The Renesas RZ/T2H (R9A09G077) and Renesas RZ/N2H (R9A09G087) SoCs have
an Interrupt Controller (ICU) that supports interrupts from external
pins IRQ0 to IRQ15, and SEI, and software-triggered interrupts INTCPU0
to INTCPU15.

INTCPU0 to INTCPU13, IRQ0 to IRQ13 are non-safety interrupts, while
INTCPU14, INTCPU15, IRQ14, IRQ15 and SEI are safety interrupts, and are
exposed via a separate register space.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
---

V2:
 * use 100 columns where necessary
 * move SEI comment above if
 * inline declarations of the same type
 * use scoped_guard() in rzt2h_icu_irq_set_type() to avoid keeping the
   guard across the irq_chip_set_type_parent() call
 * align struct irq_chip members initialization

 drivers/irqchip/Kconfig                   |   8 +
 drivers/irqchip/Makefile                  |   1 +
 drivers/irqchip/irq-renesas-rzt2h.c       | 283 ++++++++++++++++++++++
 drivers/soc/renesas/Kconfig               |   1 +
 include/linux/irqchip/irq-renesas-rzt2h.h |  23 ++
 5 files changed, 316 insertions(+)
 create mode 100644 drivers/irqchip/irq-renesas-rzt2h.c
 create mode 100644 include/linux/irqchip/irq-renesas-rzt2h.h

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index f334f49c9791..118d0c16e633 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -297,6 +297,14 @@ config RENESAS_RZG2L_IRQC
 	  Enable support for the Renesas RZ/G2L (and alike SoC) Interrupt Controller
 	  for external devices.
 
+config RENESAS_RZT2H_ICU
+	bool "Renesas RZ/{T2H,N2H} ICU support" if COMPILE_TEST
+	select GENERIC_IRQ_CHIP
+	select IRQ_DOMAIN_HIERARCHY
+	help
+	  Enable support for the Renesas RZ/{T2H,N2H} Interrupt Controller
+	  (ICU).
+
 config RENESAS_RZV2H_ICU
 	bool "Renesas RZ/V2H(P) ICU support" if COMPILE_TEST
 	select GENERIC_IRQ_CHIP
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 6a229443efe0..26aa3b6ec99f 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -54,6 +54,7 @@ obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
 obj-$(CONFIG_RENESAS_IRQC)		+= irq-renesas-irqc.o
 obj-$(CONFIG_RENESAS_RZA1_IRQC)		+= irq-renesas-rza1.o
 obj-$(CONFIG_RENESAS_RZG2L_IRQC)	+= irq-renesas-rzg2l.o
+obj-$(CONFIG_RENESAS_RZT2H_ICU)		+= irq-renesas-rzt2h.o
 obj-$(CONFIG_RENESAS_RZV2H_ICU)		+= irq-renesas-rzv2h.o
 obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
 obj-$(CONFIG_ARCH_NSPIRE)		+= irq-zevio.o
diff --git a/drivers/irqchip/irq-renesas-rzt2h.c b/drivers/irqchip/irq-renesas-rzt2h.c
new file mode 100644
index 000000000000..1b2fb1782982
--- /dev/null
+++ b/drivers/irqchip/irq-renesas-rzt2h.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bitfield.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/irq-renesas-rzt2h.h>
+#include <linux/irqdomain.h>
+#include <linux/of_platform.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/spinlock.h>
