[RFC/PATCH v2 2/2] drivers: dma-contiguous: add initialization from device tree
Marek Szyprowski
m.szyprowski at samsung.com
Thu Apr 11 21:22:10 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>
---
.../devicetree/bindings/contiguous-memory.txt | 69 +++++++++++
arch/arm/boot/dts/skeleton.dtsi | 8 +-
drivers/base/dma-contiguous.c | 124 ++++++++++++++++++++
3 files changed, 200 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/contiguous-memory.txt
diff --git a/Documentation/devicetree/bindings/contiguous-memory.txt b/Documentation/devicetree/bindings/contiguous-memory.txt
new file mode 100644
index 0000000..fa598bf
--- /dev/null
+++ b/Documentation/devicetree/bindings/contiguous-memory.txt
@@ -0,0 +1,69 @@
+* Contiguous memory binding
+
+The /chosen/contiguous-memory node provides runtime configuration of
+contiguous memory regions for Linux kernel. One can create such regions
+for 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:
+
+contiguous-memory {
+
+ (name): region@(base-address) {
+ reg = <(baseaddr) (size)>;
+ (linux,default-contiguous-region);
+ device = <&device_0 &device_1 ...>
+ };
+};
+
+name: an name given to the defined region.
+base-address: the base address of the defined region.
+size: the size of the memory region (bytes).
+linux,default-contiguous-region: property indicating that the region
+ is the default region for all contiguous memory
+ allocations, Linux specific (optional)
+device: array of phandles to the client device nodes, which use
+ the given contiguous region
+
+* Example:
+
+This example defines a memory configuration containing 2 contiguous
+regions 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.
+
+/ {
+ /* ... */
+
+ chosen {
+ bootargs = /* ... */
+
+ contiguous-memory {
+ contig_mem: region at 72000000 {
+ reg = <0x72000000 0x4000000>;
+ linux,default-contiguous-region;
+ };
+
+ display_mem: region at 78000000 {
+ reg = <0x78000000 0x1000000>;
+ device = <&fb0>;
+ };
+ };
+ };
+
+ /* ... */
+
+ fb0: fb at 12300000 {
+ status = "okay";
+ };
+};
diff --git a/arch/arm/boot/dts/skeleton.dtsi b/arch/arm/boot/dts/skeleton.dtsi
index b41d241..538a868 100644
--- a/arch/arm/boot/dts/skeleton.dtsi
+++ b/arch/arm/boot/dts/skeleton.dtsi
@@ -7,7 +7,13 @@
/ {
#address-cells = <1>;
#size-cells = <1>;
- chosen { };
+ chosen {
+ contiguous-memory {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ };
+ };
aliases { };
memory { device_type = "memory"; reg = <0 0>; };
};
+
diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index 01fe743..6a8abab 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>
@@ -37,6 +40,7 @@ struct cma {
unsigned long base_pfn;
unsigned long count;
unsigned long *bitmap;
+ char full_name[32];
};
static DEFINE_MUTEX(cma_mutex);
@@ -133,6 +137,53 @@ static __init int cma_activate_area(struct cma *cma)
return 0;
}
+/*****************************************************************************/
+
+#ifdef CONFIG_OF
+int __init cma_fdt_scan(unsigned long node, const char *uname,
+ int depth, void *data)
+{
+ static int level;
+ phys_addr_t base, size;
+ unsigned long len;
+ struct cma *cma;
+ __be32 *prop;
+
+ if (depth == 1 && strcmp(uname, "chosen") == 0) {
+ level = depth;
+ return 0;
+ }
+
+ if (depth == 2 && strcmp(uname, "contiguous-memory") == 0) {
+ level = depth;
+ return 0;
+ }
+
+ if (level != 2 || depth != 3 || strncmp(uname, "region@", 7) != 0)
+ 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, &cma);
+
+ strcpy(cma->full_name, uname);
+
+ if (of_get_flat_dt_prop(node, "linux,default-contiguous-region", NULL)) {
+
+ dma_contiguous_default_area = cma;
+ }
+ return 0;
+}
+#endif
+
/**
* dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
* @limit: End address of the reserved memory (optional, 0 for any).
@@ -149,6 +200,10 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
+#ifdef CONFIG_OF
+ of_scan_flat_dt(cma_fdt_scan, NULL);
+#endif
+
if (size_cmdline != -1) {
sel_size = size_cmdline;
} else {
@@ -265,6 +320,71 @@ int __init dma_contiguous_add_device(struct device *dev, struct cma *cma)
return 0;
}
+#ifdef CONFIG_OF
+static struct cma_map {
+ struct cma *cma;
+ struct device_node *node;
+} cma_maps[MAX_CMA_AREAS];
+static unsigned cma_map_count;
+
+static void cma_assign_device_from_dt(struct device *dev)
+{
+ int i;
+ for (i=0; i<cma_map_count; i++) {
+ if (cma_maps[i].node == dev->of_node) {
+ dev_set_cma_area(dev, cma_maps[i].cma);
+ pr_info("Assigned CMA %s to %s device\n",
+ cma_maps[i].cma->full_name,
+ 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,
+};
+
+void scan_cma_nodes(void)
+{
+ struct device_node *parent = of_find_node_by_path("/chosen/contiguous-memory");
+ struct device_node *child;
+
+ if (!parent)
+ return;
+
+ for_each_child_of_node(parent, child) {
+ struct cma *cma = NULL;
+ int i;
+
+ for (i=0; i<cma_area_count; i++)
+ if (strstr(child->full_name, cma_areas[i].full_name))
+ cma = &cma_areas[i];
+ if (!cma)
+ continue;
+
+ for (i=0;; i++) {
+ struct device_node *node;
+ node = of_parse_phandle(child, "device", i);
+ if (!node)
+ break;
+
+ cma_maps[cma_map_count].cma = cma;
+ cma_maps[cma_map_count].node = node;
+ cma_map_count++;
+ }
+ }
+}
+#endif
+
static int __init cma_init_reserved_areas(void)
{
int i;
@@ -275,6 +395,10 @@ static int __init cma_init_reserved_areas(void)
return ret;
}
+#ifdef CONFIG_OF
+ scan_cma_nodes();
+ 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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