PCI: imx6: Simplify switch-case logic by involve core_reset callback

Instead of using the switch case statement to assert/dassert the core
reset handled by this driver itself, let's introduce a new callback
core_reset() and define it for platforms that require it.

This simplifies the code.

Link: https://lore.kernel.org/linux-pci/20240729-pci2_upstream-v8-5-b68ee5ef2b4d@nxp.comSigned-off-by: Frank Li <Frank.Li@nxp.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

drivers/pci/controller/dwc/pci-imx6.c

@@ -102,6 +102,7 @@ struct imx_pcie_drvdata {
 	const struct pci_epc_features *epc_features;
 	int (*init_phy)(struct imx_pcie *pcie);
 	int (*enable_ref_clk)(struct imx_pcie *pcie, bool enable);
+	int (*core_reset)(struct imx_pcie *pcie, bool assert);
 };
 
 struct imx_pcie {
@@ -668,83 +669,86 @@ static void imx_pcie_clk_disable(struct imx_pcie *imx_pcie)
 	clk_bulk_disable_unprepare(imx_pcie->drvdata->clks_cnt, imx_pcie->clks);
 }
 
-static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
+static int imx6sx_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
 {
-	reset_control_assert(imx_pcie->pciephy_reset);
-	reset_control_assert(imx_pcie->apps_reset);
-
-	switch (imx_pcie->drvdata->variant) {
-	case IMX6SX:
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
-				   IMX6SX_GPR12_PCIE_TEST_POWERDOWN,
+	if (assert)
+		regmap_set_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
 				IMX6SX_GPR12_PCIE_TEST_POWERDOWN);
+
 	/* Force PCIe PHY reset */
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR5,
-				   IMX6SX_GPR5_PCIE_BTNRST_RESET,
-				   IMX6SX_GPR5_PCIE_BTNRST_RESET);
-		break;
-	case IMX6QP:
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
-				   IMX6Q_GPR1_PCIE_SW_RST,
-				   IMX6Q_GPR1_PCIE_SW_RST);
-		break;
-	case IMX6Q:
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
-				   IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
-				   IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);
-		break;
-	default:
-		break;
-	}
+	regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR5, IMX6SX_GPR5_PCIE_BTNRST_RESET,
+			   assert ? IMX6SX_GPR5_PCIE_BTNRST_RESET : 0);
+	return 0;
+}
 
-	/* Some boards don't have PCIe reset GPIO. */
-	gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 1);
+static int imx6qp_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
+{
+	regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1, IMX6Q_GPR1_PCIE_SW_RST,
+			   assert ? IMX6Q_GPR1_PCIE_SW_RST : 0);
+	if (!assert)
+		usleep_range(200, 500);
+
+	return 0;
 }
 
-static int imx_pcie_deassert_core_reset(struct imx_pcie *imx_pcie)
+static int imx6q_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
+{
+	if (!assert)
+		return 0;
+
+	regmap_set_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1, IMX6Q_GPR1_PCIE_TEST_PD);
+	regmap_set_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1, IMX6Q_GPR1_PCIE_REF_CLK_EN);
+
+	return 0;
+}
+
+static int imx7d_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
 {
 	struct dw_pcie *pci = imx_pcie->pci;
 	struct device *dev = pci->dev;
 
-	reset_control_deassert(imx_pcie->pciephy_reset);
+	if (assert)
+		return 0;
 
