Message-Id: <20250513-gicv5-host-v4-25-b36e9b15a6c3@kernel.org>
Date: Tue, 13 May 2025 19:48:18 +0200
From: Lorenzo Pieralisi <lpieralisi@...nel.org>
To: Marc Zyngier <maz@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>, 
 Sascha Bischoff <sascha.bischoff@....com>, 
 Timothy Hayes <timothy.hayes@....com>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Mark Rutland <mark.rutland@....com>, Jiri Slaby <jirislaby@...nel.org>, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, Lorenzo Pieralisi <lpieralisi@...nel.org>
Subject: [PATCH v4 25/26] irqchip/gic-v5: Add GICv5 IWB support

The GICv5 architecture implements the Interrupt Wire Bridge (IWB) in
order to support wired interrupts that cannot be connected directly
to an IRS and instead uses the ITS to translate a wire event into
an IRQ signal.

Add the wired-to-MSI IWB driver to manage IWB wired interrupts.

An IWB is connected to an ITS and it has its own deviceID for all
interrupt wires that it manages; the IWB input wire number must be
exposed to the ITS as an eventID with a 1:1 mapping.

This eventID is not programmable and therefore requires a new
msi_alloc_info_t flag to make sure the ITS driver does not allocate
an eventid for the wire but rather it uses the msi_alloc_info_t.hwirq
number to gather the ITS eventID.

Co-developed-by: Sascha Bischoff <sascha.bischoff@....com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@....com>
Co-developed-by: Timothy Hayes <timothy.hayes@....com>
Signed-off-by: Timothy Hayes <timothy.hayes@....com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/Makefile           |   3 +-
 drivers/irqchip/irq-gic-v5-its.c   |  40 ++++--
 drivers/irqchip/irq-gic-v5-iwb.c   | 285 +++++++++++++++++++++++++++++++++++++
 include/asm-generic/msi.h          |   1 +
 include/linux/irqchip/arm-gic-v5.h |  14 ++
 5 files changed, 333 insertions(+), 10 deletions(-)

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 18724910f2bdc20597d3d3e4852d593a4bd163da..1f1b22c4a39ea3c72c521c01efcc63ab0a77b31f 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -36,7 +36,8 @@ obj-$(CONFIG_ARM_GIC_ITS_PARENT)	+= irq-gic-its-msi-parent.o
 obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o irq-gic-v4.o
 obj-$(CONFIG_ARM_GIC_V3_ITS_FSL_MC)	+= irq-gic-v3-its-fsl-mc-msi.o
 obj-$(CONFIG_PARTITION_PERCPU)		+= irq-partition-percpu.o
-obj-$(CONFIG_ARM_GIC_V5)		+= irq-gic-v5.o irq-gic-v5-irs.o irq-gic-v5-its.o
+obj-$(CONFIG_ARM_GIC_V5)		+= irq-gic-v5.o irq-gic-v5-irs.o irq-gic-v5-its.o \
+					   irq-gic-v5-iwb.o
 obj-$(CONFIG_HISILICON_IRQ_MBIGEN)	+= irq-mbigen.o
 obj-$(CONFIG_ARM_NVIC)			+= irq-nvic.o
 obj-$(CONFIG_ARM_VIC)			+= irq-vic.o
diff --git a/drivers/irqchip/irq-gic-v5-its.c b/drivers/irqchip/irq-gic-v5-its.c
index e26becc5ce504acf4ed83c4c3b1b8d7903426ba4..f01b8e832c40a908e709ff75f7388baf21751bf7 100644
--- a/drivers/irqchip/irq-gic-v5-its.c
+++ b/drivers/irqchip/irq-gic-v5-its.c
@@ -863,19 +863,41 @@ static void gicv5_its_unmap_event(struct gicv5_its_dev *its_dev, u16 event_id)
 	gicv5_its_itt_cache_inv(its, its_dev->device_id, event_id);
 }
 
-static int gicv5_its_alloc_eventid(struct gicv5_its_dev *its_dev,
+static int gicv5_its_alloc_eventid(struct gicv5_its_dev *its_dev, msi_alloc_info_t *info,
 				   unsigned int nr_irqs, u32 *eventid)
 {
-	int ret;
+	int event_id_base;
 
-	ret = bitmap_find_free_region(its_dev->event_map,
-				      its_dev->num_events,
-				      get_count_order(nr_irqs));
+	if (!(info->flags & MSI_ALLOC_FLAGS_FIXED_MSG_DATA)) {
+		event_id_base = bitmap_find_free_region(its_dev->event_map,
+							its_dev->num_events,
+							get_count_order(nr_irqs));
+		if (event_id_base < 0)
+			return event_id_base;
+	} else {
+		/*
+		 * We want to have a fixed EventID mapped for hardcoded
+		 * message data allocations.
+		 */
+		if (WARN_ON_ONCE(nr_irqs != 1))
+			return -EINVAL;
 
