Device Tree support for CMA (Contiguous Memory Allocator)

This patch cleans the initialization of dma contiguous framework. The all-in-one dma_declare_contiguous() function is now separated into dma_contiguous_reserve_area() which only steals the the memory from memblock allocator and dma_contiguous_add_device() function, which assigns given device to the specified reserved memory area. This improves the flexibility in defining contiguous memory areas and assigning device to them, because now it is possible to assign more than one device to the given contiguous memory area. Such split in initialization procedure is also required for upcoming device tree support.

Signed-off-by Marek Szyprowski <[email protected]>

Acked-by Kyungmin Park <[email protected]>

drivers/base/dma-contiguous.c +4 -3

 		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
 			 (unsigned long)selected_size / SZ_1M);
 
-		dma_declare_contiguous(NULL, selected_size, 0, limit);
+		dma_contiguous_reserve_area(selected_size, 0, limit,
+					    &dma_contiguous_default_area);
 	}
 };
 
 static DEFINE_MUTEX(cma_mutex);
 
 
-int __init dma_declare_contiguous(struct device *dev, phys_addr_t size,
-				  phys_addr_t base, phys_addr_t limit)
+int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
+				       phys_addr_t limit, struct cma **res_cma)
 

include/linux/dma-contiguous.h +6 -0

+	ret = dma_contiguous_reserve_area(size, base, limit, &cma);
+	if (ret == 0)
+		dma_contiguous_add_device(dev, cma);
+
+	return ret;
+}

Add a function to scan the flattened device-tree starting from the node given by the path. It is used to extract information (like reserved memory), which is required on ealy boot before we can unflatten the

tree.

Signed-off-by Marek Szyprowski <[email protected]>

Acked-by Kyungmin Park <[email protected]>

drivers/of/fdt.c +9 -0

+static int __init fdt_scan_node_by_path(unsigned long node, const char *uname,
+					int depth, void *data)
+{
+	struct fdt_scan_status *st = data;
+
+	/*
+	 * if scan at the requested fdt node has been completed,
+	 * return -ENXIO to abort further scanning
+	 */

drivers/of/fdt.c +23 -0

+		}
+		return 0;
+	}
+
+	/* scan next fdt node */
+	return 0;
+}
+
+/**
+ * of_scan_flat_dt_by_path - scan flattened tree blob and call callback on each
+ *			     child of the given path.
+ * @path: path to start searching for children
+ * @it: callback function
+ * @data: context data pointer
+ *
+ * This function is used to scan the flattened device-tree starting from the
+ * node given by path. It is used to extract information (like reserved
+ * memory), which is required on ealy boot before we can unflatten the tree.
+ */
+int __init of_scan_flat_dt_by_path(const char *path,
+	int (*it)(unsigned long node, const char *name, int depth, void *data),
+	void *data)
+{

drivers/of/fdt.c +2 -0

+}
+
 #ifdef CONFIG_BLK_DEV_INITRD
 /**
  * early_init_dt_check_for_initrd - Decode initrd location from flat tree

Add device tree support for contiguous and reserved memory regions defined in device tree. Initialization is done in 2 steps. First, the memory is reserved, what happens very early when only flattened device tree is available. Then on device initialization the corresponding cma and reserved regions are assigned to each device structure.

Signed-off-by Marek Szyprowski <[email protected]>

Acked-by Kyungmin Park <[email protected]>

---
 Documentation/devicetree/bindings/memory.txt |  152 ++++++++++++++++++++++
 drivers/of/Kconfig                           |    6 +
 drivers/of/Makefile                          |    1 +
 drivers/of/of_reserved_mem.c                 |  175 ++++++++++++++++++++++++++
 include/asm-generic/dma-coherent.h           |    6 +
 5 files changed, 340 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/memory.txt
 create mode 100644 drivers/of/of_reserved_mem.c

