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Message-ID: <CADaLNDkrqwnEOX1HgQ7V3-1o4cDJnG4dW1=U4ujod7fUW_PQ0w@mail.gmail.com>
Date: Fri, 10 Apr 2015 16:42:42 -0700
From: Duc Dang <dhdang@....com>
To: Marc Zyngier <marc.zyngier@....com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Liviu Dudau <Liviu.Dudau@....com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Tanmay Inamdar <tinamdar@....com>, Loc Ho <lho@....com>,
Feng Kan <fkan@....com>
Subject: Re: [PATCH v3 1/4] PCI: X-Gene: Add the APM X-Gene v1 PCIe MSI/MSIX
termination driver
On Fri, Apr 10, 2015 at 10:20 AM, Marc Zyngier <marc.zyngier@....com> wrote:
> On 09/04/15 18:05, Duc Dang wrote:
>> X-Gene v1 SoC supports total 2688 MSI/MSIX vectors coalesced into
>> 16 HW IRQ lines.
>>
>> Signed-off-by: Duc Dang <dhdang@....com>
>> Signed-off-by: Tanmay Inamdar <tinamdar@....com>
>> ---
>> drivers/pci/host/Kconfig | 6 +
>> drivers/pci/host/Makefile | 1 +
>> drivers/pci/host/pci-xgene-msi.c | 407 +++++++++++++++++++++++++++++++++++++++
>> drivers/pci/host/pci-xgene.c | 21 ++
>> 4 files changed, 435 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..c9b61fa 100644
>> --- a/drivers/pci/host/Kconfig
>> +++ b/drivers/pci/host/Kconfig
>> @@ -89,11 +89,17 @@ 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
>> +
>> 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..4f0ff42
>> --- /dev/null
>> +++ b/drivers/pci/host/pci-xgene-msi.c
>> @@ -0,0 +1,407 @@
>> +/*
>> + * APM X-Gene MSI Driver
>> + *
>> + * Copyright (c) 2014, Applied Micro Circuits Corporation
>> + * Author: Tanmay Inamdar <tinamdar@....com>
>> + * Duc Dang <dhdang@....com>
>> + *
>> + * 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/interrupt.h>
>> +#include <linux/module.h>
>> +#include <linux/msi.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/pci.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of_pci.h>
>> +
>> +#define MSI_INDEX0 0x000000
>> +#define MSI_INT0 0x800000
>> +
>> +struct xgene_msi_settings {
>> + u32 index_per_group;
>> + u32 irqs_per_index;
>> + u32 nr_msi_vec;
>> + u32 nr_hw_irqs;
>> +};
>> +
>> +struct xgene_msi {
>> + struct device_node *node;
>> + struct msi_controller mchip;
>> + struct irq_domain *domain;
>> + struct xgene_msi_settings *settings;
>> + u32 msi_addr_lo;
>> + u32 msi_addr_hi;
>
> I'd rather see the mailbox address directly, and only do the split when
> assigning it to the message (you seem to play all kind of tricks on the
> address anyway).
msi_addr_lo and msi_addr_hi store the physical base address of MSI
controller registers. I will add comment to clarify this.
>
>> + void __iomem *msi_regs;
>> + unsigned long *bitmap;
>> + struct mutex bitmap_lock;
>> + int *msi_virqs;
>> +};
>> +
>> +struct xgene_msi_settings storm_msi_settings = {
>> + .index_per_group = 8,
>> + .irqs_per_index = 21,
>> + .nr_msi_vec = 2688,
>> + .nr_hw_irqs = 16,
>> +};
>
> It would really help understanding how index, group and hw irq lines are
> structured. nr_msi_vec is obviously the product of these three numbers,
> so maybe you can loose it (we have computers, remember... ;-).
>
> Do you expect more than this single "storm" implementation? If so, maybe
> they should be described in the DT. If not, why do we need a separate
> structure with an indirection if we know these are constants?
>
Yes, I will add description about index, group, and hw irq lines
structure and also replace the fields in this storm_msi_settings
structure with constant dedinitions.
>> +
>> +typedef int (*xgene_msi_initcall_t)(struct xgene_msi *);
>> +
>> +static int xgene_msi_init_storm_settings(struct xgene_msi *xgene_msi)
>> +{
>> + xgene_msi->settings = &storm_msi_settings;
>> + return 0;
>> +}
>> +
>> +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,
>> +};
>> +
>> +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 nr_hw_irqs = msi->settings->nr_hw_irqs;
>> + u32 irqs_per_index = msi->settings->irqs_per_index;
>> + u32 reg_set = data->hwirq / (nr_hw_irqs * irqs_per_index);
>> + u32 group = data->hwirq % nr_hw_irqs;
>> +
>> + msg->address_hi = msi->msi_addr_hi;
>> + msg->address_lo = msi->msi_addr_lo +
>> + (((8 * group) + reg_set) << 16);
>> + msg->data = (data->hwirq / nr_hw_irqs) % irqs_per_index;
>
> ... (sound of head exploding...). I hate it when I have to reverse
> engineer the hardware by looking at the code...
