Re: [PATCH v8 13/16] irqchip: Add RISC-V advanced PLIC driver for direct-mode

[Sunil V L]

Hi Anup,

On Tue, Sep 12, 2023 at 11:19:25PM +0530, Anup Patel wrote:
> The RISC-V advanced interrupt architecture (AIA) specification defines
> advanced platform-level interrupt controller (APLIC) which has two modes
> of operation: 1) Direct mode and 2) MSI mode.
> (For more details, refer https://github.com/riscv/riscv-aia)
> 
> In APLIC direct-mode, wired interrupts are forwared to CPUs (or HARTs)
> as a local external interrupt.
> 
> We add a platform irqchip driver for the RISC-V APLIC direct-mode to
> support RISC-V platforms having only wired interrupts.
> 
> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
> ---
>  drivers/irqchip/Kconfig                  |   5 +
>  drivers/irqchip/Makefile                 |   1 +
>  drivers/irqchip/irq-riscv-aplic-direct.c | 326 +++++++++++++++++++++++
>  drivers/irqchip/irq-riscv-aplic-main.c   | 240 +++++++++++++++++
>  drivers/irqchip/irq-riscv-aplic-main.h   |  45 ++++
>  include/linux/irqchip/riscv-aplic.h      | 119 +++++++++
>  6 files changed, 736 insertions(+)
>  create mode 100644 drivers/irqchip/irq-riscv-aplic-direct.c
>  create mode 100644 drivers/irqchip/irq-riscv-aplic-main.c
>  create mode 100644 drivers/irqchip/irq-riscv-aplic-main.h
>  create mode 100644 include/linux/irqchip/riscv-aplic.h
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index a6aad78076a0..44c455084d09 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -545,6 +545,11 @@ config SIFIVE_PLIC
>  	select IRQ_DOMAIN_HIERARCHY
>  	select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
>  
> +config RISCV_APLIC
> +	bool
> +	depends on RISCV
> +	select IRQ_DOMAIN_HIERARCHY
> +
>  config RISCV_IMSIC
>  	bool
>  	depends on RISCV
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index abca445a3229..7f8289790ed8 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -95,6 +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-$(CONFIG_RISCV_APLIC)		+= irq-riscv-aplic-main.o irq-riscv-aplic-direct.o
>  obj-$(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-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
> new file mode 100644
> index 000000000000..e36d655a1490
> --- /dev/null
> +++ b/drivers/irqchip/irq-riscv-aplic-direct.c
> @@ -0,0 +1,326 @@
> +// 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/chained_irq.h>
> +#include <linux/irqchip/riscv-aplic.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/printk.h>
> +#include <linux/smp.h>
> +
> +#include "irq-riscv-aplic-main.h"
> +
> +#define APLIC_DISABLE_IDELIVERY		0
> +#define APLIC_ENABLE_IDELIVERY		1
> +#define APLIC_DISABLE_ITHRESHOLD	1
> +#define APLIC_ENABLE_ITHRESHOLD		0
> +
> +struct aplic_direct {
> +	struct aplic_priv	priv;
> +	struct irq_domain	*irqdomain;
> +	struct cpumask		lmask;
> +};
> +
> +struct aplic_idc {
> +	unsigned int		hart_index;
> +	void __iomem		*regs;
> +	struct aplic_direct	*direct;
> +};
> +
> +static unsigned int aplic_direct_parent_irq;
> +static DEFINE_PER_CPU(struct aplic_idc, aplic_idcs);
> +
> +static void aplic_direct_irq_eoi(struct irq_data *d)
> +{
> +	/*
> +	 * The fasteoi_handler requires irq_eoi() callback hence
> +	 * provide a dummy handler.