Documentation/devicetree/bindings/memory.txt new file +152 -0

new file mode 100644
index 0000000..4aece19
@@ -0,0 +1,152 @@
+*** Memory binding ***
+
+The /memory node provides basic information about the address and size
+of the physical memory. This node is usually filled or updated by the
+bootloader, depending on the actual memory configuration of the given
+hardware.
+
+The memory layout is described by the folllowing node:
+
+memory {
+	reg =  <(baseaddr1) (size1)
+		(baseaddr2) (size2)
+		...
+		(baseaddrN) (sizeN)>;
+};
+
+baseaddrX:	the base address of the defined memory bank
+sizeX:		the size of the defined memory bank
+
+More than one memory bank can be defined.
+
+
+*** Reserved memory regions ***
+
+In /memory/reserved-memory node one can create additional nodes
+describing particular reserved (excluded from normal use) memory
+regions. Such memory regions are usually designed for the special usage
+by various device drivers. A good example are contiguous memory
+allocations or memory sharing with other operating system on the same
+hardware board. Those special memory regions might depend on the board
+configuration and devices used on the target system.
+
+Parameters for each memory region can be encoded into the device tree
+wit the following convention:
+
+[(label):] (name)@(address) {
+	compatible = "contiguous-memory-region", "reserved-memory-region";
+	reg = <(address) (size)>;
+	(linux,contiguous-region);
+	(linux,default-contiguous-region);
+};
+
+label:		label given to the defined region (optional)
+name:		an name given to the defined region
+address:	the base address of the defined region
+size:		the size of the memory region
+
+compatible:	"contiguous-memory-region" - enables binding of this
+		region to Contiguous Memory Allocator (special region for
+		contiguous memory allocations, shared with movable system
+		memory, Linux kernel-specific), alternatively if
+		"reserved-memory-region" - compatibility is defined, given
+		region is assigned for exclusive usage for DMA transfers
+
+linux,default-contiguous-region: property indicating that the region
+		is the default region for all contiguous memory
+		allocations, Linux specific (optional)
+
+Each defined region must use unique name. It is optional to specify the
+base address, so if one wants to use autoconfiguration of the base
+address, he must specify the '0' as base address in the 'reg' property
+and assign ann uniqe name to such regions.
+
+
+*** Device node's properties ***
+
+Once the regions in the /memory/reserved-memory node are defined, they
+can be assigned to device nodes to enable drivers for their special use.
+The following properties are defined:
+
+dma-memory-region = <&phandle_to_defined_region>;
+
+This property indicates that the device driver should use the
+memory region pointed by the given phandle.
+
+
+*** Example ***
+
+This example defines a memory consisting of 4 memory banks. 3 contiguous
+regions are defined for Linux kernel, one default of all device drivers
+(named contig_mem, placed at 0x72000000, 64MiB), one dedicated to the
+framebuffer device (labelled display_mem, placed at 0x78000000, 8MiB)
+and one for multimedia processing (labelled multimedia_mem, placed at
+0x77000000, 64MiB). 'display_mem' region is then assigned to fb at 12300000
+device for DMA memory allocations (Linux kernel drivers will use CMA is
+available or dma-exclusive usage otherwise). 'multimedia_mem' is
+assigned to scaller at 12500000 and codec at 12600000 devices for contiguous
+memory allocations when CMA driver is enabled.
+
+The reason for creating a separate region for framebuffer device is to
+match the framebuffer base address to the one configured by bootloader,
+so once Linux kernel drivers starts no glitches on the displayed boot
+logo appears. Scaller and codec drivers should share the memory
+allocations.
+
+/ {
+	/* ... */
+	memory {
+		reg =  <0x40000000 0x10000000
+			0x50000000 0x10000000
+			0x60000000 0x10000000
+			0x70000000 0x10000000>;
+
+		reserved-memory {
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			/*
+			 * global autoconfigured region for contiguous allocations
+			 * (used only with Contiguous Memory Allocator)
+			 */
+			contig_region at 0 {
+				compatible = "contiguous-memory-region";
+				reg = <0x0 0x4000000>;
+				linux,default-contiguous-region;
+			};
+
+			/*
+			 * special region for framebuffer
+			 */
+			display_mem: region at 78000000 {
+				compatible = "contiguous-memory-region", "reserved-memory-region";
+				reg = <0x78000000 0x800000>;
+			};
+
+			/*
+			 * special region for multimedia processing devices
+			 */
+			multimedia_mem: region at 77000000 {
+				compatible = "contiguous-memory-region";
+				reg = <0x77000000 0x4000000>;
+			};
+		};
+	};
+
+	/* ... */
+
+	fb0: fb at 12300000 {
+		status = "okay";
+		dma-memory-region = <&display_mem>;
+	};
+
+	scaller: scaller at 12500000 {
+		status = "okay";
+		dma-memory-region = <&multimedia_mem>;
+	};
+
+	codec: codec at 12600000 {
+		status = "okay";
+		dma-memory-region = <&multimedia_mem>;
+	};
+};

