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.

Since the gpio line names should be provided by the user, there
is an interface through configfs that allows the userspace to
load a DT overlay that will provide gpio-line-names property.
The interface can be invoked like this:

cat rpi-rp1-gpios-5-b.dtbo > /sys/kernel/config/rp1-cfg/gpio_set_names

and is designed to be similar to what users are already used to
from distro with downstream kernel.

For reasons why this driver is contained in drivers/misc, 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@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    | 366 ++++++++++++++++++++++++++++++++++
 drivers/misc/rp1/rp1_pci.h    |  14 ++
 drivers/pci/quirks.c          |   1 +
 include/linux/pci_ids.h       |   3 +
 10 files changed, 419 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 510a071ede78..032678fb2470 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19389,6 +19389,7 @@ 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 3fe7e2a9bd29..ac85cb154100 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -628,4 +628,5 @@ 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 a9f94525e181..ae86d69997b4 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -72,3 +72,4 @@ obj-$(CONFIG_TPS6594_PFSM)	+= tps6594-pfsm.o
 obj-$(CONFIG_NSM)		+= nsm.o
 obj-$(CONFIG_MARVELL_CN10K_DPI)	+= mrvl_cn10k_dpi.o
 obj-y				+= keba/
+obj-$(CONFIG_MISC_RP1)		+= rp1/
diff --git a/drivers/misc/rp1/Kconfig b/drivers/misc/rp1/Kconfig
new file mode 100644
index 000000000000..39c4aa4bf634
--- /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..440909a070ed
--- /dev/null
+++ b/drivers/misc/rp1/rp1_pci.c
@@ -0,0 +1,366 @@
+// 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"
+
+#define RP1_DRIVER_NAME		"rp1"
+
+#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_IO_BANK0	0
+#define RP1_INT_IO_BANK1	1
+#define RP1_INT_IO_BANK2	2
+#define RP1_INT_AUDIO_IN	3
+#define RP1_INT_AUDIO_OUT	4
+#define RP1_INT_PWM0		5
+#define RP1_INT_ETH		6
+#define RP1_INT_I2C0		7
+#define RP1_INT_I2C1		8
+#define RP1_INT_I2C2		9
+#define RP1_INT_I2C3		10
+#define RP1_INT_I2C4		11
+#define RP1_INT_I2C5		12
+#define RP1_INT_I2C6		13
+#define RP1_INT_I2S0		14
+#define RP1_INT_I2S1		15
+#define RP1_INT_I2S2		16
+#define RP1_INT_SDIO0		17
+#define RP1_INT_SDIO1		18
+#define RP1_INT_SPI0		19
+#define RP1_INT_SPI1		20
+#define RP1_INT_SPI2		21
+#define RP1_INT_SPI3		22
+#define RP1_INT_SPI4		23
+#define RP1_INT_SPI5		24
+#define RP1_INT_UART0		25
+#define RP1_INT_TIMER_0		26
+#define RP1_INT_TIMER_1		27
+#define RP1_INT_TIMER_2		28
+#define RP1_INT_TIMER_3		29
+#define RP1_INT_USBHOST0	30
+#define RP1_INT_USBHOST0_0	31
+#define RP1_INT_USBHOST0_1	32
+#define RP1_INT_USBHOST0_2	33
+#define RP1_INT_USBHOST0_3	34
+#define RP1_INT_USBHOST1	35
+#define RP1_INT_USBHOST1_0	36
+#define RP1_INT_USBHOST1_1	37
+#define RP1_INT_USBHOST1_2	38
+#define RP1_INT_USBHOST1_3	39
+#define RP1_INT_DMA		40
+#define RP1_INT_PWM1		41
+#define RP1_INT_UART1		42
+#define RP1_INT_UART2		43
+#define RP1_INT_UART3		44
+#define RP1_INT_UART4		45
+#define RP1_INT_UART5		46
+#define RP1_INT_MIPI0		47
+#define RP1_INT_MIPI1		48
+#define RP1_INT_VIDEO_OUT	49
+#define RP1_INT_PIO_0		50
+#define RP1_INT_PIO_1		51
+#define RP1_INT_ADC_FIFO	52
+#define RP1_INT_PCIE_OUT	53
+#define RP1_INT_SPI6		54
+#define RP1_INT_SPI7		55
+#define RP1_INT_SPI8		56
+#define RP1_INT_SYSCFG		58
+#define RP1_INT_CLOCKS_DEFAULT	59
+#define RP1_INT_VBUSCTRL	60
+#define RP1_INT_PROC_MISC	57
+#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;
+	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);
+		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;
+	}
+
+	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;
+
+	return 0;
+
+err_unload_overlay:
+	of_overlay_remove(&rp1->ovcs_id);
+err_unregister_interrupts:
+	rp1_unregister_interrupts(pdev);
+
+	return err;
+}
+
+static void rp1_remove(struct pci_dev *pdev)
+{
+	struct rp1_dev *rp1 = pci_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+
+	of_platform_depopulate(dev);
+	of_overlay_remove(&rp1->ovcs_id);
+	rp1_unregister_interrupts(pdev);
+}
+
+static const struct pci_device_id dev_id_table[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_RPI, PCI_DEVICE_ID_RPI_RP1_C0), },
+	{ 0, }
+};
+MODULE_DEVICE_TABLE(pci, dev_id_table);
+
+static struct pci_driver rp1_driver = {
+	.name		= RP1_DRIVER_NAME,
+	.id_table	= dev_id_table,
+	.probe		= rp1_probe,
+	.remove		= rp1_remove,
+};
+
+module_pci_driver(rp1_driver);
+
+MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.com>");
+MODULE_AUTHOR("Andrea della Porta <andrea.porta@suse.com>");
+MODULE_DESCRIPTION("RP1 wrapper");
+MODULE_LICENSE("GPL");
diff --git a/drivers/misc/rp1/rp1_pci.h b/drivers/misc/rp1/rp1_pci.h
new file mode 100644
index 000000000000..7982f13bad9b
--- /dev/null
+++ b/drivers/misc/rp1/rp1_pci.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Copyright (c) 2018-24 Raspberry Pi Ltd.
+ * All rights reserved.
+ */
+
+#ifndef _RP1_EXTERN_H_
+#define _RP1_EXTERN_H_
+
+extern char __dtbo_rp1_pci_begin[];
+extern char __dtbo_rp1_pci_end[];
+
+#endif
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index dccb60c1d9cc..41e77d94ff73 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -6266,6 +6266,7 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0xa76e, dpc_log_size);
 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_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 4cf6aaed5f35..c7e6cd10ac52 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -2611,6 +2611,9 @@
 #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

> +++ 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"

This is probably O.K, for now, but really the tooling should be
extended so that DT files can be checked anywhere in the tree. I can
see more such embedded DT overlays appearing with time, and there is
nothing actually arm64 specific here, it is architecture agnostic. It
is just a PCIe device, there is no reason it could not be used on a
S390, Risc-V, or loongarch.

      Andrew

Hi Andrew,

On 20:33 Sun 24 Nov     , Andrew Lunn wrote:
> > +++ 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"
> 
> This is probably O.K, for now, but really the tooling should be
> extended so that DT files can be checked anywhere in the tree. I can
> see more such embedded DT overlays appearing with time, and there is
> nothing actually arm64 specific here, it is architecture agnostic. It
> is just a PCIe device, there is no reason it could not be used on a
> S390, Risc-V, or loongarch.

I completely agree with you.

Regards,
Andrea

> 
>       Andrew