[Qemu-devel] [RFC v2 1/4] hw/arm/virt: Allow multiple agents to modify dt

[Alvise Rigo <a.rigo@virtualopensystems.com>]

Keep a global list with all the functions that need to modify the device
tree.  Using qemu_add_machine_init_done_notifier we register a notifier
that executes all the functions on the list and loads the kernel.

Signed-off-by: Alvise Rigo <a.rigo@virtualopensystems.com>
---
 hw/arm/virt.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 314e55b..e8d527d 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -70,6 +70,16 @@ enum {
     VIRT_RTC,
 };
 
+typedef void (*modify_dtb_func)(void *fdt, DeviceState *dev);
+typedef struct DTModifier {
+    QLIST_ENTRY(DTModifier) entry;
+    modify_dtb_func modify_dtb;
+    DeviceState *dev;
+} DTModifier;
+
+static QLIST_HEAD(, DTModifier) dtb_modifiers =
+                    QLIST_HEAD_INITIALIZER(dtb_modifiers);
+
 typedef struct MemMapEntry {
     hwaddr base;
     hwaddr size;
@@ -149,6 +159,23 @@ static VirtBoardInfo *find_machine_info(const char *cpu)
     return NULL;
 }
 
+static void add_dtb_modifier(modify_dtb_func func, DeviceState *dev)
+{
+    DTModifier *mod_entry = g_new(DTModifier, 1);
+    mod_entry->modify_dtb = func;
+    mod_entry->dev = dev;
+    QLIST_INSERT_HEAD(&dtb_modifiers, mod_entry, entry);
+}
+
+static void free_dtb_modifiers(void)
+{
+    while (!QLIST_EMPTY(&dtb_modifiers)) {
+        DTModifier *modifier = QLIST_FIRST(&dtb_modifiers);
+        QLIST_REMOVE(modifier, entry);
+        g_free(modifier);
+    }
+}
+
 static void create_fdt(VirtBoardInfo *vbi)
 {
     void *fdt = create_device_tree(&vbi->fdt_size);
@@ -527,6 +554,29 @@ static void *machvirt_dtb(const struct arm_boot_info *binfo, int *fdt_size)
     return board->fdt;
 }
 
+static void machvirt_finalize_dt(Notifier *notify, void *data)
+{
+    VirtBoardInfo *vbi;
+    MachineState *machine;
+
+    machine = MACHINE(qdev_get_machine());
+
+    vbi = find_machine_info(machine->cpu_model);
+    if (!vbi) {
+        vbi = find_machine_info("cortex-a15");
+    }
+
+    struct DTModifier *modifier, *next;
+    QLIST_FOREACH_SAFE(modifier, &dtb_modifiers, entry, next) {
+        modifier->modify_dtb(vbi->fdt, modifier->dev);
+    }
+
+    free_dtb_modifiers();
+
+    /* Load the kernel only after that the device tree has been modified. */
+    arm_load_kernel(ARM_CPU(first_cpu), &vbi->bootinfo);
+}
+
 static void machvirt_init(MachineState *machine)
 {
     qemu_irq pic[NUM_IRQS];
@@ -604,6 +654,10 @@ static void machvirt_init(MachineState *machine)
      */
     create_virtio_devices(vbi, pic);
 
+    Notifier *finalize_dtb_notifier = g_new(Notifier, 1);
+    finalize_dtb_notifier->notify = machvirt_finalize_dt;
+    qemu_add_machine_init_done_notifier(finalize_dtb_notifier);
+
     vbi->bootinfo.ram_size = machine->ram_size;
     vbi->bootinfo.kernel_filename = machine->kernel_filename;
     vbi->bootinfo.kernel_cmdline = machine->kernel_cmdline;
@@ -612,7 +666,6 @@ static void machvirt_init(MachineState *machine)
     vbi->bootinfo.board_id = -1;
     vbi->bootinfo.loader_start = vbi->memmap[VIRT_MEM].base;
     vbi->bootinfo.get_dtb = machvirt_dtb;
-    arm_load_kernel(ARM_CPU(first_cpu), &vbi->bootinfo);
 }
 
 static QEMUMachine machvirt_a15_machine = {
-- 
2.1.0