Add support for HTIF interfaces

Makefile.am

@@ -79,6 +79,7 @@ nobase_include_HEADERS = \
 	metal/drivers/sifive_trace.h \
 	metal/drivers/sifive_uart0.h \
 	metal/drivers/sifive_wdog0.h \
+	metal/drivers/ucb_htif0.h \
 	metal/machine/inline.h \
 	metal/machine/platform.h \
 	metal/button.h \
@@ -185,6 +186,7 @@ libriscv__mmachine__@MACHINE_NAME@_a_SOURCES = \
 	src/drivers/sifive_trace.c \
 	src/drivers/sifive_uart0.c \
 	src/drivers/sifive_wdog0.c \
+	src/drivers/ucb_htif0.c \
 	src/button.c \
 	src/cache.c \
 	src/clock.c \

metal/drivers/ucb_htif0.h

@@ -0,0 +1,48 @@
+/* Copyright 2018 SiFive, Inc */
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#ifndef METAL__DRIVERS__UCB_HTIF0_H
+#define METAL__DRIVERS__UCB_HTIF0_H
+
+#include <metal/compiler.h>
+#include <metal/shutdown.h>
+#include <metal/uart.h>
+
+struct __metal_driver_vtable_ucb_htif0_shutdown {
+    const struct __metal_shutdown_vtable shutdown;
+};
+
+struct __metal_driver_vtable_ucb_htif0_uart {
+    const struct metal_uart_vtable uart;
+};
+
+struct __metal_driver_ucb_htif0;
+
+void __metal_driver_ucb_htif0_exit(const struct __metal_shutdown *test,
+                                   int code) __attribute__((noreturn));
+
+void __metal_driver_ucb_htif0_init(struct metal_uart *uart, int baud_rate);
+int __metal_driver_ucb_htif0_putc(struct metal_uart *uart, int c);
+int __metal_driver_ucb_htif0_getc(struct metal_uart *uart, int *c);
+int __metal_driver_ucb_htif0_get_baud_rate(struct metal_uart *guart);
+int __metal_driver_ucb_htif0_set_baud_rate(struct metal_uart *guart,
+                                           int baud_rate);
+struct metal_interrupt *
+__metal_driver_ucb_htif0_interrupt_controller(struct metal_uart *uart);
+int __metal_driver_ucb_htif0_get_interrupt_id(struct metal_uart *uart);
+
+__METAL_DECLARE_VTABLE(__metal_driver_vtable_ucb_htif0_shutdown)
+
+__METAL_DECLARE_VTABLE(__metal_driver_vtable_ucb_htif0_uart)
+
+struct __metal_driver_ucb_htif0_shutdown {
+    struct __metal_shutdown shutdown;
+    const struct __metal_driver_vtable_ucb_htif0_shutdown *vtable;
+};
+
+struct __metal_driver_ucb_htif0_uart {
+    struct metal_uart uart;
+    const struct __metal_driver_vtable_ucb_htif0_uart *vtable;
+};
+
+#endif

src/drivers/ucb_htif0.c

@@ -0,0 +1,128 @@
+/* Copyright 2018 SiFive, Inc */
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#include <metal/machine/platform.h>
+
+#ifdef METAL_UCB_HTIF0
+
+#include <metal/drivers/ucb_htif0.h>
+#include <metal/io.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define FINISHER_OFFSET 0
+
+volatile uint64_t fromhost __attribute__((aligned(4096)));
+volatile uint64_t tohost __attribute__((aligned(4096)));
+
+#if __riscv_xlen == 64
+#define TOHOST_CMD(dev, cmd, payload)                                          \
+    (((uint64_t)(dev) << 56) | ((uint64_t)(cmd) << 48) | (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) >> 56)
+#define FROMHOST_CMD(fromhost_value) ((uint64_t)(fromhost_value) << 8 >> 56)
+#define FROMHOST_DATA(fromhost_value) ((uint64_t)(fromhost_value) << 16 >> 16)
+
+static void __check_fromhost() {
+    uint64_t fh = fromhost;
+    if (!fh)
+        return;
+    fromhost = 0;
+}
+
+static void __set_tohost(uintptr_t dev, uintptr_t cmd, uintptr_t data) {
+    while (tohost)
+        __check_fromhost();
+    tohost = TOHOST_CMD(dev, cmd, data);
+}
+
+static void do_tohost_fromhost(uintptr_t dev, uintptr_t cmd, uintptr_t data) {
+    __set_tohost(dev, cmd, data);
+
+    while (1) {
+        uint64_t fh = fromhost;
+        if (fh) {
+            if (FROMHOST_DEV(fh) == dev && FROMHOST_CMD(fh) == cmd) {
+                fromhost = 0;
+                break;
+            }
+            __check_fromhost();
+        }
+    }
+}
+
+void __metal_driver_ucb_htif0_init(struct metal_uart *uart, int baud_rate) {}
+
+void __metal_driver_ucb_htif0_exit(const struct __metal_shutdown *sd,
+                                   int code) {
+    volatile uint64_t magic_mem[8];
+    magic_mem[0] = 93; // SYS_exit
+    magic_mem[1] = code;
+    magic_mem[2] = 0;
+    magic_mem[3] = 0;
+
+    do_tohost_fromhost(0, 0, (uintptr_t)magic_mem);
+
+    while (1) {
+        // loop forever
+    }
+}
+
+int __metal_driver_ucb_htif0_putc(struct metal_uart *htif, int c) {
+    volatile uint64_t magic_mem[8];
+    magic_mem[0] = 64; // SYS_write
+    magic_mem[1] = 1;
+    magic_mem[2] = (uintptr_t)&c;
+    magic_mem[3] = 1;
+
+    do_tohost_fromhost(0, 0, (uintptr_t)magic_mem);
+
+    return 0;
+}
+
+int __metal_driver_ucb_htif0_getc(struct metal_uart *htif, int *c) {
+    return -1;
+}
+
+int __metal_driver_ucb_htif0_get_baud_rate(struct metal_uart *guart) {
+    return 0;
+}
+
+int __metal_driver_ucb_htif0_set_baud_rate(struct metal_uart *guart,
+                                           int baud_rate) {
+    return 0;
+}
+
+struct metal_interrupt *
+__metal_driver_ucb_htif0_interrupt_controller(struct metal_uart *uart) {
+    return NULL;
+}
+
+int __metal_driver_ucb_htif0_get_interrupt_id(struct metal_uart *uart) {
+    return -1;
+}
+
+__METAL_DEFINE_VTABLE(__metal_driver_vtable_ucb_htif0_shutdown) = {
+    .shutdown.exit = &__metal_driver_ucb_htif0_exit,
+};
+
+__METAL_DEFINE_VTABLE(__metal_driver_vtable_ucb_htif0_uart) = {
+    .uart.init = __metal_driver_ucb_htif0_init,
+    .uart.putc = __metal_driver_ucb_htif0_putc,
+    .uart.getc = __metal_driver_ucb_htif0_getc,
+    .uart.get_baud_rate = __metal_driver_ucb_htif0_get_baud_rate,
+    .uart.set_baud_rate = __metal_driver_ucb_htif0_set_baud_rate,
+    .uart.controller_interrupt = __metal_driver_ucb_htif0_interrupt_controller,
+    .uart.get_interrupt_id = __metal_driver_ucb_htif0_get_interrupt_id,
+};
+
+#endif /* METAL_UCB_HTIF0 */
+
+typedef int no_empty_translation_units;