Re: [PATCH v11 12/14] irqchip/riscv-aplic: Add support for MSI-mode

[Anup Patel]

On Thu, Nov 2, 2023 at 11:55 AM Ben <figure1802@xxxxxxx> wrote:
>
>
> At 2023-10-24 01:27:58, "Anup Patel" <apatel@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxx>
> >---
> > 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.

Regards,
Anup


>
>
> >+
> >+ return 0;
> >+}
> >+
> >+static const struct irq_domain_ops aplic_msi_irqdomain_ops = {
> >+ .translate = aplic_msi_irqdomain_translate,
> >+ .alloc = aplic_msi_irqdomain_alloc,
> >+ .free = platform_msi_device_domain_free,
> >+};
> >+
> >+static void aplic_msi_write_msg(struct msi_desc *desc, struct msi_msg *msg)
> >+{
> >+ unsigned int group_index, hart_index, guest_index, val;
> >+ struct irq_data *d = irq_get_irq_data(desc->irq);
> >+ struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> >+ struct aplic_msicfg *mc = &priv->msicfg;
> >+ phys_addr_t tppn, tbppn, msg_addr;
> >+ void __iomem *target;
> >+
> >+ /* For zeroed MSI, simply write zero into the target register */
> >+ if (!msg->address_hi && !msg->address_lo && !msg->data) {
> >+ target = priv->regs + APLIC_TARGET_BASE;
> >+ target += (d->hwirq - 1) * sizeof(u32);
> >+ writel(0, target);
> >+ return;
> >+ }
> >+
> >+ /* Sanity check on message data */
> >+ WARN_ON(msg->data > APLIC_TARGET_EIID_MASK);
> >+
> >+ /* Compute target MSI address */
> >+ msg_addr = (((u64)msg->address_hi) << 32) | msg->address_lo;
> >+ tppn = msg_addr >> APLIC_xMSICFGADDR_PPN_SHIFT;
> >+
> >+ /* Compute target HART Base PPN */
> >+ tbppn = tppn;
> >+ tbppn &= ~APLIC_xMSICFGADDR_PPN_HART(mc->lhxs);
> >+ tbppn &= ~APLIC_xMSICFGADDR_PPN_LHX(mc->lhxw, mc->lhxs);
> >+ tbppn &= ~APLIC_xMSICFGADDR_PPN_HHX(mc->hhxw, mc->hhxs);
> >+ WARN_ON(tbppn != mc->base_ppn);
> >+
> >+ /* Compute target group and hart indexes */
> >+ group_index = (tppn >> APLIC_xMSICFGADDR_PPN_HHX_SHIFT(mc->hhxs)) &
> >+     APLIC_xMSICFGADDR_PPN_HHX_MASK(mc->hhxw);
> >+ hart_index = (tppn >> APLIC_xMSICFGADDR_PPN_LHX_SHIFT(mc->lhxs)) &
> >+     APLIC_xMSICFGADDR_PPN_LHX_MASK(mc->lhxw);
> >+ hart_index |= (group_index << mc->lhxw);
> >+ WARN_ON(hart_index > APLIC_TARGET_HART_IDX_MASK);
> >+
> >+ /* Compute target guest index */
> >+ guest_index = tppn & APLIC_xMSICFGADDR_PPN_HART(mc->lhxs);
> >+ WARN_ON(guest_index > APLIC_TARGET_GUEST_IDX_MASK);
> >+
> >+ /* Update IRQ TARGET register */
> >+ target = priv->regs + APLIC_TARGET_BASE;
> >+ target += (d->hwirq - 1) * sizeof(u32);
> >+ val = (hart_index & APLIC_TARGET_HART_IDX_MASK)
> >+ << APLIC_TARGET_HART_IDX_SHIFT;
> >+ val |= (guest_index & APLIC_TARGET_GUEST_IDX_MASK)
> >+ << APLIC_TARGET_GUEST_IDX_SHIFT;
> >+ val |= (msg->data & APLIC_TARGET_EIID_MASK);
> >+ writel(val, target);
> >+}
> >+
> >+int aplic_msi_setup(struct device *dev, void __iomem *regs)
> >+{
> >+ const struct imsic_global_config *imsic_global;
> >+ struct irq_domain *irqdomain;
> >+ struct aplic_priv *priv;
> >+ struct aplic_msicfg *mc;
> >+ phys_addr_t pa;
> >+ int rc;
> >+
> >+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> >+ if (!priv)
> >+ return -ENOMEM;
> >+
> >+ rc = aplic_setup_priv(priv, dev, regs);
> >+ if (!priv) {
> >+ dev_err(dev, "failed to create APLIC context\n");
> >+ return rc;
> >+ }
> >+ mc = &priv->msicfg;
