Re: [PATCH v5 2/3] PCI: mobiveil: Add Mobiveil PCIe Host Bridge IP driver

[Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>]

On Wed, Dec 13, 2017 at 11:08:37AM -0500, Subrahmanya Lingappa wrote:
> Adds driver for Mobiveil AXI PCIe Host Bridge Soft IP -
> GPEX 4.0, a PCIe gen4 IP. This IP has upto 8
> outbound and inbound windows for the address translation.
> 
> Signed-off-by: Subrahmanya Lingappa <l.subrahmanya-DTHOJn6Rh8lhmhkoCovsdw@public.gmane.org>
> Cc: Bjorn Helgaas <bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
> Cc: Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>
> Cc: linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> ---
>  drivers/pci/host/Kconfig         |   8 +
>  drivers/pci/host/Makefile        |   1 +
>  drivers/pci/host/pcie-mobiveil.c | 653 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 662 insertions(+)
>  create mode 100644 drivers/pci/host/pcie-mobiveil.c
> 
> diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
> index 38d1298..09bf1d9 100644
> --- a/drivers/pci/host/Kconfig
> +++ b/drivers/pci/host/Kconfig
> @@ -27,6 +27,14 @@ config PCIE_XILINX_NWL
>  	 or End Point. The current option selection will only
>  	 support root port enabling.
>  
> +config PCIE_MOBIVEIL
> +        bool "Mobiveil AXI PCIe host bridge support"
> +        depends on ARCH_ZYNQMP || COMPILE_TEST
> +        depends on PCI_MSI_IRQ_DOMAIN

There is no PCI_MSI_IRQ_DOMAIN dependency in this patch.

> +        help
> +          Say 'Y' here if you want kernel to support the Mobiveil AXI PCIe
> +          Host Bridge driver.
> +
>  config PCI_FTPCI100
>  	bool "Faraday Technology FTPCI100 PCI controller"
>  	depends on OF
> diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
> index 34ec1d8..d745d68 100644
> --- a/drivers/pci/host/Makefile
> +++ b/drivers/pci/host/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_PCIE_ROCKCHIP) += pcie-rockchip.o
>  obj-$(CONFIG_PCIE_MEDIATEK) += pcie-mediatek.o
>  obj-$(CONFIG_PCIE_TANGO_SMP8759) += pcie-tango.o
>  obj-$(CONFIG_VMD) += vmd.o
> +obj-$(CONFIG_PCIE_MOBIVEIL) += pcie-mobiveil.o
>  
>  # The following drivers are for devices that use the generic ACPI
>  # pci_root.c driver but don't support standard ECAM config access.
> diff --git a/drivers/pci/host/pcie-mobiveil.c b/drivers/pci/host/pcie-mobiveil.c
> new file mode 100644
> index 0000000..8611aaa
> --- /dev/null
> +++ b/drivers/pci/host/pcie-mobiveil.c
> @@ -0,0 +1,653 @@
> +/*
> + * PCIe host controller driver for Mobiveil PCIe Host controller
> + *
> + * SPDX-License-Identifier: GPL-2.0
> + * Copyright (c) 2017 Mobiveil Inc.
> + * Author: Subrahmanya Lingappa <l.subrahmanya-DTHOJn6Rh8lhmhkoCovsdw@public.gmane.org>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/init.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_pci.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +/* register offsets and bit positions */
> +
> +/*
> + * translation tables are grouped into windows, each window registers are
> + * grouped into blocks of 4 or 16 registers each
> + */
> +#define PAB_REG_BLOCK_SIZE_4	4
> +#define PAB_REG_BLOCK_SIZE_16	16

What I wanted to say is that you can tag the block with a name
instead of using a number.

