[ARM] 3209/1: Configurable DMA-consistent memory region

Patch from Kevin Hilman

This patch increase available DMA-consistent memory allocated by dma_coherent_alloc(). The default remains at 2M (defined in asm/memory.h) and each platform has the ability to override in asm/arch-foo/memory.h.

Signed-off-by: Kevin Hilman <kevin@hilman.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c
index 0513ed1b2fcf8334ffdcf12a78277008e23e07c8..c2ee18d2075e7bd22312835cf9c3d859c0913f5b 100644 (file)
--- a/arch/arm/mm/consistent.c
+++ b/arch/arm/mm/consistent.c
@@ -20,15 +20,25 @@
 
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
+#include <asm/sizes.h>
+
+/* Sanity check size */
+#if (CONSISTENT_DMA_SIZE % SZ_2M)
+#error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
+#endif
 
-#define CONSISTENT_BASE        (0xffc00000)
 #define CONSISTENT_END (0xffe00000)
+#define CONSISTENT_BASE        (CONSISTENT_END - CONSISTENT_DMA_SIZE)
+
 #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)
+
 
 /*
- * This is the page table (2MB) covering uncached, DMA consistent allocations
+ * These are the page tables (2MB each) covering uncached, DMA consistent allocations
  */
-static pte_t *consistent_pte;
+static pte_t *consistent_pte[NUM_CONSISTENT_PTES];
 static DEFINE_SPINLOCK(consistent_lock);
 
 /*
@@ -142,7 +152,7 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
        unsigned long order;
        u64 mask = ISA_DMA_THRESHOLD, limit;
 
-       if (!consistent_pte) {
+       if (!consistent_pte[0]) {
                printk(KERN_ERR "%s: not initialised\n", __func__);
                dump_stack();
                return NULL;
@@ -205,9 +215,12 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
        c = vm_region_alloc(&consistent_head, size,
                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
        if (c) {
-               pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
+               pte_t *pte;
                struct page *end = page + (1 << order);
+               int idx = CONSISTENT_PTE_INDEX(c->vm_start);
+               u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 
+               pte = consistent_pte[idx] + off;
                c->vm_pages = page;
 
                /*
@@ -226,6 +239,11 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
                        set_pte(pte, mk_pte(page, prot));
                        page++;
                        pte++;
+                       off++;
+                       if (off >= PTRS_PER_PTE) {
+                               off = 0;
+                               pte = consistent_pte[++idx];
+                       }
                } while (size -= PAGE_SIZE);
 
                /*
@@ -327,6 +345,8 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr
        struct vm_region *c;
        unsigned long flags, addr;
        pte_t *ptep;
+       int idx;
+       u32 off;
 
        WARN_ON(irqs_disabled());
 
@@ -347,7 +367,9 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr
                size = c->vm_end - c->vm_start;
        }
 
-       ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
+       idx = CONSISTENT_PTE_INDEX(c->vm_start);
+       off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
+       ptep = consistent_pte[idx] + off;
        addr = c->vm_start;
        do {
                pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
@@ -355,6 +377,11 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr
 
                ptep++;
                addr += PAGE_SIZE;
+               off++;
+               if (off >= PTRS_PER_PTE) {
+                       off = 0;
+                       ptep = consistent_pte[++idx];
+               }
 
                if (!pte_none(pte) && pte_present(pte)) {
                        pfn = pte_pfn(pte);
@@ -401,11 +428,12 @@ static int __init consistent_init(void)
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte;
-       int ret = 0;
+       int ret = 0, i = 0;
+       u32 base = CONSISTENT_BASE;
 
        do {
-               pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
-               pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
+               pgd = pgd_offset(&init_mm, base);
+               pmd = pmd_alloc(&init_mm, pgd, base);
                if (!pmd) {
                        printk(KERN_ERR "%s: no pmd tables\n", __func__);
                        ret = -ENOMEM;
@@ -413,15 +441,16 @@ static int __init consistent_init(void)
                }
                WARN_ON(!pmd_none(*pmd));
 
-               pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
+               pte = pte_alloc_kernel(pmd, base);
                if (!pte) {
                        printk(KERN_ERR "%s: no pte tables\n", __func__);
                        ret = -ENOMEM;
                        break;
                }
 
-               consistent_pte = pte;
-       } while (0);
+               consistent_pte[i++] = pte;
+               base += (1 << PGDIR_SHIFT);
+       } while (base < CONSISTENT_END);
 
        return ret;
 }

diff --git a/include/asm-arm/memory.h b/include/asm-arm/memory.h
index 3d7f08bd9030f84e7828c99db876d216032066d6..b4e1146ab682cf97fce022c83c8be81b1f02fc7e 100644 (file)
--- a/include/asm-arm/memory.h
+++ b/include/asm-arm/memory.h
@@ -25,6 +25,7 @@
 #include <linux/config.h>
 #include <linux/compiler.h>
 #include <asm/arch/memory.h>
+#include <asm/sizes.h>
 
 #ifndef TASK_SIZE
 /*
@@ -47,6 +48,14 @@
 #define PAGE_OFFSET            UL(0xc0000000)
 #endif
 
+/*
+ * Size of DMA-consistent memory region.  Must be multiple of 2M,
+ * between 2MB and 14MB inclusive.
+ */
+#ifndef CONSISTENT_DMA_SIZE
+#define CONSISTENT_DMA_SIZE SZ_2M
+#endif
+
 /*
  * Physical vs virtual RAM address space conversion.  These are
  * private definitions which should NOT be used outside memory.h