PCI: mediatek: Implement chained IRQ handling setup

Implement irq_chip based solution for IRQs management in order to
comply with IRQ framework.

Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

2 files changed, 116 insertions, 91 deletions

diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index 0d0177ce436c..e2f323a52843 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig
@@ -194,6 +194,7 @@ config PCIE_MEDIATEK
 	depends on (ARM || ARM64) && (ARCH_MEDIATEK || COMPILE_TEST)
 	depends on OF
 	depends on PCI
+	depends on PCI_MSI_IRQ_DOMAIN
 	select PCIEPORTBUS
 	help
 	  Say Y here if you want to enable PCIe controller support on
diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c
index c3dc5499d1b7..dabf10869bcd 100644
--- a/drivers/pci/host/pcie-mediatek.c
+++ b/drivers/pci/host/pcie-mediatek.c
@@ -11,8 +11,10 @@
 #include <linux/delay.h>
 #include <linux/iopoll.h>
 #include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>
+#include <linux/msi.h>
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
@@ -130,14 +132,12 @@ struct mtk_pcie_port;
 /**
  * struct mtk_pcie_soc - differentiate between host generations
  * @need_fix_class_id: whether this host's class ID needed to be fixed or not
- * @has_msi: whether this host supports MSI interrupts or not
  * @ops: pointer to configuration access functions
  * @startup: pointer to controller setting functions
  * @setup_irq: pointer to initialize IRQ functions
  */
 struct mtk_pcie_soc {
 	bool need_fix_class_id;
-	bool has_msi;
 	struct pci_ops *ops;
 	int (*startup)(struct mtk_pcie_port *port);
 	int (*setup_irq)(struct mtk_pcie_port *port, struct device_node *node);
@@ -161,7 +161,9 @@ struct mtk_pcie_soc {
  * @lane: lane count
  * @slot: port slot
  * @irq_domain: legacy INTx IRQ domain
+ * @inner_domain: inner IRQ domain
  * @msi_domain: MSI IRQ domain
+ * @lock: protect the msi_irq_in_use bitmap
  * @msi_irq_in_use: bit map for assigned MSI IRQ
  */
 struct mtk_pcie_port {
@@ -179,7 +181,9 @@ struct mtk_pcie_port {
 	u32 lane;
 	u32 slot;
 	struct irq_domain *irq_domain;
+	struct irq_domain *inner_domain;
 	struct irq_domain *msi_domain;
+	struct mutex lock;
 	DECLARE_BITMAP(msi_irq_in_use, MTK_MSI_IRQS_NUM);
 };
 
@@ -446,103 +450,130 @@ static int mtk_pcie_startup_port_v2(struct mtk_pcie_port *port)
 	return 0;
 }
 
-static int mtk_pcie_msi_alloc(struct mtk_pcie_port *port)
+static void mtk_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 {
-	int msi;
+	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
+	phys_addr_t addr;
 
-	msi = find_first_zero_bit(port->msi_irq_in_use, MTK_MSI_IRQS_NUM);
-	if (msi < MTK_MSI_IRQS_NUM)
-		set_bit(msi, port->msi_irq_in_use);
-	else
-		return -ENOSPC;
+	/* MT2712/MT7622 only support 32-bit MSI addresses */
+	addr = virt_to_phys(port->base + PCIE_MSI_VECTOR);
+	msg->address_hi = 0;
+	msg->address_lo = lower_32_bits(addr);
+
+	msg->data = data->hwirq;
 
-	return msi;
+	dev_dbg(port->pcie->dev, "msi#%d address_hi %#x address_lo %#x\n",
+		(int)data->hwirq, msg->address_hi, msg->address_lo);
 }
 
-static void mtk_pcie_msi_free(struct mtk_pcie_port *port, unsigned long hwirq)
+static int mtk_msi_set_affinity(struct irq_data *irq_data,
+				const struct cpumask *mask, bool force)
 {
-	clear_bit(hwirq, port->msi_irq_in_use);
+	 return -EINVAL;
 }
 
-static int mtk_pcie_msi_setup_irq(struct msi_controller *chip,
-				  struct pci_dev *pdev, struct msi_desc *desc)
+static void mtk_msi_ack_irq(struct irq_data *data)
 {
-	struct mtk_pcie_port *port;
-	struct msi_msg msg;
-	unsigned int irq;
-	int hwirq;
-	phys_addr_t msg_addr;
+	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
+	u32 hwirq = data->hwirq;
 
-	port = mtk_pcie_find_port(pdev->bus, pdev->devfn);
-	if (!port)
-		return -EINVAL;
+	writel(1 << hwirq, port->base + PCIE_IMSI_STATUS);
+}
 
-	hwirq = mtk_pcie_msi_alloc(port);
-	if (hwirq < 0)
-		return hwirq;
+static struct irq_chip mtk_msi_bottom_irq_chip = {
+	.name			= "MTK MSI",
+	.irq_compose_msi_msg	= mtk_compose_msi_msg,
+	.irq_set_affinity	= mtk_msi_set_affinity,
+	.irq_ack		= mtk_msi_ack_irq,
+};
 
