Re: [RFC PATCH 2/2] PCI: apple: Add driver for the Apple M1

[Marc Zyngier]

On Sun, 15 Aug 2021 05:25:25 +0100,
Alyssa Rosenzweig <alyssa@xxxxxxxxxxxxx> wrote:
> 
> Add a driver for the PCIe controller found in Apple system-on-chips,
> particularly the Apple M1. This driver exposes the internal bus used for
> the USB type-A ports, Ethernet, Wi-Fi, and Bluetooth. This patch brings
> up the USB type-A ports and Ethernet. Bringing up the radios requires
> interfacing with the System Management Coprocessor via Apple's
> mailboxes, so that's left to a future patch.
> 
> In this state, the driver consists of two major parts: hardware
> initialization and MSI handling. The hardware initialization is derived
> from Mark Kettenis's U-Boot patches which in turn is derived from
> Corellium's patches for the hardware. The rest of the driver is derived
> from Marc Zyngier's driver for the hardware.

This really needs to be split into multiple patches:

- PCI probing
- Clock management
- MSI implementation

A couple of comments below:

> 
> Co-developed-by: Stan Skowronek <stan@xxxxxxxxxxxxx>
> Signed-off-by: Stan Skowronek <stan@xxxxxxxxxxxxx>
> Co-developed-by: Marc Zyngier <maz@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Signed-off-by: Alyssa Rosenzweig <alyssa@xxxxxxxxxxxxx>
> ---
>  MAINTAINERS                         |   1 +
>  drivers/pci/controller/Kconfig      |  13 +
>  drivers/pci/controller/Makefile     |   1 +
>  drivers/pci/controller/pcie-apple.c | 466 ++++++++++++++++++++++++++++
>  4 files changed, 481 insertions(+)
>  create mode 100644 drivers/pci/controller/pcie-apple.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index d7d2e1d1e2f2..f13f65a844f7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1274,6 +1274,7 @@ M:	Alyssa Rosenzweig <alyssa@xxxxxxxxxxxxx>
>  L:	linux-pci@xxxxxxxxxxxxxxx
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/pci/apple,pcie.yaml
> +F:	drivers/pci/controller/pcie-apple.c
>  
>  APPLE SMC DRIVER
>  M:	Henrik Rydberg <rydberg@xxxxxxxxxxx>
> diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> index 326f7d13024f..881a6a81f3e2 100644
> --- a/drivers/pci/controller/Kconfig
> +++ b/drivers/pci/controller/Kconfig
> @@ -312,6 +312,19 @@ config PCIE_HISI_ERR
>  	  Say Y here if you want error handling support
>  	  for the PCIe controller's errors on HiSilicon HIP SoCs
>  
> +config PCIE_APPLE
> +	tristate "Apple PCIe controller"
> +	depends on ARCH_APPLE || COMPILE_TEST
> +	depends on OF
> +	depends on PCI_MSI_IRQ_DOMAIN
> +	depends on GPIOLIB
> +	help
> +	  Say Y here if you want to enable PCIe controller support on Apple
> +	  system-on-chips, like the Apple M1. This is required for the USB
> +	  type-A ports, Ethernet, Wi-Fi, and Bluetooth.
> +
> +	  If unsure, say Y if you have an Apple Silicon system.
> +
>  source "drivers/pci/controller/dwc/Kconfig"
>  source "drivers/pci/controller/mobiveil/Kconfig"
>  source "drivers/pci/controller/cadence/Kconfig"
> diff --git a/drivers/pci/controller/Makefile b/drivers/pci/controller/Makefile
> index aaf30b3dcc14..f9d40bad932c 100644
> --- a/drivers/pci/controller/Makefile
> +++ b/drivers/pci/controller/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_VMD) += vmd.o
>  obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb.o
>  obj-$(CONFIG_PCI_LOONGSON) += pci-loongson.o
>  obj-$(CONFIG_PCIE_HISI_ERR) += pcie-hisi-error.o
> +obj-$(CONFIG_PCIE_APPLE) += pcie-apple.o
>  # pcie-hisi.o quirks are needed even without CONFIG_PCIE_DW
>  obj-y				+= dwc/
>  obj-y				+= mobiveil/
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> new file mode 100644
> index 000000000000..08088e06460f
> --- /dev/null
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -0,0 +1,466 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * PCIe host bridge driver for Apple system-on-chips.
> + *
> + * The HW is ECAM compliant, so once the controller is initialized, the driver
> + * mostly only needs MSI handling. Initialization requires enabling power and
> + * clocks, along with a number of register pokes.
> + *
> + * Copyright (C) 2021 Google LLC
> + * Copyright (C) 2021 Corellium LLC
> + * Copyright (C) 2021 Mark Kettenis <kettenis@xxxxxxxxxxx>
> + * Copyright (C) 2021 Alyssa Rosenzweig <alyssa@xxxxxxxxxxxxx>