> +	 */
> +}
> +
> +#ifdef CONFIG_SMP
> +static int aplic_direct_set_affinity(struct irq_data *d,
> +				  const struct cpumask *mask_val, bool force)
> +{
> +	struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> +	struct aplic_direct *direct =
> +			container_of(priv, struct aplic_direct, priv);
> +	struct aplic_idc *idc;
> +	unsigned int cpu, val;
> +	struct cpumask amask;
> +	void __iomem *target;
> +
> +	cpumask_and(&amask, &direct->lmask, mask_val);
> +
> +	if (force)
> +		cpu = cpumask_first(&amask);
> +	else
> +		cpu = cpumask_any_and(&amask, cpu_online_mask);
> +
> +	if (cpu >= nr_cpu_ids)
> +		return -EINVAL;
> +
> +	idc = per_cpu_ptr(&aplic_idcs, cpu);
> +	target = priv->regs + APLIC_TARGET_BASE;
> +	target += (d->hwirq - 1) * sizeof(u32);
> +	val = idc->hart_index & APLIC_TARGET_HART_IDX_MASK;
> +	val <<= APLIC_TARGET_HART_IDX_SHIFT;
> +	val |= APLIC_DEFAULT_PRIORITY;
> +	writel(val, target);
> +
> +	irq_data_update_effective_affinity(d, cpumask_of(cpu));
> +
> +	return IRQ_SET_MASK_OK_DONE;
> +}
> +#endif
> +
> +static struct irq_chip aplic_direct_chip = {
> +	.name		= "APLIC-DIRECT",
> +	.irq_mask	= aplic_irq_mask,
> +	.irq_unmask	= aplic_irq_unmask,
> +	.irq_set_type	= aplic_irq_set_type,
> +	.irq_eoi	= aplic_direct_irq_eoi,
> +#ifdef CONFIG_SMP
> +	.irq_set_affinity = aplic_direct_set_affinity,
> +#endif
> +	.flags		= IRQCHIP_SET_TYPE_MASKED |
> +			  IRQCHIP_SKIP_SET_WAKE |
> +			  IRQCHIP_MASK_ON_SUSPEND,
> +};
> +
> +static int aplic_direct_irqdomain_translate(struct irq_domain *d,
> +					 struct irq_fwspec *fwspec,
> +					 unsigned long *hwirq,
> +					 unsigned int *type)
> +{
> +	struct aplic_priv *priv = d->host_data;
> +
> +	return aplic_irqdomain_translate(fwspec, priv->gsi_base,
> +					 hwirq, type);
> +}
> +
> +static int aplic_direct_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 = domain->host_data;
> +	struct aplic_direct *direct =
> +			container_of(priv, struct aplic_direct, priv);
> +
> +	ret = aplic_irqdomain_translate(fwspec, priv->gsi_base,
> +					&hwirq, &type);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; i < nr_irqs; i++) {
> +		irq_domain_set_info(domain, virq + i, hwirq + i,
> +				    &aplic_direct_chip, priv,
> +				    handle_fasteoi_irq, NULL, NULL);
> +		irq_set_affinity(virq + i, &direct->lmask);
> +		/* See the reason described in aplic_msi_irqdomain_alloc() */
> +		irq_set_status_flags(virq + i, IRQ_DISABLE_UNLAZY);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops aplic_direct_irqdomain_ops = {
> +	.translate	= aplic_direct_irqdomain_translate,
> +	.alloc		= aplic_direct_irqdomain_alloc,
> +	.free		= irq_domain_free_irqs_top,
> +};
> +
> +/*
> + * To handle an APLIC direct interrupts, we just read the CLAIMI register
> + * which will return highest priority pending interrupt and clear the
> + * pending bit of the interrupt. This process is repeated until CLAIMI
> + * register return zero value.
