soc: ti: Add MSI domain bus support for Interrupt Aggregator

With the system coprocessor managing the range allocation of the
inputs to Interrupt Aggregator, it is difficult to represent
the device IRQs from DT.

The suggestion is to use MSI in such cases where devices wants
to allocate and group interrupts dynamically.

Create a MSI domain bus layer that allocates and frees MSIs for
a device.

APIs that are implemented:
- ti_sci_inta_msi_create_irq_domain() that creates a MSI domain
- ti_sci_inta_msi_domain_alloc_irqs() that creates MSIs for the
  specified device and resource.
- ti_sci_inta_msi_domain_free_irqs() frees the irqs attached to the device.
- ti_sci_inta_msi_get_virq() for getting the virq attached to a specific event.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

3 files changed, 153 insertions, 0 deletions

diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
index be4570baad96..82f110fe4953 100644
--- a/drivers/soc/ti/Kconfig
+++ b/drivers/soc/ti/Kconfig
@@ -73,4 +73,10 @@ config TI_SCI_PM_DOMAINS
 	  called ti_sci_pm_domains. Note this is needed early in boot before
 	  rootfs may be available.
 
+config TI_SCI_INTA_MSI_DOMAIN
+	bool
+	select GENERIC_MSI_IRQ_DOMAIN
+	help
+	  Driver to enable Interrupt Aggregator specific MSI Domain.
+
 endif # SOC_TI
diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
index a22edc0b258a..b3868d392d4f 100644
--- a/drivers/soc/ti/Makefile
+++ b/drivers/soc/ti/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_KEYSTONE_NAVIGATOR_DMA)	+= knav_dma.o
 obj-$(CONFIG_AMX3_PM)			+= pm33xx.o
 obj-$(CONFIG_WKUP_M3_IPC)		+= wkup_m3_ipc.o
 obj-$(CONFIG_TI_SCI_PM_DOMAINS)		+= ti_sci_pm_domains.o
+obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN)	+= ti_sci_inta_msi.o
diff --git a/drivers/soc/ti/ti_sci_inta_msi.c b/drivers/soc/ti/ti_sci_inta_msi.c
new file mode 100644
index 000000000000..0eb9462f609e
--- /dev/null
+++ b/drivers/soc/ti/ti_sci_inta_msi.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Texas Instruments' K3 Interrupt Aggregator MSI bus
+ *
+ * Copyright (C) 2018-2019 Texas Instruments Incorporated - http://www.ti.com/
+ *	Lokesh Vutla <lokeshvutla@ti.com>
+ */
+
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/msi.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/soc/ti/ti_sci_inta_msi.h>
+#include <linux/soc/ti/ti_sci_protocol.h>
+
+static void ti_sci_inta_msi_write_msg(struct irq_data *data,
+				      struct msi_msg *msg)
+{
+	/* Nothing to do */
+}
+
+static void ti_sci_inta_msi_compose_msi_msg(struct irq_data *data,
+					    struct msi_msg *msg)
+{
+	/* Nothing to do */
+}
+
+static void ti_sci_inta_msi_update_chip_ops(struct msi_domain_info *info)
+{
+	struct irq_chip *chip = info->chip;
+
+	if (WARN_ON(!chip))
+		return;
+
+	chip->irq_request_resources = irq_chip_request_resources_parent;
+	chip->irq_release_resources = irq_chip_release_resources_parent;
+	chip->irq_compose_msi_msg = ti_sci_inta_msi_compose_msi_msg;
+	chip->irq_write_msi_msg = ti_sci_inta_msi_write_msg;
+	chip->irq_set_type = irq_chip_set_type_parent;
+	chip->irq_unmask = irq_chip_unmask_parent;
+	chip->irq_mask = irq_chip_mask_parent;
+	chip->irq_ack = irq_chip_ack_parent;
+}
+
+struct irq_domain *ti_sci_inta_msi_create_irq_domain(struct fwnode_handle *fwnode,
+						     struct msi_domain_info *info,
+						     struct irq_domain *parent)
+{
+	struct irq_domain *domain;
+
+	ti_sci_inta_msi_update_chip_ops(info);
+
+	domain = msi_create_irq_domain(fwnode, info, parent);
+	if (domain)
+		irq_domain_update_bus_token(domain, DOMAIN_BUS_TI_SCI_INTA_MSI);
+
+	return domain;
+}
+EXPORT_SYMBOL_GPL(ti_sci_inta_msi_create_irq_domain);
+
+static void ti_sci_inta_msi_free_descs(struct device *dev)
+{
+	struct msi_desc *desc, *tmp;
+
+	list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {
+		list_del(&desc->list);
+		free_msi_entry(desc);
+	}
+}
+
+static int ti_sci_inta_msi_alloc_descs(struct device *dev,
+				       struct ti_sci_resource *res)
+{
+	struct msi_desc *msi_desc;
+	int set, i, count = 0;
+
+	for (set = 0; set < res->sets; set++) {
+		for (i = 0; i < res->desc[set].num; i++) {
+			msi_desc = alloc_msi_entry(dev, 1, NULL);
+			if (!msi_desc) {
+				ti_sci_inta_msi_free_descs(dev);
+				return -ENOMEM;
+			}
+
+			msi_desc->inta.dev_index = res->desc[set].start + i;
+			INIT_LIST_HEAD(&msi_desc->list);
+			list_add_tail(&msi_desc->list, dev_to_msi_list(dev));
+			count++;
+		}
+	}
+
+	return count;
+}
+
+int ti_sci_inta_msi_domain_alloc_irqs(struct device *dev,
+				      struct ti_sci_resource *res)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct irq_domain *msi_domain;
+	int ret, nvec;
+
+	msi_domain = dev_get_msi_domain(dev);
+	if (!msi_domain)
+		return -EINVAL;
+
+	if (pdev->id < 0)
+		return -ENODEV;
+
+	nvec = ti_sci_inta_msi_alloc_descs(dev, res);
+	if (nvec <= 0)
+		return nvec;
+
+	ret = msi_domain_alloc_irqs(msi_domain, dev, nvec);
+	if (ret) {
+		dev_err(dev, "Failed to allocate IRQs %d\n", ret);
+		goto cleanup;
+	}
+
+	return 0;
+
+cleanup:
+	ti_sci_inta_msi_free_descs(&pdev->dev);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ti_sci_inta_msi_domain_alloc_irqs);
+
+void ti_sci_inta_msi_domain_free_irqs(struct device *dev)
+{
+	msi_domain_free_irqs(dev->msi_domain, dev);
+	ti_sci_inta_msi_free_descs(dev);
+}
+EXPORT_SYMBOL_GPL(ti_sci_inta_msi_domain_free_irqs);
+
+unsigned int ti_sci_inta_msi_get_virq(struct device *dev, u32 dev_index)
+{
+	struct msi_desc *desc;
+
+	for_each_msi_entry(desc, dev)
+		if (desc->inta.dev_index == dev_index)
+			return desc->irq;
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(ti_sci_inta_msi_get_virq);