PCI: mediatek-gen3: Add INTx support

Add INTx support for MediaTek Gen3 PCIe controller.

Link: https://lore.kernel.org/r/20210420061723.989-5-jianjun.wang@mediatek.comSigned-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>

drivers/pci/controller/pcie-mediatek-gen3.c

@@ -9,6 +9,9 @@
 #include <linux/clk.h>
 #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/module.h>
 #include <linux/pci.h>
@@ -45,6 +48,13 @@
 #define PCIE_LINK_STATUS_REG		0x154
 #define PCIE_PORT_LINKUP		BIT(8)
 
+#define PCIE_INT_ENABLE_REG		0x180
+#define PCIE_INTX_SHIFT			24
+#define PCIE_INTX_ENABLE \
+	GENMASK(PCIE_INTX_SHIFT + PCI_NUM_INTX - 1, PCIE_INTX_SHIFT)
+
+#define PCIE_INT_STATUS_REG		0x184
+
 #define PCIE_TRANS_TABLE_BASE_REG	0x800
 #define PCIE_ATR_SRC_ADDR_MSB_OFFSET	0x4
 #define PCIE_ATR_TRSL_ADDR_LSB_OFFSET	0x8
@@ -73,6 +83,9 @@
  * @phy: PHY controller block
  * @clks: PCIe clocks
  * @num_clks: PCIe clocks count for this port
+ * @irq: PCIe controller interrupt number
+ * @irq_lock: lock protecting IRQ register access
+ * @intx_domain: legacy INTx IRQ domain
  */
 struct mtk_pcie_port {
 	struct device *dev;
@@ -83,6 +96,10 @@ struct mtk_pcie_port {
 	struct phy *phy;
 	struct clk_bulk_data *clks;
 	int num_clks;
+
+	int irq;
+	raw_spinlock_t irq_lock;
+	struct irq_domain *intx_domain;
 };
 
 /**
@@ -198,6 +215,11 @@ static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
 	val |= PCI_CLASS(PCI_CLASS_BRIDGE_PCI << 8);
 	writel_relaxed(val, port->base + PCIE_PCI_IDS_1);
 
+	/* Mask all INTx interrupts */
+	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
+	val &= ~PCIE_INTX_ENABLE;
+	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);
+
 	/* Assert all reset signals */
 	val = readl_relaxed(port->base + PCIE_RST_CTRL_REG);
 	val |= PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | PCIE_PE_RSTB;
@@ -261,6 +283,150 @@ static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
 	return 0;
 }
 
