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 bd6dd6e..d003409 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -285,6 +285,10 @@
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 d98c1ec..6d74167 100644
--- 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 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 ee78f6e..dfd99ef 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -40,6 +40,26 @@
#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 2c8e90f..687e7f7 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -260,6 +260,54 @@
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 @@
{
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 @@
(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();