[PATCH v4 00/10] Add support for RaspberryPi RP1 PCI device using a DT overlay

Andrea della Porta
2024-11-24T10:52:54Z

RP1 is an MFD chipset that acts as a south-bridge PCIe endpoint sporting
a pletora of subdevices (i.e. Ethernet, USB host controller, I2C, PWM,
etc.) whose registers are all reachable starting from an offset from the
BAR address. The main point here is that while the RP1 as an endpoint
itself is discoverable via usual PCI enumeraiton, the devices it contains
are not discoverable and must be declared e.g. via the devicetree.

This patchset is an attempt to provide a minimum infrastructure to allow
the RP1 chipset to be discovered and perpherals it contains to be added
from a devictree overlay loaded during RP1 PCI endpoint enumeration.
Followup patches should add support for the several peripherals contained
in RP1.

This work is based upon dowstream drivers code and the proposal from RH
et al. (see [1] and [2]). A similar approach is also pursued in [3].

The patches are ordered as follows:

-PATCHES 1 to 4: add binding schemas for clock, gpio and RP1 peripherals.
They are needed to support the other peripherals, e.g. the ethernet mac
depends on a clock generated by RP1 and the phy is reset though the
on-board gpio controller.

-PATCH 5 and 6: add clock and gpio device drivers.

-PATCH 7: the devicetree overlay describing the RP1 chipset. Please
note that this patch should be taken by the same maintainer that will
also take patch 11, since txeieh dtso is compiled in as binary blob and is
closely coupled to the driver.

-PATCH 8: this is the main patch to support RP1 chipset and peripherals
enabling through dtb overlay. The dtso since is intimately coupled with
the driver and will be linked in as binary blob in the driver obj.
The real dtso is in devicetree folder while the dtso in driver folder is
just a placeholder to include the real dtso.
In this way it is possible to check the dtso against dt-bindings.
The reason why drivers/misc has been selected as containing folder
for this driver can be seen in [6], [7] and [8].

-PATCH 9: add the external clock node (used by RP1) to the main dts.

-PATCH 10: add the relevant kernel CONFIG_ options to defconfig.

This patchset is also a first attempt to be more agnostic wrt hardware
description standards such as OF devicetree and ACPI, where 'agnostic'
means "using DT in coexistence with ACPI", as been already promoted
by e.g. AL (see [4]). Although there's currently no evidence it will also
run out of the box on purely ACPI system, it is a first step towards
that direction.

Please note that albeit this patchset has no prerequisites in order to
be applied cleanly, it still depends on Stanimir's WIP patchset for BCM2712
PCIe controller (see [5]) in order to work at runtime.

Many thanks,
Andrea della Porta

Links:
- [1]: https://lpc.events/event/17/contributions/1421/attachments/1337/2680/LPC2023%20Non-discoverable%20devices%20in%20PCI.pdf
- [2]: https://lore.kernel.org/lkml/20230419231155.GA899497-robh@kernel.org/t/
- [3]: https://lore.kernel.org/all/20240808154658.247873-1-herve.codina@bootlin.com/#t
- [4]: https://lore.kernel.org/all/73e05c77-6d53-4aae-95ac-415456ff0ae4@lunn.ch/
- [5]: https://lore.kernel.org/all/20240626104544.14233-1-svarbanov@suse.de/
- [6]: https://lore.kernel.org/all/20240612140208.GC1504919@google.com/
- [7]: https://lore.kernel.org/all/83f7fa09-d0e6-4f36-a27d-cee08979be2a@app.fastmail.com/
- [8]: https://lore.kernel.org/all/2024081356-mutable-everyday-6f9d@gregkh/

CHANGES IN V4:

NEW ADDITIONS ------------------------------------------------

- Patches dealing with bugfix of core functions (1:1 dma-range
translation and PCI address translation) have been splitted
in a submission of their own. Also added CC: stable since
they deal with bugfixes

DEFCONFIG -----------------------------------------

- CONFIG_PINCTRL_RP1 value changed from 'y' to 'm'

RP1 MISC DRIVER -----------------------------------

- Drop 'dev' variable in struct rp1_dev since it's
redundant

- Substitute some indentation spaces with tabs

- Virtual irq and local irq automatic variables are now unsigned

- Add a check to unregister interrupts only if the domain has
been correctly created

- Replace dev_err() with dev_err_probe() where applicable

- Add an exit path check after pci_alloc_irq_vectors() in case
that less than RP1_INT_END irqs are allocated

- Fix the exit path in case irq_create_mapping() returns an error

GPIO/PINCTRL --------------------------------------

- Can now can be built as a module

- Add MODULE_*() macros

- Replace dev_err() with dev_err_probe() where applicable

- Replace builtin_platform_driver() with module_platform_driver()

- Fix a circular dependency involving CONFIG_GPIOLIB and
CONFIG_GPIOLIB_IRQCHIP

- PINCTRL_RP1 defaults to MISC_RP1 (and depends also on it)

CLOCKS --------------------------------------

- Dropped all CLK_IGNORE_UNUSED references and reduced the use of
CLK_IS_CRITICAL to a minium

- COMMON_CLK_RP1 defaults to MISC_RP1

- Drop 'name' and 'flags' variables from clock specific data struct
in favor of the ones defined in struct clk_init_data. This
in turn leads to some simplifications in both clock declarations
and in registration functions, and a general rework of the array
containing the clock definitions

- Inline substitution of FIELD_SET() macro

- Unify rp1_register_pll*() functions into a single one (with the
exception of rp1_register_pll_divider)

- Use CLK_HW_INIT_PARENTS_DATA() to initialize the various clocks

- Replace dev_err() with dev_err_probe() where applicable

- Use clk_hw_get_name() to retrieve the clock name for better isolation

- Added a sanity check in rp1_clk_probe() to skip registering NULL entries
in clk_desc_array[]

- Fixed a bug in rp1_pll_divider_off(): the divider register was
cleared upon unpreparing the clock, causing some peripherals to
obtain wrong clock rates.

