On Tue, Jan 21, 2025 at 09:43:37AM +0100, Andrea della Porta wrote: > Hi Greg, > > On 12:47 Fri 17 Jan , Greg Kroah-Hartman wrote: > > On Mon, Jan 13, 2025 at 03:58:07PM +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. > > > > > > 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. > > > > > > For reasons why this driver is contained in drivers/misc, please > > > check the links. > > > > Links aren't always around all the time, please document it here why > > this is needed, and then links can "add to" that summary. > > Ack. > > > > > > 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 > > ... > > > > diff --git a/drivers/misc/rp1/rp1_pci.c b/drivers/misc/rp1/rp1_pci.c > > > new file mode 100644 > > > index 000000000000..3e8ba3fa7fd5 > > > --- /dev/null > > > +++ b/drivers/misc/rp1/rp1_pci.c > > > @@ -0,0 +1,305 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +/* > > > + * Copyright (c) 2018-24 Raspberry Pi Ltd. > > > + * All rights reserved. > > > + */ > > > + > > > +#include <linux/err.h> > > > +#include <linux/interrupt.h> > > > +#include <linux/irq.h> > > > +#include <linux/irqchip/chained_irq.h> > > > +#include <linux/irqdomain.h> > > > +#include <linux/module.h> > > > +#include <linux/msi.h> > > > +#include <linux/of_platform.h> > > > +#include <linux/pci.h> > > > +#include <linux/platform_device.h> > > > + > > > +#include "rp1_pci.h" > > > > Why does a self-contained .c file need a .h file? Please put it all in > > here. > > I agree with you. Indeed, the very first version of this patch had the header > file placed inside the .c, but I received concerns about it and some advice to > do it differently, as you can see here: > https://lore.kernel.org/all/ZtWDpaqUG9d9yPPf@apocalypse/ > so I've changed it accordingly in V2. So right now I'm not sure what the > acceptable behaviour should be ... It's a pretty simple rule: Only use a .h file if multiple .c files need to see the symbol. So no .h file is needed here. > > > +struct rp1_dev { > > > + struct pci_dev *pdev; > > > + struct irq_domain *domain; > > > + struct irq_data *pcie_irqds[64]; > > > + void __iomem *bar1; > > > + int ovcs_id; /* overlay changeset id */ > > > + bool level_triggered_irq[RP1_INT_END]; > > > +}; > > > + > > > +static void msix_cfg_set(struct rp1_dev *rp1, unsigned int hwirq, u32 value) > > > +{ > > > + iowrite32(value, rp1->bar1 + RP1_PCIE_APBS_BASE + REG_SET + MSIX_CFG(hwirq)); > > > > Do your writes need a read to flush them properly? Or can they handle > > this automatically? > > > > I had some thoughts with RaspberryPi foundation folks to double check it, and it > seems that there should be no need to readback the value (unless we want to go > really paranoid), so I would avoid that since in case of level handled interrupt > we would end up reading the register on every triggering interrupts. Ok, if it passes testing, that's fine, hopefully it works properly, but if not, you now have a trail to go and fix it in the future :) thanks, greg k-h
