Re: [PATCH 08/11] misc: rp1: RaspberryPi RP1 misc driver

[Krzysztof Kozlowski <krzk@xxxxxxxxxx>]

On 30/08/2024 15:49, Andrea della Porta wrote:
> Hi Krzysztof,
> 
> On 10:38 Wed 21 Aug     , Krzysztof Kozlowski wrote:
>> On Tue, Aug 20, 2024 at 04:36:10PM +0200, Andrea della Porta wrote:
>>> The RaspberryPi RP1 is ia PCI multi function device containing
>>> peripherals ranging from Ethernet to USB controller, I2C, SPI
>>> and others.
>>> Implement a bare minimum driver to operate the RP1, leveraging
>>> actual OF based driver implementations for the on-borad peripherals
>>> by loading a devicetree overlay during driver probe.
>>> The peripherals are accessed by mapping MMIO registers starting
>>> from PCI BAR1 region.
>>> As a minimum driver, the peripherals will not be added to the
>>> dtbo here, but in following patches.
>>>
>>> Link: https://datasheets.raspberrypi.com/rp1/rp1-peripherals.pdf
>>> Signed-off-by: Andrea della Porta <andrea.porta@xxxxxxxx>
>>> ---
>>>  MAINTAINERS                           |   2 +
>>>  arch/arm64/boot/dts/broadcom/rp1.dtso | 152 ++++++++++++
>>
>> Do not mix DTS with drivers.
>>
>> These MUST be separate.
> 
> Separating the dtso from the driver in two different patches would mean
> that the dtso patch would be ordered before the driver one. This is because
> the driver embeds the dtbo binary blob inside itself, at build time. So
> in order to build the driver, the dtso needs to be there also. This is not

Sure, in such case DTS will have to go through the same tree as driver
as an exception. Please document it in patch changelog (---).

> the standard approach used with 'normal' dtb/dtbo, where the dtb patch is
> ordered last wrt the driver it refers to.

It's not exactly the "ordered last" that matters, but lack of dependency
and going through separate tree and branch - arm-soc/dts. Here there
will be an exception how we handle patch, but still DTS is hardware
description so should not be combined with driver code.

> Are you sure you want to proceed in this way?


