m68k: mm: simplify detection of memory zone boundaries

free_area_init() only requires the definition of maximal PFN for each of
the supported zone rater than calculation of actual zone sizes and the
sizes of the holes between the zones.

After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP the free_area_init() is
available to all architectures.

Using this function instead of free_area_init_node() simplifies the zone
detection.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Hoan Tran <hoan@os.amperecomputing.com>	[arm64]
Cc: Baoquan He <bhe@redhat.com>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200412194859.12663-11-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/m68k/mm/motorola.c

@@ -365,7 +365,7 @@ static void __init map_node(int node)
  */
 void __init paging_init(void)
 {
-	unsigned long zones_size[MAX_NR_ZONES] = { 0, };
+	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
 	unsigned long min_addr, max_addr;
 	unsigned long addr;
 	int i;
@@ -448,11 +448,10 @@ void __init paging_init(void)
 #ifdef DEBUG
 	printk ("before free_area_init\n");
 #endif
-	for (i = 0; i < m68k_num_memory; i++) {
-		zones_size[ZONE_DMA] = m68k_memory[i].size >> PAGE_SHIFT;
-		free_area_init_node(i, zones_size,
-				    m68k_memory[i].addr >> PAGE_SHIFT, NULL);
+	for (i = 0; i < m68k_num_memory; i++)
 		if (node_present_pages(i))
 			node_set_state(i, N_NORMAL_MEMORY);
-	}
+
+	max_zone_pfn[ZONE_DMA] = memblock_end_of_DRAM();
+	free_area_init(max_zone_pfn);
 }

arch/m68k/mm/sun3mmu.c

@@ -42,7 +42,7 @@ void __init paging_init(void)
 	unsigned long address;
 	unsigned long next_pgtable;
 	unsigned long bootmem_end;
-	unsigned long zones_size[MAX_NR_ZONES] = { 0, };
+	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
 	unsigned long size;
 
 	empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
@@ -89,14 +89,10 @@ void __init paging_init(void)
 	current->mm = NULL;
 
 	/* memory sizing is a hack stolen from motorola.c..  hope it works for us */
-	zones_size[ZONE_DMA] = ((unsigned long)high_memory - PAGE_OFFSET) >> PAGE_SHIFT;
+	max_zone_pfn[ZONE_DMA] = ((unsigned long)high_memory) >> PAGE_SHIFT;
 
 	/* I really wish I knew why the following change made things better...  -- Sam */
-/*	free_area_init(zones_size); */
-	free_area_init_node(0, zones_size,
-			    (__pa(PAGE_OFFSET) >> PAGE_SHIFT) + 1, NULL);
+	free_area_init(max_zone_pfn);
 
 
 }
-
-