> + */
> +static void aplic_direct_handle_irq(struct irq_desc *desc)
> +{
> +	struct aplic_idc *idc = this_cpu_ptr(&aplic_idcs);
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct irq_domain *irqdomain = idc->direct->irqdomain;
> +	irq_hw_number_t hw_irq;
> +	int irq;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	while ((hw_irq = readl(idc->regs + APLIC_IDC_CLAIMI))) {
> +		hw_irq = hw_irq >> APLIC_IDC_TOPI_ID_SHIFT;
> +		irq = irq_find_mapping(irqdomain, hw_irq);
> +
> +		if (unlikely(irq <= 0))
> +			dev_warn_ratelimited(idc->direct->priv.dev,
> +					     "hw_irq %lu mapping not found\n",
> +					     hw_irq);
> +		else
> +			generic_handle_irq(irq);
> +	}
> +
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static void aplic_idc_set_delivery(struct aplic_idc *idc, bool en)
> +{
> +	u32 de = (en) ? APLIC_ENABLE_IDELIVERY : APLIC_DISABLE_IDELIVERY;
> +	u32 th = (en) ? APLIC_ENABLE_ITHRESHOLD : APLIC_DISABLE_ITHRESHOLD;
> +
> +	/* Priority must be less than threshold for interrupt triggering */
> +	writel(th, idc->regs + APLIC_IDC_ITHRESHOLD);
> +
> +	/* Delivery must be set to 1 for interrupt triggering */
> +	writel(de, idc->regs + APLIC_IDC_IDELIVERY);
> +}
> +
> +static int aplic_direct_dying_cpu(unsigned int cpu)
> +{
> +	if (aplic_direct_parent_irq)
> +		disable_percpu_irq(aplic_direct_parent_irq);
> +
> +	return 0;
> +}
> +
> +static int aplic_direct_starting_cpu(unsigned int cpu)
> +{
> +	if (aplic_direct_parent_irq)
> +		enable_percpu_irq(aplic_direct_parent_irq,
> +				irq_get_trigger_type(aplic_direct_parent_irq));
> +
> +	return 0;
> +}
> +
> +int aplic_direct_setup(struct device *dev, void __iomem *regs)
> +{
> +	int i, j, rc, cpu, setup_count = 0;
> +	struct fwnode_reference_args parent;
> +	struct aplic_direct *direct;
> +	struct aplic_priv *priv;
> +	struct irq_domain *domain;
> +	unsigned long hartid;
> +	struct aplic_idc *idc;
> +	u32 val;
> +
> +	direct = kzalloc(sizeof(*direct), GFP_KERNEL);
> +	if (!direct)
> +		return -ENOMEM;
> +	priv = &direct->priv;
> +
> +	rc = aplic_setup_priv(priv, dev, regs);
> +	if (rc) {
> +		dev_err(dev, "failed to create APLIC context\n");
> +		kfree(direct);
> +		return rc;
> +	}
> +
> +	/* Setup per-CPU IDC and target CPU mask */
> +	for (i = 0; i < priv->nr_idcs; i++) {
> +		rc = fwnode_property_get_reference_args(dev->fwnode,
> +				"interrupts-extended", "#interrupt-cells",
> +				0, i, &parent);
> +		if (rc) {
> +			dev_warn(dev, "parent irq for IDC%d not found\n", i);
> +			continue;
> +		}
> +
> +		/*
> +		 * Skip interrupts other than external interrupts for
> +		 * current privilege level.
> +		 */
> +		if (parent.args[0] != RV_IRQ_EXT)
> +			continue;
> +
> +		rc = riscv_get_intc_hartid(parent.fwnode, &hartid);
> +		if (rc) {
> +			dev_warn(dev, "invalid hartid for IDC%d\n", i);
> +			continue;
> +		}
> +
> +		cpu = riscv_hartid_to_cpuid(hartid);
> +		if (cpu < 0) {
> +			dev_warn(dev, "invalid cpuid for IDC%d\n", i);
> +			continue;
> +		}
> +
> +		cpumask_set_cpu(cpu, &direct->lmask);
> +
> +		idc = per_cpu_ptr(&aplic_idcs, cpu);
> +		idc->hart_index = i;
> +		idc->regs = priv->regs + APLIC_IDC_BASE + i * APLIC_IDC_SIZE;
> +		idc->direct = direct;
> +
> +		aplic_idc_set_delivery(idc, true);
> +
> +		/*
> +		 * Boot cpu might not have APLIC hart_index = 0 so check
> +		 * and update target registers of all interrupts.