+
+#define RZT2H_ICU_INTCPU_NS_START		0
+#define RZT2H_ICU_INTCPU_NS_COUNT		14
+
+#define RZT2H_ICU_INTCPU_S_START		(RZT2H_ICU_INTCPU_NS_START + \
+						 RZT2H_ICU_INTCPU_NS_COUNT)
+#define RZT2H_ICU_INTCPU_S_COUNT		2
+
+#define RZT2H_ICU_IRQ_NS_START			(RZT2H_ICU_INTCPU_S_START + \
+						 RZT2H_ICU_INTCPU_S_COUNT)
+#define RZT2H_ICU_IRQ_NS_COUNT			14
+
+#define RZT2H_ICU_IRQ_S_START			(RZT2H_ICU_IRQ_NS_START + \
+						 RZT2H_ICU_IRQ_NS_COUNT)
+#define RZT2H_ICU_IRQ_S_COUNT			2
+
+#define RZT2H_ICU_SEI_START			(RZT2H_ICU_IRQ_S_START + \
+						 RZT2H_ICU_IRQ_S_COUNT)
+#define RZT2H_ICU_SEI_COUNT			1
+
+#define RZT2H_ICU_NUM_IRQ			(RZT2H_ICU_INTCPU_NS_COUNT + \
+						 RZT2H_ICU_INTCPU_S_COUNT + \
+						 RZT2H_ICU_IRQ_NS_COUNT + \
+						 RZT2H_ICU_IRQ_S_COUNT + \
+						 RZT2H_ICU_SEI_COUNT)
+
+#define RZT2H_ICU_IRQ_IN_RANGE(n, type) \
+	((n) >= RZT2H_ICU_##type##_START && \
+	 (n) <  RZT2H_ICU_##type##_START + RZT2H_ICU_##type##_COUNT)
+
+#define RZT2H_ICU_PORTNF_MD			0xc
+#define RZT2H_ICU_PORTNF_MDi_MASK(i)		(GENMASK(1, 0) << ((i) * 2))
+#define RZT2H_ICU_PORTNF_MDi_PREP(i, val)	(FIELD_PREP(GENMASK(1, 0), val) << ((i) * 2))
+
+#define RZT2H_ICU_MD_LOW_LEVEL			0b00
+#define RZT2H_ICU_MD_FALLING_EDGE		0b01
+#define RZT2H_ICU_MD_RISING_EDGE		0b10
+#define RZT2H_ICU_MD_BOTH_EDGES			0b11
+
+#define RZT2H_ICU_DMACn_RSSELi(n, i)		(0x7d0 + 0x18 * (n) + 0x4 * (i))
+#define RZT2H_ICU_DMAC_REQ_SELx_MASK(x)		(GENMASK(9, 0) << ((x) * 10))
+#define RZT2H_ICU_DMAC_REQ_SELx_PREP(x, val)	(FIELD_PREP(GENMASK(9, 0), val) << ((x) * 10))
+
+struct rzt2h_icu_priv {
+	void __iomem			*base_ns;
+	void __iomem			*base_s;
+	struct irq_fwspec		fwspec[RZT2H_ICU_NUM_IRQ];
+	raw_spinlock_t			lock;
+};
+
+void rzt2h_icu_register_dma_req(struct platform_device *icu_dev, u8 dmac_index, u8 dmac_channel,
+				u16 req_no)
+{
+	struct rzt2h_icu_priv *priv = platform_get_drvdata(icu_dev);
+	u8 y, upper;
+	u32 val;
+
+	y = dmac_channel / 3;
+	upper = dmac_channel % 3;
+
+	guard(raw_spinlock_irqsave)(&priv->lock);
+
+	val = readl(priv->base_ns + RZT2H_ICU_DMACn_RSSELi(dmac_index, y));
+	val &= ~RZT2H_ICU_DMAC_REQ_SELx_MASK(upper);
+	val |= RZT2H_ICU_DMAC_REQ_SELx_PREP(upper, req_no);
+	writel(val, priv->base_ns + RZT2H_ICU_DMACn_RSSELi(dmac_index, y));
+}
+EXPORT_SYMBOL_GPL(rzt2h_icu_register_dma_req);
+
+static inline struct rzt2h_icu_priv *irq_data_to_priv(struct irq_data *data)
+{
+	return data->domain->host_data;
+}
+
+static inline int rzt2h_icu_irq_to_offset(struct irq_data *d, void __iomem **base,
+					  unsigned int *offset)
+{
+	struct rzt2h_icu_priv *priv = irq_data_to_priv(d);
+	unsigned int hwirq = irqd_to_hwirq(d);
+
+	/*
+	 * Safety IRQs and SEI use a separate register space from the non-safety IRQs.
+	 * SEI interrupt number follows immediately after the safety IRQs.