-	switch (imx_pcie->drvdata->variant) {
-	case IMX7D:
-		/* Workaround for ERR010728, failure of PCI-e PLL VCO to
+	/*
+	 * Workaround for ERR010728, failure of PCI-e PLL VCO to
 	 * oscillate, especially when cold. This turns off "Duty-cycle
 	 * Corrector" and other mysterious undocumented things.
 	 */
+
 	if (likely(imx_pcie->phy_base)) {
 		/* De-assert DCC_FB_EN */
-			writel(PCIE_PHY_CMN_REG4_DCC_FB_EN,
-			       imx_pcie->phy_base + PCIE_PHY_CMN_REG4);
+		writel(PCIE_PHY_CMN_REG4_DCC_FB_EN, imx_pcie->phy_base + PCIE_PHY_CMN_REG4);
 		/* Assert RX_EQS and RX_EQS_SEL */
-			writel(PCIE_PHY_CMN_REG24_RX_EQ_SEL
-				| PCIE_PHY_CMN_REG24_RX_EQ,
+		writel(PCIE_PHY_CMN_REG24_RX_EQ_SEL | PCIE_PHY_CMN_REG24_RX_EQ,
 		       imx_pcie->phy_base + PCIE_PHY_CMN_REG24);
 		/* Assert ATT_MODE */
-			writel(PCIE_PHY_CMN_REG26_ATT_MODE,
-			       imx_pcie->phy_base + PCIE_PHY_CMN_REG26);
+		writel(PCIE_PHY_CMN_REG26_ATT_MODE, imx_pcie->phy_base + PCIE_PHY_CMN_REG26);
 	} else {
 		dev_warn(dev, "Unable to apply ERR010728 workaround. DT missing fsl,imx7d-pcie-phy phandle ?\n");
 	}
-
 	imx7d_pcie_wait_for_phy_pll_lock(imx_pcie);
-		break;
-	case IMX6SX:
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR5,
-				   IMX6SX_GPR5_PCIE_BTNRST_RESET, 0);
-		break;
-	case IMX6QP:
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR1,
-				   IMX6Q_GPR1_PCIE_SW_RST, 0);
+	return 0;
+}
 
-		usleep_range(200, 500);
-		break;
-	default:
-		break;
-	}
+static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
+{
+	reset_control_assert(imx_pcie->pciephy_reset);
+	reset_control_assert(imx_pcie->apps_reset);
+
+	if (imx_pcie->drvdata->core_reset)
+		imx_pcie->drvdata->core_reset(imx_pcie, true);
+
+	/* Some boards don't have PCIe reset GPIO. */
+	gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 1);
+}
+
+static int imx_pcie_deassert_core_reset(struct imx_pcie *imx_pcie)
+{
+	reset_control_deassert(imx_pcie->pciephy_reset);
+
+	if (imx_pcie->drvdata->core_reset)
+		imx_pcie->drvdata->core_reset(imx_pcie, false);
 
 	/* Some boards don't have PCIe reset GPIO. */
 	if (imx_pcie->reset_gpiod) {
@@ -1441,6 +1445,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.mode_mask[0] = IMX6Q_GPR12_DEVICE_TYPE,
 		.init_phy = imx_pcie_init_phy,
 		.enable_ref_clk = imx6q_pcie_enable_ref_clk,
+		.core_reset = imx6q_pcie_core_reset,
 	},
 	[IMX6SX] = {
 		.variant = IMX6SX,
@@ -1456,6 +1461,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.mode_mask[0] = IMX6Q_GPR12_DEVICE_TYPE,
 		.init_phy = imx6sx_pcie_init_phy,
 		.enable_ref_clk = imx6sx_pcie_enable_ref_clk,
+		.core_reset = imx6sx_pcie_core_reset,
 	},
 	[IMX6QP] = {
 		.variant = IMX6QP,
@@ -1472,6 +1478,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.mode_mask[0] = IMX6Q_GPR12_DEVICE_TYPE,
 		.init_phy = imx_pcie_init_phy,
 		.enable_ref_clk = imx6q_pcie_enable_ref_clk,
+		.core_reset = imx6qp_pcie_core_reset,
 	},
 	[IMX7D] = {
 		.variant = IMX7D,
@@ -1485,6 +1492,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.mode_mask[0] = IMX6Q_GPR12_DEVICE_TYPE,
 		.init_phy = imx7d_pcie_init_phy,
 		.enable_ref_clk = imx7d_pcie_enable_ref_clk,
+		.core_reset = imx7d_pcie_core_reset,
 	},
 	[IMX8MQ] = {
 		.variant = IMX8MQ,