> +		 */
> +		if (cpu == smp_processor_id() && idc->hart_index) {
> +			val = idc->hart_index & APLIC_TARGET_HART_IDX_MASK;
> +			val <<= APLIC_TARGET_HART_IDX_SHIFT;
> +			val |= APLIC_DEFAULT_PRIORITY;
> +			for (j = 1; j <= priv->nr_irqs; j++)
> +				writel(val, priv->regs + APLIC_TARGET_BASE +
> +					    (j - 1) * sizeof(u32));
> +		}
> +
> +		setup_count++;
> +	}
> +
> +	/* Find parent domain and register chained handler */
> +	domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(),
> +					  DOMAIN_BUS_ANY);
> +	if (!aplic_direct_parent_irq && domain) {
> +		aplic_direct_parent_irq = irq_create_mapping(domain, RV_IRQ_EXT);
> +		if (aplic_direct_parent_irq) {
> +			irq_set_chained_handler(aplic_direct_parent_irq,
> +						aplic_direct_handle_irq);
> +
> +			/*
> +			 * Setup CPUHP notifier to enable parent
> +			 * interrupt on all CPUs
> +			 */
> +			cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> +					  "irqchip/riscv/aplic:starting",
> +					  aplic_direct_starting_cpu,
> +					  aplic_direct_dying_cpu);
> +		}
> +	}
> +
> +	/* Fail if we were not able to setup IDC for any CPU */
> +	if (!setup_count) {
> +		kfree(direct);
> +		return -ENODEV;
> +	}
> +
> +	/* Setup global config and interrupt delivery */
> +	aplic_init_hw_global(priv, false);
> +
> +	/* Create irq domain instance for the APLIC */
> +	direct->irqdomain = irq_domain_create_linear(dev->fwnode,
> +						   priv->nr_irqs + 1,
> +						   &aplic_direct_irqdomain_ops,
> +						   priv);
> +	if (!direct->irqdomain) {
> +		dev_err(dev, "failed to create direct irq domain\n");
> +		kfree(direct);
> +		return -ENOMEM;
> +	}
> +
> +	/* Advertise the interrupt controller */
> +	dev_info(dev, "%d interrupts directly connected to %d CPUs\n",
> +		 priv->nr_irqs, priv->nr_idcs);
> +
> +	return 0;
> +}
> diff --git a/drivers/irqchip/irq-riscv-aplic-main.c b/drivers/irqchip/irq-riscv-aplic-main.c
> new file mode 100644
> index 000000000000..d62a096774c4
> --- /dev/null
> +++ b/drivers/irqchip/irq-riscv-aplic-main.c
> @@ -0,0 +1,240 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> + * Copyright (C) 2022 Ventana Micro Systems Inc.
> + */
> +
> +#include <linux/printk.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/irqchip/riscv-aplic.h>
> +
> +#include "irq-riscv-aplic-main.h"
> +
> +void aplic_irq_unmask(struct irq_data *d)
> +{
> +	struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> +
> +	writel(d->hwirq, priv->regs + APLIC_SETIENUM);
> +}
> +
> +void aplic_irq_mask(struct irq_data *d)
> +{
> +	struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> +
> +	writel(d->hwirq, priv->regs + APLIC_CLRIENUM);
> +}
> +
> +int aplic_irq_set_type(struct irq_data *d, unsigned int type)
> +{
> +	u32 val = 0;
> +	void __iomem *sourcecfg;
> +	struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> +
> +	switch (type) {
> +	case IRQ_TYPE_NONE:
> +		val = APLIC_SOURCECFG_SM_INACTIVE;
> +		break;
> +	case IRQ_TYPE_LEVEL_LOW:
> +		val = APLIC_SOURCECFG_SM_LEVEL_LOW;
> +		break;
> +	case IRQ_TYPE_LEVEL_HIGH:
> +		val = APLIC_SOURCECFG_SM_LEVEL_HIGH;
