Message-ID: <CAK9=C2XSEFx5gGvjHfhfygUbYqAQYC84-smNB588M2gFj9TRng@mail.gmail.com>
Date:   Mon, 25 Sep 2023 18:38:53 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Ruan Jinjie <ruanjinjie@...wei.com>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Frank Rowand <frowand.list@...il.com>,
        Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
        Saravana Kannan <saravanak@...gle.com>,
        Anup Patel <anup@...infault.org>, linux-kernel@...r.kernel.org,
        Atish Patra <atishp@...shpatra.org>,
        linux-riscv@...ts.infradead.org,
        Andrew Jones <ajones@...tanamicro.com>
Subject: Re: [PATCH v8 10/16] irqchip/riscv-imsic: Add support for platform
 MSI irqdomain

On Mon, Sep 25, 2023 at 6:31 PM Ruan Jinjie <ruanjinjie@...wei.com> wrote:
>
>
>
> On 2023/9/13 1:49, Anup Patel wrote:
> > The Linux platform MSI support requires a platform MSI irqdomain so
> > let us add a platform irqchip driver for RISC-V IMSIC which provides
> > a base IRQ domain and platform MSI domain. This driver assumes that
> > the IMSIC state is already initialized by the IMSIC early driver.
> >
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> >  drivers/irqchip/Makefile                   |   2 +-
> >  drivers/irqchip/irq-riscv-imsic-platform.c | 280 +++++++++++++++++++++
> >  2 files changed, 281 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/irqchip/irq-riscv-imsic-platform.c
> >
> > diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> > index d714724387ce..abca445a3229 100644
> > --- a/drivers/irqchip/Makefile
> > +++ b/drivers/irqchip/Makefile
> > @@ -95,7 +95,7 @@ obj-$(CONFIG_QCOM_MPM)                      += irq-qcom-mpm.o
> >  obj-$(CONFIG_CSKY_MPINTC)            += irq-csky-mpintc.o
> >  obj-$(CONFIG_CSKY_APB_INTC)          += irq-csky-apb-intc.o
> >  obj-$(CONFIG_RISCV_INTC)             += irq-riscv-intc.o
> > -obj-$(CONFIG_RISCV_IMSIC)            += irq-riscv-imsic-state.o irq-riscv-imsic-early.o
> > +obj-$(CONFIG_RISCV_IMSIC)            += irq-riscv-imsic-state.o irq-riscv-imsic-early.o irq-riscv-imsic-platform.o
> >  obj-$(CONFIG_SIFIVE_PLIC)            += irq-sifive-plic.o
> >  obj-$(CONFIG_IMX_IRQSTEER)           += irq-imx-irqsteer.o
> >  obj-$(CONFIG_IMX_INTMUX)             += irq-imx-intmux.o
> > diff --git a/drivers/irqchip/irq-riscv-imsic-platform.c b/drivers/irqchip/irq-riscv-imsic-platform.c
> > new file mode 100644
> > index 000000000000..b78f1b2ee3dc
> > --- /dev/null
> > +++ b/drivers/irqchip/irq-riscv-imsic-platform.c
> > @@ -0,0 +1,280 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > + * Copyright (C) 2022 Ventana Micro Systems Inc.
> > + */
> > +
> > +#include <linux/bitmap.h>
> > +#include <linux/cpu.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/irqchip.h>
> > +#include <linux/irqdomain.h>
> > +#include <linux/module.h>
> > +#include <linux/msi.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/smp.h>
> > +
> > +#include "irq-riscv-imsic-state.h"
> > +
> > +static int imsic_cpu_page_phys(unsigned int cpu,
> > +                            unsigned int guest_index,
> > +                            phys_addr_t *out_msi_pa)
> > +{
> > +     struct imsic_global_config *global;
> > +     struct imsic_local_config *local;
> > +
> > +     global = &imsic->global;
> > +     local = per_cpu_ptr(global->local, cpu);
