Re: [PATCH v7 3/3] clk: stm32h7: Add stm32h743 clock driver
From: Gabriel FERNANDEZ
Date: Thu Jul 20 2017 - 04:32:41 EST
Hi Vladimir,
On 07/19/2017 11:20 PM, Vladimir Zapolskiy wrote:
> Hello Gabriel,
>
> On 07/19/2017 05:25 PM, 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>
>>
>> for MFD changes:
>> Acked-by: Lee Jones <lee.jones@xxxxxxxxxx>
>>
>> for DT-Bindings
>> Acked-by: Rob Herring <robh@xxxxxxxxxx>
>> ---
>> .../devicetree/bindings/clock/st,stm32h7-rcc.txt | 82 ++
> I'll provide some review comments about device tree bindings only.
>
>> drivers/clk/Makefile | 1 +
>> drivers/clk/clk-stm32h7.c | 1409 ++++++++++++++++++++
>> include/dt-bindings/clock/stm32h7-clks.h | 165 +++
>> include/dt-bindings/mfd/stm32h7-rcc.h | 136 ++
>> 5 files changed, 1793 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..442c50c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
>> @@ -0,0 +1,82 @@
>> +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)
>> +
>> +Optional properties:
>> +- st,syscfg: phandle for pwrcfg, mandatory to disable/enable backup domain
>> + write protection (RTC clock).
>> +
>> +Example:
>> +
>> + rcc: rcc@58024400 {
> 'rcc' as a generic device node name is awkward.
>
> I believe the main function of the device is clock controller (unlikely
> a generic reset controller can be converted into a clock controller),
> the locations of the document and device driver also indicate that
> primarily it is a clock controller, so I suggest to replace device node
> name with 'clock-controller' like below:
I prefer to keep rcc node name, to be coherent with the other ST
platforms (STM32F4/F7)
> rcc: clock-controller@58024400 {
>
>> + #reset-cells = <1>;
>> + #clock-cells = <2>
> Missing trailing semicolon ^^^
ok
> My recommendation is to move #reset-cells and #clock-cells properties
> down after 'reg' or 'clocks' property in the list.
ok
>
>> + 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>;
> Please drop #address-cells and #size-cells properties completely, from
> the document the device node does not define any children subnodes.
ok
>> + };
>> +
>> +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>;
>> +
> Please remote the empty line above.
ok
>> + };
>> +
>> +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
> Double slashes ----------> ^^^^
ok
> I have doubts if it is permitted to add source paths into the device
> tree bindings documentation, because such information is specific to
> the Linux source code.
>
> Rob, can you clarify please?
>
>> +header and can be used in device tree sources.
>> +
>> +example:
> For unification, please capitalize it: 'Example:'
ok
>> +
>> + timer2 {
>> + resets = <&rcc STM32H7_APB1L_RESET(TIM2)>;
>> + };
> --
> With best wishes,
> Vladimir
Best Regards
Gabriel