Re: [PATCH v7 08/11] misc: rp1: RaspberryPi RP1 misc driver

[Stefan Wahren <wahrenst@xxxxxxx>]

Hi Andrea,

Am 07.02.25 um 22:31 schrieb Andrea della Porta:
> 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.
>
> 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>
> ---
>   MAINTAINERS                   |   1 +
>   drivers/misc/Kconfig          |   1 +
>   drivers/misc/Makefile         |   1 +
>   drivers/misc/rp1/Kconfig      |  20 +++
>   drivers/misc/rp1/Makefile     |   3 +
>   drivers/misc/rp1/rp1-pci.dtso |   8 +
>   drivers/misc/rp1/rp1_pci.c    | 305 ++++++++++++++++++++++++++++++++++
>   drivers/pci/quirks.c          |   1 +
>   include/linux/pci_ids.h       |   3 +
>   9 files changed, 343 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
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4cb38064694e..54f9e09f02ed 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19757,6 +19757,7 @@ 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 56bc72c7ce4a..af8c3be967bf 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -649,4 +649,5 @@ 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 545aad06d088..5df79dd90c9c 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -75,3 +75,4 @@ 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..cfb02b2f186c
> --- /dev/null
> +++ b/drivers/misc/rp1/Kconfig
> @@ -0,0 +1,20 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# RaspberryPi RP1 misc device
> +#
> +
> +config MISC_RP1
> +	tristate "RaspberryPi RP1 PCIe support"
> +	depends on OF_IRQ && OF_OVERLAY && PCI_MSI && PCI_QUIRKS
> +	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..c2d76e01bf57
> --- /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>
> +
> +#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
> +
> +/* Embedded dtbo symbols created by cmd_wrap_S_dtb in scripts/Makefile.lib */
> +extern char __dtbo_rp1_pci_begin[];
> +extern char __dtbo_rp1_pci_end[];
> +
> +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));
> +}
> +
> +static void msix_cfg_clr(struct rp1_dev *rp1, unsigned int hwirq, u32 value)
> +{
> +	iowrite32(value, rp1->bar1 + RP1_PCIE_APBS_BASE + REG_CLR + MSIX_CFG(hwirq));
> +}
> +
> +static void rp1_mask_irq(struct irq_data *irqd)
> +{
> +	struct rp1_dev *rp1 = irqd->domain->host_data;
> +	struct irq_data *pcie_irqd = rp1->pcie_irqds[irqd->hwirq];
> +
> +	pci_msi_mask_irq(pcie_irqd);
> +}
> +
> +static void rp1_unmask_irq(struct irq_data *irqd)
> +{
> +	struct rp1_dev *rp1 = irqd->domain->host_data;
> +	struct irq_data *pcie_irqd = rp1->pcie_irqds[irqd->hwirq];
> +
> +	pci_msi_unmask_irq(pcie_irqd);
> +}
> +
> +static int rp1_irq_set_type(struct irq_data *irqd, unsigned int type)
> +{
> +	struct rp1_dev *rp1 = irqd->domain->host_data;
> +	unsigned int hwirq = (unsigned int)irqd->hwirq;
> +
> +	switch (type) {
> +	case IRQ_TYPE_LEVEL_HIGH:
> +		dev_dbg(&rp1->pdev->dev, "MSIX IACK EN for irq %d\n", hwirq);
This looks a little bit inconsistent. Only this type has a debug
message. So either we drop this or add at least a message for
IRQ_TYPE_EDGE_RISING, too. Btw the format specifier looks wrong
(unsigned int vs %d).
> +		msix_cfg_set(rp1, hwirq, MSIX_CFG_IACK_EN);
> +		rp1->level_triggered_irq[hwirq] = true;
> +	break;
> +	case IRQ_TYPE_EDGE_RISING:
> +		msix_cfg_clr(rp1, hwirq, MSIX_CFG_IACK_EN);
> +		rp1->level_triggered_irq[hwirq] = false;
> +		break;
> +	default:
> +		return -EINVAL;
It would be nice to document why only IRQ_TYPE_LEVEL_HIGH and
IRQ_TYPE_EDGE_RISING are supported. In case it's a software limitation,
this function would be a good place. In case this is a hardware
limitation this should be in the binding.
> +	}
> +
> +	return 0;
> +}
> +
> +static struct irq_chip rp1_irq_chip = {
> +	.name		= "rp1_irq_chip",
> +	.irq_mask	= rp1_mask_irq,
> +	.irq_unmask	= rp1_unmask_irq,
> +	.irq_set_type	= rp1_irq_set_type,
> +};
> +
> +static void rp1_chained_handle_irq(struct irq_desc *desc)
> +{
> +	unsigned int hwirq = desc->irq_data.hwirq & RP1_HW_IRQ_MASK;
> +	struct rp1_dev *rp1 = irq_desc_get_handler_data(desc);
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	unsigned int virq;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	virq = irq_find_mapping(rp1->domain, hwirq);
