Re: [PATCH v7 2/4] PCI: X-Gene: Add the APM X-Gene v1 PCIe MSI/MSIX termination driver

From: Marc Zyngier
Date: Wed May 20 2015 - 05:16:59 EST

On Mon, 18 May 2015 10:55:19 +0100
Duc Dang <dhdang@xxxxxxx> wrote:

> APM X-Gene v1 SoC supports its own implementation of MSI, which is not compliant
> to GIC V2M specification for MSI Termination.
>
> There is single MSI block in X-Gene v1 SOC which serves all 5 PCIe ports. This MSI
> block supports 2048 MSI termination ports coalesced into 16 physical HW IRQ lines
> and shared across all 5 PCIe ports.
>
> As there are only 16 HW IRQs to serve 2048 MSI vectors, to support set_affinity
> correctly for each MSI vectors, the 16 HW IRQs are statically allocated to 8 X-Gene
> v1 cores (2 HW IRQs for each cores). To steer MSI interrupt to target CPU, MSI vector
> is moved around these HW IRQs lines. With this approach, the total MSI vectors this
> driver supports is reduced to 256.
>
> Signed-off-by: Duc Dang <dhdang@xxxxxxx>
> Signed-off-by: Tanmay Inamdar <tinamdar@xxxxxxx>
> ---
> drivers/pci/host/Kconfig | 10 +
> drivers/pci/host/Makefile | 1 +
> drivers/pci/host/pci-xgene-msi.c | 550 +++++++++++++++++++++++++++++++++++++++
> drivers/pci/host/pci-xgene.c | 21 ++
> 4 files changed, 582 insertions(+)
> create mode 100644 drivers/pci/host/pci-xgene-msi.c
>
> diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
> index 7b892a9..0932118 100644
> --- a/drivers/pci/host/Kconfig
> +++ b/drivers/pci/host/Kconfig
> @@ -89,11 +89,21 @@ config PCI_XGENE
> depends on ARCH_XGENE
> depends on OF
> select PCIEPORTBUS
> + select PCI_MSI_IRQ_DOMAIN if PCI_MSI
> + select PCI_XGENE_MSI if PCI_MSI
> help
> Say Y here if you want internal PCI support on APM X-Gene SoC.
> There are 5 internal PCIe ports available. Each port is GEN3 capable
> and have varied lanes from x1 to x8.
>
> +config PCI_XGENE_MSI
> + bool "X-Gene v1 PCIe MSI feature"
> + depends on PCI_XGENE && PCI_MSI
> + help
> + Say Y here if you want PCIE MSI support for APM X-Gene v1 SoC.
> + This MSI driver will provide MSI support for 5 PCIe ports of
> + APM X-Gene v1 SoC
> +
> config PCI_LAYERSCAPE
> bool "Freescale Layerscape PCIe controller"
> depends on OF && ARM
> diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
> index e61d91c..f39bde3 100644
> --- a/drivers/pci/host/Makefile
> +++ b/drivers/pci/host/Makefile
> @@ -11,5 +11,6 @@ obj-$(CONFIG_PCIE_SPEAR13XX) += pcie-spear13xx.o
> obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone-dw.o pci-keystone.o
> obj-$(CONFIG_PCIE_XILINX) += pcie-xilinx.o
> obj-$(CONFIG_PCI_XGENE) += pci-xgene.o
> +obj-$(CONFIG_PCI_XGENE_MSI) += pci-xgene-msi.o
> obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
> obj-$(CONFIG_PCI_VERSATILE) += pci-versatile.o
> diff --git a/drivers/pci/host/pci-xgene-msi.c b/drivers/pci/host/pci-xgene-msi.c
> new file mode 100644
> index 0000000..648bc8f
> --- /dev/null
> +++ b/drivers/pci/host/pci-xgene-msi.c
> @@ -0,0 +1,550 @@
> +/*
> + * APM X-Gene MSI Driver
> + *
> + * Copyright (c) 2014, Applied Micro Circuits Corporation
> + * Author: Tanmay Inamdar <tinamdar@xxxxxxx>
> + * Duc Dang <dhdang@xxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published by the