I can say that block size 4 is only for PAB_EXT_*, you can tag
it as such.

eg PAB_EXT_REG_BLOCK_SIZE

> +#define PAB_REG_ADDR_4(offset, win) (offset + (win * PAB_REG_BLOCK_SIZE_4))
> +#define PAB_REG_ADDR_16(offset, win) (offset + (win * PAB_REG_BLOCK_SIZE_16))
> +
> +#define LTSSM_STATUS		0x0404
> +#define  LTSSM_STATUS_L0_MASK	0x3f
> +#define  LTSSM_STATUS_L0	0x2d
> +
> +#define PAB_CTRL		0x0808
> +#define  AMBA_PIO_ENABLE_SHIFT	0
> +#define  PEX_PIO_ENABLE_SHIFT	1
> +#define  PAGE_SEL_SHIFT		13
> +#define  PAGE_SEL_MASK		0x3f
> +#define  PAGE_LO_MASK		0x3ff
> +#define  PAGE_SEL_EN		0xc00
> +#define  PAGE_SEL_OFFSET_SHIFT	10
> +
> +#define PAB_AXI_PIO_CTRL	0x0840
> +#define  APIO_EN_MASK		0xf
> +
> +#define PAB_PEX_PIO_CTRL	0x08c0
> +#define  PIO_ENABLE_SHIFT	0
> +
> +#define PAB_INTP_AMBA_MISC_ENB	0x0b0c
> +#define PAB_INTP_AMBA_MISC_STAT	0x0b1c
> +#define  PAB_INTP_INTX_MASK	0x1e0
> +
> +#define PAB_AXI_AMAP_CTRL(win)	PAB_REG_ADDR_16(0x0ba0, win)
> +#define  WIN_ENABLE_SHIFT	0
> +#define  WIN_TYPE_SHIFT		1
> +#define  WIN_SIZE_SHIFT		10
> +
> +#define PAB_EXT_AXI_AMAP_SIZE(win)	PAB_REG_ADDR_4(0xbaf0, win)
> +
> +#define PAB_AXI_AMAP_AXI_WIN(win)	PAB_REG_ADDR_16(0x0ba4, win)
> +#define  AXI_WINDOW_BASE_SHIFT		2
> +
> +#define PAB_AXI_AMAP_PEX_WIN_L(win)	PAB_REG_ADDR_16(0x0ba8, win)
> +#define  PAB_BUS_SHIFT			24
> +#define  PAB_DEVICE_SHIFT		19
> +#define  PAB_FUNCTION_SHIFT		16
> +
> +#define PAB_AXI_AMAP_PEX_WIN_H(win)	PAB_REG_ADDR_16(0x0bac, win)
> +#define PAB_INTP_AXI_PIO_CLASS		0x474

This one is a bit odd here, move it up in the file.

> +#define PAB_PEX_AMAP_CTRL(win)		PAB_REG_ADDR_16(0x4ba0, win)
> +#define  AMAP_CTRL_EN_SHIFT		0
> +#define  AMAP_CTRL_TYPE_SHIFT		1
> +
> +#define PAB_EXT_PEX_AMAP_SIZEN(win)	PAB_REG_ADDR_4(0xbef0, win)
> +#define PAB_PEX_AMAP_AXI_WIN(win)	PAB_REG_ADDR_16(0x4ba4, win)
> +#define PAB_PEX_AMAP_PEX_WIN_L(win)	PAB_REG_ADDR_16(0x4ba8, win)
> +#define PAB_PEX_AMAP_PEX_WIN_H(win)	PAB_REG_ADDR_16(0x4bac, win)

Here you have three base offsets:

0xb00
0x4000
0xb000

you can create a macro for each of them, according to what they
represent and then add an offset into each.

