Add support for Embedded Controller found in the Microsoft Surface RT and
used to monitor battery cell and charger input status and properties.
Controller works both for UEFI and APX booting.

---
Changes in v3:
- fixed i2c_smbus_read_i2c_block_data read size

Changes in v2:
- srt_bat_get_string > i2c_smbus_read_i2c_block_data
- added devm_kasprintf return check
---

Jonas Schwöbel (1):
  power: supply: Add support for Surface RT battery and charger

Svyatoslav Ryhel (1):
  dt-bindings: embedded-controller: Document Surface RT EC

 .../microsoft,surface-rt-ec.yaml              |  63 +++
 drivers/power/supply/Kconfig                  |  11 +
 drivers/power/supply/Makefile                 |   1 +
 drivers/power/supply/surface-rt-ec.c          | 389 ++++++++++++++++++
 4 files changed, 464 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/embedded-controller/microsoft,surface-rt-ec.yaml
 create mode 100644 drivers/power/supply/surface-rt-ec.c

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2.51.0