> + * Free Software Foundation; either version 2 of the License, or (at your
> + * option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/cpu.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/of_irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/of_pci.h>
> +
> +#define MSI_IR0 0x000000
> +#define MSI_INT0 0x800000
> +#define IDX_PER_GROUP 8
> +#define IRQS_PER_IDX 16
> +#define NR_HW_IRQS 16
> +#define NR_MSI_VEC (IDX_PER_GROUP * IRQS_PER_IDX * NR_HW_IRQS)
> +
> +struct xgene_msi_group {
> + struct xgene_msi *msi;
> + int gic_irq;
> + u32 msi_grp;
> +};
> +
> +struct xgene_msi {
> + struct device_node *node;
> + struct msi_controller mchip;
> + struct irq_domain *domain;
> + u64 msi_addr;
> + void __iomem *msi_regs;
> + unsigned long *bitmap;
> + struct mutex bitmap_lock;
> + struct xgene_msi_group *msi_groups;
> + int num_cpus;
> +};
> +
> +/* Global data */
> +static struct xgene_msi xgene_msi_ctrl;
> +
> +static struct irq_chip xgene_msi_top_irq_chip = {
> + .name = "X-Gene1 MSI",
> + .irq_enable = pci_msi_unmask_irq,
> + .irq_disable = pci_msi_mask_irq,
> + .irq_mask = pci_msi_mask_irq,
> + .irq_unmask = pci_msi_unmask_irq,
> +};
> +
> +static struct msi_domain_info xgene_msi_domain_info = {
> + .flags = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> + MSI_FLAG_PCI_MSIX),
> + .chip = &xgene_msi_top_irq_chip,
> +};
> +
> +/*
> + * X-Gene v1 has 16 groups of MSI termination registers MSInIRx, where
> + * n is group number (0..F), x is index of registers in each group (0..7)
> + * The registers layout is like following:
> + * MSI0IR0 base_addr
> + * MSI0IR1 base_addr + 0x10000
> + * ... ...
> + * MSI0IR6 base_addr + 0x60000
> + * MSI0IR7 base_addr + 0x70000
> + * MSI1IR0 base_addr + 0x80000
> + * MSI1IR1 base_addr + 0x90000
> + * ... ...
> + * MSI1IR7 base_addr + 0xF0000
> + * MSI2IR0 base_addr + 0x100000
> + * ... ...
> + * MSIFIR0 base_addr + 0x780000
> + * MSIFIR1 base_addr + 0x790000
> + * ... ...
> + * MSIFIR7 base_addr + 0x7F0000
> + *
> + * Each index register support 16 MSI vectors (0..15) to generate interrupt.
> + * There are total 16 GIC IRQs assigned for these 16 groups of MSI termination
> + * registers.
> + *
> + * With 2048 MSI vectors supported, the MSI message can be construct using
> + * following scheme:
> + * - Divide into 8 256-vector groups
> + * Group 0: 0-255
> + * Group 1: 256-511
> + * Group 2: 512-767
> + * ...
> + * Group 7: 1792-2047
> + * - Each 256-vector group is divided into 16 16-vector groups
> + * As an example: 16 16-vector groups for 256-vector group 0-255 is
> + * Group 0: 0-15
> + * Group 1: 16-32
> + * ...
> + * Group 15: 240-255
> + * - The termination address of MSI vector in 256-vector group n and 16-vector
> + * group x is the address of MSIxIRn
> + * - The data for MSI vector in 16-vector group x is x
> + */
> +static void xgene_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> + struct xgene_msi *msi = irq_data_get_irq_chip_data(data);
> + u32 reg_set = data->hwirq / (NR_HW_IRQS * IRQS_PER_IDX);
> + u32 group = data->hwirq % NR_HW_IRQS;
> +
> + msg->address_hi = upper_32_bits(msi->msi_addr);
> + msg->address_lo = lower_32_bits(msi->msi_addr) +
> + (((8 * group) + reg_set) << 16);

