PCI: mediatek-gen3: Split out device power helpers

In preparation for adding full power on/off control with the pwrctrl API,
split out the existing code that only partially deals with device power
sequencing into separate helper functions. The existing code only handles
PERST#.

This is purely moving code around, and brings no functional changes.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
[mani: moved the 'err' variable to next commit]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20260324052002.4072430-6-wenst@chromium.org

Author: wens

drivers/pci/controller/pcie-mediatek-gen3.c

@@ -403,6 +403,53 @@ static void mtk_pcie_enable_msi(struct mtk_gen3_pcie *pcie)
 	writel_relaxed(val, pcie->base + PCIE_INT_ENABLE_REG);
 }
 
+static int mtk_pcie_devices_power_up(struct mtk_gen3_pcie *pcie)
+{
+	u32 val;
+
+	/*
+	 * Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal
+	 * causing occasional PCIe link down. In order to overcome the issue,
+	 * PCIE_RSTB signals are not asserted/released at this stage and the
+	 * PCIe block is reset using en7523_reset_assert() and
+	 * en7581_pci_enable().
+	 */
+	if (!(pcie->soc->flags & SKIP_PCIE_RSTB)) {
+		/* Assert all reset signals */
+		val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG);
+		val |= PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB |
+		       PCIE_PE_RSTB;
+		writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
+
+		/*
+		 * Described in PCIe CEM specification revision 6.0.
+		 *
+		 * The deassertion of PERST# should be delayed 100ms (TPVPERL)
+		 * for the power and clock to become stable.
+		 */
+		msleep(PCIE_T_PVPERL_MS);
+
+		/* De-assert reset signals */
+		val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB |
+			 PCIE_PE_RSTB);
+		writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
+	}
+
+	return 0;
+}
+
+static void mtk_pcie_devices_power_down(struct mtk_gen3_pcie *pcie)
+{
+	u32 val;
+
+	if (!(pcie->soc->flags & SKIP_PCIE_RSTB)) {
+		/* Assert the PERST# pin */
+		val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG);
+		val |= PCIE_PE_RSTB;
+		writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
+	}
+}
+
 static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
 {
 	struct resource_entry *entry;
@@ -489,33 +536,9 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
 			return err;
 	}
 
-	/*
-	 * Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal
-	 * causing occasional PCIe link down. In order to overcome the issue,
-	 * PCIE_RSTB signals are not asserted/released at this stage and the
-	 * PCIe block is reset using en7523_reset_assert() and
-	 * en7581_pci_enable().
-	 */
-	if (!(pcie->soc->flags & SKIP_PCIE_RSTB)) {
-		/* Assert all reset signals */
-		val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG);
-		val |= PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB |
-		       PCIE_PE_RSTB;
-		writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
-
-		/*
-		 * Described in PCIe CEM specification revision 6.0.
-		 *
-		 * The deassertion of PERST# should be delayed 100ms (TPVPERL)
-		 * for the power and clock to become stable.
-		 */
-		msleep(PCIE_T_PVPERL_MS);
-
-		/* De-assert reset signals */
-		val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB |
-			 PCIE_PE_RSTB);
-		writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
-	}
+	err = mtk_pcie_devices_power_up(pcie);
+	if (err)
+		return err;
 
 	/* Check if the link is up or not */
 	err = readl_poll_timeout(pcie->base + PCIE_LINK_STATUS_REG, val,
@@ -1270,7 +1293,6 @@ static int mtk_pcie_suspend_noirq(struct device *dev)
 {
 	struct mtk_gen3_pcie *pcie = dev_get_drvdata(dev);
 	int err;
-	u32 val;
 
 	/* Trigger link to L2 state */
 	err = mtk_pcie_turn_off_link(pcie);
@@ -1279,13 +1301,7 @@ static int mtk_pcie_suspend_noirq(struct device *dev)
 		return err;
 	}
 
-	if (!(pcie->soc->flags & SKIP_PCIE_RSTB)) {
-		/* Assert the PERST# pin */
-		val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG);
-		val |= PCIE_PE_RSTB;
-		writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
-	}
-
+	mtk_pcie_devices_power_down(pcie);
 	dev_dbg(pcie->dev, "entered L2 states successfully");
 
 	mtk_pcie_irq_save(pcie);