hw/arm/boot: arm_load_kernel implemented as a machine init done notifier

Device tree nodes for the platform bus and its children dynamic sysbus
devices are added in a machine init done notifier. To load the dtb once,
after those latter nodes are built and before ROM freeze, the actual
arm_load_kernel existing code is moved into a notifier notify function,
arm_load_kernel_notify. arm_load_kernel now only registers the
corresponding notifier.

Machine files that do not support platform bus stay unchanged. Machine
files willing to support dynamic sysbus devices must call arm_load_kernel
before sysbus-fdt arm_register_platform_bus_fdt_creator to make sure
dynamic sysbus device nodes are integrated in the dtb.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
Reviewed-by: Shannon Zhao <zhaoshenglong@huawei.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1433244554-12898-3-git-send-email-eric.auger@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 41 insertions, 1 deletions

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index fa6950352c..d036624948 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -557,7 +557,7 @@ static void load_image_to_fw_cfg(FWCfgState *fw_cfg, uint16_t size_key,
     fw_cfg_add_bytes(fw_cfg, data_key, data, size);
 }
 
-void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
+static void arm_load_kernel_notify(Notifier *notifier, void *data)
 {
     CPUState *cs;
     int kernel_size;
@@ -568,6 +568,11 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
     hwaddr entry, kernel_load_offset;
     int big_endian;
     static const ARMInsnFixup *primary_loader;
+    ArmLoadKernelNotifier *n = DO_UPCAST(ArmLoadKernelNotifier,
+                                         notifier, notifier);
+    ARMCPU *cpu = n->cpu;
+    struct arm_boot_info *info =
+        container_of(n, struct arm_boot_info, load_kernel_notifier);
 
     /* CPU objects (unlike devices) are not automatically reset on system
      * reset, so we must always register a handler to do so. If we're
@@ -775,3 +780,10 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
         ARM_CPU(cs)->env.boot_info = info;
     }
 }
+
+void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
+{
+    info->load_kernel_notifier.cpu = cpu;
+    info->load_kernel_notifier.notifier.notify = arm_load_kernel_notify;
+    qemu_add_machine_init_done_notifier(&info->load_kernel_notifier.notifier);
+}
diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h
index 5c940eb412..760804cc46 100644
--- a/include/hw/arm/arm.h
+++ b/include/hw/arm/arm.h
@@ -13,11 +13,21 @@
 
 #include "exec/memory.h"
 #include "hw/irq.h"
+#include "qemu/notify.h"
 
 /* armv7m.c */
 qemu_irq *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
                       const char *kernel_filename, const char *cpu_model);
 
+/*
+ * struct used as a parameter of the arm_load_kernel machine init
+ * done notifier
+ */
+typedef struct {
+    Notifier notifier; /* actual notifier */
+    ARMCPU *cpu; /* handle to the first cpu object */
+} ArmLoadKernelNotifier;
+
 /* arm_boot.c */
 struct arm_boot_info {
     uint64_t ram_size;
@@ -64,6 +74,8 @@ struct arm_boot_info {
      * the user it should implement this hook.
      */
     void (*modify_dtb)(const struct arm_boot_info *info, void *fdt);
+    /* machine init done notifier executing arm_load_dtb */
+    ArmLoadKernelNotifier load_kernel_notifier;
     /* Used internally by arm_boot.c */
     int is_linux;
     hwaddr initrd_start;
@@ -75,6 +87,22 @@ struct arm_boot_info {
      */
     bool firmware_loaded;
 };
+
+/**
+ * arm_load_kernel - Loads memory with everything needed to boot
+ *
+ * @cpu: handle to the first CPU object
+ * @info: handle to the boot info struct
+ * Registers a machine init done notifier that copies to memory
+ * everything needed to boot, depending on machine and user options:
+ * kernel image, boot loaders, initrd, dtb. Also registers the CPU
+ * reset handler.
+ *
+ * In case the machine file supports the platform bus device and its
+ * dynamically instantiable sysbus devices, this function must be called
+ * before sysbus-fdt arm_register_platform_bus_fdt_creator. Indeed the
+ * machine init done notifiers are called in registration reverse order.
+ */
 void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info);
 
 /* Multiplication factor to convert from system clock ticks to qemu timer