+	 */
+	if (RZT2H_ICU_IRQ_IN_RANGE(hwirq, IRQ_NS)) {
+		*offset = hwirq - RZT2H_ICU_IRQ_NS_START;
+		*base = priv->base_ns;
+	} else if (RZT2H_ICU_IRQ_IN_RANGE(hwirq, IRQ_S) ||
+		   RZT2H_ICU_IRQ_IN_RANGE(hwirq, SEI)) {
+		*offset = hwirq - RZT2H_ICU_IRQ_S_START;
+		*base = priv->base_s;
+	} else {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int rzt2h_icu_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct rzt2h_icu_priv *priv = irq_data_to_priv(d);
+	unsigned int offset, parent_type;
+	void __iomem *base;
+	u32 val, md;
+	int ret;
+
+	ret = rzt2h_icu_irq_to_offset(d, &base, &offset);
+	if (ret)
+		return ret;
+
+	switch (type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_LEVEL_LOW:
+		md = RZT2H_ICU_MD_LOW_LEVEL;
+		parent_type = IRQ_TYPE_LEVEL_HIGH;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		md = RZT2H_ICU_MD_FALLING_EDGE;
+		parent_type = IRQ_TYPE_EDGE_RISING;
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		md = RZT2H_ICU_MD_RISING_EDGE;
+		parent_type = IRQ_TYPE_EDGE_RISING;
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		md = RZT2H_ICU_MD_BOTH_EDGES;
+		parent_type = IRQ_TYPE_EDGE_RISING;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	scoped_guard(raw_spinlock, &priv->lock) {
+		val = readl_relaxed(base + RZT2H_ICU_PORTNF_MD);
+		val &= ~RZT2H_ICU_PORTNF_MDi_MASK(offset);
+		val |= RZT2H_ICU_PORTNF_MDi_PREP(offset, md);
+		writel_relaxed(val, base + RZT2H_ICU_PORTNF_MD);
+	}
+
+	return irq_chip_set_type_parent(d, parent_type);
+}
+
+static int rzt2h_icu_set_type(struct irq_data *d, unsigned int type)
+{
+	unsigned int hw_irq = irqd_to_hwirq(d);
+
+	/* IRQn and SEI are selectable, others are edge-only. */
+	if (RZT2H_ICU_IRQ_IN_RANGE(hw_irq, IRQ_NS) ||
+	    RZT2H_ICU_IRQ_IN_RANGE(hw_irq, IRQ_S) ||
+	    RZT2H_ICU_IRQ_IN_RANGE(hw_irq, SEI))
+		return rzt2h_icu_irq_set_type(d, type);
+
+	if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_EDGE_RISING)
+		return -EINVAL;
+
+	return irq_chip_set_type_parent(d, IRQ_TYPE_EDGE_RISING);
+}
+
+static const struct irq_chip rzt2h_icu_chip = {
+	.name			= "rzt2h-icu",
+	.irq_mask		= irq_chip_mask_parent,
+	.irq_unmask		= irq_chip_unmask_parent,
+	.irq_eoi		= irq_chip_eoi_parent,
+	.irq_set_type		= rzt2h_icu_set_type,
+	.irq_set_wake		= irq_chip_set_wake_parent,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+	.irq_retrigger		= irq_chip_retrigger_hierarchy,
+	.irq_get_irqchip_state	= irq_chip_get_parent_state,
+	.irq_set_irqchip_state	= irq_chip_set_parent_state,
+	.flags			= IRQCHIP_MASK_ON_SUSPEND |
+				  IRQCHIP_SET_TYPE_MASKED |
+				  IRQCHIP_SKIP_SET_WAKE,
+};
+
+static int rzt2h_icu_alloc(struct irq_domain *domain, unsigned int virq, unsigned int nr_irqs,
+			   void *arg)
+{
+	struct rzt2h_icu_priv *priv = domain->host_data;
+	irq_hw_number_t hwirq;
+	unsigned int type;
+	int ret;
+
+	ret = irq_domain_translate_twocell(domain, arg, &hwirq, &type);
+	if (ret)
+		return ret;
+
+	ret = irq_domain_set_hwirq_and_chip(domain, virq, hwirq, &rzt2h_icu_chip, NULL);
+	if (ret)
+		return ret;
+
+	return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, &priv->fwspec[hwirq]);
+}
+
+static const struct irq_domain_ops rzt2h_icu_domain_ops = {
+	.alloc		= rzt2h_icu_alloc,
+	.free		= irq_domain_free_irqs_common,
