Message-ID: <CAK9=C2Xe-ODWUgbeYs4TXySrKKZuA7LWGr-UUaLdZGTnLZ2-7g@mail.gmail.com>
Date:   Fri, 3 Nov 2023 16:34:32 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Ben <figure1802@....com>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        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>,
        Marc Zyngier <maz@...nel.org>,
        Anup Patel <anup@...infault.org>, linux-kernel@...r.kernel.org,
        Björn Töpel <bjorn@...nel.org>,
        Atish Patra <atishp@...shpatra.org>,
        linux-riscv@...ts.infradead.org,
        Andrew Jones <ajones@...tanamicro.com>
Subject: Re: Re: [PATCH v11 12/14] irqchip/riscv-aplic: Add support for MSI-mode

On Fri, Nov 3, 2023 at 3:14 PM Ben <figure1802@....com> wrote:
>
>
>
> 在 2023-11-02 20:37:42，"Anup Patel" <apatel@...tanamicro.com> 写道：
> >On Thu, Nov 2, 2023 at 11:55 AM Ben <figure1802@....com> wrote:
> >>
> >>
> >> At 2023-10-24 01:27:58, "Anup Patel" <apatel@...tanamicro.com> wrote:
> >> >The RISC-V advanced platform-level interrupt controller (APLIC) has
> >> >two modes of operation: 1) Direct mode and 2) MSI mode.
> >> >(For more details, refer https://github.com/riscv/riscv-aia)
> >> >
> >> >In APLIC MSI-mode, wired interrupts are forwared as message signaled
> >> >interrupts (MSIs) to CPUs via IMSIC.
> >> >
> >> >We extend the existing APLIC irqchip driver to support MSI-mode for
> >> >RISC-V platforms having both wired interrupts and MSIs.
> >> >
> >> >Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> >> >---
> >> > drivers/irqchip/Kconfig                |   6 +
> >> > drivers/irqchip/Makefile               |   1 +
> >> > drivers/irqchip/irq-riscv-aplic-main.c |   2 +-
> >> > drivers/irqchip/irq-riscv-aplic-main.h |   8 +
> >> > drivers/irqchip/irq-riscv-aplic-msi.c  | 285 +++++++++++++++++++++++++
> >> > 5 files changed, 301 insertions(+), 1 deletion(-)
> >> > create mode 100644 drivers/irqchip/irq-riscv-aplic-msi.c
> >> >
> >> >diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> >> >index 1996cc6f666a..7adc4dbe07ff 100644
> >> >--- a/drivers/irqchip/Kconfig
> >> >+++ b/drivers/irqchip/Kconfig
> >> >@@ -551,6 +551,12 @@ config RISCV_APLIC
> >> > depends on RISCV
> >> > select IRQ_DOMAIN_HIERARCHY
> >> >
> >> >+config RISCV_APLIC_MSI
> >> >+ bool
> >> >+ depends on RISCV_APLIC
> >> >+ select GENERIC_MSI_IRQ
> >> >+ default RISCV_APLIC
> >> >+
> >> > config RISCV_IMSIC
> >> > bool
> >> > depends on RISCV
> >> >diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> >> >index 7f8289790ed8..47995fdb2c60 100644
> >> >--- a/drivers/irqchip/Makefile
> >> >+++ b/drivers/irqchip/Makefile
> >> >@@ -96,6 +96,7 @@ 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_APLIC) += irq-riscv-aplic-main.o irq-riscv-aplic-direct.o
> >> >+obj-$(CONFIG_RISCV_APLIC_MSI) += irq-riscv-aplic-msi.o
> >> > obj-$(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
> >> >diff --git a/drivers/irqchip/irq-riscv-aplic-main.c b/drivers/irqchip/irq-riscv-aplic-main.c
> >> >index 87450708a733..d1b342b66551 100644
> >> >--- a/drivers/irqchip/irq-riscv-aplic-main.c
> >> >+++ b/drivers/irqchip/irq-riscv-aplic-main.c
> >> >@@ -205,7 +205,7 @@ static int aplic_probe(struct platform_device *pdev)
> >> > msi_mode = of_property_present(to_of_node(dev->fwnode),
> >> > "msi-parent");
> >> > if (msi_mode)
> >> >- rc = -ENODEV;
> >> >+ rc = aplic_msi_setup(dev, regs);
> >> > else
> >> > rc = aplic_direct_setup(dev, regs);
> >> > if (rc) {
> >> >diff --git a/drivers/irqchip/irq-riscv-aplic-main.h b/drivers/irqchip/irq-riscv-aplic-main.h
> >> >index 474a04229334..78267ec58098 100644
> >> >--- a/drivers/irqchip/irq-riscv-aplic-main.h
> >> >+++ b/drivers/irqchip/irq-riscv-aplic-main.h
> >> >@@ -41,5 +41,13 @@ void aplic_init_hw_global(struct aplic_priv *priv, bool msi_mode);
> >> > int aplic_setup_priv(struct aplic_priv *priv, struct device *dev,
> >> >     void __iomem *regs);
> >> > int aplic_direct_setup(struct device *dev, void __iomem *regs);
> >> >+#ifdef CONFIG_RISCV_APLIC_MSI
> >> >+int aplic_msi_setup(struct device *dev, void __iomem *regs);
> >> >+#else
> >> >+static inline int aplic_msi_setup(struct device *dev, void __iomem *regs)
> >> >+{
> >> >+ return -ENODEV;
> >> >+}
> >> >+#endif
> >> >
> >> > #endif
> >> >diff --git a/drivers/irqchip/irq-riscv-aplic-msi.c b/drivers/irqchip/irq-riscv-aplic-msi.c
> >> >new file mode 100644
> >> >index 000000000000..086d00e0429e
> >> >--- /dev/null
> >> >+++ b/drivers/irqchip/irq-riscv-aplic-msi.c
> >> >@@ -0,0 +1,285 @@
> >> >+// SPDX-License-Identifier: GPL-2.0
> >> >+/*
> >> >+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> >> >+ * Copyright (C) 2022 Ventana Micro Systems Inc.
