PCI: aardvark: Fix PCI_EXP_RTCTL register configuration

PCI_EXP_RTCTL is used to activate PME interrupt only, so writing into it
should not modify other interrupts' mask. The ISR mask polarity was also
inverted, when PCI_EXP_RTCTL_PMEIE is set PCIE_MSG_PM_PME_MASK mask bit
should actually be cleared.

Fixes: 8a3ebd8d ("PCI: aardvark: Implement emulated root PCI bridge config space")
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

drivers/pci/controller/pci-aardvark.c

@@ -436,7 +436,7 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 
 	case PCI_EXP_RTCTL: {
 		u32 val = advk_readl(pcie, PCIE_ISR0_MASK_REG);
-		*value = (val & PCIE_MSG_PM_PME_MASK) ? PCI_EXP_RTCTL_PMEIE : 0;
+		*value = (val & PCIE_MSG_PM_PME_MASK) ? 0 : PCI_EXP_RTCTL_PMEIE;
 		return PCI_BRIDGE_EMUL_HANDLED;
 	}
 
@@ -486,10 +486,15 @@ advk_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
 			advk_pcie_wait_for_retrain(pcie);
 		break;
 
-	case PCI_EXP_RTCTL:
-		new = (new & PCI_EXP_RTCTL_PMEIE) << 3;
-		advk_writel(pcie, new, PCIE_ISR0_MASK_REG);
+	case PCI_EXP_RTCTL: {
+		/* Only mask/unmask PME interrupt */
+		u32 val = advk_readl(pcie, PCIE_ISR0_MASK_REG) &
+			~PCIE_MSG_PM_PME_MASK;
+		if ((new & PCI_EXP_RTCTL_PMEIE) == 0)
+			val |= PCIE_MSG_PM_PME_MASK;
+		advk_writel(pcie, val, PCIE_ISR0_MASK_REG);
 		break;
+	}
 
 	case PCI_EXP_RTSTA:
 		new = (new & PCI_EXP_RTSTA_PME) >> 9;