drivers: of: add initialization code for dma reserved memory

This patch adds device tree support for contiguous and reserved memory
regions defined in device tree.

Large memory blocks can be reliably reserved only during early boot.
This must happen before the whole memory management subsystem is
initialized, because we need to ensure that the given contiguous blocks
are not yet allocated by kernel. Also it must happen before kernel
mappings for the whole low memory are created, to ensure that there will
be no mappings (for reserved blocks) or mapping with special properties
can be created (for CMA blocks). This all happens before device tree
structures are unflattened, so we need to get reserved memory layout
directly from fdt.

Later, those reserved memory regions are assigned to devices on each
device structure initialization.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>

1 files changed, 175 insertions, 0 deletions

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
new file mode 100644
index 000000000000..a754b84ba016
--- /dev/null
+++ b/drivers/of/of_reserved_mem.c
@@ -0,0 +1,175 @@
+/*
+ * Device tree based initialization code for reserved memory.
+ *
+ * Copyright (c) 2013 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ * Author: Marek Szyprowski <m.szyprowski@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License or (at your optional) any later version of the license.
+ */
+
+#include <asm/dma-contiguous.h>
+
+#include <linux/memblock.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_platform.h>
+#include <linux/mm.h>
+#include <linux/sizes.h>
+#include <linux/mm_types.h>
+#include <linux/dma-contiguous.h>
+#include <linux/dma-mapping.h>
+#include <linux/of_reserved_mem.h>
+
+#define MAX_RESERVED_REGIONS	16
+struct reserved_mem {
+	phys_addr_t		base;
+	unsigned long		size;
+	struct cma		*cma;
+	char			name[32];
+};
+static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
+static int reserved_mem_count;
+
+static int __init fdt_scan_reserved_mem(unsigned long node, const char *uname,
+					int depth, void *data)
+{
+	struct reserved_mem *rmem = &reserved_mem[reserved_mem_count];
+	phys_addr_t base, size;
+	int is_cma, is_reserved;
+	unsigned long len;
+	const char *status;
+	__be32 *prop;
+
+	is_cma = IS_ENABLED(CONFIG_DMA_CMA) &&
+	       of_flat_dt_is_compatible(node, "linux,contiguous-memory-region");
+	is_reserved = of_flat_dt_is_compatible(node, "reserved-memory-region");
+
+	if (!is_reserved && !is_cma) {
+		/* ignore node and scan next one */
+		return 0;
+	}
+
+	status = of_get_flat_dt_prop(node, "status", &len);
+	if (status && strcmp(status, "okay") != 0) {
+		/* ignore disabled node nad scan next one */
+		return 0;
+	}
+
+	prop = of_get_flat_dt_prop(node, "reg", &len);
+	if (!prop || (len < (dt_root_size_cells + dt_root_addr_cells) *
+			     sizeof(__be32))) {
+		pr_err("Reserved mem: node %s, incorrect \"reg\" property\n",
+		       uname);
+		/* ignore node and scan next one */
+		return 0;
+	}
+	base = dt_mem_next_cell(dt_root_addr_cells, &prop);
+	size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+	if (!size) {
+		/* ignore node and scan next one */
+		return 0;
+	}
+
+	pr_info("Reserved mem: found %s, memory base %lx, size %ld MiB\n",
+		uname, (unsigned long)base, (unsigned long)size / SZ_1M);
+
+	if (reserved_mem_count == ARRAY_SIZE(reserved_mem))
+		return -ENOSPC;
+
+	rmem->base = base;
+	rmem->size = size;
+	strlcpy(rmem->name, uname, sizeof(rmem->name));
+
+	if (is_cma) {
+		struct cma *cma;
+		if (dma_contiguous_reserve_area(size, base, 0, &cma) == 0) {
+			rmem->cma = cma;
+			reserved_mem_count++;
+			if (of_get_flat_dt_prop(node,
+						"linux,default-contiguous-region",
+						NULL))
+				dma_contiguous_set_default(cma);
+		}
+	} else if (is_reserved) {
+		if (memblock_remove(base, size) == 0)
+			reserved_mem_count++;
+		else
+			pr_err("Failed to reserve memory for %s\n", uname);
+	}
+
+	return 0;
+}
+
+static struct reserved_mem *get_dma_memory_region(struct device *dev)
+{
+	struct device_node *node;
+	const char *name;
+	int i;
+
+	node = of_parse_phandle(dev->of_node, "memory-region", 0);
+	if (!node)
+		return NULL;
+
+	name = kbasename(node->full_name);
+	for (i = 0; i < reserved_mem_count; i++)
+		if (strcmp(name, reserved_mem[i].name) == 0)
+			return &reserved_mem[i];
+	return NULL;
+}
+
+/**
+ * of_reserved_mem_device_init() - assign reserved memory region to given device
+ *
+ * This function assign memory region pointed by "memory-region" device tree
+ * property to the given device.
+ */
+void of_reserved_mem_device_init(struct device *dev)
+{
+	struct reserved_mem *region = get_dma_memory_region(dev);
+	if (!region)
+		return;
+
+	if (region->cma) {
+		dev_set_cma_area(dev, region->cma);
+		pr_info("Assigned CMA %s to %s device\n", region->name,
+			dev_name(dev));
+	} else {
+		if (dma_declare_coherent_memory(dev, region->base, region->base,
+		    region->size, DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE) != 0)
+			pr_info("Declared reserved memory %s to %s device\n",
+				region->name, dev_name(dev));
+	}
+}
+
+/**
+ * of_reserved_mem_device_release() - release reserved memory device structures
+ *
+ * This function releases structures allocated for memory region handling for
+ * the given device.
+ */
+void of_reserved_mem_device_release(struct device *dev)
+{
+	struct reserved_mem *region = get_dma_memory_region(dev);
+	if (!region && !region->cma)
+		dma_release_declared_memory(dev);
+}
+
+/**
+ * early_init_dt_scan_reserved_mem() - create reserved memory regions
+ *
+ * This function grabs memory from early allocator for device exclusive use
+ * defined in device tree structures. It should be called by arch specific code
+ * once the early allocator (memblock) has been activated and all other
+ * subsystems have already allocated/reserved memory.
+ */
+void __init early_init_dt_scan_reserved_mem(void)
+{
+	of_scan_flat_dt_by_path("/memory/reserved-memory",
+				fdt_scan_reserved_mem, NULL);
+}