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author | Vikas Manocha <vikas.manocha@st.com> | 2017-02-12 18:25:45 (GMT) |
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committer | Tom Rini <trini@konsulko.com> | 2017-03-17 18:15:12 (GMT) |
commit | 712f99a5ddc404f8c6eac481cfe19f82ca2ecb4f (patch) | |
tree | e3e97565765f3816b750bd0d40a8bea0d35e168c /doc/device-tree-bindings | |
parent | 42bf5e7c27ae73b0e56c29f5af3cae5d15d35afa (diff) | |
download | u-boot-712f99a5ddc404f8c6eac481cfe19f82ca2ecb4f.tar.xz |
clk: stm32f7: add clock driver for stm32f7 family
add basic clock driver support for stm32f7 to enable clocks required by
the peripherals.
Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'doc/device-tree-bindings')
-rw-r--r-- | doc/device-tree-bindings/clock/st,stm32-rcc.txt | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/doc/device-tree-bindings/clock/st,stm32-rcc.txt b/doc/device-tree-bindings/clock/st,stm32-rcc.txt new file mode 100644 index 0000000..0532d81 --- /dev/null +++ b/doc/device-tree-bindings/clock/st,stm32-rcc.txt @@ -0,0 +1,95 @@ +STMicroelectronics STM32 Reset and Clock Controller +=================================================== + +The RCC IP is both a reset and a clock controller. + +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" + "st,stm32f469-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 + use. + +Example: + + rcc: rcc@40023800 { + #reset-cells = <1>; + #clock-cells = <2> + compatible = "st,stm32f42xx-rcc", "st,stm32-rcc"; + reg = <0x40023800 0x400>; + }; + +Specifying gated clocks +======================= + +The primary index must be set to 0. + +The secondary index is the bit number within the RCC register bank, starting +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 STM32F4_AHB1_CLOCK(GPIOA)> + }; + + /* Gated clock, AHB2 bit 4 (CRYP) */ + ... { + clocks = <&rcc 0 STM32F4_AHB2_CLOCK(CRYP)> + }; + +Specifying other clocks +======================= + +The primary index must be set to 1. + +The secondary index is bound with the following magic numbers: + + 0 SYSTICK + 1 FCLK + +Example: + + /* Misc clock, FCLK */ + ... { + 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)>; + }; |