> >> >+ */
> >> >+
> >> >+#include <linux/bitops.h>
> >> >+#include <linux/cpu.h>
> >> >+#include <linux/interrupt.h>
> >> >+#include <linux/irqchip.h>
> >> >+#include <linux/irqchip/riscv-aplic.h>
> >> >+#include <linux/irqchip/riscv-imsic.h>
> >> >+#include <linux/module.h>
> >> >+#include <linux/msi.h>
> >> >+#include <linux/of_irq.h>
> >> >+#include <linux/platform_device.h>
> >> >+#include <linux/printk.h>
> >> >+#include <linux/smp.h>
> >> >+
> >> >+#include "irq-riscv-aplic-main.h"
> >> >+
> >> >+static void aplic_msi_irq_unmask(struct irq_data *d)
> >> >+{
> >> >+ aplic_irq_unmask(d);
> >> >+ irq_chip_unmask_parent(d);
> >> >+}
> >> >+
> >> >+static void aplic_msi_irq_mask(struct irq_data *d)
> >> >+{
> >> >+ aplic_irq_mask(d);
> >> >+ irq_chip_mask_parent(d);
> >> >+}
> >> >+
> >> >+static void aplic_msi_irq_eoi(struct irq_data *d)
> >> >+{
> >> >+ struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> >> >+ u32 reg_off, reg_mask;
> >> >+
> >> >+ /*
> >> >+ * EOI handling only required only for level-triggered
> >> >+ * interrupts in APLIC MSI mode.
> >> >+ */
> >> >+
> >> >+ reg_off = APLIC_CLRIP_BASE + ((d->hwirq / APLIC_IRQBITS_PER_REG) * 4);
> >> >+ reg_mask = BIT(d->hwirq % APLIC_IRQBITS_PER_REG);
> >> >+ switch (irqd_get_trigger_type(d)) {
> >> >+ case IRQ_TYPE_LEVEL_LOW:
> >> >+ if (!(readl(priv->regs + reg_off) & reg_mask))
> >> >+ writel(d->hwirq, priv->regs + APLIC_SETIPNUM_LE);
> >> >+ break;
> >> >+ case IRQ_TYPE_LEVEL_HIGH:
> >> >+ if (readl(priv->regs + reg_off) & reg_mask)
> >> >+ writel(d->hwirq, priv->regs + APLIC_SETIPNUM_LE);
> >> >+ break;
> >> >+ }
> >> >+}
> >> >+
> >> >+static struct irq_chip aplic_msi_chip = {
> >> >+ .name = "APLIC-MSI",
> >> >+ .irq_mask = aplic_msi_irq_mask,
> >> >+ .irq_unmask = aplic_msi_irq_unmask,
> >> >+ .irq_set_type = aplic_irq_set_type,
> >> >+ .irq_eoi = aplic_msi_irq_eoi,
> >> >+#ifdef CONFIG_SMP
> >> >+ .irq_set_affinity = irq_chip_set_affinity_parent,
> >> >+#endif
> >> >+ .flags = IRQCHIP_SET_TYPE_MASKED |
> >> >+  IRQCHIP_SKIP_SET_WAKE |
> >> >+  IRQCHIP_MASK_ON_SUSPEND,
> >> >+};
> >> >+
> >> >+static int aplic_msi_irqdomain_translate(struct irq_domain *d,
> >> >+ struct irq_fwspec *fwspec,
> >> >+ unsigned long *hwirq,
> >> >+ unsigned int *type)
> >> >+{
> >> >+ struct aplic_priv *priv = platform_msi_get_host_data(d);
> >> >+
> >> >+ return aplic_irqdomain_translate(fwspec, priv->gsi_base, hwirq, type);
> >> >+}
> >> >+
> >> >+static int aplic_msi_irqdomain_alloc(struct irq_domain *domain,
> >> >+     unsigned int virq, unsigned int nr_irqs,
> >> >+     void *arg)
> >> >+{
> >> >+ int i, ret;
> >> >+ unsigned int type;
> >> >+ irq_hw_number_t hwirq;
> >> >+ struct irq_fwspec *fwspec = arg;
> >> >+ struct aplic_priv *priv = platform_msi_get_host_data(domain);
> >> >+
> >> >+ ret = aplic_irqdomain_translate(fwspec, priv->gsi_base, &hwirq, &type);
> >> >+ if (ret)
> >> >+ return ret;
> >> >+
> >> >+ ret = platform_msi_device_domain_alloc(domain, virq, nr_irqs);
> >> >+ if (ret)
> >> >+ return ret;
> >> >+
> >> >+ for (i = 0; i < nr_irqs; i++) {
> >> >+ irq_domain_set_info(domain, virq + i, hwirq + i,
> >> >+    &aplic_msi_chip, priv, handle_fasteoi_irq,
> >> >+    NULL, NULL);
> >> >+ /*
> >> >+ * APLIC does not implement irq_disable() so Linux interrupt
> >> >+ * subsystem will take a lazy approach for disabling an APLIC
> >> >+ * interrupt. This means APLIC 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 APLIC interrupts.
> >> >+ */
> >> >+ irq_set_status_flags(virq + i, IRQ_DISABLE_UNLAZY);
> >> >+ }
> >>
> >> For platfrom MSI irq, it will call irq_domain_set_info() and irq_set_status_flags() twice, the first one is here:
> >> platform_msi_device_domain_alloc->msi_domain_populate_irqs->irq_domain_alloc_irqs_hierarchy->imsic_irq_domain_alloc->irq_domain_set_info
> >>
> >> so  i think here this for(...) is not necessary, can be removed.
> >
> >If we remove then it breaks APLIC MSI-mode because we have
> >hierarchical irq domains where the APLIC-MSI domain is a child
> >of the IMSIC-PLAT domain.
> >
> >The irq_domain_set_info() called by IMSIC driver only sets irqchip
> >for IMSIC irq whereas irq_domain_set_info() called by APLIC driver
> >sets irqchip for APLIC irq. We use a different APLIC irqchip for the
> >APLIC domain to mask, unmask, and eoi irqs in an APLIC specific
> >way.
> >
>
> As your said APLIC-MSI domain is a child of the IMSIC-PLAT domain, so all of platform IRQ or wired IRQ will go to APLIC-MSI domain firstly.
> how about the pure MSI interrupt? for example the MSI of PCIe device or device driver call platform_msi_domain_alloc_irqs() to allocate a MSI ?

