lkml.org 
[lkml]   [2018]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 01/14] dt-bindings: Document STM32MP1 Reset Clock Controller (RCC) bindings
Date
From: Gabriel Fernandez <gabriel.fernandez@st.com>

The RCC block is responsible of the management of the clock and reset
generation for the complete circuit.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
---
.../devicetree/bindings/mfd/st,stm32-rcc.txt | 85 ++++++++++++++++++++++
1 file changed, 85 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mfd/st,stm32-rcc.txt

diff --git a/Documentation/devicetree/bindings/mfd/st,stm32-rcc.txt b/Documentation/devicetree/bindings/mfd/st,stm32-rcc.txt
new file mode 100644
index 0000000..28017a1
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/st,stm32-rcc.txt
@@ -0,0 +1,85 @@
+STMicroelectronics STM32 Peripheral Reset Clock Controller
+==========================================================
+
+The RCC IP is both a reset and a clock controller.
+
+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: "simple-mfd", "syscon"
+- reg: should be register base and length as documented in the datasheet
+
+- Sub-nodes:
+ - compatible: "st,stm32mp1-rcc-clk"
+ - #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.
+
+ - compatible: "st,stm32mp1-rcc-rst"
+ - #reset-cells: Shall be 1
+
+Example:
+ rcc: rcc@50000000 {
+ compatible = "syscon", "simple-mfd";
+ reg = <0x50000000 0x1000>;
+
+ rcc_clk: rcc-clk@50000000 {
+ #clock-cells = <1>;
+ compatible = "st,stm32mp1-rcc-clk";
+ };
+
+ rcc_rst: rcc-reset@50000000 {
+ #reset-cells = <1>;
+ compatible = "st,stm32mp1-rcc-rst";
+ };
+ };
+
+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.
+
+Example:
+
+ /* Accessing DMA1 clock */
+ ... {
+ clocks = <&rcc_clk DMA1>
+ };
+
+ /* Accessing SPI6 kernel clock */
+ ... {
+ clocks = <&rcc_clk SPI6_K>
+ };
+
+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
+
+example:
+
+ ltdc {
+ resets = <&rcc_rst LTDC_R>;
+ };
--
1.9.1
\
 
 \ /
  Last update: 2018-02-02 15:07    [W:0.095 / U:7.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site