> +
> +/* supported number of interrupts */
> +#define PCI_NUM_INTX		4

It is already defined in linux/pci.h

> +#define PAB_INTA_POS		5
> +
> +/* outbound and inbound window definitions */
> +#define WIN_NUM_0		0
> +#define WIN_NUM_1		1
> +#define CFG_WINDOW_TYPE		0
> +#define IO_WINDOW_TYPE		1
> +#define MEM_WINDOW_TYPE		2
> +#define IB_WIN_SIZE		(256 * 1024 * 1024)
> +#define MAX_PIO_WINDOWS		8
> +
> +/* Parameters for the waiting for link up routine */
> +#define LINK_WAIT_MAX_RETRIES	10
> +#define LINK_WAIT_MIN		90000
> +#define LINK_WAIT_MAX		100000
> +
> +#ifndef UINT64_MAX
> +#define UINT64_MAX		(u64)(~((u64)0))
> +#endif
> +
> +struct mobiveil_pcie {
> +	struct platform_device *pdev;
> +	struct list_head resources;
> +	void __iomem *config_axi_slave_base;	/* endpoint config base */
> +	void __iomem *csr_axi_slave_base;	/* root port config base */
> +	struct irq_domain *intx_domain;
> +	int irq;
> +	int apio_wins;
> +	int ppio_wins;
> +	int ob_wins_configured;	/*  configured outbound windows */
> +	int ib_wins_configured;	/*  configured inbound windows */
> +	struct resource *ob_io_res;
> +	char root_bus_nr;
> +};
> +
> +static inline void csr_writel(struct mobiveil_pcie *pcie, const u32 value,
> +		const u32 reg)
> +{
> +	writel_relaxed(value, pcie->csr_axi_slave_base + reg);
> +}
> +
> +static inline u32 csr_readl(struct mobiveil_pcie *pcie,	const u32 reg)
> +{
> +	return readl_relaxed(pcie->csr_axi_slave_base + reg);
> +}
> +
> +static bool mobiveil_pcie_link_up(struct mobiveil_pcie *pcie)
> +{
> +	return (csr_readl(pcie, LTSSM_STATUS) &
> +		LTSSM_STATUS_L0_MASK) == LTSSM_STATUS_L0;
> +}

https://marc.info/?l=linux-pci&m=151329230814614&w=2

Bjorn would like to remove it.

> +static bool mobiveil_pcie_valid_device(struct pci_bus *bus, unsigned int devfn)
> +{
> +	struct mobiveil_pcie *pcie = bus->sysdata;
> +
> +	/* Check if link is up when trying to access downstream ports */
> +	if (bus->number != pcie->root_bus_nr)
> +		if (!mobiveil_pcie_link_up(pcie))
> +			return false;
> +
> +	/* Only one device down on each root port */
> +	if ((bus->number == pcie->root_bus_nr) && (devfn > 0))
> +		return false;
> +
> +	/*
> +	 * Do not read more than one device on the bus directly
> +	 * attached to RC
> +	 */
> +	if ((bus->primary == pcie->root_bus_nr) && (devfn > 0))
> +		return false;
> +
> +	return true;
> +}
> +
> +/*
> + * mobiveil_pcie_map_bus - routine to get the configuration base of either
> + * root port or endpoint
> + */
> +static void __iomem *mobiveil_pcie_map_bus(struct pci_bus *bus,
> +					unsigned int devfn, int where)
> +{
> +	struct mobiveil_pcie *pcie = bus->sysdata;
> +
> +	if (!mobiveil_pcie_valid_device(bus, devfn))
> +		return NULL;
> +
> +	if (bus->number == pcie->root_bus_nr) {
> +		/* RC config access */
> +		return pcie->csr_axi_slave_base + where;
> +	} else {
> +		/*
> +		 * EP config access (in Config/APIO space)
> +		 * Program PEX Address base (31..16 bits) with appropriate value
> +		 * (BDF) in PAB_AXI_AMAP_PEX_WIN_L0 Register.
> +		 * Relies on pci_lock serialization
> +		 */
> +		csr_writel(pcie,
> +			bus->number << PAB_BUS_SHIFT |
> +			PCI_SLOT(devfn) << PAB_DEVICE_SHIFT |
> +			PCI_FUNC(devfn) << PAB_FUNCTION_SHIFT,
> +			PAB_AXI_AMAP_PEX_WIN_L(WIN_NUM_0));
> +		return pcie->config_axi_slave_base + where;
> +	}
> +}
> +
> +static struct pci_ops mobiveil_pcie_ops = {
> +	.map_bus = mobiveil_pcie_map_bus,
> +	.read = pci_generic_config_read,
> +	.write = pci_generic_config_write,
> +};
> +
> +static void mobiveil_pcie_isr(struct irq_desc *desc)
> +{
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct mobiveil_pcie *pcie = irq_desc_get_handler_data(desc);
> +	struct device *dev = &pcie->pdev->dev;
> +	u32 intr_status;
> +	unsigned long shifted_status;

Why not u32 ?

