Re: [PATCH] clk: stm32h7: Add stm32h743 clock driver

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On 03/27/2017 09:04 PM, Rob Herring wrote:
On Fri, Mar 24, 2017 at 4:41 AM, Gabriel Fernandez
<gabriel.fernandez@xxxxxx> wrote:
Hi Rob,

Thanks for reviewing



On 03/24/2017 03:06 AM, Rob Herring wrote:
On Wed, Mar 15, 2017 at 10:23:30AM +0100, gabriel.fernandez@xxxxxx wrote:
From: Gabriel Fernandez <gabriel.fernandez@xxxxxx>

This patch enables clocks for STM32H743 boards.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@xxxxxx>
---
   .../devicetree/bindings/clock/st,stm32h7-rcc.txt   |  152 ++
   drivers/clk/Makefile                               |    1 +
   drivers/clk/clk-stm32h7.c                          | 1586
++++++++++++++++++++
   include/dt-bindings/clock/stm32h7-clks.h           |  165 ++
   include/dt-bindings/mfd/stm32h7-rcc.h              |  138 ++
   5 files changed, 2042 insertions(+)
   create mode 100644
Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
   create mode 100644 drivers/clk/clk-stm32h7.c
   create mode 100644 include/dt-bindings/clock/stm32h7-clks.h
   create mode 100644 include/dt-bindings/mfd/stm32h7-rcc.h

diff --git a/Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
b/Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
new file mode 100644
index 0000000..9d4b587
--- /dev/null
+++ b/Documentation/devicetree/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>;
The reg addr value and unit address don't match.
ok il will change into

         vco1@0 {
                 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"
Only 1 single PLL design for all STM32 chips ever?
no, i can change into "stm32h7,pll"
Actually, should be "st,stm32h7-pll".
ok

+
+- #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
Isn't this implied by the presence of the next property?
do you prefer this ?

- st,frac :
0 : pll is configured in integer mode
1..8191 : Fractional part of the multiplication factor and pll is configured
in fractional mode
Why not no st,frac property means integer mode?
No

no st,frac property means no change (keep default values from bootloader)


Best Regards

Gabriel

Rob

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