hw/arm/virt: Provide PL031 RTC

UEFI mandates that the platform must include an RTC, so provide
one in 'virt', using the PL031. This is also useful for directly
booting Linux kernels which would otherwise have to run ntpdate.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Tested-by: NAurelien Jarno <aurelien@aurel32.net>
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>

hw/arm/virt.c

@@ -65,6 +65,7 @@ enum {
     VIRT_GIC_CPU,
     VIRT_UART,
     VIRT_MMIO,
+    VIRT_RTC,
 };
 
 typedef struct MemMapEntry {
@@ -92,6 +93,8 @@ typedef struct VirtBoardInfo {
  * high memory region beyond 4GB).
  * This represents a compromise between how much RAM can be given to
  * a 32 bit VM and leaving space for expansion and in particular for PCI.
+ * Note that devices should generally be placed at multiples of 0x10000,
+ * to accommodate guests using 64K pages.
  */
 static const MemMapEntry a15memmap[] = {
     /* Space up to 0x8000000 is reserved for a boot ROM */
@@ -101,6 +104,7 @@ static const MemMapEntry a15memmap[] = {
     [VIRT_GIC_DIST] = { 0x8000000, 0x10000 },
     [VIRT_GIC_CPU] = { 0x8010000, 0x10000 },
     [VIRT_UART] = { 0x9000000, 0x1000 },
+    [VIRT_RTC] = { 0x90010000, 0x1000 },
     [VIRT_MMIO] = { 0xa000000, 0x200 },
     /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size */
     /* 0x10000000 .. 0x40000000 reserved for PCI */
@@ -109,6 +113,7 @@ static const MemMapEntry a15memmap[] = {
 
 static const int a15irqmap[] = {
     [VIRT_UART] = 1,
+    [VIRT_RTC] = 2,
     [VIRT_MMIO] = 16, /* ...to 16 + NUM_VIRTIO_TRANSPORTS - 1 */
 };
 
@@ -353,6 +358,29 @@ static void create_uart(const VirtBoardInfo *vbi, qemu_irq *pic)
     g_free(nodename);
 }
 
+static void create_rtc(const VirtBoardInfo *vbi, qemu_irq *pic)
+{
+    char *nodename;
+    hwaddr base = vbi->memmap[VIRT_RTC].base;
+    hwaddr size = vbi->memmap[VIRT_RTC].size;
+    int irq = vbi->irqmap[VIRT_RTC];
+    const char compat[] = "arm,pl031\0arm,primecell";
+
+    sysbus_create_simple("pl031", base, pic[irq]);
+
+    nodename = g_strdup_printf("/pl031@%" PRIx64, base);
+    qemu_fdt_add_subnode(vbi->fdt, nodename);
+    qemu_fdt_setprop(vbi->fdt, nodename, "compatible", compat, sizeof(compat));
+    qemu_fdt_setprop_sized_cells(vbi->fdt, nodename, "reg",
+                                 2, base, 2, size);
+    qemu_fdt_setprop_cells(vbi->fdt, nodename, "interrupts",
+                           GIC_FDT_IRQ_TYPE_SPI, irq,
+                           GIC_FDT_IRQ_FLAGS_EDGE_LO_HI);
+    qemu_fdt_setprop_cell(vbi->fdt, nodename, "clocks", vbi->clock_phandle);
+    qemu_fdt_setprop_string(vbi->fdt, nodename, "clock-names", "apb_pclk");
+    g_free(nodename);
+}
+
 static void create_virtio_devices(const VirtBoardInfo *vbi, qemu_irq *pic)
 {
     int i;
@@ -469,6 +497,8 @@ static void machvirt_init(MachineState *machine)
 
     create_uart(vbi, pic);
 
+    create_rtc(vbi, pic);
+
     /* Create mmio transports, so the user can create virtio backends
      * (which will be automatically plugged in to the transports). If
      * no backend is created the transport will just sit harmlessly idle.