> +	u32 bit, virq;
> +	u32 val, mask;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	/* read INTx status */
> +	val = csr_readl(pcie, PAB_INTP_AMBA_MISC_STAT);
> +	mask = csr_readl(pcie, PAB_INTP_AMBA_MISC_ENB);
> +	intr_status = val & mask;
> +
> +	/* Handle INTx */
> +	if (intr_status & PAB_INTP_INTX_MASK) {
> +		shifted_status = csr_readl(pcie, PAB_INTP_AMBA_MISC_STAT);

Why can't you reuse val to read the status and create shifted_status
from it ?

eg

shifted_status = val << PAB_INTA_POS;
csr_writel(pcie, shifted_status, PAB_INTP_AMBA_MISC_STAT);

Just a hint to make the loop more readable. BTW, I do not think that
writing shifted_status into that register is OK, see below.

> +		do {
> +			for_each_set_bit(bit, &shifted_status, PCI_NUM_INTX) {
> +
> +				/* clear interrupts */
> +				csr_writel(pcie, shifted_status << PAB_INTA_POS,
> +						PAB_INTP_AMBA_MISC_STAT);

Should not you clear just the interrupt you are about to handle ?

> +				virq = irq_find_mapping(pcie->intx_domain,
> +					bit + 1);
> +				if (virq)
> +					generic_handle_irq(virq);
> +				else
> +					dev_err_ratelimited(dev,
> +						"unexpected IRQ, INT%d\n",
> +						bit);
> +
> +			}
> +
> +			shifted_status = csr_readl(pcie,
> +						PAB_INTP_AMBA_MISC_STAT);
> +
> +		} while ((shifted_status >>  PAB_INTA_POS) != 0);

I do not understand this. Can you explain to me how the
register at:

PAB_INTP_AMBA_MISC_STAT

works ?

A patch for mediatek has been posted:

https://patchwork.ozlabs.org/patch/851181/

It looks like this loop may suffer from the same issue, so please do
have a look.

On top of that, most of the operations you are carrying out here
can be done automatically by making them part of the struct irq_chip
methods (ie acking IRQs, masking IRQs, etc, see below).

> +	}
> +
> +	csr_writel(pcie, intr_status, PAB_INTP_AMBA_MISC_STAT);

> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int mobiveil_pcie_parse_dt(struct mobiveil_pcie *pcie)
> +{
> +	struct device *dev = &pcie->pdev->dev;
> +	struct platform_device *pdev = pcie->pdev;
> +	struct device_node *node = dev->of_node;
> +	struct resource *res;
> +	const char *type;
> +
> +	type = of_get_property(node, "device_type", NULL);
> +	if (!type || strcmp(type, "pci")) {
> +		dev_err(dev, "invalid \"device_type\" %s\n", type);
> +		return -EINVAL;
> +	}
> +
> +	/* map config resource */
> +	res = platform_get_resource_byname(pdev,
> +		IORESOURCE_MEM, "config_axi_slave");
> +	pcie->config_axi_slave_base = devm_pci_remap_cfg_resource(dev, res);
> +	if (IS_ERR(pcie->config_axi_slave_base))
> +		return PTR_ERR(pcie->config_axi_slave_base);
> +	pcie->ob_io_res = res;
> +
> +	/* map csr resource */
> +	res = platform_get_resource_byname(pdev,
> +		IORESOURCE_MEM, "csr_axi_slave");
> +	pcie->csr_axi_slave_base = devm_pci_remap_cfg_resource(dev, res);
> +	if (IS_ERR(pcie->csr_axi_slave_base))
> +		return PTR_ERR(pcie->csr_axi_slave_base);
> +
> +	/* read the number of windows requested */
> +	if (!pcie->apio_wins &&
> +		of_property_read_u32(node, "apio-wins", &pcie->apio_wins)) {
> +		pcie->apio_wins = MAX_PIO_WINDOWS;
> +	}
> +
> +	if (!pcie->ppio_wins &&

What I wanted to say in my previous review is that apio_wins and
ppio_wins are zero here why would they be any different and why
do you need to check that.

