Re: [PATCH v6 08/10] misc: rp1: RaspberryPi RP1 misc driver

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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.

> 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@google.com/
> Link: https://lore.kernel.org/all/83f7fa09-d0e6-4f36-a27d-cee08979be2a@app.fastmail.com/
> Link: https://lore.kernel.org/all/2024081356-mutable-everyday-6f9d@gregkh/
> Link: https://lore.kernel.org/all/20240808154658.247873-1-herve.codina@bootlin.com/
> 
> Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
> ---
>  MAINTAINERS                   |   1 +
>  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    | 305 ++++++++++++++++++++++++++++++++++
>  drivers/misc/rp1/rp1_pci.h    |  14 ++
>  drivers/pci/quirks.c          |   1 +
>  include/linux/pci_ids.h       |   3 +
>  10 files changed, 358 insertions(+)
>  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
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fbdd8594aa7e..d67ba6d10aa8 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19583,6 +19583,7 @@ F:	Documentation/devicetree/bindings/misc/pci1de4,1.yaml
>  F:	Documentation/devicetree/bindings/pci/pci-ep-bus.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/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 09cbe3f0ab1e..ffa4d8315c35 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -651,4 +651,5 @@ source "drivers/misc/uacce/Kconfig"
>  source "drivers/misc/pvpanic/Kconfig"
>  source "drivers/misc/mchp_pci1xxxx/Kconfig"
>  source "drivers/misc/keba/Kconfig"
> +source "drivers/misc/rp1/Kconfig"
>  endmenu
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index 40bf953185c7..3b6b07a23aac 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -74,3 +74,4 @@ lan966x-pci-objs		:= lan966x_pci.o
>  lan966x-pci-objs		+= lan966x_pci.dtbo.o
>  obj-$(CONFIG_MCHP_LAN966X_PCI)	+= lan966x-pci.o
>  obj-y				+= keba/
> +obj-$(CONFIG_MISC_RP1)		+= rp1/
> diff --git a/drivers/misc/rp1/Kconfig b/drivers/misc/rp1/Kconfig
> new file mode 100644
> index 000000000000..15c443e13389
> --- /dev/null
> +++ b/drivers/misc/rp1/Kconfig
> @@ -0,0 +1,21 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# RaspberryPi RP1 misc device
> +#
> +
> +config MISC_RP1
> +	tristate "RaspberryPi RP1 PCIe support"
> +	depends on OF_IRQ && PCI_MSI && PCI_QUIRKS
> +	select OF_OVERLAY
> +	select PCI_DYNAMIC_OF_NODES
> +	help
> +	  Support the RP1 peripheral chip found on Raspberry Pi 5 board.
> +
> +	  This device supports several sub-devices including e.g. Ethernet
> +	  controller, USB controller, I2C, SPI and UART.
> +
> +	  The driver is responsible for enabling the DT node once the PCIe
> +	  endpoint has been configured, and handling interrupts.
> +
> +	  This driver uses an overlay to load other drivers to support for
> +	  RP1 internal sub-devices.
> diff --git a/drivers/misc/rp1/Makefile b/drivers/misc/rp1/Makefile
> new file mode 100644
> index 000000000000..508b4cb05627
> --- /dev/null
> +++ b/drivers/misc/rp1/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_MISC_RP1)		+= rp1-pci.o
> +rp1-pci-objs			:= rp1_pci.o rp1-pci.dtbo.o
> diff --git a/drivers/misc/rp1/rp1-pci.dtso b/drivers/misc/rp1/rp1-pci.dtso
> new file mode 100644
> index 000000000000..0bf2f4bb18e6
> --- /dev/null
> +++ b/drivers/misc/rp1/rp1-pci.dtso
> @@ -0,0 +1,8 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +
> +/* the dts overlay is included from the dts directory so
> + * it can be possible to check it with CHECK_DTBS while
> + * also compile it from the driver source directory.
> + */
> +
> +#include "arm64/broadcom/rp1.dtso"
> 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.

> +
> +#define RP1_DRIVER_NAME		"rp1"

KBUILD_MODNAME?

> +
> +#define RP1_HW_IRQ_MASK		GENMASK(5, 0)
> +
> +#define REG_SET			0x800
> +#define REG_CLR			0xc00
> +
> +/* MSI-X CFG registers start at 0x8 */
> +#define MSIX_CFG(x) (0x8 + (4 * (x)))
> +
> +#define MSIX_CFG_IACK_EN        BIT(3)
> +#define MSIX_CFG_IACK           BIT(2)
> +#define MSIX_CFG_ENABLE         BIT(0)
> +
> +/* Address map */
> +#define RP1_PCIE_APBS_BASE	0x108000
> +
> +/* Interrupts */
> +#define RP1_INT_END		61



> +
> +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?

thanks,

greg k-h