drivers/of/Kconfig +6 -0

index 80e5c13..a83ab43 100644
@@ -80,4 +80,10 @@ config OF_MTD
 	depends on MTD
 	def_bool y
 
+config OF_RESERVED_MEM
+	depends on CMA || (HAVE_GENERIC_DMA_COHERENT && HAVE_MEMBLOCK)
+	def_bool y
+	help
+	  Initialization code for DMA reserved memory
+
 endmenu # OF

drivers/of/Makefile +1 -0

index 1f9c0c4..e7e3322 100644
@@ -10,3 +10,4 @@ obj-$(CONFIG_OF_MDIO)	+= of_mdio.o
 obj-$(CONFIG_OF_PCI)	+= of_pci.o
 obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
 obj-$(CONFIG_OF_MTD)	+= of_mtd.o
+obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o

drivers/of/of_reserved_mem.c new file +35 -0

new file mode 100644
index 0000000..d97fcdf
@@ -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 <[email protected]>
+ *
+ * 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>
+
+#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;

drivers/of/of_reserved_mem.c new file +14 -0

+
+	if (!is_reserved && !(is_cma && IS_ENABLED(CONFIG_CMA)))
+		return 0;
+
+	prop = of_get_flat_dt_prop(node, "reg", &len);
+	if (!prop || (len != 2 * sizeof(unsigned long))) {
+		pr_err("Reserved mem: node %s, incorrect \"reg\" property\n",
+		       uname);
+		return 0;
+	}
+
+	if (sizeof(unsigned long) == 4) {
+		base = be32_to_cpu(((__be32 *)prop)[0]);
+		size = be32_to_cpu(((__be32 *)prop)[1]);

drivers/of/of_reserved_mem.c new file +21 -0

+
+	if (IS_ENABLED(CONFIG_CMA) && is_cma) {
+		struct cma *cma;
+		if (dma_contiguous_reserve_area(size, base, 0, &cma) == 0) {
+			reserved_mem[reserved_mem_count].cma = cma;
+			reserved_mem_count++;
+
+			if (of_get_flat_dt_prop(node,
+						"linux,default-contiguous-region",
+						NULL))
+				dma_contiguous_set_default_area(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;
+}

include/asm-generic/dma-coherent.h +0 -0

index 2be8a2d..06111d00 100644

include/asm-generic/dma-coherent.h +2 -0

+#endif
+
 #endif

Add device tree support for contiguous and reserved memory regions defined in device tree. Initialization is done in 2 steps. First, the memory is reserved, what happens very early when only flattened device tree is available. Then on device initialization the corresponding cma and reserved regions are assigned to each device structure.

