[PATCH v4 3/4] drivers: of: add initialization code for dma reserved memory
Michal Nazarewicz
mina86 at mina86.com
Mon Aug 5 14:59:23 EDT 2013
On Wed, Jul 31 2013, Marek Szyprowski wrote:
> 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 <m.szyprowski at samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park at samsung.com>
Acked-by: Michal Nazarewicz <mina86 at mina86.com>
Minor comments inline.
> ---
> 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
>
> diff --git a/Documentation/devicetree/bindings/memory.txt b/Documentation/devicetree/bindings/memory.txt
> new file mode 100644
> index 0000000..4aece19
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory.txt
> @@ -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>;
> + };
> +};
> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> index 80e5c13..a83ab43 100644
> --- a/drivers/of/Kconfig
> +++ b/drivers/of/Kconfig
> @@ -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
> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> index 1f9c0c4..e7e3322 100644
> --- a/drivers/of/Makefile
> +++ b/drivers/of/Makefile
> @@ -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
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> new file mode 100644
> index 0000000..d97fcdf
> --- /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 at 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>
> +
> +#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");
Perhaps:
+ is_cma = IS_ENABLED(CONFIG_CMA) &&
+ of_flat_dt_is_compatible(node, "contiguous-memory-region");
which will save on typing IS_ENABLED(CONFIG_CMA) later on.
> + is_reserved = of_flat_dt_is_compatible(node, "reserved-memory-region");
is_reserved value is used only if !is_cma, so maybe skip computing it if
is_cma? Just a thought.
> +
> + 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]);
> + } 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;
+ return -ENOSPC;
> +
> + reserved_mem[reserved_mem_count].base = base;
> + reserved_mem[reserved_mem_count].size = size;
> + strcpy(reserved_mem[reserved_mem_count].name, uname);
strlcpy(reserved_mem[reserved_mem_count].name,
sizeof(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;
> +}
> diff --git a/include/asm-generic/dma-coherent.h b/include/asm-generic/dma-coherent.h
> index 2be8a2d..06111d00 100644
> --- a/include/asm-generic/dma-coherent.h
> +++ b/include/asm-generic/dma-coherent.h
> @@ -32,4 +32,10 @@ dma_mark_declared_memory_occupied(struct device *dev,
> #define dma_mmap_from_coherent(dev, vma, vaddr, order, ret) (0)
> #endif
>
> +#ifdef CONFIG_OF_RESERVED_MEM
> +void __init dma_reserved_mem_of_reserve(void);
> +#else
> +#define dma_reserved_mem_of_reserve()
+#define dma_reserved_mem_of_reserve() (void)0
> +#endif
> +
> #endif
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +----<email/xmpp: mpn at google.com>--------------ooO--(_)--Ooo--
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