> +		of_property_read_u32(node, "ppio-wins", &pcie->ppio_wins)) {
> +		pcie->ppio_wins = MAX_PIO_WINDOWS;
> +	}
> +
> +	pcie->irq = platform_get_irq(pdev, 0);
> +	if (pcie->irq <= 0) {
> +		dev_err(dev, "failed to map IRQ: %d\n", pcie->irq);
> +		return -ENODEV;
> +	}
> +
> +	irq_set_chained_handler_and_data(pcie->irq, mobiveil_pcie_isr, pcie);
> +
> +	return 0;
> +}
> +
> +/*
> + * select_paged_register - routine to access paged register of root complex
> + *
> + * registers of RC are paged, for this scheme to work
> + * extracted higher 6 bits of the offset will be written to pg_sel
> + * field of PAB_CTRL register and rest of the lower 10 bits enabled with
> + * PAGE_SEL_EN are used as offset of the register.
> + *
> + */
> +static void select_paged_register(struct mobiveil_pcie *pcie, u32 offset)
> +{
> +	int pab_ctrl_dw, pg_sel;
> +
> +	/* clear pg_sel field */
> +	pab_ctrl_dw = csr_readl(pcie, PAB_CTRL);
> +	pab_ctrl_dw = (pab_ctrl_dw & ~(PAGE_SEL_MASK << PAGE_SEL_SHIFT));
> +
> +	/* set pg_sel field */
> +	pg_sel = (offset >> PAGE_SEL_OFFSET_SHIFT) & PAGE_SEL_MASK;
> +	pab_ctrl_dw |= ((pg_sel << PAGE_SEL_SHIFT));
> +	csr_writel(pcie, pab_ctrl_dw, PAB_CTRL);
> +}
> +
> +static void write_paged_register(struct mobiveil_pcie *pcie,
> +		u32 val, u32 offset)
> +{
> +	u32 off = (offset & PAGE_LO_MASK) | PAGE_SEL_EN;
> +
> +	select_paged_register(pcie, offset);
> +	csr_writel(pcie, val, off);
> +}
> +
> +static u32 read_paged_register(struct mobiveil_pcie *pcie, u32 offset)
> +{
> +	u32 off = (offset & PAGE_LO_MASK) | PAGE_SEL_EN;
> +
> +	select_paged_register(pcie, offset);
> +	return csr_readl(pcie, off);
> +}
> +
> +static void program_ib_windows(struct mobiveil_pcie *pcie, int win_num,
> +		int pci_addr, int type,	int size_kb)
> +{
> +	int pio_ctrl_val;
> +	int amap_ctrl_dw;
> +	u64 size64 = (UINT64_MAX << (WIN_SIZE_SHIFT + ilog2(size_kb)));
> +
> +	if ((pcie->ib_wins_configured + 1) > pcie->ppio_wins) {
> +		dev_err(&pcie->pdev->dev,
> +			"ERROR: max inbound windows reached !\n");
> +		return;
> +	}
> +
> +	pio_ctrl_val = csr_readl(pcie, PAB_PEX_PIO_CTRL);
> +	csr_writel(pcie,
> +		pio_ctrl_val | (1 << PIO_ENABLE_SHIFT), PAB_PEX_PIO_CTRL);
> +	amap_ctrl_dw =	read_paged_register(pcie, PAB_PEX_AMAP_CTRL(win_num));
> +	amap_ctrl_dw = (amap_ctrl_dw | (type << AMAP_CTRL_TYPE_SHIFT));
> +	amap_ctrl_dw = (amap_ctrl_dw | (1 << AMAP_CTRL_EN_SHIFT));
> +
> +	write_paged_register(pcie, amap_ctrl_dw | lower_32_bits(size64),
> +				PAB_PEX_AMAP_CTRL(win_num));
> +
> +	write_paged_register(pcie, upper_32_bits(size64),
> +				PAB_EXT_PEX_AMAP_SIZEN(win_num));
> +
> +	write_paged_register(pcie, pci_addr, PAB_PEX_AMAP_AXI_WIN(win_num));
> +	write_paged_register(pcie, pci_addr, PAB_PEX_AMAP_PEX_WIN_L(win_num));
> +	write_paged_register(pcie, 0, PAB_PEX_AMAP_PEX_WIN_H(win_num));
> +}
> +
> +static void program_ob_windows(struct mobiveil_pcie *pcie, int win_num,
> +		u64 cpu_addr, u64 pci_addr, int config_io_bit,
> +		int size_kb)
> +{
> +
> +	u32 value, type;
> +	u64 size64 = (UINT64_MAX << (WIN_SIZE_SHIFT + ilog2(size_kb)));