-	if (ret < 0)
-		return ret;
+		event_id_base = info->hwirq;
 
-	*eventid = ret;
+		if (event_id_base >= its_dev->num_events) {
+			pr_err("EventID ouside of ITT range; cannot allocate an ITT entry!\n");
+
+			return -EINVAL;
+		}
+
+		if (test_and_set_bit(event_id_base, its_dev->event_map)) {
+			pr_warn("Can't reserve event_id bitmap\n");
+			return -EINVAL;
+
+		}
+	}
+
+	*eventid = event_id_base;
 
 	return 0;
 }
@@ -905,7 +927,7 @@ static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int vi
 	msi_info = msi_get_domain_info(domain);
 	its = msi_info->data;
 
-	ret = gicv5_its_alloc_eventid(its_dev, nr_irqs, &event_id_base);
+	ret = gicv5_its_alloc_eventid(its_dev, info, nr_irqs, &event_id_base);
 	if (ret)
 		return ret;
 
diff --git a/drivers/irqchip/irq-gic-v5-iwb.c b/drivers/irqchip/irq-gic-v5-iwb.c
new file mode 100644
index 0000000000000000000000000000000000000000..d65afc8f0192977836dc5d7a4a7d3db1a06242f2
--- /dev/null
+++ b/drivers/irqchip/irq-gic-v5-iwb.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024-2025 ARM Limited, All Rights Reserved.
+ */
+#define pr_fmt(fmt)	"GICv5 IWB: " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/msi.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+
+#include <linux/irqchip.h>
+#include <linux/irqchip/arm-gic-v5.h>
+
+struct gicv5_iwb_chip_data {
+	void __iomem		*iwb_base;
+	u16			nr_regs;
+};
+
+static u32 iwb_readl_relaxed(struct gicv5_iwb_chip_data *iwb_node, const u32 reg_offset)
+{
+	return readl_relaxed(iwb_node->iwb_base + reg_offset);
+}
+
+static void iwb_writel_relaxed(struct gicv5_iwb_chip_data *iwb_node, const u32 val,
+			       const u32 reg_offset)
+{
+	writel_relaxed(val, iwb_node->iwb_base + reg_offset);
+}
+
+static int gicv5_iwb_wait_for_wenabler(struct gicv5_iwb_chip_data *iwb_node)
+{
+	return gicv5_wait_for_op_atomic(iwb_node->iwb_base, GICV5_IWB_WENABLE_STATUSR,
+					GICV5_IWB_WENABLE_STATUSR_IDLE, NULL);
+}
+
+static int __gicv5_iwb_set_wire_enable(struct gicv5_iwb_chip_data *iwb_node,
+				       u32 iwb_wire, bool enable)
+{
+	u32 n = iwb_wire / 32;
+	u8 i = iwb_wire % 32;
+	u32 val;
+
+	if (n >= iwb_node->nr_regs) {
+		pr_err("IWB_WENABLER<n> is invalid for n=%u\n", n);
+		return -EINVAL;
+	}
+
+	/*
+	 * Enable IWB wire/pin at this point
+	 * Note: This is not the same as enabling the interrupt
+	 */
+	val = iwb_readl_relaxed(iwb_node, GICV5_IWB_WENABLER + (4 * n));
+	if (enable)
+		val |= BIT(i);
+	else
+		val &= ~BIT(i);
+	iwb_writel_relaxed(iwb_node, val, GICV5_IWB_WENABLER + (4 * n));
+
+	return gicv5_iwb_wait_for_wenabler(iwb_node);
+}
+
+static int gicv5_iwb_enable_wire(struct gicv5_iwb_chip_data *iwb_node,
+				 u32 iwb_wire)
+{
+	return __gicv5_iwb_set_wire_enable(iwb_node, iwb_wire, true);
+}
+
+static int gicv5_iwb_disable_wire(struct gicv5_iwb_chip_data *iwb_node,
+				  u32 iwb_wire)
+{
+	return __gicv5_iwb_set_wire_enable(iwb_node, iwb_wire, false);
+}
+
+static void gicv5_iwb_irq_disable(struct irq_data *d)
+{
+	struct gicv5_iwb_chip_data *iwb_node = irq_data_get_irq_chip_data(d);
+
+	gicv5_iwb_disable_wire(iwb_node, d->hwirq);
+	irq_chip_disable_parent(d);
+}
+
+static void gicv5_iwb_irq_enable(struct irq_data *d)
+{
+	struct gicv5_iwb_chip_data *iwb_node = irq_data_get_irq_chip_data(d);
+
+	gicv5_iwb_enable_wire(iwb_node, d->hwirq);
+	irq_chip_enable_parent(d);
+}
+
+static int gicv5_iwb_set_type(struct irq_data *d, unsigned int type)
+{
+	struct gicv5_iwb_chip_data *iwb_node = irq_data_get_irq_chip_data(d);
+	u32 iwb_wire, n, wtmr;
+	u8 i;
+
+	iwb_wire = d->hwirq;
+
+	i = iwb_wire % 32;
+	n = iwb_wire / 32;
+
+	if (n >= iwb_node->nr_regs) {
+		pr_err_once("reg %u out of range\n", n);
+		return -EINVAL;
+	}
+
+	wtmr = iwb_readl_relaxed(iwb_node, GICV5_IWB_WTMR + (4 * n));
+
+	switch (type) {
+	case IRQ_TYPE_LEVEL_HIGH:
+	case IRQ_TYPE_LEVEL_LOW:
+		wtmr |= BIT(i);
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+	case IRQ_TYPE_EDGE_FALLING:
+		wtmr &= ~BIT(i);
+		break;
+	default:
+		pr_debug("unexpected wire trigger mode");
+		return -EINVAL;
+	}
+
+	iwb_writel_relaxed(iwb_node, wtmr, GICV5_IWB_WTMR + (4 * n));
+
+	return 0;
+}
+
+static void gicv5_iwb_domain_set_desc(msi_alloc_info_t *alloc_info, struct msi_desc *desc)
+{
+	alloc_info->desc = desc;
