ARM: Add init_consistent_dma_size()

This function can be called during boot to increase the size of the consistent
DMA region above it's default value of 2MB. It must be called before the memory
allocator is initialised, i.e. before any core_initcall.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

1 files changed, 38 insertions, 11 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 0a0a1e7c20d2..5b59ce572877 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -18,12 +18,14 @@
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/highmem.h>
+#include <linux/slab.h>
 
 #include <asm/memory.h>
 #include <asm/highmem.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/sizes.h>
+#include <asm/mach/arch.h>
 
 #include "mm.h"
 
@@ -117,26 +119,41 @@ static void __dma_free_buffer(struct page *page, size_t size)
 }
 
 #ifdef CONFIG_MMU
-/* Sanity check size */
-#if (CONSISTENT_DMA_SIZE % SZ_2M)
-#error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
-#endif
 
-#define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
-#define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PGDIR_SHIFT)
-#define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PGDIR_SHIFT)
+
+#define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - consistent_base) >> PAGE_SHIFT)
+#define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - consistent_base) >> PGDIR_SHIFT)
 
 /*
  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
  */
-static pte_t *consistent_pte[NUM_CONSISTENT_PTES];
+static pte_t **consistent_pte;
+
+#ifdef CONSISTENT_DMA_SIZE
+#define DEFAULT_CONSISTENT_DMA_SIZE CONSISTENT_DMA_SIZE
+#else
+#define DEFAULT_CONSISTENT_DMA_SIZE SZ_2M
+#endif
+
+unsigned long consistent_base = CONSISTENT_END - DEFAULT_CONSISTENT_DMA_SIZE;
+
+void __init init_consistent_dma_size(unsigned long size)
+{
+	unsigned long base = CONSISTENT_END - ALIGN(size, SZ_2M);
+
+	BUG_ON(consistent_pte); /* Check we're called before DMA region init */
+	BUG_ON(base < VMALLOC_END);
+
+	/* Grow region to accommodate specified size  */
+	if (base < consistent_base)
+		consistent_base = base;
+}
 
 #include "vmregion.h"
 
 static struct arm_vmregion_head consistent_head = {
 	.vm_lock	= __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
 	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
-	.vm_start	= CONSISTENT_BASE,
 	.vm_end		= CONSISTENT_END,
 };
 
@@ -155,7 +172,17 @@ static int __init consistent_init(void)
 	pmd_t *pmd;
 	pte_t *pte;
 	int i = 0;
-	u32 base = CONSISTENT_BASE;
+	unsigned long base = consistent_base;
+	unsigned long num_ptes = (CONSISTENT_END - base) >> PGDIR_SHIFT;
+
+	consistent_pte = kmalloc(num_ptes * sizeof(pte_t), GFP_KERNEL);
+	if (!consistent_pte) {
+		pr_err("%s: no memory\n", __func__);
+		return -ENOMEM;
+	}
+
+	pr_debug("DMA memory: 0x%08lx - 0x%08lx:\n", base, CONSISTENT_END);
+	consistent_head.vm_start = base;
 
 	do {
 		pgd = pgd_offset(&init_mm, base);
@@ -198,7 +225,7 @@ __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
 	size_t align;
 	int bit;
 
-	if (!consistent_pte[0]) {
+	if (!consistent_pte) {
 		printk(KERN_ERR "%s: not initialised\n", __func__);
 		dump_stack();
 		return NULL;