCHAR:
+		ret = sbi_console_putchar(arg0);
+		break;
+	case SBI_CONSOLE_GETCHAR:
+		ret = sbi_console_getchar();
+		break;
+#endif
+	case SBI_CLEAR_IPI:
+		ret = sbi_clear_ipi();
+		break;
+	case SBI_SEND_IPI:
+		ret = send_ipi((uintptr_t *)arg0, IPI_SOFT);
+		break;
+	case SBI_REMOTE_FENCE_I:
+		ret = send_ipi((uintptr_t *)arg0, IPI_FENCE_I);
+		break;
+	case SBI_REMOTE_SFENCE_VMA:
+		ret = send_ipi((uintptr_t *)arg0, IPI_SFENCE_VMA);
+		break;
+	case SBI_REMOTE_SFENCE_VMA_ASID:
+		ret = send_ipi((uintptr_t *)arg0, IPI_SFENCE_VMA_ASID);
+		break;
+	case SBI_SHUTDOWN:
+		ret = send_ipi((uintptr_t *)arg0, IPI_SHUTDOWN);
+		break;
+	default:
+		ret = -38;
+		break;
+	}
+	tf->gpr[10] = ret;
+	write_csr(mepc, read_csr(mepc) + 4);
+}