[PATCH v1 00/15] create power sequencing subsystem

[Dmitry Baryshkov]

This is a proposed power sequencer subsystem. This is a
generification of the MMC pwrseq code. The subsystem tries to abstract
the idea of complex power-up/power-down/reset of the devices.

The primary set of devices that promted me to create this patchset is
the Qualcomm BT+WiFi family of chips. They reside on serial+platform
or serial + SDIO interfaces (older generations) or on serial+PCIe (newer
generations).  They require a set of external voltage regulators to be
powered on and (some of them) have separate WiFi and Bluetooth enable
GPIOs.

The major drawback for now is the lack of proper PCIe integration
At this moment support for PCIe is hacked up to be able to test the
PCIe part of qca6390. Proper PCIe support would require automatically
powering up the devices before the scan basing on the proper device
structure in the device tree. This two last patches are noted as WIP and
are included into the patchset for the purpose of testing WiFi on newer
chips (like qca6390/qca6391).

Changes since RFC v2:
 - Add documentation for the pwrseq code. Document data structures,
   macros and exported functions.
 - Export of_pwrseq_xlate_onecell()
 - Add separate pwrseq_set_drvdata() function to follow the typical API
   design
 - Remove pwrseq_get_optional()/devm_pwrseq_get_optional()
 - Moved code to handle old mmc-pwrseq binding to the MMC patch
 - Split of_pwrseq_xlate_onecell() support to a separate patch

Changes since RFC v1:
 - Provider pwrseq fallback support
 - Implement fallback support in pwrseq_qca.
 - Mmove susclk handling to pwrseq_qca.
 - Significantly simplify hci_qca.c changes, by dropping all legacy
   code. Now hci_qca uses only pwrseq calls to power up/down bluetooth
   parts of the chip.