[PATCH 2/4] dt-bindings: Document the STM32 reset bindings

[p.zabel@pengutronix.de (Philipp Zabel)]

Am Montag, den 04.07.2016, 15:47 +0200 schrieb gabriel.fernandez at st.com:
> From: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> 
> This adds documentation of device tree bindings for the
> STM32 reset controller.
> 
> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>

The way I understand Documentation/SubmittingPatches, this should also
have your Signed-off-by.

> ---
>  .../devicetree/bindings/reset/st,stm32-rcc.txt     | 50 ++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reset/st,stm32-rcc.txt
> 
> diff --git a/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt b/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt
> new file mode 100644
> index 0000000..333080c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt
> @@ -0,0 +1,50 @@
> +STMicroelectronics STM32 Peripheral Reset Controller
> +====================================================
> +
> +The RCC IP is both a reset and a clock controller. This documentation only
> +documents the reset part.
> +
> +Please also refer to reset.txt in this directory for common reset
> +controller binding usage.
> +
> +Required properties:
> +- compatible: Should be "st,stm32-rcc"
> +- reg: should be register base and length as documented in the
> +  datasheet
> +- #reset-cells: 1, see below
> +
> +example:
> +
> +rcc: reset at 40023800 {
> +	#reset-cells = <1>;
> +	compatible = "st,stm32-rcc";
> +	reg = <0x40023800 0x400>;
> +};
> +
> +Specifying softreset control of devices
> +=======================================
> +
> +Device nodes should specify the reset channel required in their "resets"
> +property, containing a phandle to the reset device node and an index specifying
> +which channel to use.
> +The index is the bit number within the RCC registers bank, starting from RCC
> +base address.
> +It is calculated as: index = register_offset / 4 * 32 + bit_offset.
> +Where bit_offset is the bit offset within the register.
> +For example, for CRC reset:
> +  crc = AHB1RSTR_offset / 4 * 32 + CRCRST_bit_offset = 0x10 / 4 * 32 + 12 = 140

I see you decided to keep the register offset encoded in the reset
index.

> +
> +To simplify the usagen and to share bit definition with the clock driver of

s/usagen/usage/

> +the RCC IP, macros are available to generate the index in human-readble
> +format.
> +
> +For STM32F4 series, the macro are available here:
> + - include/dt-bindings/mfd/stm32f4-rcc.h

If DT and ARM/STI and maintainers agree with the binding and header
macros, I'm inclined to take patches 1-3.

regards
Philipp