> +		break;
> +	case IRQ_TYPE_EDGE_FALLING:
> +		val = APLIC_SOURCECFG_SM_EDGE_FALL;
> +		break;
> +	case IRQ_TYPE_EDGE_RISING:
> +		val = APLIC_SOURCECFG_SM_EDGE_RISE;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	sourcecfg = priv->regs + APLIC_SOURCECFG_BASE;
> +	sourcecfg += (d->hwirq - 1) * sizeof(u32);
> +	writel(val, sourcecfg);
> +
> +	return 0;
> +}
> +
> +int aplic_irqdomain_translate(struct irq_fwspec *fwspec, u32 gsi_base,
> +			      unsigned long *hwirq, unsigned int *type)
> +{
> +	if (WARN_ON(fwspec->param_count < 2))
> +		return -EINVAL;
> +	if (WARN_ON(!fwspec->param[0]))
> +		return -EINVAL;
> +
> +	/* For DT, gsi_base is always zero. */
> +	*hwirq = fwspec->param[0] - gsi_base;
> +	*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
> +
> +	WARN_ON(*type == IRQ_TYPE_NONE);
> +
> +	return 0;
> +}
> +
> +void aplic_init_hw_global(struct aplic_priv *priv, bool msi_mode)
> +{
> +	u32 val;
> +#ifdef CONFIG_RISCV_M_MODE
> +	u32 valH;
> +
> +	if (msi_mode) {
> +		val = priv->msicfg.base_ppn;
> +		valH = ((u64)priv->msicfg.base_ppn >> 32) &
> +			APLIC_xMSICFGADDRH_BAPPN_MASK;
> +		valH |= (priv->msicfg.lhxw & APLIC_xMSICFGADDRH_LHXW_MASK)
> +			<< APLIC_xMSICFGADDRH_LHXW_SHIFT;
> +		valH |= (priv->msicfg.hhxw & APLIC_xMSICFGADDRH_HHXW_MASK)
> +			<< APLIC_xMSICFGADDRH_HHXW_SHIFT;
> +		valH |= (priv->msicfg.lhxs & APLIC_xMSICFGADDRH_LHXS_MASK)
> +			<< APLIC_xMSICFGADDRH_LHXS_SHIFT;
> +		valH |= (priv->msicfg.hhxs & APLIC_xMSICFGADDRH_HHXS_MASK)
> +			<< APLIC_xMSICFGADDRH_HHXS_SHIFT;
> +		writel(val, priv->regs + APLIC_xMSICFGADDR);
> +		writel(valH, priv->regs + APLIC_xMSICFGADDRH);
> +	}
> +#endif
> +
> +	/* Setup APLIC domaincfg register */
> +	val = readl(priv->regs + APLIC_DOMAINCFG);
> +	val |= APLIC_DOMAINCFG_IE;
> +	if (msi_mode)
> +		val |= APLIC_DOMAINCFG_DM;
> +	writel(val, priv->regs + APLIC_DOMAINCFG);
> +	if (readl(priv->regs + APLIC_DOMAINCFG) != val)
> +		dev_warn(priv->dev, "unable to write 0x%x in domaincfg\n",
> +			 val);
> +}
> +
> +static void aplic_init_hw_irqs(struct aplic_priv *priv)
> +{
> +	int i;
> +
> +	/* Disable all interrupts */
> +	for (i = 0; i <= priv->nr_irqs; i += 32)
> +		writel(-1U, priv->regs + APLIC_CLRIE_BASE +
> +			    (i / 32) * sizeof(u32));
> +
> +	/* Set interrupt type and default priority for all interrupts */
> +	for (i = 1; i <= priv->nr_irqs; i++) {
> +		writel(0, priv->regs + APLIC_SOURCECFG_BASE +
> +			  (i - 1) * sizeof(u32));
> +		writel(APLIC_DEFAULT_PRIORITY,
> +		       priv->regs + APLIC_TARGET_BASE +
> +		       (i - 1) * sizeof(u32));
> +	}
> +
> +	/* Clear APLIC domaincfg */
> +	writel(0, priv->regs + APLIC_DOMAINCFG);
> +}
> +
> +int aplic_setup_priv(struct aplic_priv *priv, struct device *dev,
> +		     void __iomem *regs)
> +{
> +	struct fwnode_reference_args parent;
> +	int rc;
> +
> +	/* Save device pointer and register base */
> +	priv->dev = dev;
> +	priv->regs = regs;
> +
> +	/*
> +	 * Find out GSI base number
> +	 *
> +	 * Note: DT does not define "riscv,gsi-base" property so GSI
> +	 * base is always zero for DT.