> + * Author: Marc Zyngier <maz@xxxxxxxxxx>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/irqdomain.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/of_irq.h>
> +#include <linux/pci-ecam.h>
> +#include <linux/iopoll.h>
> +#include <linux/gpio/consumer.h>
> +
> +#define CORE_RC_PHYIF_CTL		0x00024
> +#define   CORE_RC_PHYIF_CTL_RUN		BIT(0)
> +#define CORE_RC_PHYIF_STAT		0x00028
> +#define   CORE_RC_PHYIF_STAT_REFCLK	BIT(4)
> +#define CORE_RC_CTL			0x00050
> +#define   CORE_RC_CTL_RUN		BIT(0)
> +#define CORE_RC_STAT			0x00058
> +#define   CORE_RC_STAT_READY		BIT(0)
> +#define CORE_FABRIC_STAT		0x04000
> +#define   CORE_FABRIC_STAT_MASK		0x001F001F
> +#define CORE_PHY_CTL			0x80000
> +#define   CORE_PHY_CTL_CLK0REQ		BIT(0)
> +#define   CORE_PHY_CTL_CLK1REQ		BIT(1)
> +#define   CORE_PHY_CTL_CLK0ACK		BIT(2)
> +#define   CORE_PHY_CTL_CLK1ACK		BIT(3)
> +#define   CORE_PHY_CTL_RESET		BIT(7)
> +#define CORE_LANE_CFG(port)		(0x84000 + 0x4000 * (port))
> +#define   CORE_LANE_CFG_REFCLK0REQ	BIT(0)
> +#define   CORE_LANE_CFG_REFCLK1		BIT(1)
> +#define   CORE_LANE_CFG_REFCLK0ACK	BIT(2)
> +#define   CORE_LANE_CFG_REFCLKEN	(BIT(9) | BIT(10))
> +#define CORE_LANE_CTL(port)		(0x84004 + 0x4000 * (port))
> +#define   CORE_LANE_CTL_CFGACC		BIT(15)
> +
> +#define PORT_LTSSMCTL			0x00080
> +#define   PORT_LTSSMCTL_START		BIT(0)
> +#define PORT_INTSTAT			0x00100
> +#define   PORT_INT_TUNNEL_ERR		BIT(31)
> +#define   PORT_INT_CPL_TIMEOUT		BIT(23)
> +#define   PORT_INT_RID2SID_MAPERR	BIT(22)
> +#define   PORT_INT_CPL_ABORT		BIT(21)
> +#define   PORT_INT_MSI_BAD_DATA		BIT(19)
> +#define   PORT_INT_MSI_ERR		BIT(18)
> +#define   PORT_INT_REQADDR_GT32		BIT(17)
> +#define   PORT_INT_AF_TIMEOUT		BIT(15)
> +#define   PORT_INT_LINK_DOWN		BIT(14)
> +#define   PORT_INT_LINK_UP		BIT(12)
> +#define   PORT_INT_LINK_BWMGMT		BIT(11)
> +#define   PORT_INT_AER_MASK		(15 << 4)
> +#define   PORT_INT_PORT_ERR		BIT(4)
> +#define   PORT_INT_INTx(i)		BIT(i)
> +#define   PORT_INT_INTxALL		15
> +#define PORT_INTMSK			0x00104
> +#define PORT_INTMSKSET			0x00108
> +#define PORT_INTMSKCLR			0x0010c
> +#define PORT_MSICFG			0x00124
> +#define   PORT_MSICFG_EN		BIT(0)
> +#define   PORT_MSICFG_L2MSINUM_SHIFT	4
> +#define PORT_MSIBASE			0x00128
> +#define   PORT_MSIBASE_1_SHIFT		16
> +#define PORT_MSIADDR			0x00168
> +#define PORT_LINKSTS			0x00208
> +#define   PORT_LINKSTS_UP		BIT(0)
> +#define   PORT_LINKSTS_BUSY		BIT(2)
> +#define PORT_LINKCMDSTS			0x00210
> +#define PORT_OUTS_NPREQS		0x00284
> +#define   PORT_OUTS_NPREQS_REQ		BIT(24)
> +#define   PORT_OUTS_NPREQS_CPL		BIT(16)
> +#define PORT_RXWR_FIFO			0x00288
> +#define   PORT_RXWR_FIFO_HDR		GENMASK(15, 10)
> +#define   PORT_RXWR_FIFO_DATA		GENMASK(9, 0)
> +#define PORT_RXRD_FIFO			0x0028C
> +#define   PORT_RXRD_FIFO_REQ		GENMASK(6, 0)
> +#define PORT_OUTS_CPLS			0x00290
> +#define   PORT_OUTS_CPLS_SHRD		GENMASK(14, 8)
> +#define   PORT_OUTS_CPLS_WAIT		GENMASK(6, 0)
> +#define PORT_APPCLK			0x00800
> +#define   PORT_APPCLK_EN		BIT(0)
> +#define   PORT_APPCLK_CGDIS		BIT(8)
> +#define PORT_STATUS			0x00804
> +#define   PORT_STATUS_READY		BIT(0)
> +#define PORT_REFCLK			0x00810
> +#define   PORT_REFCLK_EN		BIT(0)
> +#define   PORT_REFCLK_CGDIS		BIT(8)
> +#define PORT_PERST			0x00814
> +#define   PORT_PERST_OFF		BIT(0)
> +#define PORT_RID2SID(i16)		(0x00828 + 4 * (i16))
> +#define   PORT_RID2SID_VALID		BIT(31)
> +#define   PORT_RID2SID_SID_SHIFT	16
> +#define   PORT_RID2SID_BUS_SHIFT	8
> +#define   PORT_RID2SID_DEV_SHIFT	3
> +#define   PORT_RID2SID_FUNC_SHIFT	0
> +#define PORT_OUTS_PREQS_HDR		0x00980
> +#define   PORT_OUTS_PREQS_HDR_MASK	GENMASK(9, 0)
> +#define PORT_OUTS_PREQS_DATA		0x00984
> +#define   PORT_OUTS_PREQS_DATA_MASK	GENMASK(15, 0)
> +#define PORT_TUNCTRL			0x00988
> +#define   PORT_TUNCTRL_PERST_ON		BIT(0)
> +#define   PORT_TUNCTRL_PERST_ACK_REQ	BIT(1)
> +#define PORT_TUNSTAT			0x0098c
> +#define   PORT_TUNSTAT_PERST_ON		BIT(0)
> +#define   PORT_TUNSTAT_PERST_ACK_PEND	BIT(1)
> +#define PORT_PREFMEM_ENABLE		0x00994
> +
> +/* The doorbell address is "well known" */
> +#define DOORBELL_ADDR			0xfffff000
> +
> +/* The hardware exposes 3 ports. Port 0 (WiFi and Bluetooth) is special, as it
> + * is power-gated by SMC to facilitate rfkill.
> + */
> +enum apple_pcie_port {
> +	APPLE_PCIE_PORT_RADIO    = 0,
> +	APPLE_PCIE_PORT_USB      = 1,
> +	APPLE_PCIE_PORT_ETHERNET = 2,