+static int mtk_pcie_set_affinity(struct irq_data *data,
+				 const struct cpumask *mask, bool force)
+{
+	return -EINVAL;
+}
+
+static void mtk_intx_mask(struct irq_data *data)
+{
+	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
+	unsigned long flags;
+	u32 val;
+
+	raw_spin_lock_irqsave(&port->irq_lock, flags);
+	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
+	val &= ~BIT(data->hwirq + PCIE_INTX_SHIFT);
+	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);
+	raw_spin_unlock_irqrestore(&port->irq_lock, flags);
+}
+
+static void mtk_intx_unmask(struct irq_data *data)
+{
+	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
+	unsigned long flags;
+	u32 val;
+
+	raw_spin_lock_irqsave(&port->irq_lock, flags);
+	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
+	val |= BIT(data->hwirq + PCIE_INTX_SHIFT);
+	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);
+	raw_spin_unlock_irqrestore(&port->irq_lock, flags);
+}
+
+/**
+ * mtk_intx_eoi() - Clear INTx IRQ status at the end of interrupt
+ * @data: pointer to chip specific data
+ *
+ * As an emulated level IRQ, its interrupt status will remain
+ * until the corresponding de-assert message is received; hence that
+ * the status can only be cleared when the interrupt has been serviced.
+ */
+static void mtk_intx_eoi(struct irq_data *data)
+{
+	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
+	unsigned long hwirq;
+
+	hwirq = data->hwirq + PCIE_INTX_SHIFT;
+	writel_relaxed(BIT(hwirq), port->base + PCIE_INT_STATUS_REG);
+}
+
+static struct irq_chip mtk_intx_irq_chip = {
+	.irq_mask		= mtk_intx_mask,
+	.irq_unmask		= mtk_intx_unmask,
+	.irq_eoi		= mtk_intx_eoi,
+	.irq_set_affinity	= mtk_pcie_set_affinity,
+	.name			= "INTx",
+};
+
+static int mtk_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
+			     irq_hw_number_t hwirq)
+{
+	irq_set_chip_data(irq, domain->host_data);
+	irq_set_chip_and_handler_name(irq, &mtk_intx_irq_chip,
+				      handle_fasteoi_irq, "INTx");
+	return 0;
+}
+
+static const struct irq_domain_ops intx_domain_ops = {
+	.map = mtk_pcie_intx_map,
+};
+
+static int mtk_pcie_init_irq_domains(struct mtk_pcie_port *port)
+{
+	struct device *dev = port->dev;
+	struct device_node *intc_node, *node = dev->of_node;
+
+	raw_spin_lock_init(&port->irq_lock);
+
+	/* Setup INTx */
+	intc_node = of_get_child_by_name(node, "interrupt-controller");
+	if (!intc_node) {
+		dev_err(dev, "missing interrupt-controller node\n");
+		return -ENODEV;
+	}
+
+	port->intx_domain = irq_domain_add_linear(intc_node, PCI_NUM_INTX,
+						  &intx_domain_ops, port);
+	if (!port->intx_domain) {
+		dev_err(dev, "failed to create INTx IRQ domain\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void mtk_pcie_irq_teardown(struct mtk_pcie_port *port)
+{
+	irq_set_chained_handler_and_data(port->irq, NULL, NULL);
+
+	if (port->intx_domain)
+		irq_domain_remove(port->intx_domain);
+
+	irq_dispose_mapping(port->irq);
+}
+
+static void mtk_pcie_irq_handler(struct irq_desc *desc)
+{
+	struct mtk_pcie_port *port = irq_desc_get_handler_data(desc);
+	struct irq_chip *irqchip = irq_desc_get_chip(desc);
+	unsigned long status;
+	unsigned int virq;
+	irq_hw_number_t irq_bit = PCIE_INTX_SHIFT;
+
+	chained_irq_enter(irqchip, desc);
+
+	status = readl_relaxed(port->base + PCIE_INT_STATUS_REG);
+	for_each_set_bit_from(irq_bit, &status, PCI_NUM_INTX +
+			      PCIE_INTX_SHIFT) {
+		virq = irq_find_mapping(port->intx_domain,
+					irq_bit - PCIE_INTX_SHIFT);
+		generic_handle_irq(virq);
+	}
+
+	chained_irq_exit(irqchip, desc);
+}
+
+static int mtk_pcie_setup_irq(struct mtk_pcie_port *port)
+{
+	struct device *dev = port->dev;
+	struct platform_device *pdev = to_platform_device(dev);
+	int err;
+
+	err = mtk_pcie_init_irq_domains(port);
+	if (err)
+		return err;
+
+	port->irq = platform_get_irq(pdev, 0);
+	if (port->irq < 0)
+		return port->irq;
+
+	irq_set_chained_handler_and_data(port->irq, mtk_pcie_irq_handler, port);
+
+	return 0;
+}
+
 static int mtk_pcie_parse_port(struct mtk_pcie_port *port)
 {
 	struct device *dev = port->dev;
@@ -393,6 +559,10 @@ static int mtk_pcie_setup(struct mtk_pcie_port *port)
 	if (err)
 		goto err_setup;
 
+	err = mtk_pcie_setup_irq(port);
+	if (err)
+		goto err_setup;
+
 	return 0;
 
 err_setup:
@@ -426,6 +596,7 @@ static int mtk_pcie_probe(struct platform_device *pdev)
 
 	err = pci_host_probe(host);
 	if (err) {
+		mtk_pcie_irq_teardown(port);
 		mtk_pcie_power_down(port);
 		return err;
 	}
@@ -443,6 +614,7 @@ static int mtk_pcie_remove(struct platform_device *pdev)
 	pci_remove_root_bus(host->bus);
 	pci_unlock_rescan_remove();
 
+	mtk_pcie_irq_teardown(port);
 	mtk_pcie_power_down(port);
 
 	return 0;