> > +
> > +     if (BIT(global->guest_index_bits) <= guest_index)
> > +             return -EINVAL;
> > +
> > +     if (out_msi_pa)
> > +             *out_msi_pa = local->msi_pa +
> > +                           (guest_index * IMSIC_MMIO_PAGE_SZ);
> > +
> > +     return 0;
> > +}
> > +
> > +static int imsic_get_cpu(const struct cpumask *mask_val, bool force,
> > +                      unsigned int *out_target_cpu)
> > +{
> > +     unsigned int cpu;
> > +
> > +     if (force)
> > +             cpu = cpumask_first(mask_val);
> > +     else
> > +             cpu = cpumask_any_and(mask_val, cpu_online_mask);
> > +
> > +     if (cpu >= nr_cpu_ids)
> > +             return -EINVAL;
> > +
> > +     if (out_target_cpu)
> > +             *out_target_cpu = cpu;
> > +
> > +     return 0;
> > +}
> > +
> > +static void imsic_irq_mask(struct irq_data *d)
> > +{
> > +     unsigned long flags;
> > +
> > +     raw_spin_lock_irqsave(&imsic->ids_lock, flags);
> > +     bitmap_clear(imsic->ids_enabled_bimap, d->hwirq, 1);
> > +     __imsic_id_disable(d->hwirq);
> > +     raw_spin_unlock_irqrestore(&imsic->ids_lock, flags);
> > +
> > +     imsic_ids_remote_sync();
> > +}
> > +
> > +static void imsic_irq_unmask(struct irq_data *d)
> > +{
> > +     unsigned long flags;
> > +
> > +     raw_spin_lock_irqsave(&imsic->ids_lock, flags);
> > +     bitmap_set(imsic->ids_enabled_bimap, d->hwirq, 1);
> > +     __imsic_id_enable(d->hwirq);
> > +     raw_spin_unlock_irqrestore(&imsic->ids_lock, flags);
> > +
> > +     imsic_ids_remote_sync();
> > +}
> > +
> > +static void imsic_irq_compose_msi_msg(struct irq_data *d,
> > +                                   struct msi_msg *msg)
> > +{
> > +     phys_addr_t msi_addr;
> > +     unsigned int cpu;
> > +     int err;
> > +
> > +     cpu = imsic_id_get_target(d->hwirq);
> > +     if (WARN_ON(cpu == UINT_MAX))
> > +             return;
> > +
> > +     err = imsic_cpu_page_phys(cpu, 0, &msi_addr);
> > +     if (WARN_ON(err))
> > +             return;
> > +
> > +     msg->address_hi = upper_32_bits(msi_addr);
> > +     msg->address_lo = lower_32_bits(msi_addr);
> > +     msg->data = d->hwirq;
> > +}
> > +
> > +#ifdef CONFIG_SMP
> > +static int imsic_irq_set_affinity(struct irq_data *d,
> > +                               const struct cpumask *mask_val,
> > +                               bool force)
> > +{
> > +     unsigned int target_cpu;
> > +     int rc;
> > +
> > +     rc = imsic_get_cpu(mask_val, force, &target_cpu);
> > +     if (rc)
> > +             return rc;
> > +
> > +     imsic_id_set_target(d->hwirq, target_cpu);
> > +     irq_data_update_effective_affinity(d, cpumask_of(target_cpu));
>
> According to the “The RISC-V Advanced Interrupt Architecture Version
> 0.2-draft”，the "3.1 Interrupt files and interrupt identities" has
> following description.
>
> Thus the total number of MSI sources that can be separately distinguished
> within a system is potentially the product of the number of interrupt
> identities at a single interrupt
> file times the total number of interrupt files in the system, over all
> harts.
>
> In my opinion, the MSI interrupt number is a local interrupt number.
> However, when the above interrupt affinity is set, it is processed as a
> global interrupt number, which seems not comply with the above RISC-V
> specifications.

