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 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 -- 2.34.1
