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| author | Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> | 2023-08-18 14:57:22 +0100 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-09-01 09:08:59 -0700 |
| commit | d34599bcd2e4e93a28d5904bf94bc7dafc511f04 (patch) | |
| tree | 8860fa9cfc9470f29a733c01bafb20348278088d /MAINTAINERS | |
| parent | 3e7bf4685e42786dc10a57512c8a767947f25c10 (diff) | |
| download | lwn-d34599bcd2e4e93a28d5904bf94bc7dafc511f04.tar.gz lwn-d34599bcd2e4e93a28d5904bf94bc7dafc511f04.zip | |
cache: Add L2 cache management for Andes AX45MP RISC-V core
I/O Coherence Port (IOCP) provides an AXI interface for connecting
external non-caching masters, such as DMA controllers. The accesses
from IOCP are coherent with D-Caches and L2 Cache.
IOCP is a specification option and is disabled on the Renesas RZ/Five
SoC due to this reason IP blocks using DMA will fail.
The Andes AX45MP core has a Programmable Physical Memory Attributes (PMA)
block that allows dynamic adjustment of memory attributes in the runtime.
It contains a configurable amount of PMA entries implemented as CSR
registers to control the attributes of memory locations in interest.
Below are the memory attributes supported:
* Device, Non-bufferable
* Device, bufferable
* Memory, Non-cacheable, Non-bufferable
* Memory, Non-cacheable, Bufferable
* Memory, Write-back, No-allocate
* Memory, Write-back, Read-allocate
* Memory, Write-back, Write-allocate
* Memory, Write-back, Read and Write-allocate
More info about PMA (section 10.3):
Link: http://www.andestech.com/wp-content/uploads/AX45MP-1C-Rev.-5.0.0-Datasheet.pdf
As a workaround for SoCs with IOCP disabled CMO needs to be handled by
software. Firstly OpenSBI configures the memory region as
"Memory, Non-cacheable, Bufferable" and passes this region as a global
shared dma pool as a DT node. With DMA_GLOBAL_POOL enabled all DMA
allocations happen from this region and synchronization callbacks are
implemented to synchronize when doing DMA transactions.
Example PMA region passes as a DT node from OpenSBI:
reserved-memory {
#address-cells = <2>;
#size-cells = <2>;
ranges;
pma_resv0@58000000 {
compatible = "shared-dma-pool";
reg = <0x0 0x58000000 0x0 0x08000000>;
no-map;
linux,dma-default;
};
};
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com> # tyre-kicking on a d1
Link: https://lore.kernel.org/r/20230818135723.80612-6-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'MAINTAINERS')
| -rw-r--r-- | MAINTAINERS | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 3be1bdfe8ecc..7f3abc958bbc 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20241,6 +20241,13 @@ S: Supported T: git git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git F: drivers/staging/ +STANDALONE CACHE CONTROLLER DRIVERS +M: Conor Dooley <conor@kernel.org> +L: linux-riscv@lists.infradead.org +S: Maintained +T: git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/ +F: drivers/cache + STARFIRE/DURALAN NETWORK DRIVER M: Ion Badulescu <ionut@badula.org> S: Odd Fixes |