On Wed, Mar 19, 2025 at 10:52:29PM +0100, Andrea della Porta wrote: > The RaspberryPi RP1 is a 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-board peripherals > by loading a devicetree overlay during driver probe if the RP1 > node is not already present in the DT. > > The peripherals are accessed by mapping MMIO registers starting > from PCI BAR1 region. > > With the overlay approach we can achieve more generic and agnostic > approach to managing this chipset, being that it is a PCI endpoint > and could possibly be reused in other hw implementations. The > presented approach is also used by Bootlin's Microchip LAN966x > patchset (see link) as well, for a similar chipset. > In this case, the inclusion tree for the DT overlay is as follow > (the arrow points to the includer): > > rp1-pci.dtso <---- rp1-common.dtsi > > On the other hand, to ensure compatibility with downstream, this > driver can also work with a DT already comprising the RP1 node, so > the dynamically loaded overlay will not be used if the DT is already > fully defined. > > The reason why this driver is contained in drivers/misc has > been paved by Bootlin's LAN966X driver, which first used the > overlay approach to implement non discoverable peripherals behind a > PCI bus. For RP1, the same arguments apply: it's not used as an SoC > since the driver code is not running on-chip and is not like an MFD > since it does not really need all the MFD infrastructure (shared regs, > etc.). So, for this particular use, misc has been proposed and deemed > as a good choice. For further details about that please check the links. > > This driver is heavily based on downstream code from RaspberryPi > Foundation, and the original author is Phil Elwell. > > Link: https://datasheets.raspberrypi.com/rp1/rp1-peripherals.pdf > Link: https://lore.kernel.org/all/20240612140208.GC1504919@xxxxxxxxxx/ > Link: https://lore.kernel.org/all/83f7fa09-d0e6-4f36-a27d-cee08979be2a@xxxxxxxxxxxxxxxx/ > Link: https://lore.kernel.org/all/2024081356-mutable-everyday-6f9d@gregkh/ > Link: https://lore.kernel.org/all/20240808154658.247873-1-herve.codina@xxxxxxxxxxx/ > > Signed-off-by: Andrea della Porta <andrea.porta@xxxxxxxx> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> # quirks.c, pci_ids.h > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > index b84ff7bade82..4dfda527c76b 100644 > --- a/drivers/pci/quirks.c > +++ b/drivers/pci/quirks.c > @@ -6283,6 +6283,7 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5020, of_pci_make_dev_node); > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5021, of_pci_make_dev_node); > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_REDHAT, 0x0005, of_pci_make_dev_node); > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_EFAR, 0x9660, of_pci_make_dev_node); > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_RPI, PCI_DEVICE_ID_RPI_RP1_C0, of_pci_make_dev_node); > > /* > * Devices known to require a longer delay before first config space access > diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h > index de5deb1a0118..b7a2c0fd589e 100644 > --- a/include/linux/pci_ids.h > +++ b/include/linux/pci_ids.h > @@ -2620,6 +2620,9 @@ > #define PCI_VENDOR_ID_TEKRAM 0x1de1 > #define PCI_DEVICE_ID_TEKRAM_DC290 0xdc29 > > +#define PCI_VENDOR_ID_RPI 0x1de4 > +#define PCI_DEVICE_ID_RPI_RP1_C0 0x0001 > + > #define PCI_VENDOR_ID_ALIBABA 0x1ded > > #define PCI_VENDOR_ID_CXL 0x1e98 > -- > 2.35.3 >
