[PATCH v8 14/16] irqchip/riscv-aplic: Add support for MSI-mode

Anup Patel
2023-09-12T17:51:55Z

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@ventanamicro.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 44c455084d09..31c069bf7343 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -550,6 +550,12 @@ 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 d62a096774c4..f225ac77ea3c 100644
--- a/drivers/irqchip/irq-riscv-aplic-main.c
+++ b/drivers/irqchip/irq-riscv-aplic-main.c
@@ -203,7 +203,7 @@ static int aplic_probe(struct platform_device *pdev)
* otherwise setup APLIC direct mode.
*/
if (fwnode_property_present(dev->fwnode, "msi-parent"))
- 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);
+ }
+
+ 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;
+}