[PATCH v14 4/7] PCI: dwc: Handle MSIs routed to multiple GIC interrupts

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On some of Qualcomm platforms each group of 32 MSI vectors is routed to the
separate GIC interrupt. Implement support for such configurations by
parsing "msi0" ... "msiN" interrupts and attaching them to the chained
handler.

Note, that if DT doesn't list an array of MSI interrupts and uses single
"msi" IRQ, the driver will limit the amount of supported MSI vectors
accordingly (to 32).

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 .../pci/controller/dwc/pcie-designware-host.c | 63 +++++++++++++++++--
 1 file changed, 59 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 85c1160792e1..26b50948d6fc 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -289,6 +289,46 @@ static void dw_pcie_msi_init(struct pcie_port *pp)
 	dw_pcie_writel_dbi(pci, PCIE_MSI_ADDR_HI, upper_32_bits(msi_target));
 }
 
+static int dw_pcie_parse_split_msi_irq(struct pcie_port *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct device *dev = pci->dev;
+	struct platform_device *pdev = to_platform_device(dev);
+	int irq;
+	u32 ctrl, max_vectors;
+
+	/* Parse as many IRQs as described in the devicetree. */
+	for (ctrl = 0; ctrl < MAX_MSI_CTRLS; ctrl++) {
+		char msi_name[] = "msiX";
+
+		msi_name[3] = '0' + ctrl;
+		irq = platform_get_irq_byname_optional(pdev, msi_name);
+		if (irq == -ENXIO)
+			break;
+		if (irq < 0)
+			return dev_err_probe(dev, irq,
+					     "Failed to parse MSI IRQ '%s'\n",
+					     msi_name);
+
+		pp->msi_irq[ctrl] = irq;
+	}
+
+	/* If there were no "msiN" IRQs at all, fallback to the standard "msi" IRQ. */
+	if (ctrl == 0)
+		return -ENXIO;
+
+	max_vectors = ctrl * MAX_MSI_IRQS_PER_CTRL;
+	if (pp->num_vectors > max_vectors) {
+		dev_warn(dev, "Exceeding number of MSI vectors, limiting to %u\n",
+			 max_vectors);
+		pp->num_vectors = max_vectors;
+	}
+	if (!pp->num_vectors)
+		pp->num_vectors = max_vectors;
+
+	return 0;
+}
+
 static int dw_pcie_msi_host_init(struct pcie_port *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -297,21 +337,32 @@ static int dw_pcie_msi_host_init(struct pcie_port *pp)
 	int ret;
 	u32 ctrl, num_ctrls;
 
-	num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
-	for (ctrl = 0; ctrl < num_ctrls; ctrl++)
+	for (ctrl = 0; ctrl < MAX_MSI_CTRLS; ctrl++)
 		pp->irq_mask[ctrl] = ~0;
 
+	if (!pp->msi_irq[0]) {
+		ret = dw_pcie_parse_split_msi_irq(pp);
+		if (ret < 0 && ret != -ENXIO)
+			return ret;
+	}
+
+	if (!pp->num_vectors)
+		pp->num_vectors = MSI_DEF_NUM_VECTORS;
+	num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
+
 	if (!pp->msi_irq[0]) {
 		int irq = platform_get_irq_byname_optional(pdev, "msi");
 
 		if (irq < 0) {
 			irq = platform_get_irq(pdev, 0);
 			if (irq < 0)
-				return irq;
+				return dev_err_probe(dev, irq, "Failed to parse MSI irq\n");
 		}
 		pp->msi_irq[0] = irq;
 	}
 
+	dev_dbg(dev, "Using %d MSI vectors\n", pp->num_vectors);
+
 	pp->msi_irq_chip = &dw_pci_msi_bottom_irq_chip;
 
 	ret = dw_pcie_allocate_domains(pp);
@@ -409,7 +460,11 @@ int dw_pcie_host_init(struct pcie_port *pp)
 				     of_property_read_bool(np, "msi-parent") ||
 				     of_property_read_bool(np, "msi-map"));
 
-		if (!pp->num_vectors) {
+		/*
+		 * For the has_msi_ctrl case the default assignment is handled
+		 * in the dw_pcie_msi_host_init().
+		 */
+		if (!pp->has_msi_ctrl && !pp->num_vectors) {
 			pp->num_vectors = MSI_DEF_NUM_VECTORS;
 		} else if (pp->num_vectors > MAX_MSI_IRQS) {
 			dev_err(dev, "Invalid number of vectors\n");
-- 
2.35.1