PCI: aardvark: Optimize writing PCI_EXP_RTCTL_PMEIE and PCI_EXP_RTSTA_PME on emulated bridge

To optimize advk_pci_bridge_emul_pcie_conf_write() code, touch
PCIE_ISR0_REG and PCIE_ISR0_MASK_REG registers only when it is really
needed, when processing PCI_EXP_RTCTL_PMEIE and PCI_EXP_RTSTA_PME bits.

Link: https://lore.kernel.org/r/20220110015018.26359-16-kabel@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Author: pali

drivers/pci/controller/pci-aardvark.c

@@ -925,19 +925,21 @@ advk_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
 			advk_pcie_wait_for_retrain(pcie);
 		break;
 
-	case PCI_EXP_RTCTL: {
+	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);
+		if (mask & PCI_EXP_RTCTL_PMEIE) {
+			u32 val = advk_readl(pcie, PCIE_ISR0_MASK_REG);
+			if (new & PCI_EXP_RTCTL_PMEIE)
+				val &= ~PCIE_MSG_PM_PME_MASK;
+			else
+				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;
-		advk_writel(pcie, new, PCIE_ISR0_REG);
+		if (new & PCI_EXP_RTSTA_PME)
+			advk_writel(pcie, PCIE_MSG_PM_PME_MASK, PCIE_ISR0_REG);
 		break;
 
 	case PCI_EXP_DEVCTL: