The STM32 MCUs family IP can be reset by accessing some shared registers.

The specificity is that some reset lines are used by the timers.
At timer initialization time, the timer has to be reset, that's why
we cannot use a regular driver.

Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
---
 .../devicetree/bindings/reset/st,stm32-reset.txt   |  19 ++++
 drivers/reset/Makefile                             |   1 +
 drivers/reset/reset-stm32.c                        | 124 +++++++++++++++++++++
 3 files changed, 144 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/st,stm32-reset.txt
 create mode 100644 drivers/reset/reset-stm32.c

diff --git a/Documentation/devicetree/bindings/reset/st,stm32-reset.txt b/Documentation/devicetree/bindings/reset/st,stm32-reset.txt
new file mode 100644
index 0000000..add1298
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/st,stm32-reset.txt

@@ -0,0 +1,19 @@
+STMicroelectronics STM32 Peripheral Reset Controller
+====================================================
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "st,stm32-reset"
+- reg: should be register base and length as documented in the
+  datasheet
+- #reset-cells: 1, see below
+
+example:
+
+reset_ahb1: reset@40023810 {
+	#reset-cells = <1>;
+	compatible = "st,stm32-reset";
+	reg = <0x40023810 0x4>;
+};