sparc/leon3: Initialize stack pointer

A lot of real world LEON3 systems are shipped with the GRMON boot
loader.  This boot loader initializes the stack pointer with the end of
RAM address.  The application can use this to detect the RAM size of a
particular board variant.

Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
Reviewed-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/sparc/leon3.c

@@ -45,6 +45,7 @@
 typedef struct ResetData {
     SPARCCPU *cpu;
     uint32_t  entry;            /* save kernel entry in case of reset */
+    target_ulong sp;            /* initial stack pointer */
 } ResetData;
 
 static void main_cpu_reset(void *opaque)
@@ -58,6 +59,7 @@ static void main_cpu_reset(void *opaque)
     cpu->halted = 0;
     env->pc     = s->entry;
     env->npc    = s->entry + 4;
+    env->regbase[6] = s->sp;
 }
 
 void leon3_irq_ack(void *irq_manager, int intno)
@@ -133,6 +135,7 @@ static void leon3_generic_hw_init(QEMUMachineInitArgs *args)
     /* Reset data */
     reset_info        = g_malloc0(sizeof(ResetData));
     reset_info->cpu   = cpu;
+    reset_info->sp    = 0x40000000 + ram_size;
     qemu_register_reset(main_cpu_reset, reset_info);
 
     /* Allocate IRQ manager */