> +	generic_handle_irq(virq);
> +	if (rp1->level_triggered_irq[hwirq])
> +		msix_cfg_set(rp1, hwirq, MSIX_CFG_IACK);
> +
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int rp1_irq_xlate(struct irq_domain *d, struct device_node *node,
> +			 const u32 *intspec, unsigned int intsize,
> +			 unsigned long *out_hwirq, unsigned int *out_type)
> +{
> +	struct rp1_dev *rp1 = d->host_data;
> +	struct irq_data *pcie_irqd;
> +	unsigned long hwirq;
> +	int pcie_irq;
> +	int ret;
> +
> +	ret = irq_domain_xlate_twocell(d, node, intspec, intsize,
> +				       &hwirq, out_type);
> +	if (ret)
> +		return ret;
> +
> +	pcie_irq = pci_irq_vector(rp1->pdev, hwirq);
> +	pcie_irqd = irq_get_irq_data(pcie_irq);
> +	rp1->pcie_irqds[hwirq] = pcie_irqd;
> +	*out_hwirq = hwirq;
> +
> +	return 0;
> +}
> +
> +static int rp1_irq_activate(struct irq_domain *d, struct irq_data *irqd,
> +			    bool reserve)
> +{
> +	struct rp1_dev *rp1 = d->host_data;
> +
> +	msix_cfg_set(rp1, (unsigned int)irqd->hwirq, MSIX_CFG_ENABLE);
> +
> +	return 0;
> +}
> +
> +static void rp1_irq_deactivate(struct irq_domain *d, struct irq_data *irqd)
> +{
> +	struct rp1_dev *rp1 = d->host_data;
> +
> +	msix_cfg_clr(rp1, (unsigned int)irqd->hwirq, MSIX_CFG_ENABLE);
> +}
> +
> +static const struct irq_domain_ops rp1_domain_ops = {
> +	.xlate      = rp1_irq_xlate,
> +	.activate   = rp1_irq_activate,
> +	.deactivate = rp1_irq_deactivate,
> +};
> +
> +static void rp1_unregister_interrupts(struct pci_dev *pdev)
> +{
> +	struct rp1_dev *rp1 = pci_get_drvdata(pdev);
> +	int irq, i;
> +
> +	if (rp1->domain) {
> +		for (i = 0; i < RP1_INT_END; i++) {
> +			irq = irq_find_mapping(rp1->domain, i);
> +			irq_dispose_mapping(irq);
> +		}
> +
> +		irq_domain_remove(rp1->domain);
> +	}
> +
> +	pci_free_irq_vectors(pdev);
> +}
> +
> +static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> +{
> +	u32 dtbo_size = __dtbo_rp1_pci_end - __dtbo_rp1_pci_begin;
> +	void *dtbo_start = __dtbo_rp1_pci_begin;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *rp1_node;
> +	struct rp1_dev *rp1;
> +	int err = 0;
> +	int i;
> +
> +	rp1_node = dev_of_node(dev);
> +	if (!rp1_node) {
> +		dev_err(dev, "Missing of_node for device\n");
> +		return -EINVAL;
> +	}
> +
> +	rp1 = devm_kzalloc(&pdev->dev, sizeof(*rp1), GFP_KERNEL);
> +	if (!rp1)
> +		return -ENOMEM;
> +
> +	rp1->pdev = pdev;
> +
> +	if (pci_resource_len(pdev, 1) <= 0x10000) {
> +		dev_err(&pdev->dev,
> +			"Not initialised - is the firmware running?\n");
> +		return -EINVAL;
> +	}
> +
> +	err = pcim_enable_device(pdev);
> +	if (err < 0)
> +		return dev_err_probe(&pdev->dev, err,
> +				     "Enabling PCI device has failed");
> +
> +	rp1->bar1 = pcim_iomap(pdev, 1, 0);
> +	if (!rp1->bar1) {
> +		dev_err(&pdev->dev, "Cannot map PCI BAR\n");
> +		return -EIO;
> +	}
> +
> +	pci_set_master(pdev);
> +
> +	err = pci_alloc_irq_vectors(pdev, RP1_INT_END, RP1_INT_END,
> +				    PCI_IRQ_MSIX);
> +	if (err < 0) {
> +		return dev_err_probe(&pdev->dev, err,
> +				     "pci_alloc_irq_vectors failed");
> +	} else if (err != RP1_INT_END) {
> +		dev_err(&pdev->dev, "Cannot allocate enough interrupts\n");
> +		return -EINVAL;
> +	}
> +
> +	pci_set_drvdata(pdev, rp1);
> +	rp1->domain = irq_domain_add_linear(rp1_node, RP1_INT_END,
> +					    &rp1_domain_ops, rp1);
> +	if (!rp1->domain) {
> +		dev_err(&pdev->dev, "Error creating IRQ domain\n");
> +		err = -ENOMEM;
> +		goto err_unregister_interrupts;
> +	}
> +
> +	for (i = 0; i < RP1_INT_END; i++) {
> +		unsigned int irq = irq_create_mapping(rp1->domain, i);
> +
> +		if (!irq) {
> +			dev_err(&pdev->dev, "failed to create irq mapping\n");
> +			err = -EINVAL;
> +			goto err_unregister_interrupts;
> +		}
> +
> +		irq_set_chip_and_handler(irq, &rp1_irq_chip, handle_level_irq);
> +		irq_set_probe(irq);
> +		irq_set_chained_handler_and_data(pci_irq_vector(pdev, i),
> +						 rp1_chained_handle_irq, rp1);
> +	}
> +
> +	err = of_overlay_fdt_apply(dtbo_start, dtbo_size, &rp1->ovcs_id, rp1_node);
> +	if (err)
> +		goto err_unregister_interrupts;
> +
> +	err = of_platform_default_populate(rp1_node, NULL, dev);
> +	if (err)
> +		goto err_unload_overlay;
I think in this case it's worth to add a suitable dev_err() here.

Thanks