+	.translate	= irq_domain_translate_twocell,
+};
+
+static int rzt2h_icu_parse_interrupts(struct rzt2h_icu_priv *priv, struct device_node *np)
+{
+	struct of_phandle_args map;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < RZT2H_ICU_NUM_IRQ; i++) {
+		ret = of_irq_parse_one(np, i, &map);
+		if (ret)
+			return ret;
+
+		of_phandle_args_to_fwspec(np, map.args, map.args_count, &priv->fwspec[i]);
+	}
+
+	return 0;
+}
+
+static int rzt2h_icu_init(struct platform_device *pdev, struct device_node *parent)
+{
+	struct irq_domain *irq_domain, *parent_domain;
+	struct device_node *node = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct rzt2h_icu_priv *priv;
+	int ret;
+
+	parent_domain = irq_find_host(parent);
+	if (!parent_domain)
+		return dev_err_probe(dev, -ENODEV, "cannot find parent domain\n");
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->base_ns = devm_of_iomap(dev, dev->of_node, 0, NULL);
+	if (IS_ERR(priv->base_ns))
+		return PTR_ERR(priv->base_ns);
+
+	priv->base_s = devm_of_iomap(dev, dev->of_node, 1, NULL);
+	if (IS_ERR(priv->base_s))
+		return PTR_ERR(priv->base_s);
+
+	ret = rzt2h_icu_parse_interrupts(priv, node);
+	if (ret)
+		return dev_err_probe(dev, ret, "cannot parse interrupts: %d\n", ret);
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "devm_pm_runtime_enable failed: %d\n", ret);
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "pm_runtime_resume_and_get failed: %d\n", ret);
+
+	raw_spin_lock_init(&priv->lock);
+
+	irq_domain = irq_domain_create_hierarchy(parent_domain, 0, RZT2H_ICU_NUM_IRQ,
+						 dev_fwnode(dev), &rzt2h_icu_domain_ops, priv);
+	if (!irq_domain) {
+		pm_runtime_put(dev);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+IRQCHIP_PLATFORM_DRIVER_BEGIN(rzt2h_icu)
+IRQCHIP_MATCH("renesas,r9a09g077-icu", rzt2h_icu_init)
+IRQCHIP_PLATFORM_DRIVER_END(rzt2h_icu)
+MODULE_AUTHOR("Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>");
+MODULE_DESCRIPTION("Renesas RZ/T2H ICU Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/soc/renesas/Kconfig b/drivers/soc/renesas/Kconfig
index 340a1ff7e92b..198baf890b14 100644
--- a/drivers/soc/renesas/Kconfig
+++ b/drivers/soc/renesas/Kconfig
@@ -423,6 +423,7 @@ config ARCH_R9A09G057
 config ARCH_R9A09G077
 	bool "ARM64 Platform support for R9A09G077 (RZ/T2H)"
 	default y if ARCH_RENESAS
+	select RENESAS_RZT2H_ICU
 	help
 	  This enables support for the Renesas RZ/T2H SoC variants.
 
diff --git a/include/linux/irqchip/irq-renesas-rzt2h.h b/include/linux/irqchip/irq-renesas-rzt2h.h
new file mode 100644
index 000000000000..853fd5ee0b22
--- /dev/null
+++ b/include/linux/irqchip/irq-renesas-rzt2h.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Renesas RZ/T2H Interrupt Control Unit (ICU)
+ *
+ * Copyright (C) 2025 Renesas Electronics Corporation.
+ */
+
+#ifndef __LINUX_IRQ_RENESAS_RZT2H
+#define __LINUX_IRQ_RENESAS_RZT2H
+
+#include <linux/platform_device.h>
+
+#define RZT2H_ICU_DMAC_REQ_NO_DEFAULT		0x3ff
+
+#ifdef CONFIG_RENESAS_RZT2H_ICU
+void rzt2h_icu_register_dma_req(struct platform_device *icu_dev, u8 dmac_index, u8 dmac_channel,
+				u16 req_no);
+#else
+static inline void rzt2h_icu_register_dma_req(struct platform_device *icu_dev, u8 dmac_index,
+					      u8 dmac_channel, u16 req_no) { }
+#endif
+
+#endif /* __LINUX_IRQ_RENESAS_RZT2H */
-- 
2.52.0