[PATCH 7/9] irqchip/google-cpm: Add CPM IRQ driver

[Brian Norris]

The Central Power Manager (CPM) on Google Tensor SoCs can signal
events/interrupts over its mailbox communication protocol. Today, the
downstream driver for these chips only supports interrupt notification,
although the CPM firmware may also have mask/unmask support (not
currently used) that could be added later if needed.

In practice, this driver is used for RTC alarms and for events driven by
the Always-on Compute (AoC) subsystem.

Signed-off-by: Brian Norris <briannorris at chromium.org>
---

 drivers/irqchip/Kconfig          |  10 +++
 drivers/irqchip/Makefile         |   1 +
 drivers/irqchip/irq-google-cpm.c | 123 +++++++++++++++++++++++++++++++
 3 files changed, 134 insertions(+)
 create mode 100644 drivers/irqchip/irq-google-cpm.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index ca915fca0ef5..47f9739b1d74 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -556,6 +556,16 @@ config CSKY_APB_INTC
 	  by C-SKY single core SOC system. It uses mmio map apb-bus to visit
 	  the controller's register.
 
+config GOOGLE_CPM_IRQ
+	tristate "Google Tensor CPM interrupt controller"
+	depends on GOOGLE_CPM_MBA
+	depends on ARCH_GOOGLE || COMPILE_TEST
+	select IRQ_DOMAIN
+	help
+	  Support for the Central Power Manager (CPM) interrupt controller
+	  found on Google Tensor SoCs. This controller routes interrupts from
+	  the CPM to the Application Processor.
+
 config IMX_IRQSTEER
 	bool "i.MX IRQSTEER support"
 	depends on ARCH_MXC || ARCH_S32 || COMPILE_TEST
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 16a5fd126c9a..ca10888687fd 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
 obj-$(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-$(CONFIG_GOOGLE_CPM_IRQ)		+= irq-google-cpm.o
 obj-$(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
diff --git a/drivers/irqchip/irq-google-cpm.c b/drivers/irqchip/irq-google-cpm.c
new file mode 100644
index 000000000000..a235cc1cfe7c
--- /dev/null
+++ b/drivers/irqchip/irq-google-cpm.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Google CPM IRQ chip driver
+ *
+ * Copyright 2023-2026 Google LLC
+ */
+#include <linux/auxiliary_bus.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <soc/google/goog_cpm_service_ids.h>
+#include <soc/google/google-cpm-mba.h>
+
+#define CPM_IRQ_COUNT				512
+
+struct cpm_irq_info {
+	struct device		*dev;
+	struct irq_domain	*domain;
+};
+
+static void cpm_irq_process_irq_status(struct cpm_irq_info *info, u32 irq_number)
+{
+	int ret;
+
+	ret = generic_handle_domain_irq_safe(info->domain, irq_number);
+	if (ret)
+		dev_err(info->dev, "Error handling IRQ %u, error code %d\n", irq_number, ret);
+}
+
+static void cpm_irq_rx_callback(u32 context, const struct cpm_payload *msg, void *priv)
+{
+	struct cpm_irq_info *info = priv;
+	u32 irq_number = msg->payload[0];
+
+	cpm_irq_process_irq_status(info, irq_number);
+}
+
+static void cpm_irq_domain_remove_action(void *data)
+{
+	struct irq_domain *domain = data;
+	unsigned int hwirq;
+
+	for (hwirq = 0; hwirq < CPM_IRQ_COUNT; hwirq++)
+		irq_dispose_mapping(irq_find_mapping(domain, hwirq));
+
+	irq_domain_remove(domain);
+}
+
+static int cpm_irq_domain_map(struct irq_domain *d, unsigned int virq,
+			      irq_hw_number_t hwirq)
+{
+	struct cpm_irq_info *info = d->host_data;
+
+	if (hwirq >= CPM_IRQ_COUNT)
+		return -EINVAL;
+
+	irq_set_chip_data(virq, info);
+	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
+
+	dev_dbg(info->dev, "Mapped hwirq %lu to virq %u\n", hwirq, virq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops cpm_irq_domain_ops = {
+	.map = cpm_irq_domain_map,
+	.xlate = irq_domain_xlate_onecell,
+};
+
+static int cpm_irq_probe(struct auxiliary_device *adev, const struct auxiliary_device_id *id)
+{
+	struct device *dev = &adev->dev;
+	struct cpm_client *client;
+	struct cpm_irq_info *info;
+	int ret;
+
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->dev = dev;
+	auxiliary_set_drvdata(adev, info);
+
+	info->domain = irq_domain_create_tree(dev_fwnode(dev), &cpm_irq_domain_ops, info);
+	if (!info->domain) {
+		dev_err(dev, "Unable to add irq domain\n");
+		return -ENODEV;
+	}
+
+	ret = devm_add_action_or_reset(dev, cpm_irq_domain_remove_action, info->domain);
+	if (ret) {
+		dev_err(dev, "Failed to add irq domain removal action\n");
+		return ret;
+	}
+
+	client = devm_cpm_request_client(dev, CPM_AP_NS_IRQ_SERVICE,
+					 cpm_irq_rx_callback, info);
+	if (IS_ERR(client))
+		return dev_err_probe(dev, PTR_ERR(client),
+				     "Failed to request cpm client\n");
+
+	return 0;
+}
+
+static const struct auxiliary_device_id cpm_irq_id_table[] = {
+	{ .name = "google_cpm_mba.irq" },
+	{ },
+};
+MODULE_DEVICE_TABLE(auxiliary, cpm_irq_id_table);
+
+static struct auxiliary_driver cpm_irq_driver = {
+	.probe = cpm_irq_probe,
+	.name = "cpm-irq-chip",
+	.id_table = cpm_irq_id_table,
+};
+
+module_auxiliary_driver(cpm_irq_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Google CPM IRQ chip driver");
+MODULE_AUTHOR("Jim Wylder <jwylder at google.com>");
-- 
2.56.0.307.g5fe7bd680c-goog