soc: fsl: qe: Add an interrupt controller for QUICC Engine Ports

The QUICC Engine provides interrupts for a few I/O ports. This is
handled via a separate interrupt ID and managed via a triplet of
dedicated registers hosted by the SoC.

Implement an interrupt driver for it so that those IRQs can then
be linked to the related GPIOs.

Link: https://lore.kernel.org/r/63f19db21a91729d91b3df336a56a7eb4206e561.1767804922.git.chleroy@kernel.org
Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>

Author: Christophe Leroy (CS GROUP)

drivers/soc/fsl/qe/Makefile

@@ -11,4 +11,4 @@ obj-$(CONFIG_UCC_SLOW)	+= ucc_slow.o
 obj-$(CONFIG_UCC_FAST)	+= ucc_fast.o
 obj-$(CONFIG_QE_TDM)	+= qe_tdm.o
 obj-$(CONFIG_QE_USB)	+= usb.o
-obj-$(CONFIG_QE_GPIO)	+= gpio.o
+obj-$(CONFIG_QE_GPIO)	+= gpio.o qe_ports_ic.o

drivers/soc/fsl/qe/qe_ports_ic.c

@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * QUICC ENGINE I/O Ports Interrupt Controller
+ *
+ * Copyright (c) 2025 Christophe Leroy CS GROUP France (christophe.leroy@csgroup.eu)
+ */
+
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/platform_device.h>
+
+/* QE IC registers offset */
+#define CEPIER		0x0c
+#define CEPIMR		0x10
+#define CEPICR		0x14
+
+struct qepic_data {
+	void __iomem *reg;
+	struct irq_domain *host;
+};
+
+static void qepic_mask(struct irq_data *d)
+{
+	struct qepic_data *data = irq_data_get_irq_chip_data(d);
+
+	clrbits32(data->reg + CEPIMR, 1 << (31 - irqd_to_hwirq(d)));
+}
+
+static void qepic_unmask(struct irq_data *d)
+{
+	struct qepic_data *data = irq_data_get_irq_chip_data(d);
+
+	setbits32(data->reg + CEPIMR, 1 << (31 - irqd_to_hwirq(d)));
+}
+
+static void qepic_end(struct irq_data *d)
+{
+	struct qepic_data *data = irq_data_get_irq_chip_data(d);
+
+	out_be32(data->reg + CEPIER, 1 << (31 - irqd_to_hwirq(d)));
+}
+
+static int qepic_set_type(struct irq_data *d, unsigned int flow_type)
+{
+	struct qepic_data *data = irq_data_get_irq_chip_data(d);
+	unsigned int vec = (unsigned int)irqd_to_hwirq(d);
+
+	switch (flow_type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_EDGE_FALLING:
+		setbits32(data->reg + CEPICR, 1 << (31 - vec));
+		return 0;
+	case IRQ_TYPE_EDGE_BOTH:
+	case IRQ_TYPE_NONE:
+		clrbits32(data->reg + CEPICR, 1 << (31 - vec));
+		return 0;
+	}
+	return -EINVAL;
+}
+
+static struct irq_chip qepic = {
+	.name = "QEPIC",
+	.irq_mask = qepic_mask,
+	.irq_unmask = qepic_unmask,
+	.irq_eoi = qepic_end,
+	.irq_set_type = qepic_set_type,
+};
+
+static int qepic_get_irq(struct irq_desc *desc)
+{
+	struct qepic_data *data = irq_desc_get_handler_data(desc);
+	u32 event = in_be32(data->reg + CEPIER);
+
+	if (!event)
+		return -1;
+
+	return irq_find_mapping(data->host, 32 - ffs(event));
+}
+
+static void qepic_cascade(struct irq_desc *desc)
+{
+	generic_handle_irq(qepic_get_irq(desc));
+}
+
+static int qepic_host_map(struct irq_domain *h, unsigned int virq, irq_hw_number_t hw)
+{
+	irq_set_chip_data(virq, h->host_data);
+	irq_set_chip_and_handler(virq, &qepic, handle_fasteoi_irq);
+	return 0;
+}
+
+static const struct irq_domain_ops qepic_host_ops = {
+	.map = qepic_host_map,
+};
+
+static int qepic_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct qepic_data *data;
+	int irq;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->reg = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(data->reg))
+		return PTR_ERR(data->reg);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	data->host = irq_domain_add_linear(dev->of_node, 32, &qepic_host_ops, data);
+	if (!data->host)
+		return -ENODEV;
+
+	irq_set_handler_data(irq, data);
+	irq_set_chained_handler(irq, qepic_cascade);
+
+	return 0;
+}
+
+static const struct of_device_id qepic_match[] = {
+	{
+		.compatible = "fsl,mpc8323-qe-ports-ic",
+	},
+	{},
+};
+
+static struct platform_driver qepic_driver = {
+	.driver	= {
+		.name		= "qe_ports_ic",
+		.of_match_table	= qepic_match,
+	},
+	.probe	= qepic_probe,
+};
+
+static int __init qepic_init(void)
+{
+	return platform_driver_register(&qepic_driver);
+}
+arch_initcall(qepic_init);