- Added clk_eth to the list of registered clocks. This is important
for the ethernet controller to work

DTS -----------------------------------------

- rp1.dtso: dropped clock-names = "xosc"

- rp1.dtso: ranges for reg properties now start from 0x1000000000 instead
of 0xc040000000 to better reflect the addresses in the chipset documentation.
Also changed the reg properties in the sub-nodes to reflect this.

- rp1.dtso: added RP1_PLL_SYS_SEC to the list of assigned-clocks (and relative
assigned-clock-rates). This is needed for some sub-peripherals to work

- bcm2712.dtsi: renamed clock-rp1-xosc to clock-50000000

BINDINGS ------------------------------------

- rp1-clock.yaml: dropped 'clock-names' property (xosc) from bindings,
and fixed the example accordingly

- rp1-clock.yaml: #clock-cells description now just mention the binding
header declaring the clocks

- pci-ep-bus.yaml: shortened the title to comply with coding-style

- rp1-gpio.yaml: added a newline in the main description and in the pins
description.

- rp1-gpio.yaml: replaced additionalProperties with patternProperties
enforcing the nodes and subnodes to be postfixed with, respectively,
-state and -pins. Updated the example to reflect this change.

- pci1de4,1.yaml: ranges and dma-ranges properties are now on a single
line each.

Andrea della Porta (10):
dt-bindings: clock: Add RaspberryPi RP1 clock bindings
dt-bindings: pinctrl: Add RaspberryPi RP1 gpio/pinctrl/pinmux bindings
dt-bindings: pci: Add common schema for devices accessible through PCI
BARs
dt-bindings: misc: Add device specific bindings for RaspberryPi RP1
clk: rp1: Add support for clocks provided by RP1
pinctrl: rp1: Implement RaspberryPi RP1 gpio support
arm64: dts: rp1: Add support for RaspberryPi's RP1 device
misc: rp1: RaspberryPi RP1 misc driver
arm64: dts: bcm2712: Add external clock for RP1 chipset on Rpi5
arm64: defconfig: Enable RP1 misc/clock/gpio drivers

.../clock/raspberrypi,rp1-clocks.yaml | 58 +
.../devicetree/bindings/misc/pci1de4,1.yaml | 74 +
.../devicetree/bindings/pci/pci-ep-bus.yaml | 58 +
.../pinctrl/raspberrypi,rp1-gpio.yaml | 193 +++
MAINTAINERS | 14 +
arch/arm64/boot/dts/broadcom/bcm2712.dtsi | 7 +
arch/arm64/boot/dts/broadcom/rp1.dtso | 58 +
arch/arm64/configs/defconfig | 3 +
drivers/clk/Kconfig | 9 +
drivers/clk/Makefile | 1 +
drivers/clk/clk-rp1.c | 1527 +++++++++++++++++
drivers/misc/Kconfig | 1 +
drivers/misc/Makefile | 1 +
drivers/misc/rp1/Kconfig | 21 +
drivers/misc/rp1/Makefile | 3 +
drivers/misc/rp1/rp1-pci.dtso | 8 +
drivers/misc/rp1/rp1_pci.c | 366 ++++
drivers/misc/rp1/rp1_pci.h | 14 +
drivers/pci/quirks.c | 1 +
drivers/pinctrl/Kconfig | 11 +
drivers/pinctrl/Makefile | 1 +
drivers/pinctrl/pinctrl-rp1.c | 789 +++++++++
.../clock/raspberrypi,rp1-clocks.h | 61 +
include/linux/pci_ids.h | 3 +
24 files changed, 3282 insertions(+)
create mode 100644 Documentation/devicetree/bindings/clock/raspberrypi,rp1-clocks.yaml
create mode 100644 Documentation/devicetree/bindings/misc/pci1de4,1.yaml
create mode 100644 Documentation/devicetree/bindings/pci/pci-ep-bus.yaml
create mode 100644 Documentation/devicetree/bindings/pinctrl/raspberrypi,rp1-gpio.yaml
create mode 100644 arch/arm64/boot/dts/broadcom/rp1.dtso
create mode 100644 drivers/clk/clk-rp1.c
create mode 100644 drivers/misc/rp1/Kconfig
create mode 100644 drivers/misc/rp1/Makefile
create mode 100644 drivers/misc/rp1/rp1-pci.dtso
create mode 100644 drivers/misc/rp1/rp1_pci.c
create mode 100644 drivers/misc/rp1/rp1_pci.h
create mode 100644 drivers/pinctrl/pinctrl-rp1.c
create mode 100644 include/dt-bindings/clock/raspberrypi,rp1-clocks.h

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2.35.3