-	irq = irq_create_mapping(port->msi_domain, hwirq);
-	if (!irq) {
-		mtk_pcie_msi_free(port, hwirq);
-		return -EINVAL;
-	}
+static int mtk_pcie_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				     unsigned int nr_irqs, void *args)
+{
+	struct mtk_pcie_port *port = domain->host_data;
+	unsigned long bit;
 
-	chip->dev = &pdev->dev;
+	WARN_ON(nr_irqs != 1);
+	mutex_lock(&port->lock);
 
-	irq_set_msi_desc(irq, desc);
+	bit = find_first_zero_bit(port->msi_irq_in_use, MTK_MSI_IRQS_NUM);
+	if (bit >= MTK_MSI_IRQS_NUM) {
+		mutex_unlock(&port->lock);
+		return -ENOSPC;
+	}
 
-	/* MT2712/MT7622 only support 32-bit MSI addresses */
-	msg_addr = virt_to_phys(port->base + PCIE_MSI_VECTOR);
-	msg.address_hi = 0;
-	msg.address_lo = lower_32_bits(msg_addr);
-	msg.data = hwirq;
+	__set_bit(bit, port->msi_irq_in_use);
+
+	mutex_unlock(&port->lock);
 
-	pci_write_msi_msg(irq, &msg);
+	irq_domain_set_info(domain, virq, bit, &mtk_msi_bottom_irq_chip,
+			    domain->host_data, handle_edge_irq,
+			    NULL, NULL);
 
 	return 0;
 }
 
-static void mtk_msi_teardown_irq(struct msi_controller *chip, unsigned int irq)
+static void mtk_pcie_irq_domain_free(struct irq_domain *domain,
+				     unsigned int virq, unsigned int nr_irqs)
 {
-	struct pci_dev *pdev = to_pci_dev(chip->dev);
-	struct irq_data *d = irq_get_irq_data(irq);
-	irq_hw_number_t hwirq = irqd_to_hwirq(d);
-	struct mtk_pcie_port *port;
+	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(d);
 
-	port = mtk_pcie_find_port(pdev->bus, pdev->devfn);
-	if (!port)
-		return;
+	mutex_lock(&port->lock);
+
+	if (!test_bit(d->hwirq, port->msi_irq_in_use))
+		dev_err(port->pcie->dev, "trying to free unused MSI#%lu\n",
+			d->hwirq);
+	else
+		__clear_bit(d->hwirq, port->msi_irq_in_use);
+
+	mutex_unlock(&port->lock);
 
-	irq_dispose_mapping(irq);
-	mtk_pcie_msi_free(port, hwirq);
+	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
 }
 
-static struct msi_controller mtk_pcie_msi_chip = {
-	.setup_irq = mtk_pcie_msi_setup_irq,
-	.teardown_irq = mtk_msi_teardown_irq,
+static const struct irq_domain_ops msi_domain_ops = {
+	.alloc	= mtk_pcie_irq_domain_alloc,
+	.free	= mtk_pcie_irq_domain_free,
 };
 
 static struct irq_chip mtk_msi_irq_chip = {
-	.name = "MTK PCIe MSI",
-	.irq_enable = pci_msi_unmask_irq,
-	.irq_disable = pci_msi_mask_irq,
-	.irq_mask = pci_msi_mask_irq,
-	.irq_unmask = pci_msi_unmask_irq,
+	.name		= "MTK PCIe MSI",
+	.irq_ack	= irq_chip_ack_parent,
+	.irq_mask	= pci_msi_mask_irq,
+	.irq_unmask	= pci_msi_unmask_irq,
 };
 
-static int mtk_pcie_msi_map(struct irq_domain *domain, unsigned int irq,
-			    irq_hw_number_t hwirq)
+static struct msi_domain_info mtk_msi_domain_info = {
+	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+		   MSI_FLAG_PCI_MSIX),
+	.chip	= &mtk_msi_irq_chip,
+};
+
+static int mtk_pcie_allocate_msi_domains(struct mtk_pcie_port *port)
 {
-	irq_set_chip_and_handler(irq, &mtk_msi_irq_chip, handle_simple_irq);
-	irq_set_chip_data(irq, domain->host_data);
+	struct fwnode_handle *fwnode = of_node_to_fwnode(port->pcie->dev->of_node);
+
+	mutex_init(&port->lock);
+
+	port->inner_domain = irq_domain_create_linear(fwnode, MTK_MSI_IRQS_NUM,
+						      &msi_domain_ops, port);
+	if (!port->inner_domain) {
+		dev_err(port->pcie->dev, "failed to create IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	port->msi_domain = pci_msi_create_irq_domain(fwnode, &mtk_msi_domain_info,
+						     port->inner_domain);
+	if (!port->msi_domain) {
+		dev_err(port->pcie->dev, "failed to create MSI domain\n");
+		irq_domain_remove(port->inner_domain);
+		return -ENOMEM;
+	}
 
 	return 0;
 }
 
-static const struct irq_domain_ops msi_domain_ops = {
-	.map = mtk_pcie_msi_map,
-};
-
 static void mtk_pcie_enable_msi(struct mtk_pcie_port *port)
 {
 	u32 val;
@@ -575,6 +606,7 @@ static int mtk_pcie_init_irq_domain(struct mtk_pcie_port *port,
 {
 	struct device *dev = port->pcie->dev;
 	struct device_node *pcie_intc_node;
+	int ret;
 