Signed-off-by Marek Szyprowski <[email protected]>

Acked-by Kyungmin Park <[email protected]>

---
 Documentation/devicetree/bindings/memory.txt |  152 ++++++++++++++++++++++
 drivers/of/Kconfig                           |    6 +
 drivers/of/Makefile                          |    1 +
 drivers/of/of_reserved_mem.c                 |  175 ++++++++++++++++++++++++++
 include/asm-generic/dma-coherent.h           |    6 +
 5 files changed, 340 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/memory.txt
 create mode 100644 drivers/of/of_reserved_mem.c

Documentation/devicetree/bindings/memory.txt new file +5 -0

new file mode 100644
index 0000000..4aece19
@@ -0,0 +1,152 @@
+*** Memory binding ***
+
+The /memory node provides basic information about the address and size
+of the physical memory. This node is usually filled or updated by the
+bootloader, depending on the actual memory configuration of the given

Documentation/devicetree/bindings/memory.txt new file +37 -0

+
+baseaddrX:     the base address of the defined memory bank
+sizeX:         the size of the defined memory bank
+
+More than one memory bank can be defined.
+
+
+*** Reserved memory regions ***
+
+In /memory/reserved-memory node one can create additional nodes
+describing particular reserved (excluded from normal use) memory
+regions. Such memory regions are usually designed for the special usage
+by various device drivers. A good example are contiguous memory
+allocations or memory sharing with other operating system on the same
+hardware board. Those special memory regions might depend on the board
+configuration and devices used on the target system.
+
+Parameters for each memory region can be encoded into the device tree
+wit the following convention:
+
+[(label):] (name)@(address) {
+       compatible = "contiguous-memory-region", "reserved-memory-region";
+       reg = <(address) (size)>;
+       (linux,contiguous-region);
+       (linux,default-contiguous-region);
+};
+
+label:         label given to the defined region (optional)
+name:          an name given to the defined region
+address:       the base address of the defined region
+size:          the size of the memory region
+
+compatible:    "contiguous-memory-region" - enables binding of this
+               region to Contiguous Memory Allocator (special region for
+               contiguous memory allocations, shared with movable system
+               memory, Linux kernel-specific), alternatively if
+               "reserved-memory-region" - compatibility is defined, given

Documentation/devicetree/bindings/memory.txt new file +15 -0

+
+
+*** Device node's properties ***
+
+Once the regions in the /memory/reserved-memory node are defined, they
+can be assigned to device nodes to enable drivers for their special use.
+The following properties are defined:
+
+dma-memory-region = <&phandle_to_defined_region>;
+
+This property indicates that the device driver should use the
+memory region pointed by the given phandle.
+
+
+*** Example ***

Documentation/devicetree/bindings/memory.txt new file +65 -0

+memory allocations when CMA driver is enabled.
+
+The reason for creating a separate region for framebuffer device is to
+match the framebuffer base address to the one configured by bootloader,
+so once Linux kernel drivers starts no glitches on the displayed boot
+logo appears. Scaller and codec drivers should share the memory
+allocations.
+
+/ {
+       /* ... */
+       memory {
+               reg =  <0x40000000 0x10000000
+                       0x50000000 0x10000000
+                       0x60000000 0x10000000
+                       0x70000000 0x10000000>;
+
+               reserved-memory {
+                       #address-cells = <1>;
+                       #size-cells = <1>;
+
+                       /*
+                        * global autoconfigured region for contiguous allocations
+                        * (used only with Contiguous Memory Allocator)
+                        */
+                       contig_region at 0 {
+                               compatible = "contiguous-memory-region";
+                               reg = <0x0 0x4000000>;
+                               linux,default-contiguous-region;
+                       };
+
+                       /*
+                        * special region for framebuffer
+                        */
+                       display_mem: region at 78000000 {
+                               compatible = "contiguous-memory-region", "reserved-memory-region";
+                               reg = <0x78000000 0x800000>;
+                       };
+
+                       /*
+                        * special region for multimedia processing devices
+                        */
+                       multimedia_mem: region at 77000000 {
+                               compatible = "contiguous-memory-region";
+                               reg = <0x77000000 0x4000000>;
+                       };
+               };
+       };
+
+       /* ... */
+
+       fb0: fb at 12300000 {
+               status = "okay";
+               dma-memory-region = <&display_mem>;
+       };
+
+       scaller: scaller at 12500000 {
+               status = "okay";
+               dma-memory-region = <&multimedia_mem>;
+       };
+
+       codec: codec at 12600000 {
+               status = "okay";
+               dma-memory-region = <&multimedia_mem>;
+       };
+};

