hw/riscv: sifive_u: Add reset functionality

The HiFive Unleashed board wires GPIO pin#10 to the input of the
system reset signal. Let's set up the GPIO pin#10 and insert a
"gpio-restart" device tree node so that reboot is now functional
with QEMU 'sifive_u' machine.

Signed-off-by: Bin Meng <[email protected]>
Reviewed-by: Alistair Francis <[email protected]>
Message-id: [email protected]
Message-Id: <[email protected]>
Signed-off-by: Alistair Francis <[email protected]>

Author: lbmeng

hw/riscv/sifive_u.c

@@ -37,6 +37,7 @@
 #include "qapi/error.h"
 #include "qapi/visitor.h"
 #include "hw/boards.h"
+#include "hw/irq.h"
 #include "hw/loader.h"
 #include "hw/sysbus.h"
 #include "hw/char/serial.h"
@@ -53,6 +54,7 @@
 #include "net/eth.h"
 #include "sysemu/arch_init.h"
 #include "sysemu/device_tree.h"
+#include "sysemu/runstate.h"
 #include "sysemu/sysemu.h"
 #include "exec/address-spaces.h"
 
@@ -96,7 +98,7 @@ static void create_fdt(SiFiveUState *s, const struct MemmapEntry *memmap,
     uint32_t *cells;
     char *nodename;
     char ethclk_names[] = "pclk\0hclk";
-    uint32_t plic_phandle, prci_phandle, phandle = 1;
+    uint32_t plic_phandle, prci_phandle, gpio_phandle, phandle = 1;
     uint32_t hfclk_phandle, rtcclk_phandle, phy_phandle;
 
     fdt = s->fdt = create_device_tree(&s->fdt_size);
@@ -270,9 +272,11 @@ static void create_fdt(SiFiveUState *s, const struct MemmapEntry *memmap,
     g_free(cells);
     g_free(nodename);
 
+    gpio_phandle = phandle++;
     nodename = g_strdup_printf("/soc/gpio@%lx",
         (long)memmap[SIFIVE_U_GPIO].base);
     qemu_fdt_add_subnode(fdt, nodename);
+    qemu_fdt_setprop_cell(fdt, nodename, "phandle", gpio_phandle);
     qemu_fdt_setprop_cells(fdt, nodename, "clocks",
         prci_phandle, PRCI_CLK_TLCLK);
     qemu_fdt_setprop_cell(fdt, nodename, "#interrupt-cells", 2);
@@ -292,6 +296,12 @@ static void create_fdt(SiFiveUState *s, const struct MemmapEntry *memmap,
     qemu_fdt_setprop_string(fdt, nodename, "compatible", "sifive,gpio0");
     g_free(nodename);
 
+    nodename = g_strdup_printf("/gpio-restart");
+    qemu_fdt_add_subnode(fdt, nodename);
+    qemu_fdt_setprop_cells(fdt, nodename, "gpios", gpio_phandle, 10, 1);
+    qemu_fdt_setprop_string(fdt, nodename, "compatible", "gpio-restart");
+    g_free(nodename);
+
     phy_phandle = phandle++;
     nodename = g_strdup_printf("/soc/ethernet@%lx",
         (long)memmap[SIFIVE_U_GEM].base);
@@ -352,6 +362,14 @@ static void create_fdt(SiFiveUState *s, const struct MemmapEntry *memmap,
     g_free(nodename);
 }
 
+static void sifive_u_machine_reset(void *opaque, int n, int level)
+{
+    /* gpio pin active low triggers reset */
+    if (!level) {
+        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+    }
+}
+
 static void sifive_u_machine_init(MachineState *machine)
 {
     const struct MemmapEntry *memmap = sifive_u_memmap;
@@ -380,6 +398,10 @@ static void sifive_u_machine_init(MachineState *machine)
     memory_region_add_subregion(system_memory, memmap[SIFIVE_U_FLASH0].base,
                                 flash0);
 
+    /* register gpio-restart */
+    qdev_connect_gpio_out(DEVICE(&(s->soc.gpio)), 10,
+                          qemu_allocate_irq(sifive_u_machine_reset, NULL, 0));
+
     /* create device tree */
     create_fdt(s, memmap, machine->ram_size, machine->kernel_cmdline);