powerpc/fadump: Refactor and prepare fadump_cma_init for late init

We anyway don't use any return values from fadump_cma_init(). Since
fadump_reserve_mem() from where fadump_cma_init() gets called today,
already has the required checks.
This patch makes this function return type as void. Let's also handle
extra cases like return if fadump_supported is false or dump_active, so
that in later patches we can call fadump_cma_init() separately from
setup_arch().

Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/a2afc3d6481a87a305e89cfc4a3f3d2a0b8ceab3.1729146153.git.ritesh.list@gmail.com

arch/powerpc/kernel/fadump.c

@@ -78,27 +78,23 @@ static struct cma *fadump_cma;
  * But for some reason even if it fails we still have the memory reservation
  * with us and we can still continue doing fadump.
  */
-static int __init fadump_cma_init(void)
+static void __init fadump_cma_init(void)
 {
 	unsigned long long base, size;
 	int rc;
 
-	if (!fw_dump.fadump_enabled)
-		return 0;
-
+	if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
+			fw_dump.dump_active)
+		return;
 	/*
 	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
-	 * Return 1 to continue with fadump old behaviour.
 	 */
-	if (fw_dump.nocma)
-		return 1;
+	if (fw_dump.nocma || !fw_dump.boot_memory_size)
+		return;
 
 	base = fw_dump.reserve_dump_area_start;
 	size = fw_dump.boot_memory_size;
 
-	if (!size)
-		return 0;
-
 	rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma);
 	if (rc) {
 		pr_err("Failed to init cma area for firmware-assisted dump,%d\n", rc);
@@ -108,7 +104,7 @@ static int __init fadump_cma_init(void)
 		 * blocked from production system usage.  Hence return 1,
 		 * so that we can continue with fadump.
 		 */
-		return 1;
+		return;
 	}
 
 	/*
@@ -125,10 +121,9 @@ static int __init fadump_cma_init(void)
 		cma_get_size(fadump_cma),
 		(unsigned long)cma_get_base(fadump_cma) >> 20,
 		fw_dump.reserve_dump_area_size);
-	return 1;
 }
 #else
-static int __init fadump_cma_init(void) { return 1; }
+static void __init fadump_cma_init(void) { }
 #endif /* CONFIG_CMA */
 
 /*
@@ -638,7 +633,7 @@ int __init fadump_reserve_mem(void)
 		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
 			(size >> 20), base, (memblock_phys_mem_size() >> 20));
 
-		ret = fadump_cma_init();
+		fadump_cma_init();
 	}
 
 	return ret;