>
> Please give us some clue on how interrupts are spread across the various
> pages, how the various indexes are combined to give an actual address.
I will add description about this.
>
>> +}
>> +
>> +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);
>> + unsigned int gic_irq;
>> + int ret;
>> +
>> + gic_irq = msi->msi_virqs[irq_data->hwirq % msi->settings->nr_hw_irqs];
>> + ret = irq_set_affinity(gic_irq, mask);
>
> Erm... This as the effect of moving *all* the MSIs hanging off this
> interrupt to another CPU. I'm not sure that's an acceptable effect...
> What if another MSI requires a different affinity?
We have 16 'real' hardware IRQs. Each of these has multiple MSIs attached to it.
So this will move all MSIs handing off this interrupt to another CPU;
and we don't support different affinity settings for different MSIs
that are attached to the same hardware IRQ.
>
>> + if (ret == IRQ_SET_MASK_OK)
>> + ret = IRQ_SET_MASK_OK_DONE;
>> +
>> + return ret;
>> +}
>> +
>> +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;
>> + u32 msi_irq_count = msi->settings->nr_msi_vec;
>> + int msi_irq;
>> +
>> + mutex_lock(&msi->bitmap_lock);
>> +
>> + msi_irq = find_first_zero_bit(msi->bitmap, msi_irq_count);
>> + if (msi_irq < msi_irq_count)
>> + set_bit(msi_irq, msi->bitmap);
>> + 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);
>> +
>> + mutex_lock(&msi->bitmap_lock);
>> +
>> + if (!test_bit(d->hwirq, msi->bitmap))
>> + pr_err("trying to free unused MSI#%lu\n", d->hwirq);
>> + else
>> + clear_bit(d->hwirq, msi->bitmap);
>> +
>> + 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, msi->settings->nr_msi_vec,
>> + &msi_domain_ops, msi);
>> +
>> + if (!msi->domain) {
>> + pr_err("failed to create parent MSI domain\n");
>> + return -ENOMEM;
>> + }
>> +
>> + msi->mchip.of_node = msi->node;
>> + msi->mchip.domain = pci_msi_create_irq_domain(msi->mchip.of_node,
>> + &xgene_msi_domain_info,
>> + msi->domain);
>> +
>> + if (!msi->mchip.domain) {
>> + pr_err("failed to create MSI domain\n");
>> + 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)
>> +{
>> + u32 msi_irq_count = xgene_msi->settings->nr_msi_vec;
>> + u32 hw_irq_count = xgene_msi->settings->nr_hw_irqs;
>> + int size = BITS_TO_LONGS(msi_irq_count) * sizeof(long);
>> +
>> + xgene_msi->bitmap = kzalloc(size, GFP_KERNEL);
>> + if (!xgene_msi->bitmap)
>> + return -ENOMEM;
>> +
>> + mutex_init(&xgene_msi->bitmap_lock);
>> +
>> + xgene_msi->msi_virqs = kcalloc(hw_irq_count, sizeof(int), GFP_KERNEL);
>> + if (!xgene_msi->msi_virqs)
>> + return -ENOMEM;
>> +
>> + return 0;
>> +}
>> +
>> +static irqreturn_t xgene_msi_isr(int irq, void *data)
>
> This is not a "normal" interrupt handler. This is really a chained
> interrupt controller. Please use the proper infrastructure for this
> (irq_set_chained_handler, chained_irq_enter, chained_irq_exit).
> Otherwise, your usage of irq_find_mapping is illegal wrt RCU.
>
Yes, I will change this function to protect it with chained_irq_enter,
chained_irq_exit
>> +{
>> + struct xgene_msi *xgene_msi = (struct xgene_msi *) data;
>> + unsigned int virq;
>> + int msir_index, msir_reg, msir_val, hw_irq;
>> + u32 intr_index, grp_select, msi_grp, processed = 0;
>> + u32 nr_hw_irqs, irqs_per_index, index_per_group;
>> +
>> + msi_grp = irq - xgene_msi->msi_virqs[0];
>> + if (msi_grp >= xgene_msi->settings->nr_hw_irqs) {
>> + pr_err("invalid msi received\n");
>> + return IRQ_NONE;
>> + }
>> +
>> + nr_hw_irqs = xgene_msi->settings->nr_hw_irqs;
>> + irqs_per_index = xgene_msi->settings->irqs_per_index;
>> + index_per_group = xgene_msi->settings->index_per_group;
>> +
>> + grp_select = readl(xgene_msi->msi_regs + MSI_INT0 + (msi_grp << 16));
>> + while (grp_select) {
>> + msir_index = ffs(grp_select) - 1;
>> + msir_reg = (msi_grp << 19) + (msir_index << 16);
>> + msir_val = readl(xgene_msi->msi_regs + MSI_INDEX0 + msir_reg);
>> + while (msir_val) {
>> + intr_index = ffs(msir_val) - 1;
>> + hw_irq = (((msir_index * irqs_per_index) + intr_index) *
>> + nr_hw_irqs) + msi_grp;
>
> Same thing here. This requires some explaination on how the HW is organised.
