[MIPS] Setup min_low_pfn/max_low_pfn correctly

This patch makes a better usage of these two globals.
'min_low_pfn' is now correctly setup for all configs, which
allow us to rely on it in boot memory code init.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 39 insertions, 21 deletions

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 89440a0d8528..f352cd9c834b 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -271,8 +271,7 @@ static void __init bootmem_init(void)
 static void __init bootmem_init(void)
 {
         unsigned long reserved_end;
-        unsigned long highest = 0;
-        unsigned long mapstart = -1UL;
+        unsigned long mapstart = ~0UL;
         unsigned long bootmap_size;
         int i;
 
@@ -284,6 +283,13 @@ static void __init bootmem_init(void)
         reserved_end = max(init_initrd(), PFN_UP(__pa_symbol(&_end)));
 
         /*
+         * max_low_pfn is not a number of pages. The number of pages
+         * of the system is given by 'max_low_pfn - min_low_pfn'.
+         */
+        min_low_pfn = ~0UL;
+        max_low_pfn = 0;
+
+        /*
          * Find the highest page frame number we have available.
          */
         for (i = 0; i < boot_mem_map.nr_map; i++) {
@@ -296,8 +302,10 @@ static void __init bootmem_init(void)
                 end = PFN_DOWN(boot_mem_map.map[i].addr
                                 + boot_mem_map.map[i].size);
 
-                if (end > highest)
-                        highest = end;
+                if (end > max_low_pfn)
+                        max_low_pfn = end;
+                if (start < min_low_pfn)
+                        min_low_pfn = start;
                 if (end <= reserved_end)
                         continue;
                 if (start >= mapstart)
@@ -305,22 +313,32 @@ static void __init bootmem_init(void)
                 mapstart = max(reserved_end, start);
         }
 
+        if (min_low_pfn >= max_low_pfn)
+                panic("Incorrect memory mapping !!!");
+        if (min_low_pfn > 0) {
+                printk(KERN_INFO
+                       "Wasting %lu bytes for tracking %lu unused pages\n",
+                       min_low_pfn * sizeof(struct page),
+                       min_low_pfn);
+                min_low_pfn = 0;
+        }
+
         /*
          * Determine low and high memory ranges
          */
-        if (highest > PFN_DOWN(HIGHMEM_START)) {
+        if (max_low_pfn > PFN_DOWN(HIGHMEM_START)) {
 #ifdef CONFIG_HIGHMEM
                 highstart_pfn = PFN_DOWN(HIGHMEM_START);
-                highend_pfn = highest;
+                highend_pfn = max_low_pfn;
 #endif
-                highest = PFN_DOWN(HIGHMEM_START);
+                max_low_pfn = PFN_DOWN(HIGHMEM_START);
         }
 
         /*
          * Initialize the boot-time allocator with low memory only.
          */
-        bootmap_size = init_bootmem(mapstart, highest);
-
+        bootmap_size = init_bootmem_node(NODE_DATA(0), mapstart,
+                                         min_low_pfn, max_low_pfn);
         /*
          * Register fully available low RAM pages with the bootmem allocator.
          */
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index fb427dbfe71e..5257f7b42fd2 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -341,7 +341,6 @@ static int __init page_is_ram(unsigned long pagenr)
 void __init paging_init(void)
 {
         unsigned long zones_size[MAX_NR_ZONES] = { 0, };
-        unsigned long max_dma, low;
 #ifndef CONFIG_FLATMEM
         unsigned long zholes_size[MAX_NR_ZONES] = { 0, };
         unsigned long i, j, pfn;
@@ -354,19 +353,19 @@ void __init paging_init(void)
 #endif
         kmap_coherent_init();
 
-        max_dma = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
-        low = max_low_pfn;
-
 #ifdef CONFIG_ISA
-        if (low < max_dma)
-                zones_size[ZONE_DMA] = low;
-        else {
-                zones_size[ZONE_DMA] = max_dma;
-                zones_size[ZONE_NORMAL] = low - max_dma;
-        }
-#else
-        zones_size[ZONE_DMA] = low;
+        if (max_low_pfn >= MAX_DMA_PFN)
+                if (min_low_pfn >= MAX_DMA_PFN) {
+                        zones_size[ZONE_DMA] = 0;
+                        zones_size[ZONE_NORMAL] = max_low_pfn - min_low_pfn;
+                } else {
+                        zones_size[ZONE_DMA] = MAX_DMA_PFN - min_low_pfn;
+                        zones_size[ZONE_NORMAL] = max_low_pfn - MAX_DMA_PFN;
+                }
+        else
 #endif
+        zones_size[ZONE_DMA] = max_low_pfn - min_low_pfn;
+
 #ifdef CONFIG_HIGHMEM
         zones_size[ZONE_HIGHMEM] = highend_pfn - highstart_pfn;
 
diff --git a/include/asm-mips/dma.h b/include/asm-mips/dma.h
index 23f789c80845..e06ef0776d48 100644
--- a/include/asm-mips/dma.h
+++ b/include/asm-mips/dma.h
@@ -91,6 +91,7 @@
 #else
 #define MAX_DMA_ADDRESS         (PAGE_OFFSET + 0x01000000)
 #endif
+#define MAX_DMA_PFN             PFN_DOWN(virt_to_phys((void *)MAX_DMA_ADDRESS))
 
 /* 8237 DMA controllers */
 #define IO_DMA1_BASE    0x00    /* 8 bit slave DMA, channels 0..3 */