Refactor internal dma_contiguous_init_reserved_mem() function, which
creates CMA area from previously reserved memory region and add support
for handling 'shared-dma-pool' reserved-memory device tree nodes.

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

Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.com>
---
 drivers/base/dma-contiguous.c |  129 ++++++++++++++++++++++++++++++++++-------
 1 file changed, 107 insertions(+), 22 deletions(-)

diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index 165c2c299e57..0efdf1986990 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -182,6 +182,49 @@ static int __init cma_init_reserved_areas(void)
 core_initcall(cma_init_reserved_areas);
 
 /**
+ * dma_contiguous_init_reserved_mem() - reserve custom contiguous area
+ * @size: Size of the reserved area (in bytes),
+ * @base: Base address of the reserved area optional, use 0 for any
+ * @limit: End address of the reserved memory (optional, 0 for any).
+ * @res_cma: Pointer to store the created cma region.
+ *
+ * This function reserves memory from early allocator. It should be
+ * called by arch specific code once the early allocator (memblock or bootmem)
+ * has been activated and all other subsystems have already allocated/reserved
+ * memory. This function allows to create custom reserved areas for specific
+ * devices.
+ */
+static int __init dma_contiguous_init_reserved_mem(phys_addr_t size,
+                                       phys_addr_t base, struct cma **res_cma)
+{
+       struct cma *cma = &cma_areas[cma_area_count];
+       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;
+
+       /* Sanitise input arguments */
+       alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
+       if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
+               return -EINVAL;
+
+       cma->base_pfn = PFN_DOWN(base);
+       cma->count = size >> PAGE_SHIFT;
+       *res_cma = cma;
+       cma_area_count++;
+
+       /* Architecture specific contiguous memory fixup. */
+       dma_contiguous_early_fixup(base, size);
+       return 0;
+}
+
+/**
  * dma_contiguous_reserve_area() - reserve custom contiguous area
  * @size: Size of the reserved area (in bytes),
  * @base: Base address of the reserved area optional, use 0 for any
@@ -197,7 +240,6 @@ core_initcall(cma_init_reserved_areas);
 int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
                                       phys_addr_t limit, struct cma **res_cma)
 {
-       struct cma *cma = &cma_areas[cma_area_count];
        phys_addr_t alignment;
        int ret = 0;
 
@@ -205,12 +247,6 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, 
phys_addr_t base,
                 (unsigned long)size, (unsigned long)base,
                 (unsigned long)limit);
 
-       /* Sanity checks */
-       if (cma_area_count == ARRAY_SIZE(cma_areas)) {
-               pr_err("Not enough slots for CMA reserved regions!\n");
-               return -ENOSPC;
-       }
-
        if (!size)
                return -EINVAL;
 
@@ -241,21 +277,12 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, 
phys_addr_t base,
                }
        }
 
-       /*
-        * Each reserved area must be initialised later, when more kernel
-        * subsystems (like slab allocator) are available.
-        */
-       cma->base_pfn = PFN_DOWN(base);
-       cma->count = size >> PAGE_SHIFT;
-       *res_cma = cma;
-       cma_area_count++;
-
-       pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
-               (unsigned long)base);
-
-       /* Architecture specific contiguous memory fixup. */
-       dma_contiguous_early_fixup(base, size);
-       return 0;
+       ret = dma_contiguous_init_reserved_mem(size, base, res_cma);
+       if (ret == 0) {
+               pr_info("CMA: reserved %ld MiB at %08lx\n",
+                       (unsigned long)size / SZ_1M, (unsigned long)base);
+               return 0;
+       }
 err:
        pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
        return ret;
@@ -357,3 +384,61 @@ bool dma_release_from_contiguous(struct device *dev, 
struct page *pages,
 
        return true;
 }
+
+/*
+ * Support for reserved memory regions defined in device tree
+ */
+#ifdef CONFIG_OF_RESERVED_MEM
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+
+#undef pr_fmt
+#define pr_fmt(fmt) fmt
+
+static void rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
+{
+       struct cma *cma = rmem->priv;
+       dev_set_cma_area(dev, cma);
+}
+
+static const struct reserved_mem_ops rmem_cma_ops = {
+       .device_init    = rmem_cma_device_init,
+};
+
+static int __init rmem_cma_setup(struct reserved_mem *rmem,
+                                unsigned long node,
+                                const char *uname)
+{
+       phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
+       phys_addr_t mask = align - 1;
+       struct cma *cma;
+       int err;
+
+       if (!of_get_flat_dt_prop(node, "reusable", NULL))
+               return -EINVAL;
+
+       if ((rmem->base & mask) || (rmem->size & mask)) {
+               pr_err("Reserved memory: incorrect alignment of CMA region\n");
+               return -EINVAL;
+       }
+
+       err = dma_contiguous_init_reserved_mem(rmem->size, rmem->base, &cma);
+       if (err) {
+               pr_err("Reserved memory: unable to setup CMA region\n");
+               return err;
+       }
+
+       if (of_get_flat_dt_prop(node, "linux,cma-default", NULL))
+               dma_contiguous_set_default(cma);
+
+       rmem->ops = &rmem_cma_ops;
+       rmem->priv = cma;
+
+       pr_info("Reserved memory: created CMA memory pool at %pa, size %ld 
MiB\n",
+               &rmem->base, (unsigned long)rmem->size / SZ_1M);
+
+       return 0;
+}
+RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
+#endif
-- 
1.7.9.5

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