This really doesn't belong in a low-level PCIe controller driver. The
ports should be purely generic.

> +	APPLE_PCIE_NUM_PORTS
> +};
> +
> +struct apple_pcie {
> +	u32			msi_base;
> +	u32			nvecs;
> +	struct mutex		lock;
> +	struct device		*dev;
> +	struct irq_domain	*domain;
> +	unsigned long		*bitmap;
> +	void __iomem            *rc;
> +};
> +
> +static inline void rmwl(u32 clr, u32 set, void __iomem *addr)
> +{
> +	writel((readl(addr) & ~clr) | set, addr);

Please use relaxed accessors. If the barriers are actually needed,
please document what you are ordering against. This applies throughout
the patch.

This also begs the question: can this be called concurrently?

> +}
> +
> +static void apple_msi_top_irq_mask(struct irq_data *d)
> +{
> +	pci_msi_mask_irq(d);
> +	irq_chip_mask_parent(d);
> +}
> +
> +static void apple_msi_top_irq_unmask(struct irq_data *d)
> +{
> +	pci_msi_unmask_irq(d);
> +	irq_chip_unmask_parent(d);
> +}
> +
> +static void apple_msi_top_irq_eoi(struct irq_data *d)
> +{
> +	irq_chip_eoi_parent(d);
> +}

Drop this and use the irq_chip_eoi_parent() directly in the
irqchip. This was only here for debug.

> +
> +static struct irq_chip apple_msi_top_chip = {
> +	.name			= "PCIe MSI",
> +	.irq_mask		= apple_msi_top_irq_mask,
> +	.irq_unmask		= apple_msi_top_irq_unmask,
> +	.irq_eoi		= apple_msi_top_irq_eoi,
> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
> +	.irq_set_type		= irq_chip_set_type_parent,
> +};
> +
> +static void apple_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +	msg->address_hi = 0;
> +	msg->address_lo = DOORBELL_ADDR;

What was never clear is whether this doorbell address really is always
at this location, or whether it is actually programmed by *something*.

In any case, please use the lower_32bit/upper_32bit helpers, just in
case we can move the address somewhere else.

> +	msg->data = data->hwirq;
> +}
> +
> +static struct irq_chip apple_msi_bottom_chip = {
> +	.name			= "MSI",
> +	.irq_mask		= irq_chip_mask_parent,
> +	.irq_unmask		= irq_chip_unmask_parent,
> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
> +	.irq_eoi		= irq_chip_eoi_parent,
> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
> +	.irq_set_type		= irq_chip_set_type_parent,
> +	.irq_compose_msi_msg	= apple_msi_compose_msg,
> +};
> +
> +static int apple_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
> +				  unsigned int nr_irqs, void *args)
> +{
> +	struct apple_pcie *pcie = domain->host_data;
> +	struct irq_fwspec fwspec;
> +	unsigned int i;
> +	int ret, hwirq;
> +
> +	mutex_lock(&pcie->lock);
> +
> +	hwirq = bitmap_find_free_region(pcie->bitmap, pcie->nvecs,
> +					order_base_2(nr_irqs));
> +
> +	mutex_unlock(&pcie->lock);
> +
> +	if (hwirq < 0)
> +		return -ENOSPC;
> +
> +	fwspec.fwnode = domain->parent->fwnode;
> +	fwspec.param_count = 3;
> +	fwspec.param[0] = 0;
> +	fwspec.param[1] = hwirq + pcie->msi_base;
> +	fwspec.param[2] = IRQ_TYPE_EDGE_RISING;
> +
> +	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, &fwspec);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; i < nr_irqs; i++) {
> +		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
