pseries: Return the token when we register an RTAS call

The kernel will soon be able to service some RTAS calls. However the
choice of tokens will still be up to userspace. To support this have
spapr_rtas_register() return the token that is allocated for an
RTAS call, that allows the calling code to tell the kernel what the
token value is.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/spapr.h

@@ -320,7 +320,7 @@ static inline void rtas_st(target_ulong phys, int n, uint32_t val)
 typedef void (*spapr_rtas_fn)(sPAPREnvironment *spapr, uint32_t token,
                               uint32_t nargs, target_ulong args,
                               uint32_t nret, target_ulong rets);
-void spapr_rtas_register(const char *name, spapr_rtas_fn fn);
+int spapr_rtas_register(const char *name, spapr_rtas_fn fn);
 target_ulong spapr_rtas_call(sPAPREnvironment *spapr,
                              uint32_t token, uint32_t nargs, target_ulong args,
                              uint32_t nret, target_ulong rets);

hw/spapr_rtas.c

@@ -242,7 +242,7 @@ target_ulong spapr_rtas_call(sPAPREnvironment *spapr,
     return H_PARAMETER;
 }
 
-void spapr_rtas_register(const char *name, spapr_rtas_fn fn)
+int spapr_rtas_register(const char *name, spapr_rtas_fn fn)
 {
     int i;
 
@@ -258,7 +258,7 @@ void spapr_rtas_register(const char *name, spapr_rtas_fn fn)
     rtas_next->name = name;
     rtas_next->fn = fn;
 
-    rtas_next++;
+    return (rtas_next++ - rtas_table) + TOKEN_BASE;
 }
 
 int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,