ARM: Virt: Add QEMU powerdown notifier and hook it to GPIO Pin 3

Currently mach-virt model doesn't support powerdown request. Guest VM
doesn't react to system_powerdown from monitor console (or QMP) because
there is no communication mechanism for such requests. This patch registers
GPIO Pin 3 with powerdown notification. So guest VM can receive notification
when such powerdown request is triggered.
Signed-off-by: NWei Huang <wei@redhat.com>
Signed-off-by: NShannon Zhao <zhaoshenglong@huawei.com>
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NWei Huang <wei@redhat.com>
Tested-by: NWei Huang <wei@redhat.com>
Message-id: 1449804086-3464-10-git-send-email-zhaoshenglong@huawei.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/arm/virt.c

@@ -540,6 +540,17 @@ static void create_rtc(const VirtBoardInfo *vbi, qemu_irq *pic)
     g_free(nodename);
 }
 
+static DeviceState *pl061_dev;
+static void virt_powerdown_req(Notifier *n, void *opaque)
+{
+    /* use gpio Pin 3 for power button event */
+    qemu_set_irq(qdev_get_gpio_in(pl061_dev, 3), 1);
+}
+
+static Notifier virt_system_powerdown_notifier = {
+    .notify = virt_powerdown_req
+};
+
 static void create_gpio(const VirtBoardInfo *vbi, qemu_irq *pic)
 {
     char *nodename;
@@ -548,7 +559,7 @@ static void create_gpio(const VirtBoardInfo *vbi, qemu_irq *pic)
     int irq = vbi->irqmap[VIRT_GPIO];
     const char compat[] = "arm,pl061\0arm,primecell";
 
-    sysbus_create_simple("pl061", base, pic[irq]);
+    pl061_dev = sysbus_create_simple("pl061", base, pic[irq]);
 
     nodename = g_strdup_printf("/pl061@%" PRIx64, base);
     qemu_fdt_add_subnode(vbi->fdt, nodename);
@@ -563,6 +574,9 @@ static void create_gpio(const VirtBoardInfo *vbi, qemu_irq *pic)
     qemu_fdt_setprop_cell(vbi->fdt, nodename, "clocks", vbi->clock_phandle);
     qemu_fdt_setprop_string(vbi->fdt, nodename, "clock-names", "apb_pclk");
 
+    /* connect powerdown request */
+    qemu_register_powerdown_notifier(&virt_system_powerdown_notifier);
+
     g_free(nodename);
 }