platform: Add Spike initial support

This patch adds initial platform support Spike emulator.

Signed-off-by: James Clarke <jrtc27@jrtc27.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

2 files changed, 150 insertions, 0 deletions

diff --git a/lib/utils/sys/htif.c b/lib/utils/sys/htif.c
new file mode 100644
index 0000000..f0ba814
--- /dev/null
+++ b/lib/utils/sys/htif.c
@@ -0,0 +1,149 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2010-2020, The Regents of the University of California
+ * (Regents).  All Rights Reserved.
+ */
+
+#include <sbi/riscv_locks.h>
+#include <sbi_utils/sys/htif.h>
+
+#define HTIF_DATA_BITS		48
+#define HTIF_DATA_MASK		((1UL << HTIF_DATA_BITS) - 1)
+#define HTIF_DATA_SHIFT		0
+#define HTIF_CMD_BITS		8
+#define HTIF_CMD_MASK		((1UL << HTIF_CMD_BITS) - 1)
+#define HTIF_CMD_SHIFT		48
+#define HTIF_DEV_BITS		8
+#define HTIF_DEV_MASK		((1UL << HTIF_DEV_BITS) - 1)
+#define HTIF_DEV_SHIFT		56
+
+#define HTIF_DEV_SYSTEM		0
+#define HTIF_DEV_CONSOLE	1
+
+#define HTIF_CONSOLE_CMD_GETC	0
+#define HTIF_CONSOLE_CMD_PUTC	1
+
+#if __riscv_xlen == 64
+# define TOHOST_CMD(dev, cmd, payload) \
+	(((uint64_t)(dev) << HTIF_DEV_SHIFT) | \
+	 ((uint64_t)(cmd) << HTIF_CMD_SHIFT) | \
+	 (uint64_t)(payload))
+#else
+# define TOHOST_CMD(dev, cmd, payload) ({ \
+  if ((dev) || (cmd)) __builtin_trap(); \
+  (payload); })
+#endif
+#define FROMHOST_DEV(fromhost_value) \
+	((uint64_t)((fromhost_value) >> HTIF_DEV_SHIFT) & HTIF_DEV_MASK)
+#define FROMHOST_CMD(fromhost_value) \
+	((uint64_t)((fromhost_value) >> HTIF_CMD_SHIFT) & HTIF_CMD_MASK)
+#define FROMHOST_DATA(fromhost_value) \
+	((uint64_t)((fromhost_value) >> HTIF_DATA_SHIFT) & HTIF_DATA_MASK)
+
+#define PK_SYS_write 64
+
+volatile uint64_t tohost __attribute__((section(".htif")));
+volatile uint64_t fromhost __attribute__((section(".htif")));
+static int htif_console_buf;
+static spinlock_t htif_lock = SPIN_LOCK_INITIALIZER;
+
+static void __check_fromhost()
+{
+	uint64_t fh = fromhost;
+	if (!fh)
+		return;
+	fromhost = 0;
+
+	/* this should be from the console */
+	if (FROMHOST_DEV(fh) != HTIF_DEV_CONSOLE)
+		__builtin_trap();
+	switch (FROMHOST_CMD(fh)) {
+		case HTIF_CONSOLE_CMD_GETC:
+			htif_console_buf = 1 + (uint8_t)FROMHOST_DATA(fh);
+			break;
+		case HTIF_CONSOLE_CMD_PUTC:
+			break;
+		default:
+			__builtin_trap();
+	}
+}
+
+static void __set_tohost(uint64_t dev, uint64_t cmd, uint64_t data)
+{
+	while (tohost)
+		__check_fromhost();
+	tohost = TOHOST_CMD(dev, cmd, data);
+}
+
+#if __riscv_xlen == 32
+static void do_tohost_fromhost(uint64_t dev, uint64_t cmd, uint64_t data)
+{
+	spin_lock(&htif_lock);
+
+	__set_tohost(HTIF_DEV_SYSTEM, cmd, data);
+
+	while (1) {
+		uint64_t fh = fromhost;
+		if (fh) {
+			if (FROMHOST_DEV(fh) == HTIF_DEV_SYSTEM &&
+			    FROMHOST_CMD(fh) == cmd) {
+				fromhost = 0;
+				break;
+			}
+			__check_fromhost();
+		}
+	}
+
+	spin_unlock(&htif_lock);
+}
+
+void htif_putc(char ch)
+{
+	/* HTIF devices are not supported on RV32, so do a proxy write call */
+	volatile uint64_t magic_mem[8];
+	magic_mem[0] = PK_SYS_write;
+	magic_mem[1] = HTIF_DEV_CONSOLE;
+	magic_mem[2] = (uint64_t)(uintptr_t)&ch;
+	magic_mem[3] = HTIF_CONSOLE_CMD_PUTC;
+	do_tohost_fromhost(HTIF_DEV_SYSTEM, 0, (uint64_t)(uintptr_t)magic_mem);
+}
+#else
+void htif_putc(char ch)
+{
+	spin_lock(&htif_lock);
+	__set_tohost(HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_PUTC, ch);
+	spin_unlock(&htif_lock);
+}
+#endif
+
+int htif_getc(void)
+{
+	int ch;
+
+#if __riscv_xlen == 32
+	/* HTIF devices are not supported on RV32 */
+	return -1;
+#endif
+
+	spin_lock(&htif_lock);
+
+	__check_fromhost();
+	ch = htif_console_buf;
+	if (ch >= 0) {
+		htif_console_buf = -1;
+		__set_tohost(HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_GETC, 0);
+	}
+
+	spin_unlock(&htif_lock);
+
+	return ch - 1;
+}
+
+int htif_system_down(u32 type)
+{
+	while (1) {
+		fromhost = 0;
+		tohost = 1;
+	}
+}
diff --git a/lib/utils/sys/objects.mk b/lib/utils/sys/objects.mk
index baed884..c6df2bd 100644
--- a/lib/utils/sys/objects.mk
+++ b/lib/utils/sys/objects.mk
@@ -8,3 +8,4 @@
 #
 
 libsbiutils-objs-y += sys/clint.o
+libsbiutils-objs-y += sys/htif.o