Can you explain to me the sizing mechanism please ? It is just to make
sure I got it right.

> +	if ((pcie->ob_wins_configured + 1) > pcie->apio_wins) {
> +		dev_err(&pcie->pdev->dev,
> +			"ERROR: max outbound windows reached !\n");
> +		return;
> +	}
> +
> +	/*
> +	 * program Enable Bit to 1, Type Bit to (00) base 2, AXI Window Size Bit
> +	 * to 4 KB in PAB_AXI_AMAP_CTRL register
> +	 */
> +	type = config_io_bit;
> +	value = csr_readl(pcie, PAB_AXI_AMAP_CTRL(win_num));
> +	csr_writel(pcie,
> +			1 << WIN_ENABLE_SHIFT |
> +			type << WIN_TYPE_SHIFT |
> +			lower_32_bits(size64),
> +			PAB_AXI_AMAP_CTRL(win_num));
> +
> +	write_paged_register(pcie, upper_32_bits(size64),
> +				PAB_EXT_AXI_AMAP_SIZE(win_num));
> +
> +	/*
> +	 * program AXI window base with appropriate value in
> +	 * PAB_AXI_AMAP_AXI_WIN0 register
> +	 */
> +	value = csr_readl(pcie, PAB_AXI_AMAP_AXI_WIN(win_num));
> +	csr_writel(pcie,
> +			cpu_addr >> AXI_WINDOW_BASE_SHIFT <<
> +			AXI_WINDOW_BASE_SHIFT, PAB_AXI_AMAP_AXI_WIN(win_num));
> +
> +	value = csr_readl(pcie, PAB_AXI_AMAP_PEX_WIN_H(win_num));

What's "value" used for in this function ?

> +	csr_writel(pcie, lower_32_bits(pci_addr),
> +			PAB_AXI_AMAP_PEX_WIN_L(win_num));
> +	csr_writel(pcie, upper_32_bits(pci_addr),
> +			PAB_AXI_AMAP_PEX_WIN_H(win_num));
> +
> +	pcie->ob_wins_configured++;
> +}
> +
> +static int mobiveil_bringup_link(struct mobiveil_pcie *pcie)
> +{
> +	int retries;
> +
> +	/* check if the link is up or not */
> +	for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
> +		if (mobiveil_pcie_link_up(pcie))
> +			return 0;
> +
> +		usleep_range(LINK_WAIT_MIN, LINK_WAIT_MAX);
> +	}
> +	dev_err(&pcie->pdev->dev, "link never came up\n");
> +	return -ETIMEDOUT;
> +}
> +
> +static int mobiveil_host_init(struct mobiveil_pcie *pcie)
> +{
> +	u32 value;
> +	int type = 0;

You reinitialize it later and it should not be an int but an unsigned
type.

> +	u32 pab_ctrl;
> +	int err;
> +	struct resource_entry *win, *tmp;
> +
> +	/* setup the PCIe slot link power*/

Comment is useless, remove it.

> +	err = mobiveil_bringup_link(pcie);
> +	if (err) {
> +		dev_info(&pcie->pdev->dev, "link bring-up failed\n");
> +		return err;
> +	}
> +
> +	/*
> +	 * program Bus Master Enable Bit in Command Register in PAB Config
> +	 * Space
> +	 */
> +	value = csr_readl(pcie, PCI_COMMAND);
> +	csr_writel(pcie,
> +		value |

Why is this on a separate line ?