> +	 */
> +	rc = fwnode_property_read_u32_array(dev->fwnode, "riscv,gsi-base",
> +					    &priv->gsi_base, 1);
For DT, you can just initialize this to 0 without reading the property.

> +	if (rc)
> +		priv->gsi_base = 0;
> +
> +	/* Find out number of interrupt sources */
> +	rc = fwnode_property_read_u32_array(dev->fwnode, "riscv,num-sources",
> +					    &priv->nr_irqs, 1);
> +	if (rc) {
> +		dev_err(dev, "failed to get number of interrupt sources\n");
> +		return rc;
> +	}
> +
> +	/* Setup initial state APLIC interrupts */
> +	aplic_init_hw_irqs(priv);
> +
> +	/*
> +	 * Find out number of IDCs based on parent interrupts
> +	 *
> +	 * If "msi-parent" property is present then we ignore the
> +	 * APLIC IDCs which forces the APLIC driver to use MSI mode.
> +	 */
> +	if (!fwnode_property_present(dev->fwnode, "msi-parent")) {
> +		while (!fwnode_property_get_reference_args(dev->fwnode,
> +				"interrupts-extended", "#interrupt-cells",
> +				0, priv->nr_idcs, &parent))
> +			priv->nr_idcs++;
> +	}
> +
Can this finding nr_idcs be done after aplic_init_hw_irqs() above?

> +	return 0;
> +}
> +
> +static int aplic_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	void __iomem *regs;
> +	int rc;
> +
> +	/* Map the MMIO registers */
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "failed to get MMIO resource\n");
> +		return -EINVAL;
> +	}
> +	regs = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!regs) {
> +		dev_err(dev, "failed map MMIO registers\n");
> +		return -ENOMEM;
> +	}
> +
> +	/*
> +	 * If msi-parent property is present then setup APLIC MSI mode
> +	 * otherwise setup APLIC direct mode.
> +	 */
> +	if (fwnode_property_present(dev->fwnode, "msi-parent"))
Can this check be based on nr_idcs instead of checking for msi-parent
again?

Thanks!
Sunil
> +		rc = -ENODEV;
> +	else
> +		rc = aplic_direct_setup(dev, regs);
> +	if (rc) {
> +		dev_err(dev, "failed setup APLIC in %s mode\n",
> +			fwnode_property_present(dev->fwnode, "msi-parent") ?
> +			"MSI" : "direct");
> +		return rc;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id aplic_match[] = {
> +	{ .compatible = "riscv,aplic" },
> +	{}
> +};
> +
> +static struct platform_driver aplic_driver = {
> +	.driver = {
> +		.name		= "riscv-aplic",
> +		.of_match_table	= aplic_match,
> +	},
> +	.probe = aplic_probe,
> +};
> +
> +static int __init aplic_init(void)
> +{
> +	/*
> +	 * Register APLIC driver as early as possible so that APLIC
> +	 * platform device is probed as soon as it is created.
> +	 */
> +	return platform_driver_register(&aplic_driver);
> +}
> +core_initcall(aplic_init);
> diff --git a/drivers/irqchip/irq-riscv-aplic-main.h b/drivers/irqchip/irq-riscv-aplic-main.h
> new file mode 100644
> index 000000000000..474a04229334
> --- /dev/null
> +++ b/drivers/irqchip/irq-riscv-aplic-main.h
> @@ -0,0 +1,45 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> + * Copyright (C) 2022 Ventana Micro Systems Inc.
