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SubjectRe: [PATCH v2,RESEND] misc: new driver sram_uapi for user level SRAM access
On Sun, Apr 19, 2020 at 10:06 PM Wang Wenhu <> wrote:
> A generic User-Kernel interface that allows a misc device created
> by it to support file-operations of ioctl and mmap to access SRAM
> memory from user level. Different kinds of SRAM alloction and free
> APIs could be registered by specific SRAM hardware level driver to
> the available list and then be chosen by users to allocate and map
> SRAM memory from user level.
> It is extremely helpful for the user space applications that require
> high performance memory accesses, such as embedded networking devices
> that would process data in user space, and PowerPC e500 is a case.
> Signed-off-by: Wang Wenhu <>
> Cc: Greg Kroah-Hartman <>
> Cc: Arnd Bergmann <>
> Cc: Christophe Leroy <>
> Cc: Scott Wood <>
> Cc: Michael Ellerman <>
> Cc: Randy Dunlap <>
> Cc:
> ---
> Changes since v1: addressed comments from Arnd
> * Changed the ioctl cmd definitions using _IO micros
> * Export interfaces for HW-SRAM drivers to register apis to available list
> * Modified allocation alignment to PAGE_SIZE
> * Use phys_addr_t as type of SRAM resource size and offset
> * Support compat_ioctl
> * Misc device name:sram
> Note: From this on, the SRAM_UAPI driver is independent to any hardware
> drivers, so I would only commit the patch itself as v2, while the v1 of
> it was wrapped together with patches for Freescale L2-Cache-SRAM device.
> Then after, I'd create patches for Freescale L2-Cache-SRAM device as
> another series.

There's work to add SRAM support to dma-buf heaps[1]. Take a look and
see if that works for you.



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