 	/* Setup INTx */
 	pcie_intc_node = of_get_next_child(node, NULL);
@@ -591,27 +623,28 @@ static int mtk_pcie_init_irq_domain(struct mtk_pcie_port *port,
 	}
 
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
-		port->msi_domain = irq_domain_add_linear(node, MTK_MSI_IRQS_NUM,
-							 &msi_domain_ops,
-							 &mtk_pcie_msi_chip);
-		if (!port->msi_domain) {
-			dev_err(dev, "failed to create MSI IRQ domain\n");
-			return -ENODEV;
-		}
+		ret = mtk_pcie_allocate_msi_domains(port);
+		if (ret)
+			return ret;
+
 		mtk_pcie_enable_msi(port);
 	}
 
 	return 0;
 }
 
-static irqreturn_t mtk_pcie_intr_handler(int irq, void *data)
+static void mtk_pcie_intr_handler(struct irq_desc *desc)
 {
-	struct mtk_pcie_port *port = (struct mtk_pcie_port *)data;
+	struct mtk_pcie_port *port = irq_desc_get_handler_data(desc);
+	struct irq_chip *irqchip = irq_desc_get_chip(desc);
 	unsigned long status;
 	u32 virq;
 	u32 bit = INTX_SHIFT;
 
-	while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) {
+	chained_irq_enter(irqchip, desc);
+
+	status = readl(port->base + PCIE_INT_STATUS);
+	if (status & INTX_MASK) {
 		for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) {
 			/* Clear the INTx */
 			writel(1 << bit, port->base + PCIE_INT_STATUS);
@@ -622,14 +655,12 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data)
 	}
 
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
-		while ((status = readl(port->base + PCIE_INT_STATUS)) & MSI_STATUS) {
+		if (status & MSI_STATUS){
 			unsigned long imsi_status;
 
 			while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) {
 				for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) {
-					/* Clear the MSI */
-					writel(1 << bit, port->base + PCIE_IMSI_STATUS);
-					virq = irq_find_mapping(port->msi_domain, bit);
+					virq = irq_find_mapping(port->inner_domain, bit);
 					generic_handle_irq(virq);
 				}
 			}
@@ -638,7 +669,9 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data)
 		}
 	}
 
-	return IRQ_HANDLED;
+	chained_irq_exit(irqchip, desc);
+
+	return;
 }
 
 static int mtk_pcie_setup_irq(struct mtk_pcie_port *port,
@@ -649,20 +682,15 @@ static int mtk_pcie_setup_irq(struct mtk_pcie_port *port,
 	struct platform_device *pdev = to_platform_device(dev);
 	int err, irq;
 
-	irq = platform_get_irq(pdev, port->slot);
-	err = devm_request_irq(dev, irq, mtk_pcie_intr_handler,
-			       IRQF_SHARED, "mtk-pcie", port);
-	if (err) {
-		dev_err(dev, "unable to request IRQ %d\n", irq);
-		return err;
-	}
-
 	err = mtk_pcie_init_irq_domain(port, node);
 	if (err) {
 		dev_err(dev, "failed to init PCIe IRQ domain\n");
 		return err;
 	}
 
+	irq = platform_get_irq(pdev, port->slot);
+	irq_set_chained_handler_and_data(irq, mtk_pcie_intr_handler, port);
+
 	return 0;
 }
 
@@ -1096,8 +1124,6 @@ static int mtk_pcie_register_host(struct pci_host_bridge *host)
 	host->map_irq = of_irq_parse_and_map_pci;
 	host->swizzle_irq = pci_common_swizzle;
 	host->sysdata = pcie;
-	if (IS_ENABLED(CONFIG_PCI_MSI) && pcie->soc->has_msi)
-		host->msi = &mtk_pcie_msi_chip;
 
 	err = pci_scan_root_bus_bridge(host);
 	if (err < 0)
@@ -1159,7 +1185,6 @@ static const struct mtk_pcie_soc mtk_pcie_soc_v1 = {
 };
 
 static const struct mtk_pcie_soc mtk_pcie_soc_mt2712 = {
-	.has_msi = true,
 	.ops = &mtk_pcie_ops_v2,
 	.startup = mtk_pcie_startup_port_v2,
 	.setup_irq = mtk_pcie_setup_irq,
@@ -1167,7 +1192,6 @@ static const struct mtk_pcie_soc mtk_pcie_soc_mt2712 = {
 
 static const struct mtk_pcie_soc mtk_pcie_soc_mt7622 = {
 	.need_fix_class_id = true,
-	.has_msi = true,
 	.ops = &mtk_pcie_ops_v2,
 	.startup = mtk_pcie_startup_port_v2,
 	.setup_irq = mtk_pcie_setup_irq,