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>

src/arch/riscv/Makefile.inc

@@ -50,6 +50,7 @@ bootblock-y += trap_util.S
 bootblock-y += trap_handler.c
 bootblock-y += fp_asm.S
 bootblock-y += misaligned.c
+bootblock-y += sbi.c
 bootblock-y += mcall.c
 bootblock-y += virtual_memory.c
 bootblock-y += boot.c
@@ -118,6 +119,7 @@ ramstage-y += trap_util.S
 ramstage-y += trap_handler.c
 ramstage-y += fp_asm.S
 ramstage-y += misaligned.c
+ramstage-y += sbi.c
 ramstage-y += virtual_memory.c
 ramstage-y += stages.c
 ramstage-y += misc.c

src/arch/riscv/include/sbi.h

@@ -0,0 +1,37 @@
+/*
+ * 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.
+ */
+
+#ifndef RISCV_SBI_H
+#define RISCV_SBI_H
+
+#define SBI_SET_TIMER              0
+#define SBI_CONSOLE_PUTCHAR        1
+#define SBI_CONSOLE_GETCHAR        2
+#define SBI_CLEAR_IPI              3
+#define SBI_SEND_IPI               4
+#define SBI_REMOTE_FENCE_I         5
+#define SBI_REMOTE_SFENCE_VMA      6
+#define SBI_REMOTE_SFENCE_VMA_ASID 7
+#define SBI_SHUTDOWN               8
+
+#define IPI_SOFT            1
+#define IPI_FENCE_I         2
+#define IPI_SFENCE_VMA      4
+#define IPI_SFENCE_VMA_ASID 8
+#define IPI_SHUTDOWN        16
+
+void handle_sbi(trapframe *tf);
+
+#endif /* RISCV_SBI_H */

src/arch/riscv/include/vm.h

@@ -102,6 +102,14 @@ DEFINE_MPRV_WRITE(mprv_write_u64, uint64_t, sd)
 DEFINE_MPRV_WRITE(mprv_write_long, long, sd)
 DEFINE_MPRV_WRITE(mprv_write_ulong, unsigned long, sd)
 
+#if __riscv_xlen == 32
+	DEFINE_MPRV_READ(mprv_read_uintptr_t, uintptr_t, lw)
+	DEFINE_MPRV_READ(mprv_write_uintptr_t, uintptr_t, sw)
+#elif __riscv_xlen == 64
+	DEFINE_MPRV_READ(mprv_read_uintptr_t, uintptr_t, ld)
+	DEFINE_MPRV_READ(mprv_write_uintptr_t, uintptr_t, sd)
+#endif
+
 #undef DEFINE_MPRV_READ_FLAGS
 #undef DEFINE_MPRV_READ
 #undef DEFINE_MPRV_READ_MXR

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);
+}

src/arch/riscv/trap_handler.c

@@ -19,6 +19,8 @@
 #include <console/console.h>
 #include <string.h>
 #include <vm.h>
+#include <mcall.h>
+#include <sbi.h>
 
 static const char *const exception_names[] = {
 	"Instruction address misaligned",
@@ -91,6 +93,20 @@ static void interrupt_handler(trapframe *tf)
 		clear_csr(mie, MIP_MTIP);
 		set_csr(mip, MIP_STIP);
 
+		break;
+	case IRQ_M_SOFT:
+		if (HLS()->ipi_pending & IPI_SOFT) {
+			set_csr(mip, MIP_SSIP);
+		} else if (HLS()->ipi_pending & IPI_FENCE_I) {
+			asm volatile("fence.i");
+		} else if (HLS()->ipi_pending & IPI_SFENCE_VMA) {
+			asm volatile("sfence.vma");
+		} else if (HLS()->ipi_pending & IPI_SFENCE_VMA_ASID) {
+			asm volatile("sfence.vma");
+		} else if (HLS()->ipi_pending & IPI_SHUTDOWN) {
+			while (HLS()->ipi_pending & IPI_SHUTDOWN)
+				asm volatile("wfi");
+		}
 		break;
 	default:
 		printk(BIOS_EMERG, "======================================\n");
@@ -117,11 +133,13 @@ void trap_handler(trapframe *tf)
 		case CAUSE_LOAD_ACCESS:
 		case CAUSE_STORE_ACCESS:
 		case CAUSE_USER_ECALL:
-		case CAUSE_SUPERVISOR_ECALL:
 		case CAUSE_HYPERVISOR_ECALL:
 		case CAUSE_MACHINE_ECALL:
 			print_trap_information(tf);
 			break;
+		case CAUSE_SUPERVISOR_ECALL:
+			handle_sbi(tf);
+			return;
 		case CAUSE_MISALIGNED_LOAD:
 		case CAUSE_MISALIGNED_STORE:
 			print_trap_information(tf);