Re: [PATCH 0/4] mmc: sdhci-brcmstb: rpmb sharing by claiming host for TZOS

[Adrian Hunter <adrian.hunter@intel.com>]

On 11/07/2025 18:42, Kamal Dasu wrote:
> This patch adds support to claim host for TZOS RPMB access and synchronized
> access to the controller hardware using hwspinlock framework.
> To achieve this Linux OS and the secure TZOS make use of:
> - shared hardware semaphore register
> - a set of SDIO shared work registers and
> - IPI interrupt registers 
> 
> The currently running OS that needs access to the controller puts itself in its
> slot of work register and if its next in line it can try to grab the hardware
> semaphore and complete its mmc requests. The shared work registers indicate next
> in queue to access the controller, and current agent in the queue. Next agent
> queue state is changed under the hwspinlock is owned by the current OS accessing
> the controller hardware before release the semaphore, send and receive IPI
> interrupts between linux and secure world are used to indicate completion of
> transaction to the waiting OS. TZOS has its own RPMB driver which accesses
> partition when it wants to read/write RPMB frames. Current implementation
> assumes Linux and TZOS as the two work agents.
> 
> This patchset is an alternative method to initial RFC patch:
> [PATCH RFC 0/3] mmc: sdhci-brcmstb: Add rpmb sharing support	
> https://lkml.org/lkml/2025/2/6/1711

Does it address Ulf's comments? i.e.

	https://lore.kernel.org/all/CAPDyKFrCjo8gGnxmXWP6V39N+b1o62VQH9zwMUNb2_+D3-qrdw@mail.gmail.com/

> 
> Kamal Dasu (4):
>   dt-bindings: brcmstb-hwspinlock: support for hwspinlock
>   hwspinlock: brcmstb hardware semaphore support
>   dt-bindings: mmc: add brcmstb share register and hwlocks reference
>   mmc: sdhci-brcmstb: rpmb sharing by claiming host for TZOS
> 
>  .../hwlock/brcm,brcmstb-hwspinlock.yaml       |  36 +++
>  .../bindings/mmc/brcm,sdhci-brcmstb.yaml      |  29 ++-
>  drivers/hwspinlock/Kconfig                    |   9 +
>  drivers/hwspinlock/Makefile                   |   1 +
>  drivers/hwspinlock/brcmstb_hwspinlock.c       |  98 +++++++
>  drivers/mmc/host/sdhci-brcmstb.c              | 243 +++++++++++++++++-
>  6 files changed, 413 insertions(+), 3 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwlock/brcm,brcmstb-hwspinlock.yaml
>  create mode 100644 drivers/hwspinlock/brcmstb_hwspinlock.c
>