PCI: mediatek: Add MSI support for MT2712 and MT7622

MT2712 and MT7622's PCIe host controller support MSI, but only 32-bit MSI
addresses are supported. It connects to GIC with the same IRQ number as the
INTx IRQ, so it shares the same IRQ with INTx IRQ.

Add MSI support for MT2712 and MT7622.

Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com>
[bhelgaas: changes to follow rcar & tegra: rename to mtk_pcie_msi_alloc(),
add mtk_pcie_msi_free(), free hwirq if irq_create_mapping() fails, call
irq_dispose_mapping() from mtk_msi_teardown_irq()]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>

drivers/pci/host/pcie-mediatek.c

@@ -73,11 +73,17 @@
 #define PCIE_CSR_ASPM_L1_EN(x)	BIT(1 + (x) * 8)
 
 /* PCIe V2 per-port registers */
+#define PCIE_MSI_VECTOR		0x0c0
 #define PCIE_INT_MASK		0x420
 #define INTX_MASK		GENMASK(19, 16)
 #define INTX_SHIFT		16
 #define INTX_NUM		4
 #define PCIE_INT_STATUS		0x424
+#define MSI_STATUS		BIT(23)
+#define PCIE_IMSI_STATUS	0x42c
+#define PCIE_IMSI_ADDR		0x430
+#define MSI_MASK		BIT(23)
+#define MTK_MSI_IRQS_NUM	32
 
 #define PCIE_AHB_TRANS_BASE0_L	0x438
 #define PCIE_AHB_TRANS_BASE0_H	0x43c
@@ -128,11 +134,13 @@ struct mtk_pcie_port;
 
 /**
  * struct mtk_pcie_soc - differentiate between host generations
+ * @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 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);
@@ -156,6 +164,8 @@ struct mtk_pcie_soc {
  * @lane: lane count
  * @slot: port slot
  * @irq_domain: legacy INTx IRQ domain
+ * @msi_domain: MSI IRQ domain
+ * @msi_irq_in_use: bit map for assigned MSI IRQ
  */
 struct mtk_pcie_port {
 	void __iomem *base;
@@ -172,6 +182,8 @@ struct mtk_pcie_port {
 	u32 lane;
 	u32 slot;
 	struct irq_domain *irq_domain;
+	struct irq_domain *msi_domain;
+	DECLARE_BITMAP(msi_irq_in_use, MTK_MSI_IRQS_NUM);
 };
 
 /**
@@ -427,6 +439,117 @@ 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)
+{
+	int msi;
+
+	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;
+
+	return msi;
+}
+
+static void mtk_pcie_msi_free(struct mtk_pcie_port *port, unsigned long hwirq)
+{
+	clear_bit(hwirq, port->msi_irq_in_use);
+}
+
+static int mtk_pcie_msi_setup_irq(struct msi_controller *chip,
+				  struct pci_dev *pdev, struct msi_desc *desc)
+{
+	struct mtk_pcie_port *port;
+	struct msi_msg msg;
+	unsigned int irq;
+	int hwirq;
+	phys_addr_t msg_addr;
+
+	port = mtk_pcie_find_port(pdev->bus, pdev->devfn);
+	if (!port)
+		return -EINVAL;
+
+	hwirq = mtk_pcie_msi_alloc(port);
+	if (hwirq < 0)
+		return hwirq;
+
+	irq = irq_create_mapping(port->msi_domain, hwirq);
+	if (!irq) {
+		mtk_pcie_msi_free(port, hwirq);
+		return -EINVAL;
+	}
+
+	chip->dev = &pdev->dev;
+
+	irq_set_msi_desc(irq, desc);
+
+	/* 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;
+
+	pci_write_msi_msg(irq, &msg);
+
+	return 0;
+}
+
+static void mtk_msi_teardown_irq(struct msi_controller *chip, unsigned int irq)
+{
+	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;
+
+	port = mtk_pcie_find_port(pdev->bus, pdev->devfn);
+	if (!port)
+		return;
+
+	irq_dispose_mapping(irq);
+	mtk_pcie_msi_free(port, hwirq);
+}
+
+static struct msi_controller mtk_pcie_msi_chip = {
+	.setup_irq = mtk_pcie_msi_setup_irq,
+	.teardown_irq = mtk_msi_teardown_irq,
+};
+
+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,
+};
+
+static int mtk_pcie_msi_map(struct irq_domain *domain, unsigned int irq,
+			    irq_hw_number_t hwirq)
+{
+	irq_set_chip_and_handler(irq, &mtk_msi_irq_chip, handle_simple_irq);
+	irq_set_chip_data(irq, domain->host_data);
+
+	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;
+	phys_addr_t msg_addr;
+
+	msg_addr = virt_to_phys(port->base + PCIE_MSI_VECTOR);
+	val = lower_32_bits(msg_addr);
+	writel(val, port->base + PCIE_IMSI_ADDR);
+
+	val = readl(port->base + PCIE_INT_MASK);
+	val &= ~MSI_MASK;
+	writel(val, port->base + PCIE_INT_MASK);
+}
+
 static int mtk_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
 			     irq_hw_number_t hwirq)
 {
@@ -460,6 +583,17 @@ static int mtk_pcie_init_irq_domain(struct mtk_pcie_port *port,
 		return -ENODEV;
 	}
 
+	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;
+		}
+		mtk_pcie_enable_msi(port);
+	}
+
 	return 0;
 }
 
@@ -480,6 +614,23 @@ 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) {
+			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);
+					generic_handle_irq(virq);
+				}
+			}
+			/* Clear MSI interrupt status */
+			writel(MSI_STATUS, port->base + PCIE_INT_STATUS);
+		}
+	}
+
 	return IRQ_HANDLED;
 }
 
@@ -501,7 +652,7 @@ static int mtk_pcie_setup_irq(struct mtk_pcie_port *port,
 
 	err = mtk_pcie_init_irq_domain(port, node);
 	if (err) {
-		dev_err(dev, "failed to init PCIe legacy IRQ domain\n");
+		dev_err(dev, "failed to init PCIe IRQ domain\n");
 		return err;
 	}
 
@@ -938,6 +1089,8 @@ 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)
@@ -999,6 +1152,7 @@ static const struct mtk_pcie_soc mtk_pcie_soc_v1 = {
 };
 
 static const struct mtk_pcie_soc mtk_pcie_soc_v2 = {
+	.has_msi = true,
 	.ops = &mtk_pcie_ops_v2,
 	.startup = mtk_pcie_startup_port_v2,
 	.setup_irq = mtk_pcie_setup_irq,