> +		PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER,
> +		PCI_COMMAND);
> +
> +	/*
> +	 * program PIO Enable Bit to 1 (and PEX PIO Enable to 1) in PAB_CTRL
> +	 * register
> +	 */
> +	pab_ctrl = csr_readl(pcie, PAB_CTRL);
> +	csr_writel(pcie, pab_ctrl | (1 << AMBA_PIO_ENABLE_SHIFT) |
> +		(1 << PEX_PIO_ENABLE_SHIFT),
> +		PAB_CTRL);
> +
> +	csr_writel(pcie, PAB_INTP_INTX_MASK, PAB_INTP_AMBA_MISC_ENB);
> +
> +	/* program PIO Enable Bit to 1 and Config Window Enable Bit to 1 in
> +	 * PAB_AXI_PIO_CTRL Register
> +	 */
> +	value = csr_readl(pcie, PAB_AXI_PIO_CTRL);
> +	csr_writel(pcie, value | APIO_EN_MASK, PAB_AXI_PIO_CTRL);
> +
> +	/*
> +	 * we'll program one outbound window for config reads and
> +	 * another default inbound window for all the upstream traffic
> +	 * rest of the outbound windows will be configured according to
> +	 * the "ranges" field defined in device tree
> +	 */
> +
> +	/* config outbound translation window */
> +	program_ob_windows(pcie, pcie->ob_wins_configured,
> +			pcie->ob_io_res->start,	0, CFG_WINDOW_TYPE,
> +			resource_size(pcie->ob_io_res)/1024);
> +
> +	/* memory inbound  translation window */
> +	program_ib_windows(pcie, WIN_NUM_1, 0, MEM_WINDOW_TYPE, IB_WIN_SIZE);
> +
> +	/* Get the I/O and memory ranges from DT */
> +	resource_list_for_each_entry_safe(win, tmp, &pcie->resources) {
> +		type = 0;
> +		if (resource_type(win->res) == IORESOURCE_MEM)
> +			type = MEM_WINDOW_TYPE;
> +		if (resource_type(win->res) == IORESOURCE_IO)
> +			type = IO_WINDOW_TYPE;
> +		if (type) {
> +			/* configure outbound translation window */
> +			program_ob_windows(pcie, pcie->ob_wins_configured,
> +				win->res->start, 0, type,
> +				resource_size(win->res)/1024);
> +		}
> +	}
> +
> +	return err;
> +}
> +
> +/* routine to setup the INTx related data */
> +static int mobiveil_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
> +		irq_hw_number_t hwirq)
> +{
> +	irq_set_chip_and_handler(irq, &dummy_irq_chip, handle_simple_irq);

IIUC, the host bridge acts as an INTX/MSI controller/multiplexer.

So, instead of relying on dummy_irq_chip, you should create your own
irq_chip with the methods that you require (eg irq_ack(), irq_mask(),
irq_compose_msi_msg()) and use that as bottom irq_chip for both
INTX and MSI domains.

That's why I asked you to have a look at pcie-tango.c (except that there
INTX aren't supported but the basic idea does not change) and implement
IRQ domains handling like that same driver.

> +	irq_set_chip_data(irq, domain->host_data);
> +	return 0;
> +}
> +
> +/* INTx domain opeartions structure */

s/opeartions/operations

> +static const struct irq_domain_ops intx_domain_ops = {
> +	.map = mobiveil_pcie_intx_map,
> +};
> +
> +static int mobiveil_pcie_init_irq_domain(struct mobiveil_pcie *pcie)
> +{
> +	struct device *dev = &pcie->pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	int ret;

ret is unused

> +	/* setup INTx */
> +	pcie->intx_domain = irq_domain_add_linear(node,
> +				PCI_NUM_INTX + 1, &intx_domain_ops, pcie);

You should use PCI_NUM_INTX and add pci_irqd_intx_xlate() as the
domain ops .xlate.