drivers/of/Kconfig +6 -0

index 80e5c13..a83ab43 100644
@@ -80,4 +80,10 @@ config OF_MTD
        depends on MTD
        def_bool y
 
+config OF_RESERVED_MEM
+       depends on CMA || (HAVE_GENERIC_DMA_COHERENT && HAVE_MEMBLOCK)
+       def_bool y
+       help
+         Initialization code for DMA reserved memory
+
 endmenu # OF

drivers/of/Makefile +1 -0

index 1f9c0c4..e7e3322 100644
@@ -10,3 +10,4 @@ obj-$(CONFIG_OF_MDIO) += of_mdio.o
 obj-$(CONFIG_OF_PCI)   += of_pci.o
 obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
 obj-$(CONFIG_OF_MTD)   += of_mtd.o
+obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o

drivers/of/of_reserved_mem.c new file +48 -0

new file mode 100644
index 0000000..d97fcdf
@@ -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 <[email protected]>
+ *
+ * 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>
+
+#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 reserved_mem_fdt_scan(unsigned long node, const char *uname,
+                                   int depth, void *data)
+{
+       phys_addr_t base, size;
+       int is_cma, is_reserved;
+       unsigned long len;
+       void *prop;
+
+       is_cma = of_flat_dt_is_compatible(node, "contiguous-memory-region");
+       is_reserved = of_flat_dt_is_compatible(node, "reserved-memory-region");
+
+       if (!is_reserved && !(is_cma && IS_ENABLED(CONFIG_CMA)))

drivers/of/of_reserved_mem.c new file +69 -0

+               base = be32_to_cpu(((__be32 *)prop)[0]);
+               size = be32_to_cpu(((__be32 *)prop)[1]);
+       } else {
+               base = be64_to_cpu(((__be64 *)prop)[0]);
+               size = be64_to_cpu(((__be64 *)prop)[1]);
+       }
+
+       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 -ENOMEM;
+
+       reserved_mem[reserved_mem_count].base = base;
+       reserved_mem[reserved_mem_count].size = size;
+       strcpy(reserved_mem[reserved_mem_count].name, uname);
+
+       if (IS_ENABLED(CONFIG_CMA) && is_cma) {
+               struct cma *cma;
+               if (dma_contiguous_reserve_area(size, base, 0, &cma) == 0) {
+                       reserved_mem[reserved_mem_count].cma = cma;
+                       reserved_mem_count++;
+
+                       if (of_get_flat_dt_prop(node,
+                                               "linux,default-contiguous-region",
+                                               NULL))
+                               dma_contiguous_set_default_area(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, "dma-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;
+}
+
+static void reserved_mem_assign_device_from_dt(struct device *dev)
+{
+       struct reserved_mem *region = get_dma_memory_region(dev);
+       if (!region)
+               return;
+
+       if (region->cma) {
+               dma_contiguous_add_device(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",

drivers/of/of_reserved_mem.c line 137

Quoted 6 lines

drivers/of/of_reserved_mem.c new file +6 -0

+static void reserved_mem_release_device_from_dt(struct device *dev)
+{
+       struct reserved_mem *region = get_dma_memory_region(dev);
+       if (!region)
+               return;
+       if (!region->cma)

if (region && !region->cma)