Treating IMSIC minor interrupt identities as global instead of local is a
design choice we made to integrate cleanly with Linux IRQ subsystem
because otherwise MSI interrupts will be percpu interrupts and we can't
steer device MSIs to different CPUs using set_irq_affinity().

Regards,
Anup

>
> > +
> > +     return IRQ_SET_MASK_OK;
> > +}
> > +#endif
> > +
> > +static struct irq_chip imsic_irq_base_chip = {
> > +     .name                   = "IMSIC-BASE",
> > +     .irq_mask               = imsic_irq_mask,
> > +     .irq_unmask             = imsic_irq_unmask,
> > +#ifdef CONFIG_SMP
> > +     .irq_set_affinity       = imsic_irq_set_affinity,
> > +#endif
> > +     .irq_compose_msi_msg    = imsic_irq_compose_msi_msg,
> > +     .flags                  = IRQCHIP_SKIP_SET_WAKE |
> > +                               IRQCHIP_MASK_ON_SUSPEND,
> > +};
> > +
> > +static int imsic_irq_domain_alloc(struct irq_domain *domain,
> > +                               unsigned int virq,
> > +                               unsigned int nr_irqs,
> > +                               void *args)
> > +{
> > +     int i, hwirq, err = 0;
> > +     unsigned int cpu;
> > +
> > +     err = imsic_get_cpu(cpu_online_mask, false, &cpu);
> > +     if (err)
> > +             return err;
> > +
> > +     hwirq = imsic_ids_alloc(get_count_order(nr_irqs));
> > +     if (hwirq < 0)
> > +             return hwirq;
> > +
> > +     for (i = 0; i < nr_irqs; i++) {
> > +             imsic_id_set_target(hwirq + i, cpu);
> > +             irq_domain_set_info(domain, virq + i, hwirq + i,
> > +                                 &imsic_irq_base_chip, imsic,
> > +                                 handle_simple_irq, NULL, NULL);
> > +             irq_set_noprobe(virq + i);
> > +             irq_set_affinity(virq + i, cpu_online_mask);
> > +             /*
> > +              * IMSIC does not implement irq_disable() so Linux interrupt
> > +              * subsystem will take a lazy approach for disabling an IMSIC
> > +              * interrupt. This means IMSIC interrupts are left unmasked
> > +              * upon system suspend and interrupts are not processed
> > +              * immediately upon system wake up. To tackle this, we disable
> > +              * the lazy approach for all IMSIC interrupts.
> > +              */
> > +             irq_set_status_flags(virq + i, IRQ_DISABLE_UNLAZY);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static void imsic_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);
> > +
> > +     imsic_ids_free(d->hwirq, get_count_order(nr_irqs));
> > +     irq_domain_free_irqs_parent(domain, virq, nr_irqs);
> > +}
> > +
> > +static const struct irq_domain_ops imsic_base_domain_ops = {
> > +     .alloc          = imsic_irq_domain_alloc,
> > +     .free           = imsic_irq_domain_free,
> > +};
> > +
> > +static struct irq_chip imsic_plat_irq_chip = {
> > +     .name                   = "IMSIC-PLAT",
> > +};
> > +
> > +static struct msi_domain_ops imsic_plat_domain_ops = {
> > +};
> > +
> > +static struct msi_domain_info imsic_plat_domain_info = {
> > +     .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS),
> > +     .ops    = &imsic_plat_domain_ops,
> > +     .chip   = &imsic_plat_irq_chip,
> > +};
> > +
> > +static int imsic_irq_domains_init(struct device *dev)
> > +{
> > +     /* Create Base IRQ domain */
> > +     imsic->base_domain = irq_domain_create_tree(dev->fwnode,
> > +                                     &imsic_base_domain_ops, imsic);
> > +     if (!imsic->base_domain) {
> > +             dev_err(dev, "failed to create IMSIC base domain\n");
> > +             return -ENOMEM;
> > +     }
> > +     irq_domain_update_bus_token(imsic->base_domain, DOMAIN_BUS_NEXUS);
> > +
> > +     /* Create Platform MSI domain */
> > +     imsic->plat_domain = platform_msi_create_irq_domain(dev->fwnode,
> > +                                             &imsic_plat_domain_info,
> > +                                             imsic->base_domain);
> > +     if (!imsic->plat_domain) {
> > +             dev_err(dev, "failed to create IMSIC platform domain\n");
> > +             irq_domain_remove(imsic->base_domain);
> > +             return -ENOMEM;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int imsic_platform_probe(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     struct imsic_global_config *global;
> > +     int rc;
> > +
> > +     if (!imsic) {
> > +             dev_err(dev, "early driver not probed\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     if (imsic->base_domain) {
> > +             dev_err(dev, "irq domain already created\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     global = &imsic->global;
> > +
> > +     /* Initialize IRQ and MSI domains */
> > +     rc = imsic_irq_domains_init(dev);
> > +     if (rc) {
> > +             dev_err(dev, "failed to initialize IRQ and MSI domains\n");
> > +             return rc;
> > +     }
> > +
> > +     dev_info(dev, "  hart-index-bits: %d,  guest-index-bits: %d\n",
> > +              global->hart_index_bits, global->guest_index_bits);
> > +     dev_info(dev, " group-index-bits: %d, group-index-shift: %d\n",
> > +              global->group_index_bits, global->group_index_shift);
> > +     dev_info(dev, " mapped %d interrupts at base PPN %pa\n",
> > +              global->nr_ids, &global->base_addr);
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct of_device_id imsic_platform_match[] = {
> > +     { .compatible = "riscv,imsics" },
> > +     {}
> > +};
> > +
> > +static struct platform_driver imsic_platform_driver = {
> > +     .driver = {
> > +             .name           = "riscv-imsic",
> > +             .of_match_table = imsic_platform_match,
> > +     },
> > +     .probe = imsic_platform_probe,
> > +};
> > +
> > +static int __init imsic_platform_init(void)
> > +{
> > +     /*
> > +      * Register IMSIC driver as early as possible so that IMSIC
> > +      * platform device is probed as soon as it is created.
> > +      */
> > +     return platform_driver_register(&imsic_platform_driver);
> > +}
> > +core_initcall(imsic_platform_init);

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