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

Andrea della Porta
2024-08-30T13:50:30Z

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

>
> > +
> > + 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.

> > + compatible = "raspberrypi,rp1-clocks";
> > + #clock-cells = <1>;
> > + reg = <0xc0 0x40018000 0x0 0x10038>;
>
> Wrong order of properties - see DTS coding style.

Ack.

Many thanks,
Andrea

>
> > + clocks = <&clk_xosc>;
> > + clock-names = "xosc";
>
> Best regards,
> Krzysztof
>