[PATCH v5 0/5] firmware: ti_sci: Introduce system suspend support

[Georgi Vlaev]

This series introduces necessary ti_sci driver functionality in
preparation of supporting DeepSleep mode for suspend to mem on TI
K3 AM62x. This version is a fixup and rebase of the patch series by
Dave Gerlach [1]. It applies on top of v6.1-rc7.

Deep Sleep mode is described in section "5.2.4.4 DeepSleep" of the
AM62x Technical Reference Manual [2].

The kernel triggers entry to Deep Sleep mode through the mem suspend
transition with the following:

* Use a TF-A binary that supports PSCI_SYSTEM_SUSPEND call. This causes
  system to use PSCI system suspend as last step of mem sleep.

* The firmware requires that the OS sends a TISCI_MSG_PREPARE_SLEEP
  message in order to provide details about suspend, so we must add the
  ability to send this message. We also add TISCI_MSG_LPM_WAKE_REASON
  and TISCI_MSG_SET_IO_ISOLATION messages as part of a new PM ops. These
  messages are part of the TISCI PM Low Power Mode API [3]. (Patch 2)

* A memory address must be provided to the firmware using the above
  message, which is allocated and managed by dma_alloc_coherent()
  and friends. (Patch 3)

* System must load firmware to a specific location before Deep Sleep is
  entered, and this is accomplished using a memory region in device
  tree to indicate where this firmware should be loaded, and also a
  "firmware-name" property to indicate the name of the firmware
  to load. The ti_sci driver checks in its pm handler to see if
  the firmware has been loaded and if not, loads it. (Patch 4)

* Finally, the ti_sci driver must actually send TISCI_MSG_PREPARE_SLEEP
  message to firmware with the above information included, which it
  does during the driver suspend handler when PM_MEM_SUSPEND is the
  determined state being entered. (Patch 5)

This is tested on am625-sk using a limited dts with all devices disabled
apart from cpu0, main_uart0, i2c, rtc, mmc/sd, dmsc, and secure_proxy_main.

Testing this sequence requires K3 sdhci suspend/resume support [4],
enable the wkup_rtc in the am625-sk.dts, disable devices that don't
support system suspend/resume like OSPI and CPSW3G.

In can be tested on the following branch:
https://github.com/gvlaev/linux/tree/upstream-v6.2/lpm-ti-sci-v4

Changelog:
v5:
- Add support (patch 3) for detecting the low power modes (LPM) of the
  FW/SoC with a recently introduced core TISCI_MSG_QUERY_FW_CAPS message.
- Use TISCI_MSG_QUERY_FW_CAPS instead of misusing the TISCI_MSG_PREPARE_SLEEP
  to detect the FW/SoC low power caps (patch 4).
- Take into account the supported LPMs in ti_sci_prepare_system_suspend()
  and handle the case when CONFIG_SUSPEND is not enabled (patch 6) that
  was reported by Roger Quadros and LKP.
- Pick up Rob Herring's "Reviewed-by" tag for the binding patch.

v4:
- Fix checkpacth warnings in patches 2 and 3.
- Drop the links with anchors in patch 2.

v3:
- Fix the compile warnings on 32-bit platforms reported by the kernel
  test robot in patches (3,5).
- Pick up Roger's "Tested-by" tags.

v2:
- Addressed comments received for v1 series [1].
- Updated v1 patch 5 to use pm notifier to avoid firmware loading
  issues.
- Dropped the reserved region requirement and allocate DMA memory
  instead. The reserved region binding patch is also removed.
- Introduce two more TISCI LPM messages that are supported in SysFW.
- Fixes in error handling.

[1] https://lore.kernel.org/lkml/20220421203659.27853-1-d-gerlach@xxxxxx
[2] https://www.ti.com/lit/pdf/spruiv7
[3] https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/pm/lpm.html
[4] https://lore.kernel.org/lkml/20220408124338.27090-1-a-govindraju@xxxxxx

Georgi Vlaev (6):
  dt-bindings: ti, sci: Add lpm region and firmware-name
  firmware: ti_sci: Introduce Power Management Ops
  firmware: ti_sci: Add support for querying the firmware caps
  firmware: ti_sci: Allocate memory for the LPM modes
  firmware: ti_sci: Use dt provided fw name and address to load at
    suspend time
  firmware: ti_sci: Introduce prepare system suspend call

 .../bindings/arm/keystone/ti,sci.yaml         |  21 +-
 drivers/firmware/ti_sci.c                     | 410 ++++++++++++++++++
 drivers/firmware/ti_sci.h                     |  90 +++-
 include/linux/soc/ti/ti_sci_protocol.h        |  44 ++
 4 files changed, 560 insertions(+), 5 deletions(-)


base-commit: b7b275e60bcd5f89771e865a8239325f86d9927d
-- 
2.30.2