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+/*
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+ * Device tree based initialization code for reserved memory.
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+ *
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+ * Copyright (c) 2013 Samsung Electronics Co., Ltd.
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+ * http://www.samsung.com
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+ * Author: Marek Szyprowski <m.szyprowski@samsung.com>
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License as
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+ * published by the Free Software Foundation; either version 2 of the
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+ * License or (at your optional) any later version of the license.
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+ */
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+
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+#include <asm/dma-contiguous.h>
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+
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+#include <linux/memblock.h>
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+#include <linux/err.h>
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+#include <linux/of.h>
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+#include <linux/of_fdt.h>
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+#include <linux/of_platform.h>
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+#include <linux/mm.h>
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+#include <linux/sizes.h>
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+#include <linux/mm_types.h>
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+#include <linux/dma-contiguous.h>
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+#include <linux/dma-mapping.h>
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+#include <linux/of_reserved_mem.h>
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+
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+#define MAX_RESERVED_REGIONS 16
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+struct reserved_mem {
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+ phys_addr_t base;
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+ unsigned long size;
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+ struct cma *cma;
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+ char name[32];
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+};
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+static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
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+static int reserved_mem_count;
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+
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+static int __init fdt_scan_reserved_mem(unsigned long node, const char *uname,
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+ int depth, void *data)
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+{
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+ struct reserved_mem *rmem = &reserved_mem[reserved_mem_count];
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+ phys_addr_t base, size;
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+ int is_cma, is_reserved;
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+ unsigned long len;
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+ const char *status;
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+ __be32 *prop;
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+
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+ is_cma = IS_ENABLED(CONFIG_DMA_CMA) &&
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+ of_flat_dt_is_compatible(node, "linux,contiguous-memory-region");
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+ is_reserved = of_flat_dt_is_compatible(node, "reserved-memory-region");
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+
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+ if (!is_reserved && !is_cma) {
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+ /* ignore node and scan next one */
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+ return 0;
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+ }
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+
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+ status = of_get_flat_dt_prop(node, "status", &len);
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+ if (status && strcmp(status, "okay") != 0) {
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+ /* ignore disabled node nad scan next one */
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+ return 0;
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+ }
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+
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+ prop = of_get_flat_dt_prop(node, "reg", &len);
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+ if (!prop || (len < (dt_root_size_cells + dt_root_addr_cells) *
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+ sizeof(__be32))) {
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+ pr_err("Reserved mem: node %s, incorrect \"reg\" property\n",
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+ uname);
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+ /* ignore node and scan next one */
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+ return 0;
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+ }
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+ base = dt_mem_next_cell(dt_root_addr_cells, &prop);
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+ size = dt_mem_next_cell(dt_root_size_cells, &prop);
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+
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+ if (!size) {
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+ /* ignore node and scan next one */
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+ return 0;
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+ }
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+
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+ pr_info("Reserved mem: found %s, memory base %lx, size %ld MiB\n",
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+ uname, (unsigned long)base, (unsigned long)size / SZ_1M);
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+
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+ if (reserved_mem_count == ARRAY_SIZE(reserved_mem))
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+ return -ENOSPC;
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+
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+ rmem->base = base;
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+ rmem->size = size;
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+ strlcpy(rmem->name, uname, sizeof(rmem->name));
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+
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+ if (is_cma) {
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+ struct cma *cma;
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+ if (dma_contiguous_reserve_area(size, base, 0, &cma) == 0) {
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+ rmem->cma = cma;
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+ reserved_mem_count++;
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+ if (of_get_flat_dt_prop(node,
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+ "linux,default-contiguous-region",
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+ NULL))
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+ dma_contiguous_set_default(cma);
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+ }
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+ } else if (is_reserved) {
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+ if (memblock_remove(base, size) == 0)
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+ reserved_mem_count++;
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+ else
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+ pr_err("Failed to reserve memory for %s\n", uname);
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+ }
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+
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+ return 0;
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+}
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+
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+static struct reserved_mem *get_dma_memory_region(struct device *dev)
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+{
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+ struct device_node *node;
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+ const char *name;
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+ int i;
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+
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+ node = of_parse_phandle(dev->of_node, "memory-region", 0);
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+ if (!node)
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+ return NULL;
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+
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+ name = kbasename(node->full_name);
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+ for (i = 0; i < reserved_mem_count; i++)
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+ if (strcmp(name, reserved_mem[i].name) == 0)
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+ return &reserved_mem[i];
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+ return NULL;
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+}
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+
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+/**
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+ * of_reserved_mem_device_init() - assign reserved memory region to given device
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+ *
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+ * This function assign memory region pointed by "memory-region" device tree
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+ * property to the given device.
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+ */
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+void of_reserved_mem_device_init(struct device *dev)
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+{
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+ struct reserved_mem *region = get_dma_memory_region(dev);
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+ if (!region)
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+ return;
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+
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+ if (region->cma) {
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+ dev_set_cma_area(dev, region->cma);
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+ pr_info("Assigned CMA %s to %s device\n", region->name,
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+ dev_name(dev));
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+ } else {
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+ if (dma_declare_coherent_memory(dev, region->base, region->base,
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+ region->size, DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE) != 0)
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+ pr_info("Declared reserved memory %s to %s device\n",
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+ region->name, dev_name(dev));
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+ }
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+}
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+
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+/**
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+ * of_reserved_mem_device_release() - release reserved memory device structures
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+ *
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+ * This function releases structures allocated for memory region handling for
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+ * the given device.
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+ */
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+void of_reserved_mem_device_release(struct device *dev)
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+{
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+ struct reserved_mem *region = get_dma_memory_region(dev);
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+ if (!region && !region->cma)
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+ dma_release_declared_memory(dev);
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+}
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+
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+/**
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+ * early_init_dt_scan_reserved_mem() - create reserved memory regions
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+ *
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+ * This function grabs memory from early allocator for device exclusive use
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+ * defined in device tree structures. It should be called by arch specific code
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+ * once the early allocator (memblock) has been activated and all other
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+ * subsystems have already allocated/reserved memory.
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+ */
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+void __init early_init_dt_scan_reserved_mem(void)
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+{
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+ of_scan_flat_dt_by_path("/memory/reserved-memory",
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+ fdt_scan_reserved_mem, NULL);
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+}
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Marek Szyprowski