drivers: dma-contiguous: add initialization from device tree

Add a function to create CMA region from previously reserved memory and
add support for handling 'shared-dma-pool' reserved-memory device tree
nodes.

Based on previous code provided by Josh Cartwright <joshc@codeaurora.org>

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 51 insertions, 11 deletions

diff --git a/mm/cma.c b/mm/cma.c
index a951a3b3ed36..963bc4add9af 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -143,6 +143,54 @@ static int __init cma_init_reserved_areas(void)
 core_initcall(cma_init_reserved_areas);
 
 /**
+ * cma_init_reserved_mem() - create custom contiguous area from reserved memory
+ * @base: Base address of the reserved area
+ * @size: Size of the reserved area (in bytes),
+ * @order_per_bit: Order of pages represented by one bit on bitmap.
+ * @res_cma: Pointer to store the created cma region.
+ *
+ * This function creates custom contiguous area from already reserved memory.
+ */
+int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
+                                 int order_per_bit, struct cma **res_cma)
+{
+        struct cma *cma;
+        phys_addr_t alignment;
+
+        /* Sanity checks */
+        if (cma_area_count == ARRAY_SIZE(cma_areas)) {
+                pr_err("Not enough slots for CMA reserved regions!\n");
+                return -ENOSPC;
+        }
+
+        if (!size || !memblock_is_region_reserved(base, size))
+                return -EINVAL;
+
+        /* ensure minimal alignment requied by mm core */
+        alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
+
+        /* alignment should be aligned with order_per_bit */
+        if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
+                return -EINVAL;
+
+        if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
+                return -EINVAL;
+
+        /*
+         * Each reserved area must be initialised later, when more kernel
+         * subsystems (like slab allocator) are available.
+         */
+        cma = &cma_areas[cma_area_count];
+        cma->base_pfn = PFN_DOWN(base);
+        cma->count = size >> PAGE_SHIFT;
+        cma->order_per_bit = order_per_bit;
+        *res_cma = cma;
+        cma_area_count++;
+
+        return 0;
+}
+
+/**
  * cma_declare_contiguous() - reserve custom contiguous area
  * @base: Base address of the reserved area optional, use 0 for any
  * @size: Size of the reserved area (in bytes),
@@ -165,7 +213,6 @@ int __init cma_declare_contiguous(phys_addr_t base,
                         phys_addr_t alignment, unsigned int order_per_bit,
                         bool fixed, struct cma **res_cma)
 {
-        struct cma *cma;
         phys_addr_t memblock_end = memblock_end_of_DRAM();
         phys_addr_t highmem_start = __pa(high_memory);
         int ret = 0;
@@ -237,16 +284,9 @@ int __init cma_declare_contiguous(phys_addr_t base,
                 }
         }
 
-        /*
-         * Each reserved area must be initialised later, when more kernel
-         * subsystems (like slab allocator) are available.
-         */
-        cma = &cma_areas[cma_area_count];
-        cma->base_pfn = PFN_DOWN(base);
-        cma->count = size >> PAGE_SHIFT;
-        cma->order_per_bit = order_per_bit;
-        *res_cma = cma;
-        cma_area_count++;
+        ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
+        if (ret)
+                goto err;
 
         pr_info("Reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
                 (unsigned long)base);