PCI: iproc: Add iProc PCIe MSI support

Add PCIe MSI support for both PAXB and PAXC interfaces on all iProc-based
platforms.

The iProc PCIe MSI support deploys an event queue-based implementation.
Each event queue is serviced by a GIC interrupt and can support up to 64
MSI vectors.  Host memory is allocated for the event queues, and each event
queue consists of 64 word-sized entries.  MSI data is written to the lower
16-bit of each entry, whereas the upper 16-bit of the entry is reserved for
the controller for internal processing.

Each event queue is tracked by a head pointer and tail pointer.  Head
pointer indicates the next entry in the event queue to be processed by
the driver and is updated by the driver after processing is done.
The controller uses the tail pointer as the next MSI data insertion
point.  The controller ensures MSI data is flushed to host memory before
updating the tail pointer and then triggering the interrupt.

MSI IRQ affinity is supported by evenly distributing the interrupts to each
CPU core.  MSI vector is moved from one GIC interrupt to another in order
to steer to the target CPU.

Therefore, the actual number of supported MSI vectors is:

  M * 64 / N

where M denotes the number of GIC interrupts (event queues), and N denotes
the number of CPU cores.

This iProc event queue-based MSI support should not be used with newer
platforms with integrated MSI support in the GIC (e.g., giv2m or
gicv3-its).

[bhelgaas: fold in Kconfig fixes from Arnd Bergmann <arnd@arndb.de>]
Signed-off-by: Ray Jui <rjui@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Vikram Prakash <vikramp@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/pci/host/Kconfig

@@ -145,6 +145,16 @@ config PCIE_IPROC_BCMA
 	  Say Y here if you want to use the Broadcom iProc PCIe controller
 	  through the BCMA bus interface
 
+config PCIE_IPROC_MSI
+	bool "Broadcom iProc PCIe MSI support"
+	depends on PCIE_IPROC_PLATFORM || PCIE_IPROC_BCMA
+	depends on PCI_MSI
+	select PCI_MSI_IRQ_DOMAIN
+	default ARCH_BCM_IPROC
+	help
+	  Say Y here if you want to enable MSI support for Broadcom's iProc
+	  PCIe controller
+
 config PCIE_ALTERA
 	bool "Altera PCIe controller"
 	depends on ARM || NIOS2

drivers/pci/host/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_PCI_XGENE_MSI) += pci-xgene-msi.o
 obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
 obj-$(CONFIG_PCI_VERSATILE) += pci-versatile.o
 obj-$(CONFIG_PCIE_IPROC) += pcie-iproc.o
+obj-$(CONFIG_PCIE_IPROC_MSI) += pcie-iproc-msi.o
 obj-$(CONFIG_PCIE_IPROC_PLATFORM) += pcie-iproc-platform.o
 obj-$(CONFIG_PCIE_IPROC_BCMA) += pcie-iproc-bcma.o
 obj-$(CONFIG_PCIE_ALTERA) += pcie-altera.o

drivers/pci/host/pcie-iproc-bcma.c

@@ -55,6 +55,7 @@ static int iproc_pcie_bcma_probe(struct bcma_device *bdev)
 	bcma_set_drvdata(bdev, pcie);
 
 	pcie->base = bdev->io_addr;
+	pcie->base_addr = bdev->addr;
 
 	res_mem.start = bdev->addr_s[0];
 	res_mem.end = bdev->addr_s[0] + SZ_128M - 1;

drivers/pci/host/pcie-iproc-platform.c

@@ -71,6 +71,7 @@ static int iproc_pcie_pltfm_probe(struct platform_device *pdev)
 		dev_err(pcie->dev, "unable to map controller registers\n");
 		return -ENOMEM;
 	}
+	pcie->base_addr = reg.start;
 
 	if (of_property_read_bool(np, "brcm,pcie-ob")) {
 		u32 val;

drivers/pci/host/pcie-iproc.c

@@ -440,6 +440,26 @@ static int iproc_pcie_map_ranges(struct iproc_pcie *pcie,
 	return 0;
 }
 
+static int iproc_pcie_msi_enable(struct iproc_pcie *pcie)
+{
+	struct device_node *msi_node;
+
+	msi_node = of_parse_phandle(pcie->dev->of_node, "msi-parent", 0);
+	if (!msi_node)
+		return -ENODEV;
+
+	/*
+	 * If another MSI controller is being used, the call below should fail
+	 * but that is okay
+	 */
+	return iproc_msi_init(pcie, msi_node);
+}
+
+static void iproc_pcie_msi_disable(struct iproc_pcie *pcie)
+{
+	iproc_msi_exit(pcie);
+}
+
 int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
 {
 	int ret;
@@ -507,6 +527,10 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
 
 	iproc_pcie_enable(pcie);
 
+	if (IS_ENABLED(CONFIG_PCI_MSI))
+		if (iproc_pcie_msi_enable(pcie))
+			dev_info(pcie->dev, "not using iProc MSI\n");
+
 	pci_scan_child_bus(bus);
 	pci_assign_unassigned_bus_resources(bus);
 	pci_fixup_irqs(pci_common_swizzle, pcie->map_irq);
@@ -531,6 +555,8 @@ int iproc_pcie_remove(struct iproc_pcie *pcie)
 	pci_stop_root_bus(pcie->root_bus);
 	pci_remove_root_bus(pcie->root_bus);
 
+	iproc_pcie_msi_disable(pcie);
+
 	phy_power_off(pcie->phy);
 	phy_exit(pcie->phy);
 

drivers/pci/host/pcie-iproc.h

@@ -41,6 +41,8 @@ struct iproc_pcie_ob {
 	resource_size_t window_size;
 };
 
+struct iproc_msi;
+
 /**
  * iProc PCIe device
  *
@@ -48,19 +50,21 @@ struct iproc_pcie_ob {
  * @type: iProc PCIe interface type
  * @reg_offsets: register offsets
  * @base: PCIe host controller I/O register base
+ * @base_addr: PCIe host controller register base physical address
  * @sysdata: Per PCI controller data (ARM-specific)
  * @root_bus: pointer to root bus
  * @phy: optional PHY device that controls the Serdes
- * @irqs: interrupt IDs
  * @map_irq: function callback to map interrupts
- * @need_ob_cfg: indidates SW needs to configure the outbound mapping window
+ * @need_ob_cfg: indicates SW needs to configure the outbound mapping window
  * @ob: outbound mapping parameters
+ * @msi: MSI data
  */
 struct iproc_pcie {
 	struct device *dev;
 	enum iproc_pcie_type type;
 	const u16 *reg_offsets;
 	void __iomem *base;
+	phys_addr_t base_addr;
 #ifdef CONFIG_ARM
 	struct pci_sys_data sysdata;
 #endif
@@ -69,9 +73,24 @@ struct iproc_pcie {
 	int (*map_irq)(const struct pci_dev *, u8, u8);
 	bool need_ob_cfg;
 	struct iproc_pcie_ob ob;
+	struct iproc_msi *msi;
 };
 
 int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res);
 int iproc_pcie_remove(struct iproc_pcie *pcie);
 
+#ifdef CONFIG_PCIE_IPROC_MSI
+int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node);
+void iproc_msi_exit(struct iproc_pcie *pcie);
+#else
+static inline int iproc_msi_init(struct iproc_pcie *pcie,
+				 struct device_node *node)
+{
+	return -ENODEV;
+}
+static inline void iproc_msi_exit(struct iproc_pcie *pcie)
+{
+}
+#endif
+
 #endif /* _PCIE_IPROC_H */