[v5,0/6] imx8mp: add support for the IMX AIPSTZ bridge

Message

Laurentiu Mihalcea April 8, 2025, 3:42 p.m. UTC

From: Laurentiu Mihalcea <[e-mail]>

The AIPSTZ bridge offers some security-related configurations which can
be used to restrict master access to certain peripherals on the bridge.

Normally, this could be done from a secure environment such as ATF before
Linux boots but the configuration of AIPSTZ5 is lost each time the power
domain is powered off and then powered on. Because of this, it has to be
configured each time the power domain is turned on and before any master
tries to access the peripherals (e.g: AP, CM7, DSP, on i.MX8MP).

The child-parent relationship between the bridge and its peripherals
should guarantee that the bridge is configured before the AP attempts
to access the IPs.

Other masters should use the 'access-controllers' property to enforce
a dependency between their device and the bridge device (see the DSP,
for example).

The initial version of the series can be found at [1]. The new version
should provide better management of the device dependencies.

[1]: https://lore.kernel.org/linux-arm-kernel/[e-mail]/

---
Changes in v5:
* merge imx-aipstz.h into imx8mp-aipstz.h. imx-aipstz.h is
currently only used in the DTS so it can't be added as a binding.
* place 'ranges' property just after 'reg' in the binding DT example
as Frank suggested.
* use the  (1 << x) notation for the configuration bits. Previously,
hex values were used which didn't make it very clear that the
configuration options are bits.
* shorten the description of the bridge's AC cells.
* shorten the message of the commit introducing the bridge's binding.
* pick up some more R-b's on patches that remained untouched since V4.
* link to v4: https://lore.kernel.org/lkml/[e-mail]/

Changes in v4:
* AIPS5 node now only contains a single memory region: that of the AC
(just like in V2). 'reg-names' property is dropped.
* AIPS5 node now uses 'ranges' property to restrict the size of the bus
(1:1 mapping)
* change the number of AC cells from 0 to 3
* add binding headers
* link to v3: https://lore.kernel.org/lkml/[e-mail]/

Changes in v3:
* make '#address-cells' and '#size-cells' constants and equal to 1 in the
binding. The bus is 32-bit.
* add child node in the example DT snippet.
* the 'aips5' DT node now contains 2 memory regions: that of the
peripherals accessible via this bridge and that of the access controller.
* link to v2: https://lore.kernel.org/lkml/[e-mail]/

Changes in v2:
* adress Frank Li's comments
* pick up some A-b/R-b's
* don't use "simple-bus" as the second compatible. As per Krzysztof's
comment, AIPSTZ is not a "simple-bus".
* link to v1: https://lore.kernel.org/lkml/[e-mail]/
---

Laurentiu Mihalcea (6):
  dt-bindings: bus: document the IMX AIPSTZ bridge
  dt-bindings: dsp: fsl,dsp: document 'access-controllers' property
  bus: add driver for IMX AIPSTZ bridge
  arm64: dts: imx8mp: convert 'aips5' to 'aipstz5'
  arm64: dts: imx8mp: add aipstz-related definitions
  arm64: dts: imx8mp: make 'dsp' node depend on 'aips5'

 .../bindings/bus/fsl,imx8mp-aipstz.yaml       | 104 ++++++++++++++++++
 .../devicetree/bindings/dsp/fsl,dsp.yaml      |   3 +
 arch/arm64/boot/dts/freescale/imx8mp-aipstz.h |  39 +++++++
 arch/arm64/boot/dts/freescale/imx8mp.dtsi     |  12 +-
 drivers/bus/Kconfig                           |   6 +
 drivers/bus/Makefile                          |   1 +
 drivers/bus/imx-aipstz.c                      |  92 ++++++++++++++++
 7 files changed, 253 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/bus/fsl,imx8mp-aipstz.yaml
 create mode 100644 arch/arm64/boot/dts/freescale/imx8mp-aipstz.h
 create mode 100644 drivers/bus/imx-aipstz.c