> +					      &apple_msi_bottom_chip,
> +					      domain->host_data);
> +	}
> +
> +	return 0;
> +}
> +
> +static void apple_msi_domain_free(struct irq_domain *domain, unsigned int virq,
> +				  unsigned int nr_irqs)
> +{
> +	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
> +	struct apple_pcie *pcie = domain->host_data;
> +
> +	mutex_lock(&pcie->lock);
> +
> +	bitmap_release_region(pcie->bitmap, d->hwirq, order_base_2(nr_irqs));
> +
> +	mutex_unlock(&pcie->lock);
> +}
> +
> +static const struct irq_domain_ops apple_msi_domain_ops = {
> +	.alloc	= apple_msi_domain_alloc,
> +	.free	= apple_msi_domain_free,
> +};
> +
> +static struct msi_domain_info apple_msi_info = {
> +	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> +		   MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
> +	.chip	= &apple_msi_top_chip,
> +};
> +
> +static int apple_pcie_setup_refclk(void __iomem *rc,
> +				   void __iomem *port,
> +				   unsigned int idx)
> +{
> +	u32 stat;
> +	int res;
> +
> +	res = readl_poll_timeout(rc + CORE_RC_PHYIF_STAT, stat,
> +				 stat & CORE_RC_PHYIF_STAT_REFCLK, 100, 50000);
> +	if (res < 0)
> +		return res;
> +
> +	rmwl(0, CORE_LANE_CTL_CFGACC, rc + CORE_LANE_CTL(idx));
> +	rmwl(0, CORE_LANE_CFG_REFCLK0REQ, rc + CORE_LANE_CFG(idx));
> +
> +	res = readl_poll_timeout(rc + CORE_LANE_CFG(idx), stat,
> +				 stat & CORE_LANE_CFG_REFCLK0ACK, 100, 50000);
> +	if (res < 0)
> +		return res;
> +
> +	rmwl(0, CORE_LANE_CFG_REFCLK1, rc + CORE_LANE_CFG(idx));
> +	res = readl_poll_timeout(rc + CORE_LANE_CFG(idx), stat,
> +				 stat & CORE_LANE_CFG_REFCLK1, 100, 50000);
> +
> +	if (res < 0)
> +		return res;
> +
> +	rmwl(CORE_LANE_CTL_CFGACC, 0, rc + CORE_LANE_CTL(idx));
> +	udelay(1);
> +	rmwl(0, CORE_LANE_CFG_REFCLKEN, rc + CORE_LANE_CFG(idx));
> +
> +	rmwl(0, PORT_REFCLK_EN, port + PORT_REFCLK);
> +
> +	return 0;
> +}
> +
> +static int apple_pcie_setup_port(struct apple_pcie *pcie, unsigned int i)
> +{
> +	struct fwnode_handle *fwnode = dev_fwnode(pcie->dev);
> +	void __iomem *port;
> +	struct gpio_desc *reset;
> +	uint32_t stat;
> +	int ret;
> +
> +	port = devm_of_iomap(pcie->dev, to_of_node(fwnode), i + 3, NULL);
> +
> +	if (IS_ERR(port))
> +		return -ENODEV;
> +
> +	reset = devm_gpiod_get_index(pcie->dev, "reset", i, 0);
> +	if (IS_ERR(reset))
> +		return PTR_ERR(reset);
> +
> +	gpiod_direction_output(reset, 0);
> +
> +	rmwl(0, PORT_APPCLK_EN, port + PORT_APPCLK);
> +
> +	ret = apple_pcie_setup_refclk(pcie->rc, port, i);
> +	if (ret < 0)
> +		return ret;
> +
> +	rmwl(0, PORT_PERST_OFF, port + PORT_PERST);
> +	gpiod_set_value(reset, 1);
> +
> +	ret = readl_poll_timeout(port + PORT_STATUS, stat,
> +				 stat & PORT_STATUS_READY, 100, 250000);
> +	if (ret < 0) {
> +		dev_err(pcie->dev, "port %u ready wait timeout\n", i);
> +		return ret;
> +	}
> +
> +	rmwl(PORT_REFCLK_CGDIS, 0, port + PORT_REFCLK);
> +	rmwl(PORT_APPCLK_CGDIS, 0, port + PORT_APPCLK);
> +
> +	ret = readl_poll_timeout(port + PORT_LINKSTS, stat,
> +				 !(stat & PORT_LINKSTS_BUSY), 100, 250000);
> +	if (ret < 0) {
> +		dev_err(pcie->dev, "port %u link not busy timeout\n", i);
> +		return ret;
> +	}
> +
> +	writel(0xfb512fff, port + PORT_INTMSKSET);

