These patches add support to configure on-chip SRAM via device-tree
node or platform data and to obtain the resulting genalloc pool from
the physical address or a phandle pointing at the device tree node.
This allows drivers to allocate SRAM with the genalloc API without
hard-coding the genalloc pool pointer.
The on-chip SRAM on i.MX53 and i.MX6q can be registered via device tree
and changed to use the simple generic SRAM driver:
ocram: ocram@00900000 {
compatible = "fsl,imx-ocram", "sram";
reg = <0x00900000 0x3f000>;
};
A driver that needs to allocate SRAM buffers, like the video processing
unit on i.MX53, can retrieve the genalloc pool from a phandle in the
device tree using of_get_named_gen_pool(node, "iram", 0) from patch 1:
vpu@63ff4000 {
/* ... */
iram = <&ocram>;
};
The allocation granularity is hard-coded to 32 bytes for now,
until a way to configure it can be agreed upon. There is overhead
for bigger SRAMs, where only a much coarser allocation granularity
is needed: At 32 bytes minimum allocation size, a 256 KiB SRAM
needs a 1 KiB bitmap to track allocations.
Once everybody is ok with it, could the first two patches be merged
through the char-misc tree? I'll resend the i.MX and coda patches to
the respective lists afterwards.
Changes since v6:
- Reduced the hard coded allocation granularity to 32 bytes.
regards
Philipp
---
Documentation/devicetree/bindings/misc/sram.txt | 17 ++++
arch/arm/boot/dts/imx53.dtsi | 5 +
arch/arm/boot/dts/imx6q.dtsi | 6 ++
drivers/media/platform/Kconfig | 3 +-
drivers/media/platform/coda.c | 47 ++++++---
drivers/misc/Kconfig | 9 ++
drivers/misc/Makefile | 1 +
drivers/misc/sram.c | 121 +++++++++++++++++++++++
include/linux/genalloc.h | 14 +++
lib/genalloc.c | 67 +++++++++++++
10 files changed, 274 insertions(+), 16 deletions(-)
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