> + */
> +
> +#ifndef _IRQ_RISCV_APLIC_MAIN_H
> +#define _IRQ_RISCV_APLIC_MAIN_H
> +
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/fwnode.h>
> +
> +#define APLIC_DEFAULT_PRIORITY		1
> +
> +struct aplic_msicfg {
> +	phys_addr_t		base_ppn;
> +	u32			hhxs;
> +	u32			hhxw;
> +	u32			lhxs;
> +	u32			lhxw;
> +};
> +
> +struct aplic_priv {
> +	struct device		*dev;
> +	u32			gsi_base;
> +	u32			nr_irqs;
> +	u32			nr_idcs;
> +	void __iomem		*regs;
> +	struct aplic_msicfg	msicfg;
> +};
> +
> +void aplic_irq_unmask(struct irq_data *d);
> +void aplic_irq_mask(struct irq_data *d);
> +int aplic_irq_set_type(struct irq_data *d, unsigned int type);
> +int aplic_irqdomain_translate(struct irq_fwspec *fwspec, u32 gsi_base,
> +			      unsigned long *hwirq, unsigned int *type);
> +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);
> +
> +#endif
> diff --git a/include/linux/irqchip/riscv-aplic.h b/include/linux/irqchip/riscv-aplic.h
> new file mode 100644
> index 000000000000..97e198ea0109
> --- /dev/null
> +++ b/include/linux/irqchip/riscv-aplic.h
> @@ -0,0 +1,119 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> + * Copyright (C) 2022 Ventana Micro Systems Inc.
> + */
> +#ifndef __LINUX_IRQCHIP_RISCV_APLIC_H
> +#define __LINUX_IRQCHIP_RISCV_APLIC_H
> +
> +#include <linux/bitops.h>
> +
> +#define APLIC_MAX_IDC			BIT(14)
> +#define APLIC_MAX_SOURCE		1024
> +
> +#define APLIC_DOMAINCFG			0x0000
> +#define APLIC_DOMAINCFG_RDONLY		0x80000000
> +#define APLIC_DOMAINCFG_IE		BIT(8)
> +#define APLIC_DOMAINCFG_DM		BIT(2)
> +#define APLIC_DOMAINCFG_BE		BIT(0)
> +
> +#define APLIC_SOURCECFG_BASE		0x0004
> +#define APLIC_SOURCECFG_D		BIT(10)
> +#define APLIC_SOURCECFG_CHILDIDX_MASK	0x000003ff
> +#define APLIC_SOURCECFG_SM_MASK	0x00000007
> +#define APLIC_SOURCECFG_SM_INACTIVE	0x0
> +#define APLIC_SOURCECFG_SM_DETACH	0x1
> +#define APLIC_SOURCECFG_SM_EDGE_RISE	0x4
> +#define APLIC_SOURCECFG_SM_EDGE_FALL	0x5
> +#define APLIC_SOURCECFG_SM_LEVEL_HIGH	0x6
> +#define APLIC_SOURCECFG_SM_LEVEL_LOW	0x7
> +
> +#define APLIC_MMSICFGADDR		0x1bc0
> +#define APLIC_MMSICFGADDRH		0x1bc4
> +#define APLIC_SMSICFGADDR		0x1bc8
> +#define APLIC_SMSICFGADDRH		0x1bcc
> +
> +#ifdef CONFIG_RISCV_M_MODE
> +#define APLIC_xMSICFGADDR		APLIC_MMSICFGADDR
> +#define APLIC_xMSICFGADDRH		APLIC_MMSICFGADDRH
> +#else
> +#define APLIC_xMSICFGADDR		APLIC_SMSICFGADDR
> +#define APLIC_xMSICFGADDRH		APLIC_SMSICFGADDRH