> >+
> >+ /*
> >+ * The APLIC outgoing MSI config registers assume target MSI
> >+ * controller to be RISC-V AIA IMSIC controller.
> >+ */
> >+ imsic_global = imsic_get_global_config();
> >+ if (!imsic_global) {
> >+ dev_err(dev, "IMSIC global config not found\n");
> >+ return -ENODEV;
> >+ }
> >+
> >+ /* Find number of guest index bits (LHXS) */
> >+ mc->lhxs = imsic_global->guest_index_bits;
> >+ if (APLIC_xMSICFGADDRH_LHXS_MASK < mc->lhxs) {
> >+ dev_err(dev, "IMSIC guest index bits big for APLIC LHXS\n");
> >+ return -EINVAL;
> >+ }
> >+
> >+ /* Find number of HART index bits (LHXW) */
> >+ mc->lhxw = imsic_global->hart_index_bits;
> >+ if (APLIC_xMSICFGADDRH_LHXW_MASK < mc->lhxw) {
> >+ dev_err(dev, "IMSIC hart index bits big for APLIC LHXW\n");
> >+ return -EINVAL;
> >+ }
> >+
> >+ /* Find number of group index bits (HHXW) */
> >+ mc->hhxw = imsic_global->group_index_bits;
> >+ if (APLIC_xMSICFGADDRH_HHXW_MASK < mc->hhxw) {
> >+ dev_err(dev, "IMSIC group index bits big for APLIC HHXW\n");
> >+ return -EINVAL;
> >+ }
> >+
> >+ /* Find first bit position of group index (HHXS) */
> >+ mc->hhxs = imsic_global->group_index_shift;
> >+ if (mc->hhxs < (2 * APLIC_xMSICFGADDR_PPN_SHIFT)) {
> >+ dev_err(dev, "IMSIC group index shift should be >= %d\n",
> >+ (2 * APLIC_xMSICFGADDR_PPN_SHIFT));
> >+ return -EINVAL;
> >+ }
> >+ mc->hhxs -= (2 * APLIC_xMSICFGADDR_PPN_SHIFT);
> >+ if (APLIC_xMSICFGADDRH_HHXS_MASK < mc->hhxs) {
> >+ dev_err(dev, "IMSIC group index shift big for APLIC HHXS\n");
> >+ return -EINVAL;
> >+ }
> >+
> >+ /* Compute PPN base */
> >+ mc->base_ppn = imsic_global->base_addr >> APLIC_xMSICFGADDR_PPN_SHIFT;
> >+ mc->base_ppn &= ~APLIC_xMSICFGADDR_PPN_HART(mc->lhxs);
> >+ mc->base_ppn &= ~APLIC_xMSICFGADDR_PPN_LHX(mc->lhxw, mc->lhxs);
> >+ mc->base_ppn &= ~APLIC_xMSICFGADDR_PPN_HHX(mc->hhxw, mc->hhxs);
> >+
> >+ /* Setup global config and interrupt delivery */
> >+ aplic_init_hw_global(priv, true);
> >+
> >+ /* Set the APLIC device MSI domain if not available */
> >+ if (!dev_get_msi_domain(dev)) {
> >+ /*
> >+ * The device MSI domain for OF devices is only set at the
> >+ * time of populating/creating OF device. If the device MSI
> >+ * domain is discovered later after the OF device is created
> >+ * then we need to set it explicitly before using any platform
> >+ * MSI functions.
> >+ *
> >+ * In case of APLIC device, the parent MSI domain is always
> >+ * IMSIC and the IMSIC MSI domains are created later through
> >+ * the platform driver probing so we set it explicitly here.
> >+ */
> >+ if (is_of_node(dev->fwnode))
> >+ of_msi_configure(dev, to_of_node(dev->fwnode));
> >+ }
> >+
> >+ /* Create irq domain instance for the APLIC MSI-mode */
> >+ irqdomain = platform_msi_create_device_domain(
> >+ dev, priv->nr_irqs + 1,
> >+ aplic_msi_write_msg,
> >+ &aplic_msi_irqdomain_ops,
> >+ priv);
> >+ if (!irqdomain) {
> >+ dev_err(dev, "failed to create MSI irq domain\n");
> >+ return -ENOMEM;
> >+ }
> >+
> >+ /* Advertise the interrupt controller */
> >+ pa = priv->msicfg.base_ppn << APLIC_xMSICFGADDR_PPN_SHIFT;
> >+ dev_info(dev, "%d interrupts forwared to MSI base %pa\n",
> >+ priv->nr_irqs, &pa);
> >+
> >+ return 0;
> >+}
> >--
> >2.34.1
> >
> >
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