+	alloc_info->hwirq = (u32)desc->data.icookie.value;
+}
+
+static int gicv5_iwb_irq_domain_translate(struct irq_domain *d,
+					  struct irq_fwspec *fwspec,
+					  irq_hw_number_t *hwirq,
+					  unsigned int *type)
+{
+	if (!is_of_node(fwspec->fwnode))
+		return -EINVAL;
+
+	if (fwspec->param_count < 2)
+		return -EINVAL;
+
+	/*
+	 * param[0] is be the wire
+	 * param[1] is the interrupt type
+	 */
+	*hwirq = fwspec->param[0];
+	*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
+
+	return 0;
+}
+
+static void gicv5_iwb_write_msi_msg(struct irq_data *d, struct msi_msg *msg) {}
+
+static const struct msi_domain_template iwb_msi_template = {
+	.chip = {
+		.name			= "GICv5-IWB",
+		.irq_mask		= irq_chip_mask_parent,
+		.irq_unmask		= irq_chip_unmask_parent,
+		.irq_enable		= gicv5_iwb_irq_enable,
+		.irq_disable		= gicv5_iwb_irq_disable,
+		.irq_eoi		= irq_chip_eoi_parent,
+		.irq_set_type		= gicv5_iwb_set_type,
+		.irq_write_msi_msg	= gicv5_iwb_write_msi_msg,
+		.irq_set_affinity	= irq_chip_set_affinity_parent,
+		.irq_get_irqchip_state	= irq_chip_get_parent_state,
+		.irq_set_irqchip_state	= irq_chip_set_parent_state,
+		.flags			= IRQCHIP_SET_TYPE_MASKED |
+					  IRQCHIP_SKIP_SET_WAKE |
+					  IRQCHIP_MASK_ON_SUSPEND,
+	},
+
+	.ops = {
+		.set_desc		= gicv5_iwb_domain_set_desc,
+		.msi_translate		= gicv5_iwb_irq_domain_translate,
+	},
+
+	.info = {
+		.bus_token		= DOMAIN_BUS_WIRED_TO_MSI,
+		.flags			= MSI_FLAG_USE_DEV_FWNODE,
+	},
+
+	.alloc_info = {
+		.flags			= MSI_ALLOC_FLAGS_FIXED_MSG_DATA,
+	},
+};
+
+static bool gicv5_iwb_create_device_domain(struct device *dev, unsigned int size,
+				     struct gicv5_iwb_chip_data *iwb_node)
+{
+	if (WARN_ON_ONCE(!dev->msi.domain))
+		return false;
+
+	return msi_create_device_irq_domain(dev, MSI_DEFAULT_DOMAIN,
+					    &iwb_msi_template, size,
+					    NULL, iwb_node);
+}
+
+static struct gicv5_iwb_chip_data *
+gicv5_iwb_init_bases(void __iomem *iwb_base, struct platform_device *pdev)
+{
+	struct gicv5_iwb_chip_data *iwb_node __free(kfree) = NULL;
+	u32 nr_wires, idr0, cr0;
+	unsigned int n;
+	int ret;
+
+	iwb_node = kzalloc(sizeof(*iwb_node), GFP_KERNEL);
+	if (!iwb_node)
+		return ERR_PTR(-ENOMEM);
+
+	iwb_node->iwb_base = iwb_base;
+
+	idr0 = iwb_readl_relaxed(iwb_node, GICV5_IWB_IDR0);
+	nr_wires = (FIELD_GET(GICV5_IWB_IDR0_IW_RANGE, idr0) + 1) * 32;
+
+	cr0 = iwb_readl_relaxed(iwb_node, GICV5_IWB_CR0);
+	if (!FIELD_GET(GICV5_IWB_CR0_IWBEN, cr0)) {
+		dev_err(&pdev->dev, "IWB must be enabled in firmware\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	iwb_node->nr_regs = FIELD_GET(GICV5_IWB_IDR0_IW_RANGE, idr0) + 1;
+
+	for (n = 0; n < iwb_node->nr_regs; n++)
+		iwb_writel_relaxed(iwb_node, 0, GICV5_IWB_WENABLER + (sizeof(u32) * n));
+
+	ret = gicv5_iwb_wait_for_wenabler(iwb_node);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!gicv5_iwb_create_device_domain(&pdev->dev, nr_wires, iwb_node))
+		return ERR_PTR(-ENOMEM);
+
+	return_ptr(iwb_node);
+}
+
+static int gicv5_iwb_device_probe(struct platform_device *pdev)
+{
+	struct gicv5_iwb_chip_data *iwb_node;
+	void __iomem *iwb_base;
+	struct resource *res;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	iwb_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!iwb_base) {
+		dev_err(&pdev->dev, "failed to ioremap %pR\n", res);
+		return -ENOMEM;
+	}
+
+	iwb_node = gicv5_iwb_init_bases(iwb_base, pdev);
+	if (IS_ERR(iwb_node)) {
+		ret = PTR_ERR(iwb_node);
+		goto out_unmap;
+	}
+
+	return 0;
+out_unmap:
+	iounmap(iwb_base);
+	return ret;
+}
+
+static const struct of_device_id gicv5_iwb_of_match[] = {
+	{ .compatible = "arm,gic-v5-iwb" },
+	{ /* END */ }
+};
+MODULE_DEVICE_TABLE(of, gicv5_iwb_of_match);
+
+static struct platform_driver gicv5_iwb_platform_driver = {
+	.driver = {
+		.name			= "GICv5 IWB",
+		.of_match_table		= gicv5_iwb_of_match,
+		.suppress_bind_attrs	= true,
+	},
+	.probe				= gicv5_iwb_device_probe,
+};
+
+module_platform_driver(gicv5_iwb_platform_driver);
diff --git a/include/asm-generic/msi.h b/include/asm-generic/msi.h
index 124c734ca5d9fc0a204a2a3d951036e8270056f0..92cca4b23f138f7a8005dbdbe7f78b20e97f494c 100644
--- a/include/asm-generic/msi.h
+++ b/include/asm-generic/msi.h
@@ -33,6 +33,7 @@ typedef struct msi_alloc_info {
 