Magic. What is this for?

> +
> +	writel(PORT_INT_LINK_UP | PORT_INT_LINK_DOWN | PORT_INT_AF_TIMEOUT |
> +	       PORT_INT_REQADDR_GT32 | PORT_INT_MSI_ERR |
> +	       PORT_INT_MSI_BAD_DATA | PORT_INT_CPL_ABORT |
> +	       PORT_INT_CPL_TIMEOUT | (1 << 26), port + PORT_INTSTAT);
> +
> +	usleep_range(5000, 10000);
> +
> +	rmwl(0, PORT_LTSSMCTL_START, port + PORT_LTSSMCTL);
> +
> +	ret = readl_poll_timeout(port + PORT_LINKSTS, stat,
> +				 stat & PORT_LINKSTS_UP, 100, 500000);
> +	if (ret < 0) {
> +		dev_err(pcie->dev, "port %u link up wait timeout\n", i);
> +		return ret;
> +	}

I have the strong feeling that a lot of things in the above is to get
an interrupt when the port reports an event. Why the polling then?

> +
> +	writel(DOORBELL_ADDR, port + PORT_MSIADDR);
> +	writel(0, port + PORT_MSIBASE);

So here you go, the MSI doorbell *is* configurable. Should it be
placed somewhere else? Shouldn't it be configured before the link is
up?

> +	writel((5 << PORT_MSICFG_L2MSINUM_SHIFT) | PORT_MSICFG_EN,
> +	       port + PORT_MSICFG);

Ah, that one actually makes sense (enables 32 MSIs for the port).