> +#endif
> +
> +#define APLIC_xMSICFGADDRH_L		BIT(31)
> +#define APLIC_xMSICFGADDRH_HHXS_MASK	0x1f
> +#define APLIC_xMSICFGADDRH_HHXS_SHIFT	24
> +#define APLIC_xMSICFGADDRH_LHXS_MASK	0x7
> +#define APLIC_xMSICFGADDRH_LHXS_SHIFT	20
> +#define APLIC_xMSICFGADDRH_HHXW_MASK	0x7
> +#define APLIC_xMSICFGADDRH_HHXW_SHIFT	16
> +#define APLIC_xMSICFGADDRH_LHXW_MASK	0xf
> +#define APLIC_xMSICFGADDRH_LHXW_SHIFT	12
> +#define APLIC_xMSICFGADDRH_BAPPN_MASK	0xfff
> +
> +#define APLIC_xMSICFGADDR_PPN_SHIFT	12
> +
> +#define APLIC_xMSICFGADDR_PPN_HART(__lhxs) \
> +	(BIT(__lhxs) - 1)
> +
> +#define APLIC_xMSICFGADDR_PPN_LHX_MASK(__lhxw) \
> +	(BIT(__lhxw) - 1)
> +#define APLIC_xMSICFGADDR_PPN_LHX_SHIFT(__lhxs) \
> +	((__lhxs))
> +#define APLIC_xMSICFGADDR_PPN_LHX(__lhxw, __lhxs) \
> +	(APLIC_xMSICFGADDR_PPN_LHX_MASK(__lhxw) << \
> +	 APLIC_xMSICFGADDR_PPN_LHX_SHIFT(__lhxs))
> +
> +#define APLIC_xMSICFGADDR_PPN_HHX_MASK(__hhxw) \
> +	(BIT(__hhxw) - 1)
> +#define APLIC_xMSICFGADDR_PPN_HHX_SHIFT(__hhxs) \
> +	((__hhxs) + APLIC_xMSICFGADDR_PPN_SHIFT)
> +#define APLIC_xMSICFGADDR_PPN_HHX(__hhxw, __hhxs) \
> +	(APLIC_xMSICFGADDR_PPN_HHX_MASK(__hhxw) << \
> +	 APLIC_xMSICFGADDR_PPN_HHX_SHIFT(__hhxs))
> +
> +#define APLIC_IRQBITS_PER_REG		32
> +
> +#define APLIC_SETIP_BASE		0x1c00
> +#define APLIC_SETIPNUM			0x1cdc
> +
> +#define APLIC_CLRIP_BASE		0x1d00
> +#define APLIC_CLRIPNUM			0x1ddc
> +
> +#define APLIC_SETIE_BASE		0x1e00
> +#define APLIC_SETIENUM			0x1edc
> +
> +#define APLIC_CLRIE_BASE		0x1f00
> +#define APLIC_CLRIENUM			0x1fdc
> +
> +#define APLIC_SETIPNUM_LE		0x2000
> +#define APLIC_SETIPNUM_BE		0x2004
> +
> +#define APLIC_GENMSI			0x3000
> +
> +#define APLIC_TARGET_BASE		0x3004
> +#define APLIC_TARGET_HART_IDX_SHIFT	18
> +#define APLIC_TARGET_HART_IDX_MASK	0x3fff
> +#define APLIC_TARGET_GUEST_IDX_SHIFT	12
> +#define APLIC_TARGET_GUEST_IDX_MASK	0x3f
> +#define APLIC_TARGET_IPRIO_MASK	0xff
> +#define APLIC_TARGET_EIID_MASK	0x7ff
> +
> +#define APLIC_IDC_BASE			0x4000
> +#define APLIC_IDC_SIZE			32
> +
> +#define APLIC_IDC_IDELIVERY		0x00
> +
> +#define APLIC_IDC_IFORCE		0x04
> +
> +#define APLIC_IDC_ITHRESHOLD		0x08
> +
> +#define APLIC_IDC_TOPI			0x18
> +#define APLIC_IDC_TOPI_ID_SHIFT	16
> +#define APLIC_IDC_TOPI_ID_MASK	0x3ff
> +#define APLIC_IDC_TOPI_PRIO_MASK	0xff
> +
> +#define APLIC_IDC_CLAIMI		0x1c
> +
> +#endif
> -- 
> 2.34.1
>