It would be safer to compute the offset from msi_addr, and apply
{upper,lower}_32_bits() to the resulting value. Otherwise, you end-up
with the wrong upper bits if you cross a 4GB boundary. I know this is
not the case here, but it doesn't hurt to be correct.

> + msg->data = (data->hwirq / NR_HW_IRQS) % IRQS_PER_IDX;
> +}
> +
> +/*
> + * X-Gene v1 only has 16 MSI GIC IRQs for 2048 MSI vectors.
> + * To maintain the expected behaviour of .set_affinity for each MSI
> + * interrupt, the 16 MSI GIC IRQs are statically allocated to 8 X-Gene
> + * v1 cores (2 GIC IRQs for each core). The MSI vector is moved fom 1
> + * MSI GIC IRQ to another MSI GIC IRQ to steer its MSI interrupt to
> + * correct X-Gene v1 core. As a consequence, the total MSI vectors that
> + * X-Gene v1 supports will be reduced to 256 (2048/8) vectors.
> + */
> +static int xgene_msi_set_affinity(struct irq_data *irq_data,
> + const struct cpumask *mask, bool force)
> +{
> + struct xgene_msi *msi = irq_data_get_irq_chip_data(irq_data);
> + int target_cpu = cpumask_first(mask);
> + int curr_cpu;
> +
> + curr_cpu = (irq_data->hwirq % NR_HW_IRQS) % msi->num_cpus;
> + if (curr_cpu == target_cpu)
> + return IRQ_SET_MASK_OK_DONE;
> +
> + /* Update MSI number to target the new CPU */
> + irq_data->hwirq = irq_data->hwirq + (target_cpu - curr_cpu);
> +
> + return IRQ_SET_MASK_OK;
> +}
> +
> +static struct irq_chip xgene_msi_bottom_irq_chip = {
> + .name = "MSI",
> + .irq_set_affinity = xgene_msi_set_affinity,
> + .irq_compose_msi_msg = xgene_compose_msi_msg,
> +};
> +
> +static int xgene_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
> + unsigned int nr_irqs, void *args)
> +{
> + struct xgene_msi *msi = domain->host_data;
> + int msi_irq;
> +
> + mutex_lock(&msi->bitmap_lock);
> +
> + msi_irq = bitmap_find_next_zero_area(msi->bitmap, NR_MSI_VEC, 0,
> + msi->num_cpus, 0);
> + if (msi_irq < NR_MSI_VEC)
> + bitmap_set(msi->bitmap, msi_irq, msi->num_cpus);
> + else
> + msi_irq = -ENOSPC;
> +
> + mutex_unlock(&msi->bitmap_lock);
> +
> + if (msi_irq < 0)
> + return msi_irq;
> +
> + irq_domain_set_info(domain, virq, msi_irq,
> + &xgene_msi_bottom_irq_chip, domain->host_data,
> + handle_simple_irq, NULL, NULL);
> + set_irq_flags(virq, IRQF_VALID);
> +
> + return 0;
> +}
> +
> +static void xgene_irq_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 xgene_msi *msi = irq_data_get_irq_chip_data(d);
> + u32 hwirq;
> +
> + mutex_lock(&msi->bitmap_lock);
> +
> + hwirq = d->hwirq - (d->hwirq % msi->num_cpus);
> + bitmap_clear(msi->bitmap, hwirq, msi->num_cpus);
> +
> + mutex_unlock(&msi->bitmap_lock);
> +
> + irq_domain_free_irqs_parent(domain, virq, nr_irqs);
> +}
> +
> +static const struct irq_domain_ops msi_domain_ops = {
> + .alloc = xgene_irq_domain_alloc,
> + .free = xgene_irq_domain_free,
> +};
> +
> +static int xgene_allocate_domains(struct xgene_msi *msi)
> +{
> + msi->domain = irq_domain_add_linear(NULL, NR_MSI_VEC,
> + &msi_domain_ops, msi);
> + if (!msi->domain)
> + return -ENOMEM;
> +
> + msi->mchip.domain = pci_msi_create_irq_domain(msi->mchip.of_node,
> + &xgene_msi_domain_info,
> + msi->domain);
> +
> + if (!msi->mchip.domain) {
> + irq_domain_remove(msi->domain);
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static void xgene_free_domains(struct xgene_msi *msi)
> +{
> + if (msi->mchip.domain)
> + irq_domain_remove(msi->mchip.domain);
> + if (msi->domain)
> + irq_domain_remove(msi->domain);
> +}
> +
> +static int xgene_msi_init_allocator(struct xgene_msi *xgene_msi)
> +{
> + int size = BITS_TO_LONGS(NR_MSI_VEC) * sizeof(long);
> +
> + xgene_msi->bitmap = kzalloc(size, GFP_KERNEL);
> + if (!xgene_msi->bitmap)
> + return -ENOMEM;
> +
> + mutex_init(&xgene_msi->bitmap_lock);
> +
> + xgene_msi->msi_groups = kcalloc(NR_HW_IRQS,
> + sizeof(struct xgene_msi_group),
> + GFP_KERNEL);
> + if (!xgene_msi->msi_groups)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static void xgene_msi_isr(unsigned int irq, struct irq_desc *desc)
> +{
> + struct irq_chip *chip = irq_desc_get_chip(desc);
> + struct xgene_msi_group *msi_groups;
> + struct xgene_msi *xgene_msi;
> + unsigned int virq;
> + int msir_index, msir_reg, msir_val, hw_irq;
> + u32 intr_index, grp_select, msi_grp;
> +
> + chained_irq_enter(chip, desc);
> +
> + msi_groups = irq_desc_get_handler_data(desc);
> + xgene_msi = msi_groups->msi;
> + msi_grp = msi_groups->msi_grp;
> +
> + /*
> + * MSIINTn (n is 0..F) indicates if there is a pending MSI interrupt
> + * If bit x of this register is set (x is 0..7), one or more interupts
> + * corresponding to MSInIRx is set.
> + */
> + grp_select = readl_relaxed(xgene_msi->msi_regs +
> + MSI_INT0 + (msi_grp << 16));
> + while (grp_select) {
> + msir_index = ffs(grp_select) - 1;
> + /*
> + * Calculate MSInIRx address to read to check for interrupts
> + * (refer to termination address and data assignment
> + * described in xgene_compose_msi_msg function)
> + */
> + msir_reg = (msi_grp << 19) + (msir_index << 16);
> + msir_val = readl_relaxed(xgene_msi->msi_regs +
> + MSI_IR0 + msir_reg);
> + while (msir_val) {
> + intr_index = ffs(msir_val) - 1;
> + /*
> + * Calculate MSI vector number (refer to the termination
> + * address and data assignment described in
> + * xgene_compose_msi_msg function)
> + */
> + hw_irq = (((msir_index * IRQS_PER_IDX) + intr_index) *
> + NR_HW_IRQS) + msi_grp;
> + /*
> + * As we have multiple hw_irq that maps to single MSI,
> + * always look up the virq using the hw_irq as seen from
> + * CPU0
> + */
> + hw_irq = hw_irq - (hw_irq % xgene_msi->num_cpus);
> + virq = irq_find_mapping(xgene_msi->domain, hw_irq);
> + WARN_ON(!virq);
> + if (virq != 0)
> + generic_handle_irq(virq);
> + msir_val &= ~(1 << intr_index);
> + }
> + grp_select &= ~(1 << msir_index);
> + }

