[PATCH 2/2] drivers: dma-contiguous: add initialization from device tree
Marek Szyprowski
m.szyprowski at samsung.com
Thu Feb 14 23:45:28 EST 2013
Add device tree support for contiguous memory regions defined in device
tree. Initialization is done in 2 steps. First, the contiguous memory is
reserved, what happens very early, when only flattened device tree is
available. Then on device initialization the corresponding cma regions are
assigned to device structures.
Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
Acked-by: Kyungmin Park <kyungmin.park at samsung.com>
---
Documentation/devicetree/bindings/memory.txt | 101 ++++++++++++++++++++++++++
arch/arm/boot/dts/skeleton.dtsi | 7 +-
drivers/base/dma-contiguous.c | 72 ++++++++++++++++++
3 files changed, 179 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/memory.txt
diff --git a/Documentation/devicetree/bindings/memory.txt b/Documentation/devicetree/bindings/memory.txt
new file mode 100644
index 0000000..74e0476
--- /dev/null
+++ b/Documentation/devicetree/bindings/memory.txt
@@ -0,0 +1,101 @@
+* 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.
+
+
+* Memory regions
+
+In /memory node one can create additional nodes describing particular
+memory regions, usually 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:
+
+(name): region@(base-address) {
+ reg = <(baseaddr) (size)>;
+ (linux,contiguous-region);
+ (linux,default-contiguous-region);
+};
+
+name: an name given to the defined region.
+base-address: the base address of the defined region.
+size: the size of the memory region.
+linux,contiguous-region: property indicating that the defined memory
+ region is used for contiguous memory allocations,
+ Linux specific (optional)
+linux,default-contiguous-region: property indicating that the region
+ is the default region for all contiguous memory
+ allocations, Linux specific (optional)
+
+
+* Device nodes
+
+Once the regions in the /memory node are defined, they can be assigned
+to device some device nodes for their special use. The following
+properties are defined:
+
+linux,contiguous-region = <&phandle>;
+ 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. 2 contiguous
+regions are defined for Linux kernel, one default of all device drivers
+(named contig_mem, placed at 0x72000000, 64MiB) and one dedicated to the
+framebuffer device (named display_mem, placed at 0x78000000, 16MiB). The
+display_mem region is then assigned to fb at 12300000 device for contiguous
+memory allocation with Linux kernel drivers.
+
+The reason for creating a separate region for framebuffer device is to
+match the framebuffer address of from configuration done by bootloader,
+so once Linux kernel drivers starts, no glitches on the displayed boot
+logo appears.
+
+/ {
+ /* ... */
+ memory {
+ reg = <0x40000000 0x10000000
+ 0x50000000 0x10000000
+ 0x60000000 0x10000000
+ 0x70000000 0x10000000>;
+
+ contig_mem: region at 72000000 {
+ linux,contiguous-region;
+ linux,default-contiguous-region;
+ reg = <0x72000000 0x4000000>;
+ };
+
+ display_mem: region at 78000000 {
+ linux,contiguous-region;
+ reg = <0x78000000 0x1000000>;
+ };
+ };
+
+ fb at 12300000 {
+ linux,contiguous-region = <&display_mem>;
+ status = "okay";
+ };
+};
diff --git a/arch/arm/boot/dts/skeleton.dtsi b/arch/arm/boot/dts/skeleton.dtsi
index b41d241..f9988cd 100644
--- a/arch/arm/boot/dts/skeleton.dtsi
+++ b/arch/arm/boot/dts/skeleton.dtsi
@@ -9,5 +9,10 @@
#size-cells = <1>;
chosen { };
aliases { };
- memory { device_type = "memory"; reg = <0 0>; };
+ memory {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ device_type = "memory";
+ reg = <0 0>;
+ };
};
diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index 085389c..5761f73 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -24,6 +24,9 @@
#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/mutex.h>
#include <linux/page-isolation.h>
@@ -177,6 +180,35 @@ no_mem:
return ERR_PTR(ret);
}
+/*****************************************************************************/
+
+#ifdef CONFIG_OF
+int __init cma_fdt_scan(unsigned long node, const char *uname,
+ int depth, void *data)
+{
+ phys_addr_t base, size;
+ unsigned long len;
+ __be32 *prop;
+
+ if (strncmp(uname, "region@", 7) != 0 || depth != 2 ||
+ !of_get_flat_dt_prop(node, "contiguous-region", NULL))
+ return 0;
+
+ prop = of_get_flat_dt_prop(node, "reg", &len);
+ if (!prop || (len != 2 * sizeof(unsigned long)))
+ return 0;
+
+ base = be32_to_cpu(prop[0]);
+ size = be32_to_cpu(prop[1]);
+
+ pr_info("Found %s, memory base %lx, size %ld MiB\n", uname,
+ (unsigned long)base, (unsigned long)size / SZ_1M);
+ dma_contiguous_reserve_area(size, &base, 0);
+
+ return 0;
+}
+#endif
+
/**
* dma_contiguous_reserve() - reserve area for contiguous memory handling
* @limit: End address of the reserved memory (optional, 0 for any).
@@ -215,6 +247,9 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
if (dma_contiguous_reserve_area(sel_size, &base, limit) == 0)
dma_contiguous_def_base = base;
}
+#ifdef CONFIG_OF
+ of_scan_flat_dt(cma_fdt_scan, NULL);
+#endif
};
/**
@@ -319,6 +354,40 @@ int __init dma_contiguous_add_device(struct device *dev, phys_addr_t base)
return 0;
}
+#ifdef CONFIG_OF
+static void cma_assign_device_from_dt(struct device *dev)
+{
+ struct device_node *node;
+ struct cma *cma;
+ u32 value;
+
+ node = of_parse_phandle(dev->of_node, "linux,contiguous-region", 0);
+ if (!node)
+ return;
+ if (of_property_read_u32(node, "reg", &value) && !value)
+ return;
+ cma = cma_get_area(value);
+ if (!cma)
+ return;
+
+ dev_set_cma_area(dev, cma);
+ pr_info("Assigned CMA region at %lx to %s device\n", (unsigned long)value, dev_name(dev));
+}
+
+static int cma_device_init_notifier_call(struct notifier_block *nb,
+ unsigned long event, void *data)
+{
+ struct device *dev = data;
+ if (event == BUS_NOTIFY_ADD_DEVICE && dev->of_node)
+ cma_assign_device_from_dt(dev);
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block cma_dev_init_nb = {
+ .notifier_call = cma_device_init_notifier_call,
+};
+#endif
+
static int __init cma_init_reserved_areas(void)
{
struct cma *cma;
@@ -340,6 +409,9 @@ static int __init cma_init_reserved_areas(void)
dev_set_cma_area(cma_maps[i].dev, cma);
}
+#ifdef CONFIG_OF
+ bus_register_notifier(&platform_bus_type, &cma_dev_init_nb);
+#endif
return 0;
}
core_initcall(cma_init_reserved_areas);
--
1.7.9.5
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