 /* Device generating MSIs is proxying for another device */
 #define MSI_ALLOC_FLAGS_PROXY_DEVICE	(1UL << 0)
+#define MSI_ALLOC_FLAGS_FIXED_MSG_DATA	(1UL << 1)
 
 #define GENERIC_MSI_DOMAIN_OPS		1
 
diff --git a/include/linux/irqchip/arm-gic-v5.h b/include/linux/irqchip/arm-gic-v5.h
index 4e90b0ac1e139f101f059d17315625194e1c2ad2..6a8206ca31b1d43a20d13819749234c98ee6a078 100644
--- a/include/linux/irqchip/arm-gic-v5.h
+++ b/include/linux/irqchip/arm-gic-v5.h
@@ -236,6 +236,20 @@
 #define GICV5_ITS_HWIRQ_DEVICE_ID		GENMASK_ULL(31, 0)
 #define GICV5_ITS_HWIRQ_EVENT_ID		GENMASK_ULL(63, 32)
 
+#define GICV5_IWB_IDR0				0x0000
+#define GICV5_IWB_CR0				0x0080
+#define GICV5_IWB_WENABLE_STATUSR		0x00c0
+#define GICV5_IWB_WENABLER			0x2000
+#define GICV5_IWB_WTMR				0x4000
+
+#define GICV5_IWB_IDR0_INT_DOMS			GENMASK(14, 11)
+#define GICV5_IWB_IDR0_IW_RANGE			GENMASK(10, 0)
+
+#define GICV5_IWB_CR0_IDLE			BIT(1)
+#define GICV5_IWB_CR0_IWBEN			BIT(0)
+
+#define GICV5_IWB_WENABLE_STATUSR_IDLE		BIT(0)
+
 struct gicv5_chip_data {
 	struct fwnode_handle	*fwnode;
 	struct irq_domain	*ppi_domain;

-- 
2.48.0

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