I wonder if you wouldn't be better off resampling MSIINTn here, just in
case something else has been made pending in the meantime.

> +
> + chained_irq_exit(chip, desc);
> +}
> +
> +static int xgene_msi_remove(struct platform_device *pdev)
> +{
> + int virq, i;
> + struct xgene_msi *msi = platform_get_drvdata(pdev);
> +
> + for (i = 0; i < NR_HW_IRQS; i++) {
> + virq = msi->msi_groups[i].gic_irq;
> + if (virq != 0) {
> + irq_set_chained_handler(virq, NULL);
> + irq_set_handler_data(virq, NULL);
> + }
> + }
> + kfree(msi->msi_groups);
> +
> + kfree(msi->bitmap);
> + msi->bitmap = NULL;
> +
> + xgene_free_domains(msi);
> +
> + return 0;
> +}
> +
> +static int xgene_msi_hwirq_alloc(unsigned int cpu)
> +{
> + struct xgene_msi *msi = &xgene_msi_ctrl;
> + struct xgene_msi_group *msi_group;
> + cpumask_var_t mask;
> + int i;
> + int err;
> +
> + for (i = 0; i < NR_HW_IRQS; i++) {
> + if (i % msi->num_cpus != cpu)
> + continue;

Oh please...

for (i = cpu; i < NR_HW_IRQS; i += msi->num_cpus) {

does the same thing.

