[v3] PCI: imx: make msi work without pcieportbus

[Richard Zhu]

MSI_EN of iMX PCIe RC would be asserted when
PCIEPORTBUS driver is selected.
Thus, the MSI works fine on iMX PCIe before.
Assert it unconditionally when MSI is enabled.
Otherwise, the MSI wouldn't be triggered although
the EP is present and the MSIs are assigned.

Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
---
Changes v1 -> v2:
* Assert the MSI_EN unconditionally when MSI is supported.
Changes v2 -> v3:
* Remove the IS_ENABLED(CONFIG_PCI_MSI) since the driver
depends on PCI_MSI_IRQ_DOMAIN
* Extended with a check for pci_msi_enabled() to see
if the user explicitly want legacy IRQs
---
 drivers/pci/controller/dwc/pci-imx6.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 26087b3..1c59a93 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -74,6 +74,7 @@ struct imx6_pcie {
 #define PHY_PLL_LOCK_WAIT_USLEEP_MAX	200
 
 /* PCIe Root Complex registers (memory-mapped) */
+#define PCI_MSI_CAP				0x50
 #define PCIE_RC_LCR				0x7c
 #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1	0x1
 #define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2	0x2
@@ -926,6 +927,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 	struct resource *dbi_base;
 	struct device_node *node = dev->of_node;
 	int ret;
+	u16 val;
 
 	imx6_pcie = devm_kzalloc(dev, sizeof(*imx6_pcie), GFP_KERNEL);
 	if (!imx6_pcie)
@@ -1071,6 +1073,12 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
+	if (pci_msi_enabled()) {
+		val = dw_pcie_readw_dbi(pci, PCI_MSI_CAP + PCI_MSI_FLAGS);
+		val |= PCI_MSI_FLAGS_ENABLE;
+		dw_pcie_writew_dbi(pci, PCI_MSI_CAP + PCI_MSI_FLAGS, val);
+	}
+
 	return 0;
 }
 
-- 
2.7.4