Quoted 2 lines

(quoted diff) +2 -0

+               dma_release_declared_memory(dev);
+}

Quoted 8 lines · Rob Herring

Quoted 8 lines

Quoted 6 lines

drivers/of/of_reserved_mem.c line 137

Quoted 6 lines

drivers/of/of_reserved_mem.c new file +6 -0

+static void reserved_mem_release_device_from_dt(struct device *dev)
+{
+       struct reserved_mem *region = get_dma_memory_region(dev);
+       if (!region)
+               return;
+       if (!region->cma)

if (region && !region->cma)

!region case is handled two lines above, so no need to check if region is not null.

Quoted 10 lines · Michal Nazarewicz

Quoted 8 lines · Rob Herring

Quoted 8 lines

Quoted 6 lines

drivers/of/of_reserved_mem.c line 137

Quoted 6 lines

drivers/of/of_reserved_mem.c new file +6 -0

+static void reserved_mem_release_device_from_dt(struct device *dev)
+{
+       struct reserved_mem *region = get_dma_memory_region(dev);
+       if (!region)
+               return;
+       if (!region->cma)

if (region && !region->cma)

Quoted 2 lines

!region case is handled two lines above, so no need to check if region is not null.

I think Rob's suggestion was to replace two 'if' statements with a single one, which makes sense.

Quoted 8 lines · Rob Herring

drivers/of/of_reserved_mem.c line 137

Quoted 6 lines

drivers/of/of_reserved_mem.c new file +6 -0

+static void reserved_mem_release_device_from_dt(struct device *dev)
+{
+       struct reserved_mem *region = get_dma_memory_region(dev);
+       if (!region)
+               return;
+       if (!region->cma)

if (region && !region->cma)

!region case is handled two lines above, so no need to check if region is not null.

Add device tree support for contiguous and reserved memory regions defined in device tree. Initialization is done in 2 steps. First, the memory is reserved, what happens very early when only flattened device tree is available. Then on device initialization the corresponding cma and reserved regions are assigned to each device structure.

Signed-off-by Marek Szyprowski <[email protected]>

Acked-by Kyungmin Park <[email protected]>

---

Documentation/devicetree/bindings/memory.txt |  152 ++++++++++++++++++++++
drivers/of/Kconfig                           |    6 +
drivers/of/Makefile                          |    1 +
drivers/of/of_reserved_mem.c                 |  175 ++++++++++++++++++++++++++
include/asm-generic/dma-coherent.h           |    6 +
5 files changed, 340 insertions(+)

create mode 100644 Documentation/devicetree/bindings/memory.txt create mode 100644 drivers/of/of_reserved_mem.c

Documentation/devicetree/bindings/memory.txt new file +36 -0

new file mode 100644
index 0000000..4aece19
@@ -0,0 +1,152 @@
+*** Memory binding ***
+
+The /memory node provides basic information about the address and size
+of the physical memory. This node is usually filled or updated by the
+bootloader, depending on the actual memory configuration of the given
+hardware.
+
+The memory layout is described by the folllowing node:
+
+memory {
+	reg =  <(baseaddr1) (size1)
+		(baseaddr2) (size2)
+		...
+		(baseaddrN) (sizeN)>;
+};
+
+baseaddrX:	the base address of the defined memory bank
+sizeX:		the size of the defined memory bank
+
+More than one memory bank can be defined.
+
+
+*** Reserved memory regions ***
+
+In /memory/reserved-memory node one can create additional nodes
+describing particular reserved (excluded from normal use) memory
+regions. Such memory regions are usually designed for the special usage
+by various device drivers. A good example are contiguous memory
+allocations or memory sharing with other operating system on the same
+hardware board. Those special memory regions might depend on the board
+configuration and devices used on the target system.
+
+Parameters for each memory region can be encoded into the device tree
+wit the following convention:
+
+[(label):] (name)@(address) {