> +
> +	return 0;
> +}
> +
> +static int apple_msi_init(struct apple_pcie *pcie)
> +{
> +	struct fwnode_handle *fwnode = dev_fwnode(pcie->dev);
> +	struct device_node *parent_intc;
> +	struct irq_domain *parent;
> +	int ret, i;
> +
> +	pcie->rc = devm_of_iomap(pcie->dev, to_of_node(fwnode), 1, NULL);
> +
> +	if (IS_ERR(pcie->rc))
> +		return -ENODEV;
> +
> +	for (i = 0; i < APPLE_PCIE_NUM_PORTS; ++i) {
> +		/* Bringing up the radios requires SMC. Skip for now. */
> +		if (i == APPLE_PCIE_PORT_RADIO)
> +			continue;

Why? Shouldn't this be moved into the driver for the endpoint, rather
than hardcoding something here which is likely to change from one
system to another? If establishing the link actually requires talking
to another part of the system, then it should be described in DT.

> +
> +		ret = apple_pcie_setup_port(pcie, i);
> +
> +		if (ret) {
> +			dev_err(pcie->dev, "Port %u setup fail: %d\n", i, ret);
> +			return ret;
> +		}
> +	}
> +
> +	ret = of_property_read_u32_index(to_of_node(fwnode), "msi-interrupts",
> +					 0, &pcie->msi_base);
> +	if (ret)
> +		return ret;
> +
> +	ret = of_property_read_u32_index(to_of_node(fwnode), "msi-interrupts",
> +					 1, &pcie->nvecs);
> +	if (ret)
> +		return ret;
> +
> +	pcie->bitmap = devm_kcalloc(pcie->dev, BITS_TO_LONGS(pcie->nvecs),
> +				    sizeof(long), GFP_KERNEL);
> +	if (!pcie->bitmap)
> +		return -ENOMEM;
> +
> +	parent_intc = of_irq_find_parent(to_of_node(fwnode));
> +	parent = irq_find_host(parent_intc);
> +	if (!parent_intc || !parent) {
> +		dev_err(pcie->dev, "failed to find parent domain\n");
> +		return -ENXIO;
> +	}
> +
> +	parent = irq_domain_create_hierarchy(parent, 0, pcie->nvecs, fwnode,
> +					     &apple_msi_domain_ops, pcie);
> +	if (!parent) {
> +		dev_err(pcie->dev, "failed to create IRQ domain\n");
> +		return -ENOMEM;
> +	}
> +	irq_domain_update_bus_token(parent, DOMAIN_BUS_NEXUS);
> +
> +	pcie->domain = pci_msi_create_irq_domain(fwnode, &apple_msi_info,
> +						 parent);
> +	if (!pcie->domain) {
> +		dev_err(pcie->dev, "failed to create MSI domain\n");
> +		irq_domain_remove(parent);
> +		return -ENOMEM;
> +	}
> +
> +	return 0;
> +}
> +
> +static int apple_m1_pci_init(struct pci_config_window *cfg)
> +{
> +	struct device *dev = cfg->parent;
> +	struct apple_pcie *pcie;
> +
> +	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> +	if (!pcie)
> +		return -ENOMEM;
> +
> +	pcie->dev = dev;
> +
> +	mutex_init(&pcie->lock);
> +
> +	return apple_msi_init(pcie);
> +}
> +
> +static const struct pci_ecam_ops apple_m1_cfg_ecam_ops = {
> +	.init		= apple_m1_pci_init,
> +	.pci_ops	= {
> +		.map_bus	= pci_ecam_map_bus,
> +		.read		= pci_generic_config_read,
> +		.write		= pci_generic_config_write,
> +	}
> +};
> +
> +static const struct of_device_id apple_pci_of_match[] = {
> +	{ .compatible = "apple,pcie", .data = &apple_m1_cfg_ecam_ops },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, gen_pci_of_match);
> +
> +static struct platform_driver apple_pci_driver = {
> +	.driver = {
> +		.name = "pcie-apple",
> +		.of_match_table = apple_pci_of_match,
> +	},
> +	.probe = pci_host_common_probe,
> +	.remove = pci_host_common_remove,
> +};
> +module_platform_driver(apple_pci_driver);
> +
> +MODULE_LICENSE("GPL v2");

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.