Add INTx support for MediaTek Gen3 PCIe controller.

Signed-off-by: Jianjun Wang <redacted>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>
---
 drivers/pci/controller/pcie-mediatek-gen3.c | 176 ++++++++++++++++++++
 1 file changed, 176 insertions(+)

diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
index c602beb9afec..8b3b5f838b69 100644
--- a/drivers/pci/controller/pcie-mediatek-gen3.c
+++ b/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;
 };
 
 /**

@@ -199,6 +216,11 @@ 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;

@@ -262,6 +284,154 @@ 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
+ * @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_enable		= mtk_intx_unmask,
+	.irq_disable		= mtk_intx_mask,