powerpc: Dynamic DMA zone limits

Platform code can call limit_zone_pfn() to set appropriate limits
for ZONE_DMA and ZONE_DMA32, and dma_direct_alloc_coherent() will
select a suitable zone based on a device's mask and the pfn limits that
platform code has configured.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Shaohui Xie <Shaohui.Xie@freescale.com>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index bd6dd6ed3a9f1c30b4ae508057a264348b117b3f..d003409b5f9856185bee9e377116e8c9b1bb7b6c 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -285,6 +285,10 @@ config PPC_EMULATE_SSTEP
        bool
        default y if KPROBES || UPROBES || XMON || HAVE_HW_BREAKPOINT
 
+config ZONE_DMA32
+       bool
+       default y if PPC64
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index d98c1ecc32665444c2b046cf57952f45bdfea9fa..6d74167bb6bf8efea80923f8fce9d60dc2b63245 100644 (file)
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -4,6 +4,7 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/mmdebug.h>
+#include <linux/mmzone.h>
 #include <asm/processor.h>             /* For TASK_SIZE */
 #include <asm/mmu.h>
 #include <asm/page.h>
@@ -281,6 +282,8 @@ extern unsigned long empty_zero_page[];
 
 extern pgd_t swapper_pg_dir[];
 
+void limit_zone_pfn(enum zone_type zone, unsigned long max_pfn);
+int dma_pfn_limit_to_zone(u64 pfn_limit);
 extern void paging_init(void);
 
 /*

diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index ee78f6e49d64bddc78d58382b73008841896b38a..dfd99ef8c63d088e878dfbb3fd4639b9ba4bb40c 100644 (file)
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -40,6 +40,26 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
 #else
        struct page *page;
        int node = dev_to_node(dev);
+       u64 pfn = (dev->coherent_dma_mask >> PAGE_SHIFT) + 1;
+       int zone;
+
+       zone = dma_pfn_limit_to_zone(pfn);
+       if (zone < 0) {
+               dev_err(dev, "%s: No suitable zone for pfn %#llx\n",
+                       __func__, pfn);
+               return NULL;
+       }
+
+       switch (zone) {
+       case ZONE_DMA:
+               flag |= GFP_DMA;
+               break;
+#ifdef CONFIG_ZONE_DMA32
+       case ZONE_DMA32:
+               flag |= GFP_DMA32;
+               break;
+#endif
+       };
 
        /* ignore region specifiers */
        flag  &= ~(__GFP_HIGHMEM);

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 2c8e90f5789e4a72feb2e5a019a63a9e1dded518..687e7f7f77517915c1797c3063541d14da11d86b 100644 (file)
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -260,6 +260,54 @@ static int __init mark_nonram_nosave(void)
        return 0;
 }
 
+static bool zone_limits_final;
+
+static unsigned long max_zone_pfns[MAX_NR_ZONES] = {
+       [0 ... MAX_NR_ZONES - 1] = ~0UL
+};
+
+/*
+ * Restrict the specified zone and all more restrictive zones
+ * to be below the specified pfn.  May not be called after
+ * paging_init().
+ */
+void __init limit_zone_pfn(enum zone_type zone, unsigned long pfn_limit)
+{
+       int i;
+
+       if (WARN_ON(zone_limits_final))
+               return;
+
+       for (i = zone; i >= 0; i--) {
+               if (max_zone_pfns[i] > pfn_limit)
+                       max_zone_pfns[i] = pfn_limit;
+       }
+}
+
+/*
+ * Find the least restrictive zone that is entirely below the
+ * specified pfn limit.  Returns < 0 if no suitable zone is found.
+ *
+ * pfn_limit must be u64 because it can exceed 32 bits even on 32-bit
+ * systems -- the DMA limit can be higher than any possible real pfn.
+ */
+int dma_pfn_limit_to_zone(u64 pfn_limit)
+{
+       enum zone_type top_zone = ZONE_NORMAL;
+       int i;
+
+#ifdef CONFIG_HIGHMEM
+       top_zone = ZONE_HIGHMEM;
+#endif
+
+       for (i = top_zone; i >= 0; i--) {
+               if (max_zone_pfns[i] <= pfn_limit)
+                       return i;
+       }
+
+       return -EPERM;
+}
+
 /*
  * paging_init() sets up the page tables - in fact we've already done this.
  */
@@ -267,7 +315,7 @@ void __init paging_init(void)
 {
        unsigned long long total_ram = memblock_phys_mem_size();
        phys_addr_t top_of_ram = memblock_end_of_DRAM();
-       unsigned long max_zone_pfns[MAX_NR_ZONES];
+       enum zone_type top_zone;
 
 #ifdef CONFIG_PPC32
        unsigned long v = __fix_to_virt(__end_of_fixed_addresses - 1);
@@ -289,13 +337,16 @@ void __init paging_init(void)
               (unsigned long long)top_of_ram, total_ram);
        printk(KERN_DEBUG "Memory hole size: %ldMB\n",
               (long int)((top_of_ram - total_ram) >> 20));
-       memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
+
 #ifdef CONFIG_HIGHMEM
-       max_zone_pfns[ZONE_DMA] = lowmem_end_addr >> PAGE_SHIFT;
-       max_zone_pfns[ZONE_HIGHMEM] = top_of_ram >> PAGE_SHIFT;
+       top_zone = ZONE_HIGHMEM;
+       limit_zone_pfn(ZONE_NORMAL, lowmem_end_addr >> PAGE_SHIFT);
 #else
-       max_zone_pfns[ZONE_DMA] = top_of_ram >> PAGE_SHIFT;
+       top_zone = ZONE_NORMAL;
 #endif
+
+       limit_zone_pfn(top_zone, top_of_ram >> PAGE_SHIFT);
+       zone_limits_final = true;
        free_area_init_nodes(max_zone_pfns);
 
        mark_nonram_nosave();