armv7m: Abstract out the "load kernel" code

Abstract the "load kernel" code out of armv7m_init() into its own
function.  This includes the registration of the CPU reset function,
to parallel how we handle this for A profile cores.

We make the function public so that boards which choose to
directly instantiate an ARMv7M device object can call it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1487604965-23220-2-git-send-email-peter.maydell@linaro.org

hw/arm/armv7m.c

@@ -176,10 +176,6 @@ DeviceState *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
     ARMCPU *cpu;
     CPUARMState *env;
     DeviceState *nvic;
-    int image_size;
-    uint64_t entry;
-    uint64_t lowaddr;
-    int big_endian;
 
     if (cpu_model == NULL) {
 	cpu_model = "cortex-m3";
@@ -199,6 +195,16 @@ DeviceState *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
     qdev_init_nofail(nvic);
     sysbus_connect_irq(SYS_BUS_DEVICE(nvic), 0,
                        qdev_get_gpio_in(DEVICE(cpu), ARM_CPU_IRQ));
+    armv7m_load_kernel(cpu, kernel_filename, mem_size);
+    return nvic;
+}
+
+void armv7m_load_kernel(ARMCPU *cpu, const char *kernel_filename, int mem_size)
+{
+    int image_size;
+    uint64_t entry;
+    uint64_t lowaddr;
+    int big_endian;
 
 #ifdef TARGET_WORDS_BIGENDIAN
     big_endian = 1;
@@ -224,8 +230,15 @@ DeviceState *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
         }
     }
 
+    /* CPU objects (unlike devices) are not automatically reset on system
+     * reset, so we must always register a handler to do so. Unlike
+     * A-profile CPUs, we don't need to do anything special in the
+     * handler to arrange that it starts correctly.
+     * This is arguably the wrong place to do this, but it matches the
+     * way A-profile does it. Note that this means that every M profile
+     * board must call this function!
+     */
     qemu_register_reset(armv7m_reset, cpu);
-    return nvic;
 }
 
 static Property bitband_properties[] = {

include/hw/arm/arm.h

@@ -26,6 +26,18 @@ typedef enum {
 /* armv7m.c */
 DeviceState *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
                       const char *kernel_filename, const char *cpu_model);
+/**
+ * armv7m_load_kernel:
+ * @cpu: CPU
+ * @kernel_filename: file to load
+ * @mem_size: mem_size: maximum image size to load
+ *
+ * Load the guest image for an ARMv7M system. This must be called by
+ * any ARMv7M board, either directly or via armv7m_init(). (This is
+ * necessary to ensure that the CPU resets correctly on system reset,
+ * as well as for kernel loading.)
+ */
+void armv7m_load_kernel(ARMCPU *cpu, const char *kernel_filename, int mem_size);
 
 /*
  * struct used as a parameter of the arm_load_kernel machine init