finisher: support terminating sifive devices simulation (#61)

machine/finisher.c

@@ -0,0 +1,58 @@
+#include <string.h>
+#include "finisher.h"
+#include "fdt.h"
+
+volatile uint32_t* finisher;
+
+void finisher_exit(uint16_t code)
+{
+  if (!finisher) return;
+  if (code == 0) {
+    *finisher = FINISHER_PASS;
+  } else {
+    *finisher = code << 16 | FINISHER_FAIL;
+  }
+}
+
+struct finisher_scan
+{
+  int compat;
+  uint64_t reg;
+};
+
+static void finisher_open(const struct fdt_scan_node *node, void *extra)
+{
+  struct finisher_scan *scan = (struct finisher_scan *)extra;
+  memset(scan, 0, sizeof(*scan));
+}
+
+static void finisher_prop(const struct fdt_scan_prop *prop, void *extra)
+{
+  struct finisher_scan *scan = (struct finisher_scan *)extra;
+  if (!strcmp(prop->name, "compatible") && !strcmp((const char*)prop->value, "sifive,test0")) {
+    scan->compat = 1;
+  } else if (!strcmp(prop->name, "reg")) {
+    fdt_get_address(prop->node->parent, prop->value, &scan->reg);
+  }
+}
+
+static void finisher_done(const struct fdt_scan_node *node, void *extra)
+{
+  struct finisher_scan *scan = (struct finisher_scan *)extra;
+  if (!scan->compat || !scan->reg || finisher) return;
+  finisher = (uint32_t*)(uintptr_t)scan->reg;
+}
+
+void query_finisher(uintptr_t fdt)
+{
+  struct fdt_cb cb;
+  struct finisher_scan scan;
+
+  memset(&cb, 0, sizeof(cb));
+  cb.open = finisher_open;
+  cb.prop = finisher_prop;
+  cb.done = finisher_done;
+  cb.extra = &scan;
+
+  fdt_scan(fdt, &cb);
+}

machine/finisher.h

@@ -0,0 +1,13 @@
+#ifndef _RISCV_FINISHER_H
+#define _RISCV_FINISHER_H
+
+#include <stdint.h>
+
+#define FINISHER_REG_FINISH	0
+#define FINISHER_FAIL		0x3333
+#define FINISHER_PASS		0x5555
+
+void finisher_exit(uint16_t code);
+void query_finisher(uintptr_t fdt);
+
+#endif

machine/machine.mk.in

@@ -13,6 +13,7 @@ machine_hdrs = \
   mcall.h \
   mtrap.h \
   uart.h \
+  finisher.h \
   unprivileged_memory.h \
   vm.h \
 
@@ -26,6 +27,7 @@ machine_c_srcs = \
   fp_emulation.c \
   fp_ldst.c \
   uart.c \
+  finisher.c \
   misaligned_ldst.c \
 
 machine_asm_srcs = \

machine/minit.c

@@ -4,6 +4,7 @@
 #include "fp_emulation.h"
 #include "fdt.h"
 #include "uart.h"
+#include "finisher.h"
 #include "platform_interface.h"
 #include <string.h>
 #include <limits.h>
@@ -136,6 +137,9 @@ void init_first_hart(uintptr_t hartid, uintptr_t dtb)
   // Confirm console as early as possible
   query_uart(dtb);
 
+  // Find the power button early as well so die() works
+  query_finisher(dtb);
+
   query_mem(dtb);
   query_harts(dtb);
   query_clint(dtb);

machine/mtrap.c

@@ -5,6 +5,7 @@
 #include "bits.h"
 #include "vm.h"
 #include "uart.h"
+#include "finisher.h"
 #include "fdt.h"
 #include "unprivileged_memory.h"
 #include "platform_interface.h"
@@ -27,8 +28,10 @@ static uintptr_t mcall_console_putchar(uint8_t ch)
   return 0;
 }
 
-void poweroff()
+void poweroff(uint16_t code)
 {
+  printm("Power off\n");
+  finisher_exit(code);
   if (platform__use_htif()) {
     htif_poweroff();
   } else {
@@ -84,7 +87,7 @@ static uintptr_t mcall_clear_ipi()
 
 static uintptr_t mcall_shutdown()
 {
-  poweroff();
+  poweroff(0);
 }
 
 static uintptr_t mcall_set_timer(uint64_t when)

machine/mtrap.h

@@ -56,12 +56,12 @@ typedef struct {
 
 hls_t* hls_init(uintptr_t hart_id);
 void parse_config_string();
-void poweroff(void) __attribute((noreturn));
+void poweroff(uint16_t code) __attribute((noreturn));
 void printm(const char* s, ...);
 void vprintm(const char *s, va_list args);
 void putstring(const char* s);
 #define assert(x) ({ if (!(x)) die("assertion failed: %s", #x); })
-#define die(str, ...) ({ printm("%s:%d: " str "\n", __FILE__, __LINE__, ##__VA_ARGS__); poweroff(); })
+#define die(str, ...) ({ printm("%s:%d: " str "\n", __FILE__, __LINE__, ##__VA_ARGS__); poweroff(-1); })
 
 void enter_supervisor_mode(void (*fn)(uintptr_t), uintptr_t arg0, uintptr_t arg1)
   __attribute__((noreturn));