MSIs from PCIe device will directly go to IMSIC-PCI domain.

>  in this scenario, it also go into  APLIC-MSI domain firstly?

No

>
> would you like provide the steps how to test the PCI MSI for your patchset on QEMU? i run a QEMU system, but i cannot found any PCI devices using MSI, especially the virtio devices which using the platform IRQ.

Just add virtio-blk-pci OR some other PCI device in your QEMU
command line but ensure that you have corresponding device
driver enabled in your kernel.

>
> ~# cat /proc/interrupts
>            CPU0       CPU1       CPU2       CPU3
>  10:      38972      38946      38882      38924  RISC-V INTC   5 Edge      riscv-timer
>  11:          0       1149          0          0  APLIC-MSI   8 Level     virtio0
>  12:          0          0         21          0  APLIC-MSI   7 Level     virtio1
>  13:        149          0          0        218  APLIC-MSI  10 Level     ttyS0
> IPI0:        40         53         43         50  Rescheduling interrupts
> IPI1:      7518       8899       6679       7959  Function call interrupts
> IPI2:         0          0          0          0  CPU stop interrupts
> IPI3:         0          0          0          0  CPU stop (for crash dump) interrupts
> IPI4:         0          0          0          0  IRQ work interrupts
> IPI5:         0          0          0          0  Timer broadcast interrupts
>
>

Regards,
Anup

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