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author | Maxime Coquelin <mcoquelin.stm32@gmail.com> | 2016-07-22 11:37:48 +0200 |
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committer | Philipp Zabel <p.zabel@pengutronix.de> | 2016-08-24 15:21:27 +0200 |
commit | 57bd63a4934ff5ef6f19a9b87de5e190e91edc80 (patch) | |
tree | dcb5104e5d3dbfaf6d70a047afaa31dc8a38ddad /Documentation/devicetree/bindings | |
parent | ca9f71f05793e8d0972df4c6df30378a073e63c5 (diff) | |
download | op-kernel-dev-57bd63a4934ff5ef6f19a9b87de5e190e91edc80.zip op-kernel-dev-57bd63a4934ff5ef6f19a9b87de5e190e91edc80.tar.gz |
dt-bindings: Document the STM32 reset bindings
This adds documentation of device tree bindings for the
STM32 reset controller.
Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Diffstat (limited to 'Documentation/devicetree/bindings')
-rw-r--r-- | Documentation/devicetree/bindings/clock/st,stm32-rcc.txt | 42 | ||||
-rw-r--r-- | Documentation/devicetree/bindings/reset/st,stm32-rcc.txt | 6 |
2 files changed, 41 insertions, 7 deletions
diff --git a/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt b/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt index fee3205..c209de6 100644 --- a/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt +++ b/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt @@ -1,16 +1,16 @@ STMicroelectronics STM32 Reset and Clock Controller =================================================== -The RCC IP is both a reset and a clock controller. This documentation only -describes the clock part. +The RCC IP is both a reset and a clock controller. -Please also refer to clock-bindings.txt in this directory for common clock -controller binding usage. +Please refer to clock-bindings.txt for common clock controller binding usage. +Please also refer to reset.txt for common reset controller binding usage. Required properties: - compatible: Should be "st,stm32f42xx-rcc" - reg: should be register base and length as documented in the datasheet +- #reset-cells: 1, see below - #clock-cells: 2, device nodes should specify the clock in their "clocks" property, containing a phandle to the clock device node, an index selecting between gated clocks and other clocks and an index specifying the clock to @@ -19,6 +19,7 @@ Required properties: Example: rcc: rcc@40023800 { + #reset-cells = <1>; #clock-cells = <2> compatible = "st,stm32f42xx-rcc", "st,stm32-rcc"; reg = <0x40023800 0x400>; @@ -35,16 +36,23 @@ from the first RCC clock enable register (RCC_AHB1ENR, address offset 0x30). It is calculated as: index = register_offset / 4 * 32 + bit_offset. Where bit_offset is the bit offset within the register (LSB is 0, MSB is 31). +To simplify the usage and to share bit definition with the reset and clock +drivers of 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 + Example: /* Gated clock, AHB1 bit 0 (GPIOA) */ ... { - clocks = <&rcc 0 0> + clocks = <&rcc 0 STM32F4_AHB1_CLOCK(GPIOA)> }; /* Gated clock, AHB2 bit 4 (CRYP) */ ... { - clocks = <&rcc 0 36> + clocks = <&rcc 0 STM32F4_AHB2_CLOCK(CRYP)> }; Specifying other clocks @@ -61,5 +69,25 @@ Example: /* Misc clock, FCLK */ ... { - clocks = <&rcc 1 1> + clocks = <&rcc 1 STM32F4_APB1_CLOCK(TIM2)> + }; + + +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 + +example: + + timer2 { + resets = <&rcc STM32F4_APB1_RESET(TIM2)>; }; 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..01db343 --- /dev/null +++ b/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt @@ -0,0 +1,6 @@ +STMicroelectronics STM32 Peripheral Reset Controller +==================================================== + +The RCC IP is both a reset and a clock controller. + +Please see Documentation/devicetree/bindings/clock/st,stm32-rcc.txt |