dm: clk: add clk driver support for stm32h7 SoCs

This driver implements basic clock setup, only clock gating
is implemented.

This driver doesn't implement .of_match as it's binded
by MFD RCC driver.

Files include/dt-bindings/clock/stm32h7-clks.h and
doc/device-tree-bindings/clock/st,stm32h7-rcc.txt
will be available soon in a kernel tag, as all the
bindings have been acked by Rob Herring [1].

[1] http://lkml.iu.edu/hypermail/linux/kernel/1704.0/00935.html

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 152 insertions, 0 deletions

diff --git a/doc/device-tree-bindings/clock/st,stm32h7-rcc.txt b/doc/device-tree-bindings/clock/st,stm32h7-rcc.txt
new file mode 100644
index 0000000000..9d4b5873d9
--- /dev/null
+++ b/doc/device-tree-bindings/clock/st,stm32h7-rcc.txt
@@ -0,0 +1,152 @@
+STMicroelectronics STM32H7 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,stm32h743-rcc"
+
+- reg: should be register base and length as documented in the
+  datasheet
+
+- #reset-cells: 1, see below
+
+- #clock-cells : from common clock binding; shall be set to 1
+
+- clocks: External oscillator clock phandle
+  - high speed external clock signal (HSE)
+  - low speed external clock signal (LSE)
+  - external I2S clock (I2S_CKIN)
+
+- st,syscfg: phandle for pwrcfg, mandatory to disable/enable backup domain
+  write protection (RTC clock).
+
+- pll x node: Allow to register a pll with specific parameters.
+  Please see PLL section below.
+
+Example:
+
+	rcc: rcc@58024400 {
+		#reset-cells = <1>;
+		#clock-cells = <2>
+		compatible = "st,stm32h743-rcc", "st,stm32-rcc";
+		reg = <0x58024400 0x400>;
+		clocks = <&clk_hse>, <&clk_lse>, <&clk_i2s_ckin>;
+
+		st,syscfg = <&pwrcfg>;
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		vco1@58024430 {
+			#clock-cells = <0>;
+			compatible = "stm32,pll";
+			reg = <0>;
+		};
+
+		vco2@58024438 {
+			#clock-cells = <0>;
+			compatible = "stm32,pll";
+			reg = <1>;
+			st,clock-div = <2>;
+			st,clock-mult = <40>;
+			st,frac-status = <0>;
+			st,frac = <0>;
+			st,vcosel = <1>;
+			st,pllrge = <2>;
+		};
+	};
+
+
+STM32H7 PLL
+-----------
+
+The VCO of STM32 PLL could be reprensented like this:
+
+  Vref    ---------       --------
+    ---->| / DIVM  |---->| x DIVN | ------> VCO
+          ---------       --------
+		             ^
+			     |
+	                  -------
+		         | FRACN |
+		          -------
+
+When the PLL is configured in integer mode:
+- VCO = ( Vref / DIVM ) * DIVN
+
+When the PLL is configured in fractional mode:
+- VCO = ( Vref / DIVM ) * ( DIVN + FRACN / 2^13)
+
+
+Required properties for pll node:
+- compatible: Should be:
+  "stm32,pll"
+
+- #clock-cells: from common clock binding; shall be set to 0
+- reg: Should be the pll number.
+
+Optional properties:
+- st,clock-div:  DIVM division factor       : <1..63>
+- st,clock-mult: DIVN multiplication factor : <4..512>
+
+- st,frac-status:
+   - 0 Pll is configured in integer mode
+   - 1 Pll is configure in fractional mode
+
+- st,frac: Fractional part of the multiplication factor : <0..8191>
+
+- st,vcosel: VCO selection
+  - 0: Wide VCO range:192 to 836 MHz
+  - 1: Medium VCO range:150 to 420 MHz
+
+- st,pllrge: PLL input frequency range
+  - 0: The PLL input (Vref / DIVM) clock range frequency is between 1 and 2 MHz
+  - 1: The PLL input (Vref / DIVM) clock range frequency is between 2 and 4 MHz
+  - 2: The PLL input (Vref / DIVM) clock range frequency is between 4 and 8 MHz
+  - 3: The PLL input (Vref / DIVM) clock range frequency is between 8 and 16 MHz
+
+
+The peripheral clock consumer should specify the desired clock by
+having the clock ID in its "clocks" phandle cell.
+
+All available clocks are defined as preprocessor macros in
+dt-bindings/clock/stm32h7-clks.h header and can be used in device
+tree sources.
+
+Example:
+
+		timer5: timer@40000c00 {
+			compatible = "st,stm32-timer";
+			reg = <0x40000c00 0x400>;
+			interrupts = <50>;
+			clocks = <&rcc TIM5_CK>;
+
+		};
+
+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 = AHB4RSTR_offset / 4 * 32 + CRCRST_bit_offset = 0x88 / 4 * 32 + 19 = 1107
+
+All available preprocessor macros for reset are defined dt-bindings//mfd/stm32h7-rcc.h
+header and can be used in device tree sources.
+
+example:
+
+	timer2 {
+		resets	= <&rcc STM32H7_APB1L_RESET(TIM2)>;
+	};