Documentation/devicetree/bindings/memory.txt new file +15 -0

+
+compatible:	"contiguous-memory-region" - enables binding of this
+		region to Contiguous Memory Allocator (special region for
+		contiguous memory allocations, shared with movable system
+		memory, Linux kernel-specific), alternatively if
+		"reserved-memory-region" - compatibility is defined, given
+		region is assigned for exclusive usage for DMA transfers
+
+linux,default-contiguous-region: property indicating that the region
+		is the default region for all contiguous memory
+		allocations, Linux specific (optional)
+
+Each defined region must use unique name. It is optional to specify the
+base address, so if one wants to use autoconfiguration of the base
+address, he must specify the '0' as base address in the 'reg' property

Documentation/devicetree/bindings/memory.txt new file +71 -0

+
+This property indicates that the device driver should use the
+memory region pointed by the given phandle.
+
+
+*** Example ***
+
+This example defines a memory consisting of 4 memory banks. 3 contiguous
+regions are defined for Linux kernel, one default of all device drivers
+(named contig_mem, placed at 0x72000000, 64MiB), one dedicated to the
+framebuffer device (labelled display_mem, placed at 0x78000000, 8MiB)
+and one for multimedia processing (labelled multimedia_mem, placed at
+0x77000000, 64MiB). 'display_mem' region is then assigned to fb at 12300000
+device for DMA memory allocations (Linux kernel drivers will use CMA is
+available or dma-exclusive usage otherwise). 'multimedia_mem' is
+assigned to scaller at 12500000 and codec at 12600000 devices for contiguous
+memory allocations when CMA driver is enabled.
+
+The reason for creating a separate region for framebuffer device is to
+match the framebuffer base address to the one configured by bootloader,
+so once Linux kernel drivers starts no glitches on the displayed boot
+logo appears. Scaller and codec drivers should share the memory
+allocations.
+
+/ {
+	/* ... */
+	memory {
+		reg =  <0x40000000 0x10000000
+			0x50000000 0x10000000
+			0x60000000 0x10000000
+			0x70000000 0x10000000>;
+
+		reserved-memory {
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			/*
+			 * global autoconfigured region for contiguous allocations
+			 * (used only with Contiguous Memory Allocator)
+			 */
+			contig_region at 0 {
+				compatible = "contiguous-memory-region";
+				reg = <0x0 0x4000000>;
+				linux,default-contiguous-region;
+			};
+
+			/*
+			 * special region for framebuffer
+			 */
+			display_mem: region at 78000000 {
+				compatible = "contiguous-memory-region", "reserved-memory-region";
+				reg = <0x78000000 0x800000>;
+			};
+
+			/*
+			 * special region for multimedia processing devices
+			 */
+			multimedia_mem: region at 77000000 {
+				compatible = "contiguous-memory-region";
+				reg = <0x77000000 0x4000000>;
+			};
+		};
+	};
+
+	/* ... */
+
+	fb0: fb at 12300000 {
+		status = "okay";
+		dma-memory-region = <&display_mem>;
+	};
+

Enable reserved memory initialization from device tree.

Signed-off-by Marek Szyprowski <[email protected]>

Acked-by Kyungmin Park <[email protected]>

---
 arch/arm/mm/init.c |    3 +++
 1 file changed, 3 insertions(+)

arch/arm/mm/init.c +3 -0

index 15225d8..82db8d8 100644
@@ -20,6 +20,7 @@
 #include <linux/highmem.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
+#include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
 #include <linux/sizes.h>
 

@@ -377,6 +378,8 @@ void __init arm_memblock_init(struct meminfo *mi, struct machine_desc *mdesc)
 	if (mdesc->reserve)
 		mdesc->reserve();
 
+	dma_reserved_mem_of_reserve();
+
 	/*
 	 * reserve memory for DMA contigouos allocations,
 	 * must come from DMA area inside low memory

Signature · 1 line

1.7.9.5