> +	if (!pcie->intx_domain) {
> +		dev_err(dev, "Failed to get a INTx IRQ domain\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int mobiveil_pcie_probe(struct platform_device *pdev)
> +{
> +	struct mobiveil_pcie *pcie;
> +	struct pci_bus *bus;
> +	struct pci_bus *child;
> +	struct pci_host_bridge *bridge;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	resource_size_t iobase;
> +	int ret;
> +
> +	/* allocate the PCIe port */
> +	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
> +	if (!bridge)
> +		return -ENODEV;
> +
> +	pcie = pci_host_bridge_priv(bridge);
> +	if (!pcie)
> +		return -ENOMEM;
> +
> +	pcie->pdev = pdev;
> +
> +	/* parse the device tree */

Remove this comment, it does not add anything.

> +	ret = mobiveil_pcie_parse_dt(pcie);
> +	if (ret) {
> +		dev_err(dev, "Parsing DT failed, ret: %x\n", ret);
> +		return ret;
> +	}
> +
> +	INIT_LIST_HEAD(&pcie->resources);
> +
> +	/* parse the host bridge base addresses from the device tree file */
> +	ret = of_pci_get_host_bridge_resources(node,
> +			0, 0xff, &pcie->resources, &iobase);
> +	if (ret) {
> +		dev_err(dev, "Getting bridge resources failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	/*
> +	 * configure all inbound and outbound windows and prepare the RC for
> +	 * config access
> +	 */
> +	ret = mobiveil_host_init(pcie);
> +	if (ret) {
> +		dev_err(dev, "Failed to initialize host\n");
> +		goto error;
> +	}
> +
> +	/* fixup for PCIe class register */
> +	csr_writel(pcie, 0x060402ab, PAB_INTP_AXI_PIO_CLASS);
> +
> +	/* initialize the IRQ domains */
> +	ret = mobiveil_pcie_init_irq_domain(pcie);
> +	if (ret) {
> +		dev_err(dev, "Failed creating IRQ Domain\n");
> +		goto error;
> +	}
> +
> +

Two empty lines, should be one.

> +	ret = devm_request_pci_bus_resources(dev, &pcie->resources);
> +	if (ret)
> +		goto error;
> +
> +	/* Initialize bridge */
> +	list_splice_init(&pcie->resources, &bridge->windows);
> +	bridge->dev.parent = dev;
> +	bridge->sysdata = pcie;
> +	bridge->busnr = pcie->root_bus_nr;
> +	bridge->ops = &mobiveil_pcie_ops;
> +	bridge->map_irq = of_irq_parse_and_map_pci;
> +	bridge->swizzle_irq = pci_common_swizzle;
> +
> +	/* setup the kernel resources for the newly added PCIe root bus */
> +	ret = pci_scan_root_bus_bridge(bridge);
> +	if (ret)
> +		goto error;
> +
> +	bus = bridge->bus;
> +
> +	pci_assign_unassigned_bus_resources(bus);
> +	list_for_each_entry(child, &bus->children, node)
> +		pcie_bus_configure_settings(child);
> +	pci_bus_add_devices(bus);
> +
> +	platform_set_drvdata(pdev, pcie);

Is this really needed ?

Thanks,
Lorenzo

> +
> +	return 0;
> +error:
> +	pci_free_resource_list(&pcie->resources);
> +	return ret;
> +}
> +
> +static const struct of_device_id mobiveil_pcie_of_match[] = {
> +	{.compatible = "mbvl,gpex40-pcie",},
> +};
> +
> +MODULE_DEVICE_TABLE(of, mobiveil_pcie_of_match);
> +
> +static struct platform_driver mobiveil_pcie_driver = {
> +	.probe = mobiveil_pcie_probe,
> +	.driver = {
> +			.name = "mobiveil-pcie",
> +			.of_match_table = mobiveil_pcie_of_match,
> +			.suppress_bind_attrs = true,
> +		},
> +};
> +
> +builtin_platform_driver(mobiveil_pcie_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Mobiveil PCIe host controller driver");
> +MODULE_AUTHOR("Subrahmanya Lingappa <l.subrahmanya-DTHOJn6Rh8lhmhkoCovsdw@public.gmane.org>");
> -- 
> 1.8.3.1
> 
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