[PATCH v3 0/4] Enable shared SE support over I2C

Mukesh Kumar Savaliya
2024-09-27T06:31:33Z

This Series adds support to share QUP (Qualcomm Unified peripheral)
based I2C SE (Serial Engine) controller between two subsystems
(Apps/ADSP/TZ etc). Each SS having it's own dedicated GPII(General
Purpose Interface Instance) acting as pipe between SE and GSI(Generic SW-
Interface) DMA HW engine. Hence the sharing of SE is possible only with
I2C SE in GSI mode, not with FIFO/CPU DMA mode.

Subsystem must acquire Lock over the SE so that it gets uninterrupted
control till it unlocks the SE. It also makes sure the commonly shared
TLMM GPIOs are not touched which can impact other subsystem or cause
any interruption. Generally, GPIOs are being unconfigured during
suspend time.

GSI DMA engine is capable to perform requested transfer operations
from any of the I2C client in a seamless way and its transparent to
the subsystems. Make sure to enable “qcom,shared-se” flag only while
enabling this feature. I2C client should add in its respective parent
node.

Example :
Two clients from different SS can share an I2C SE for same slave device
OR their owned slave devices.
Assume I2C Slave EEPROM device connected with I2C controller.
Each client from ADSP SS and APPS Linux SS can perform i2c transactions.
This gets serialized by lock TRE + Transfers + Unlock TRE at HW level.

Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
---

Link to V2: https://lore.kernel.org/lkml/a88a16ff-3537-4396-b2ea-4ba02b4850e9@quicinc.com/T/

Changes in V3:
- Added missing maintainers which i forgot to add.
- Add cover letter with description of SS and EE for dt-bindings patch.
- Added acronyms expansion to commit log.
- [PATCH v2 3/4] : Removed exported symbol geni_se_clks_off().
Instead added changes to bypass pinctrl sleep configuration from
geni_se_resources_off() function.
- Changed title name of [PATCH v2 3/4] to reflect the suggested changes.
- [PATCH v2 4/4] kept geni_i2c_runtime_suspend() as is and removed
explicit call to geni_se_clks_off().
- Removed is_shared variable from i2c driver and instead used common
shared_geni_se variable from qcom-geni-se.h so that other protocols
can also extend for similar feature.
- I2C driver log changed from dev_err() to dev_dbg() for timeout.
- set gpi_mode = true if shared_geni_se is set for this usecase. Enhanced
comments around code and commit log.
---

Link to V1: https://lore.kernel.org/lkml/cb7613d0-586e-4089-a1b6-2405f4dc4883@quicinc.com/T/

Changes in V2:
- Enhanced commit log grammatically for PATCH v1 3/4 as suggested by Bryan.
- Updated Cover letter along with acronyms expansion.
- Added maintainers list from other subsystems for review, which was missing.
Thanks to Krzysztof for pointing out.
- Added cover letter with an example of Serial Engine sharing.
- Addressed review comments for all the patches.

---

Mukesh Kumar Savaliya (4):
dt-bindindgs: i2c: qcom,i2c-geni: Document shared flag
dma: gpi: Add Lock and Unlock TRE support to access SE exclusively
soc: qcom: geni-se: Do not keep GPIOs to sleep state for shared SE
usecase
i2c: i2c-qcom-geni: Enable i2c controller sharing between two
subsystems

.../bindings/i2c/qcom,i2c-geni-qcom.yaml | 4 ++
drivers/dma/qcom/gpi.c | 37 ++++++++++++++++++-
drivers/i2c/busses/i2c-qcom-geni.c | 24 ++++++++++--
drivers/soc/qcom/qcom-geni-se.c | 14 +++++--
include/linux/dma/qcom-gpi-dma.h | 6 +++
include/linux/soc/qcom/geni-se.h | 3 ++
6 files changed, 79 insertions(+), 9 deletions(-)

--
2.25.1