diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/clk.txt | 16 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.txt | 60 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/clock/ti/divider.txt | 3 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/clock/ti/mux.txt | 3 |
4 files changed, 79 insertions, 3 deletions
diff --git a/Documentation/clk.txt b/Documentation/clk.txt index be909ed45970..511628bb3d3a 100644 --- a/Documentation/clk.txt +++ b/Documentation/clk.txt @@ -268,9 +268,19 @@ The common clock framework uses two global locks, the prepare lock and the enable lock. The enable lock is a spinlock and is held across calls to the .enable, -.disable and .is_enabled operations. Those operations are thus not allowed to -sleep, and calls to the clk_enable(), clk_disable() and clk_is_enabled() API -functions are allowed in atomic context. +.disable operations. Those operations are thus not allowed to sleep, +and calls to the clk_enable(), clk_disable() API functions are allowed in +atomic context. + +For clk_is_enabled() API, it is also designed to be allowed to be used in +atomic context. However, it doesn't really make any sense to hold the enable +lock in core, unless you want to do something else with the information of +the enable state with that lock held. Otherwise, seeing if a clk is enabled is +a one-shot read of the enabled state, which could just as easily change after +the function returns because the lock is released. Thus the user of this API +needs to handle synchronizing the read of the state with whatever they're +using it for to make sure that the enable state doesn't change during that +time. The prepare lock is a mutex and is held across calls to all other operations. All those operations are allowed to sleep, and calls to the corresponding API diff --git a/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.txt b/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.txt new file mode 100644 index 000000000000..fb9495ea582c --- /dev/null +++ b/Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.txt @@ -0,0 +1,60 @@ +STMicroelectronics STM32 Peripheral Reset Clock Controller +========================================================== + +The RCC IP is both a reset and a clock controller. + +RCC makes also power management (resume/supend and wakeup interrupt). + +Please also refer to reset.txt for common reset controller binding usage. + +Please also refer to clock-bindings.txt for common clock controller +binding usage. + + +Required properties: +- compatible: "st,stm32mp1-rcc", "syscon" +- reg: should be register base and length as documented in the datasheet +- #clock-cells: 1, device nodes should specify the clock in their + "clocks" property, containing a phandle to the clock device node, + an index specifying the clock to use. +- #reset-cells: Shall be 1 +- interrupts: Should contain a general interrupt line and a interrupt line + to the wake-up of processor (CSTOP). + +Example: + rcc: rcc@50000000 { + compatible = "st,stm32mp1-rcc", "syscon"; + reg = <0x50000000 0x1000>; + #clock-cells = <1>; + #reset-cells = <1>; + interrupts = <GIC_SPI 5 IRQ_TYPE_NONE>, + <GIC_SPI 145 IRQ_TYPE_NONE>; + }; + +Specifying clocks +================= + +All available clocks are defined as preprocessor macros in +dt-bindings/clock/stm32mp1-clks.h header and can be used in device +tree sources. + +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 on STM32MP1, for LTDC reset: + ltdc = APB4_RSTSETR_offset / 4 * 32 + LTDC_bit_offset + = 0x180 / 4 * 32 + 0 = 3072 + +The list of valid indices for STM32MP1 is available in: +include/dt-bindings/reset-controller/stm32mp1-resets.h + +This file implements defines like: +#define LTDC_R 3072 diff --git a/Documentation/devicetree/bindings/clock/ti/divider.txt b/Documentation/devicetree/bindings/clock/ti/divider.txt index 35a6f5c7e5c2..9b13b32974f9 100644 --- a/Documentation/devicetree/bindings/clock/ti/divider.txt +++ b/Documentation/devicetree/bindings/clock/ti/divider.txt @@ -75,6 +75,9 @@ Optional properties: - ti,invert-autoidle-bit : autoidle is enabled by setting the bit to 0, see [2] - ti,set-rate-parent : clk_set_rate is propagated to parent +- ti,latch-bit : latch the divider value to HW, only needed if the register + access requires this. As an example dra76x DPLL_GMAC H14 divider implements + such behavior. Examples: dpll_usb_m2_ck: dpll_usb_m2_ck@4a008190 { diff --git a/Documentation/devicetree/bindings/clock/ti/mux.txt b/Documentation/devicetree/bindings/clock/ti/mux.txt index 2d0d170f8001..eec8994b9be8 100644 --- a/Documentation/devicetree/bindings/clock/ti/mux.txt +++ b/Documentation/devicetree/bindings/clock/ti/mux.txt @@ -48,6 +48,9 @@ Optional properties: zero - ti,set-rate-parent : clk_set_rate is propagated to parent clock, not supported by the composite-mux-clock subtype +- ti,latch-bit : latch the mux value to HW, only needed if the register + access requires this. As an example, dra7x DPLL_GMAC H14 muxing + implements such behavior. Examples: |