> 
>>
>>>  drivers/misc/Kconfig                  |   1 +
>>>  drivers/misc/Makefile                 |   1 +
>>>  drivers/misc/rp1/Kconfig              |  20 ++
>>>  drivers/misc/rp1/Makefile             |   3 +
>>>  drivers/misc/rp1/rp1-pci.c            | 333 ++++++++++++++++++++++++++
>>>  drivers/misc/rp1/rp1-pci.dtso         |   8 +
>>>  drivers/pci/quirks.c                  |   1 +
>>>  include/linux/pci_ids.h               |   3 +
>>>  10 files changed, 524 insertions(+)
>>>  create mode 100644 arch/arm64/boot/dts/broadcom/rp1.dtso
>>>  create mode 100644 drivers/misc/rp1/Kconfig
>>>  create mode 100644 drivers/misc/rp1/Makefile
>>>  create mode 100644 drivers/misc/rp1/rp1-pci.c
>>>  create mode 100644 drivers/misc/rp1/rp1-pci.dtso
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 67f460c36ea1..1359538b76e8 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -19119,9 +19119,11 @@ F:	include/uapi/linux/media/raspberrypi/
>>>  RASPBERRY PI RP1 PCI DRIVER
>>>  M:	Andrea della Porta <andrea.porta@xxxxxxxx>
>>>  S:	Maintained
>>> +F:	arch/arm64/boot/dts/broadcom/rp1.dtso
>>>  F:	Documentation/devicetree/bindings/clock/raspberrypi,rp1-clocks.yaml
>>>  F:	Documentation/devicetree/bindings/pinctrl/raspberrypi,rp1-gpio.yaml
>>>  F:	drivers/clk/clk-rp1.c
>>> +F:	drivers/misc/rp1/
>>>  F:	drivers/pinctrl/pinctrl-rp1.c
>>>  F:	include/dt-bindings/clock/rp1.h
>>>  F:	include/dt-bindings/misc/rp1.h
>>> diff --git a/arch/arm64/boot/dts/broadcom/rp1.dtso b/arch/arm64/boot/dts/broadcom/rp1.dtso
>>> new file mode 100644
>>> index 000000000000..d80178a278ee
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/broadcom/rp1.dtso
>>> @@ -0,0 +1,152 @@
>>> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
>>> +
>>> +#include <dt-bindings/gpio/gpio.h>
>>> +#include <dt-bindings/interrupt-controller/irq.h>
>>> +#include <dt-bindings/clock/rp1.h>
>>> +#include <dt-bindings/misc/rp1.h>
>>> +
>>> +/dts-v1/;
>>> +/plugin/;
>>> +
>>> +/ {
>>> +	fragment@0 {
>>> +		target-path="";
>>> +		__overlay__ {
>>> +			#address-cells = <3>;
>>> +			#size-cells = <2>;
>>> +
>>> +			rp1: rp1@0 {
>>> +				compatible = "simple-bus";
>>> +				#address-cells = <2>;
>>> +				#size-cells = <2>;
>>> +				interrupt-controller;
>>> +				interrupt-parent = <&rp1>;
>>> +				#interrupt-cells = <2>;
>>> +
>>> +				// ranges and dma-ranges must be provided by the includer
>>> +				ranges = <0xc0 0x40000000
>>> +					  0x01/*0x02000000*/ 0x00 0x00000000
>>> +					  0x00 0x00400000>;
>>
>> Are you 100% sure you do not have here dtc W=1 warnings?
> 
> the W=1 warnings are:
> 
> arch/arm64/boot/dts/broadcom/rp1.dtso:37.24-42.7: Warning (simple_bus_reg): /fragment@0/__overlay__/rp1@0/clk_xosc: missing or empty reg/ranges property
> arch/arm64/boot/dts/broadcom/rp1.dtso:44.26-49.7: Warning (simple_bus_reg): /fragment@0/__overlay__/rp1@0/macb_pclk: missing or empty reg/ranges property
> arch/arm64/boot/dts/broadcom/rp1.dtso:51.26-56.7: Warning (simple_bus_reg): /fragment@0/__overlay__/rp1@0/macb_hclk: missing or empty reg/ranges property
> arch/arm64/boot/dts/broadcom/rp1.dtso:14.15-173.5: Warning (avoid_unnecessary_addr_size): /fragment@0/__overlay__: unnecessary #address-cells/#size-cells without "ranges", "dma-ranges" or child "reg" property
> 
> I don't see anything related to the ranges line you mentioned.

Hm, indeed, but I would expect warning about unit address not matching
ranges/reg.

> 
>>
>>> +
>>> +				dma-ranges =
>>> +				// inbound RP1 1x_xxxxxxxx -> PCIe 1x_xxxxxxxx
>>> +					     <0x10 0x00000000
>>> +					      0x43000000 0x10 0x00000000
>>> +					      0x10 0x00000000>;
>>> +
>>> +				clk_xosc: clk_xosc {
>>
>> Nope, switch to DTS coding style.
> 
> Ack.
> 
>>
>>> +					compatible = "fixed-clock";
>>> +					#clock-cells = <0>;
>>> +					clock-output-names = "xosc";
>>> +					clock-frequency = <50000000>;
>>> +				};
>>> +
>>> +				macb_pclk: macb_pclk {
>>> +					compatible = "fixed-clock";
>>> +					#clock-cells = <0>;
>>> +					clock-output-names = "pclk";
>>> +					clock-frequency = <200000000>;
>>> +				};
>>> +
>>> +				macb_hclk: macb_hclk {
>>> +					compatible = "fixed-clock";
>>> +					#clock-cells = <0>;
>>> +					clock-output-names = "hclk";
>>> +					clock-frequency = <200000000>;
>>> +				};
>>> +
>>> +				rp1_clocks: clocks@c040018000 {
>>
>> Why do you mix MMIO with non-MMIO nodes? This really does not look
>> correct.
>>
> 
> Right. This is already under discussion here:
> https://lore.kernel.org/all/ZtBzis5CzQMm8loh@apocalypse/
> 
> IIUC you proposed to instantiate the non-MMIO nodes (the three clocks) by
> using CLK_OF_DECLARE.

Depends. Where are these clocks? Naming suggests they might not be even
part of this device. But if these are part of the device, then why this
is not a clock controller (if they are controllable) or even removed
(because we do not represent internal clock tree in DTS).

Best regards,
Krzysztof