> +
> + msi_group = &msi->msi_groups[i];
> + if (!msi_group->gic_irq)
> + continue;
> +
> + irq_set_chained_handler(msi_group->gic_irq,
> + xgene_msi_isr);
> + err = irq_set_handler_data(msi_group->gic_irq, msi_group);
> + if (err) {
> + pr_err("failed to register GIC IRQ handler\n");
> + return -EINVAL;
> + }
> + /*
> + * Statically allocate MSI GIC IRQs to each CPU core
> + * With 8-core X-Gene v1, 2 MSI GIC IRQs are allocated
> + * to each core.
> + */
> + if (alloc_cpumask_var(&mask, GFP_KERNEL)) {
> + cpumask_clear(mask);
> + cpumask_set_cpu(cpu, mask);
> + err = irq_set_affinity(msi_group->gic_irq, mask);
> + if (err) {
> + irq_set_chained_handler(msi_group->gic_irq,
> + NULL);
> + irq_set_handler_data(msi_group->gic_irq, NULL);
> + free_cpumask_var(mask);
> + pr_err("failed to set affinity for GIC IRQ");
> + return -EINVAL;
> + }
> + free_cpumask_var(mask);
> + }

And what happens if alloc_cpumask_var fails?

> + }
> +
> + return 0;
> +}
> +
> +static void xgene_msi_hwirq_free(unsigned int cpu)
> +{
> + struct xgene_msi *msi = &xgene_msi_ctrl;
> + struct xgene_msi_group *msi_group;
> + int i;
> +
> + for (i = 0; i < NR_HW_IRQS; i++) {
> + if (i % msi->num_cpus != cpu)
> + continue;

Same remark as above.

> +
> + msi_group = &msi->msi_groups[i];
> + if (!msi_group->gic_irq)
> + continue;
> +
> + irq_set_chained_handler(msi_group->gic_irq, NULL);
> + irq_set_handler_data(msi_group->gic_irq, NULL);
> + }
> +}
> +
> +static int xgene_msi_cpu_callback(struct notifier_block *nfb,
> + unsigned long action, void *hcpu)
> +{
> + unsigned cpu = (unsigned long)hcpu;
> +
> + switch (action) {
> + case CPU_ONLINE:
> + case CPU_ONLINE_FROZEN:
> + xgene_msi_hwirq_alloc(cpu);
> + break;
> + case CPU_DEAD:
> + case CPU_DEAD_FROZEN:
> + xgene_msi_hwirq_free(cpu);
> + break;
> + default:
> + break;
> + }
> +
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block xgene_msi_cpu_notifier = {
> + .notifier_call = xgene_msi_cpu_callback,
> +};
> +
> +static const struct of_device_id xgene_msi_match_table[] = {
> + {.compatible = "apm,xgene1-msi"},
> + {},
> +};
> +
> +static int xgene_msi_probe(struct platform_device *pdev)
> +{
> + struct resource *res;
> + int rc, irq_index;
> + struct xgene_msi *xgene_msi;
> + unsigned int cpu;
> + int virt_msir;
> + u32 msi_reg, msi_val, msi_idx;
> +
> + xgene_msi = &xgene_msi_ctrl;
> +
> + platform_set_drvdata(pdev, xgene_msi);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + xgene_msi->msi_regs = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(xgene_msi->msi_regs)) {
> + dev_err(&pdev->dev, "no reg space\n");
> + rc = -EINVAL;
> + goto error;
> + }
> + xgene_msi->msi_addr = res->start;
> +
> + xgene_msi->num_cpus = num_possible_cpus();
> +
> + rc = xgene_msi_init_allocator(xgene_msi);
> + if (rc) {
> + dev_err(&pdev->dev, "Error allocating MSI bitmap\n");
> + goto error;
> + }
> +
> + rc = xgene_allocate_domains(xgene_msi);
> + if (rc) {
> + dev_err(&pdev->dev, "Failed to allocate MSI domain\n");
> + goto error;
> + }
> +
> + for (irq_index = 0; irq_index < NR_HW_IRQS; irq_index++) {
> + virt_msir = platform_get_irq(pdev, irq_index);
> + if (virt_msir < 0) {
> + dev_err(&pdev->dev, "Cannot translate IRQ index %d\n",
> + irq_index);
> + rc = -EINVAL;
> + goto error;
> + }
> + xgene_msi->msi_groups[irq_index].gic_irq = virt_msir;
> + xgene_msi->msi_groups[irq_index].msi_grp = irq_index;
> + xgene_msi->msi_groups[irq_index].msi = xgene_msi;
> + }
> +
> + /*
> + * MSInIRx registers are read-to-clear, before registering interrupt
> + * handlers, reading all of them to clear all spurious interrupts
> + * that may occur before the driver is probed.
> + */
> + for (irq_index = 0; irq_index < NR_HW_IRQS; irq_index++) {
> + for (msi_idx = 0; msi_idx < IDX_PER_GROUP; msi_idx++) {
> + msi_reg = (irq_index << 19) + (msi_idx << 16);
> + msi_val = readl(xgene_msi->msi_regs +
> + MSI_IR0 + msi_reg);

Feels like the above two line could be turned into a small helper (you
have the same in your handling code).