I will have description for this.
>
>> + virq = irq_find_mapping(xgene_msi->domain, hw_irq);
>> + if (virq != 0)
>> + generic_handle_irq(virq);
>> + msir_val &= ~(1 << intr_index);
>> + processed++;
>> + }
>> + grp_select &= ~(1 << msir_index);
>> + }
>> +
>> + return processed > 0 ? IRQ_HANDLED : IRQ_NONE;
>> +}
>> +
>> +static int xgene_msi_remove(struct platform_device *pdev)
>> +{
>> + int virq, i;
>> + struct xgene_msi *msi = platform_get_drvdata(pdev);
>> + u32 nr_hw_irqs = msi->settings->nr_hw_irqs;
>> +
>> + for (i = 0; i < nr_hw_irqs; i++) {
>> + virq = msi->msi_virqs[i];
>> + if (virq != 0)
>> + free_irq(virq, msi);
>> + }
>> +
>> + kfree(msi->bitmap);
>> + msi->bitmap = NULL;
>> +
>> + xgene_free_domains(msi);
>> +
>> + return 0;
>> +}
>> +
>> +static int xgene_msi_setup_hwirq(struct xgene_msi *msi,
>> + struct platform_device *pdev,
>> + int irq_index)
>> +{
>> + int virt_msir;
>> + cpumask_var_t mask;
>> + int err;
>> +
>> + virt_msir = platform_get_irq(pdev, irq_index);
>> + if (virt_msir < 0) {
>> + dev_err(&pdev->dev, "Cannot translate IRQ index %d\n",
>> + irq_index);
>> + return -EINVAL;
>> + }
>> +
>> + err = request_irq(virt_msir, xgene_msi_isr, 0,
>> + xgene_msi_top_irq_chip.name, msi);
>
> This is where you should use irq_set_chained_handler.
I will replace request_irq with irq_set_chained_handler and irq_set_handler_data
>
>> + if (err) {
>> + dev_err(&pdev->dev, "request irq failed\n");
>> + return err;
>> + }
>> +
>> + if (alloc_cpumask_var(&mask, GFP_KERNEL)) {
>> + cpumask_setall(mask);
>> + irq_set_affinity(virt_msir, mask);
>> + free_cpumask_var(mask);
>> + }
>> +
>> + msi->msi_virqs[irq_index] = virt_msir;
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id xgene_msi_match_table[] = {
>> + {.compatible = "apm,xgene1-msi",
>> + .data = xgene_msi_init_storm_settings},
>> + {},
>> +};
>> +
>> +static int xgene_msi_probe(struct platform_device *pdev)
>> +{
>> + struct resource *res;
>> + int rc, irq_index;
>> + struct device_node *np;
>> + const struct of_device_id *matched_np;
>> + struct xgene_msi *xgene_msi;
>> + xgene_msi_initcall_t init_fn;
>> + u32 nr_hw_irqs, nr_msi_vecs;
>> +
>> + np = of_find_matching_node_and_match(NULL,
>> + xgene_msi_match_table, &matched_np);
>> + if (!np)
>> + return -ENODEV;
>> +
>> + xgene_msi = kzalloc(sizeof(struct xgene_msi), GFP_KERNEL);
>> + if (!xgene_msi) {
>> + dev_err(&pdev->dev, "failed to allocate X-Gene MSI data\n");
>> + return -ENOMEM;
>> + }
>> +
>> + xgene_msi->node = np;
>> +
>> + init_fn = (xgene_msi_initcall_t) matched_np->data;
>> + rc = init_fn(xgene_msi);
>> + if (rc)
>> + return rc;
>> +
>> + platform_set_drvdata(pdev, xgene_msi);
>> +
>> + nr_msi_vecs = xgene_msi->settings->nr_msi_vec;
>> +
>> + 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_hi = upper_32_bits(res->start);
>> + xgene_msi->msi_addr_lo = lower_32_bits(res->start);
>> +
>> + 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;
>> + }
>> +
>> + nr_hw_irqs = xgene_msi->settings->nr_hw_irqs;
>> + for (irq_index = 0; irq_index < nr_hw_irqs; irq_index++) {
>> + rc = xgene_msi_setup_hwirq(xgene_msi, pdev, irq_index);
>> + if (rc)
>> + goto error;
>> + }
>> +
>> + rc = of_pci_msi_chip_add(&xgene_msi->mchip);
>> + if (rc) {
>> + dev_err(&pdev->dev, "failed to add MSI controller chip\n");
>> + goto error;
>> + }
>> +
>> + dev_info(&pdev->dev, "APM X-Gene PCIe MSI driver loaded\n");
>> +
>> + return 0;
>> +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);
>> +
>> +MODULE_AUTHOR("Duc Dang <dhdang@....com>");
>> +MODULE_DESCRIPTION("APM X-Gene PCIe MSI driver");
>> +MODULE_LICENSE("GPL v2");
>> 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
>>
>
> Thanks,
>
> M.
> --
> Jazz is not dead. It just smells funny...
Regards,
Duc Dang.
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