> + }
> + /* Read MSIINTn to confirm */
> + msi_val = readl(xgene_msi->msi_regs +
> + MSI_INT0 + (irq_index << 16));
> + if (msi_val) {
> + dev_err(&pdev->dev, "Failed to clear spurious IRQ\n");
> + rc = -EINVAL;
> + goto error;
> + }
> + }
> +
> + cpu_notifier_register_begin();
> +
> + for_each_online_cpu(cpu)
> + if (xgene_msi_hwirq_alloc(cpu)) {
> + dev_err(&pdev->dev, "failed to regiser MSI handlers\n");
> + cpu_notifier_register_done();
> + goto error;
> + }
> +
> + rc = __register_hotcpu_notifier(&xgene_msi_cpu_notifier);
> + if (rc) {
> + dev_err(&pdev->dev, "failed to add CPU MSI notifier\n");
> + cpu_notifier_register_done();
> + goto error;
> + }
> +
> + cpu_notifier_register_done();
> +
> + xgene_msi->mchip.of_node = pdev->dev.of_node;
> + rc = of_pci_msi_chip_add(&xgene_msi->mchip);
> + if (rc) {
> + dev_err(&pdev->dev, "failed to add MSI controller chip\n");
> + goto error_notifier;
> + }
> +
> + dev_info(&pdev->dev, "APM X-Gene PCIe MSI driver loaded\n");
> +
> + return 0;
> +
> +error_notifier:
> + unregister_hotcpu_notifier(&xgene_msi_cpu_notifier);
> +error:
> + xgene_msi_remove(pdev);
> + return rc;
> +}
> +
> +static struct platform_driver xgene_msi_driver = {
> + .driver = {
> + .name = "xgene-msi",
> + .owner = THIS_MODULE,
> + .of_match_table = xgene_msi_match_table,
> + },
> + .probe = xgene_msi_probe,
> + .remove = xgene_msi_remove,
> +};
> +
> +static int __init xgene_pcie_msi_init(void)
> +{
> + return platform_driver_register(&xgene_msi_driver);
> +}
> +subsys_initcall(xgene_pcie_msi_init);
> +
> diff --git a/drivers/pci/host/pci-xgene.c b/drivers/pci/host/pci-xgene.c
> index 22751ed..3e6faa1 100644
> --- a/drivers/pci/host/pci-xgene.c
> +++ b/drivers/pci/host/pci-xgene.c
> @@ -468,6 +468,23 @@ static int xgene_pcie_setup(struct xgene_pcie_port *port,
> return 0;
> }
>
> +static int xgene_pcie_msi_enable(struct pci_bus *bus)
> +{
> + struct device_node *msi_node;
> +
> + msi_node = of_parse_phandle(bus->dev.of_node,
> + "msi-parent", 0);
> + if (!msi_node)
> + return -ENODEV;
> +
> + bus->msi = of_pci_find_msi_chip_by_node(msi_node);
> + if (bus->msi)
> + bus->msi->dev = &bus->dev;
> + else
> + return -ENODEV;
> + return 0;
> +}
> +
> static int xgene_pcie_probe_bridge(struct platform_device *pdev)
> {
> struct device_node *dn = pdev->dev.of_node;
> @@ -504,6 +521,10 @@ static int xgene_pcie_probe_bridge(struct platform_device *pdev)
> if (!bus)
> return -ENOMEM;
>
> + if (IS_ENABLED(CONFIG_PCI_MSI))
> + if (xgene_pcie_msi_enable(bus))
> + dev_info(port->dev, "failed to enable MSI\n");
> +
> pci_scan_child_bus(bus);
> pci_assign_unassigned_bus_resources(bus);
> pci_bus_add_devices(bus);
> --
> 1.9.1
>

This is finally starting to look better (that, or my pink-tainted
holiday sunglasses are keeping me in a good mood). Please fix the few
nits above, and hopefully this can make it into 4.2 (unless someone
else spots something nasty here).

Thanks,

M.
--
Jazz is not dead. It just smells funny.
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