PCI: imx6: Use DWC common suspend resume method

Call common DWC suspend/resume function. Use DWC common iATU method to
send out PME_TURN_OFF message.

In old DWC implementations, PCIE_ATU_INHIBIT_PAYLOAD in iATU Ctrl2 register
is reserved, so the generic DWC implementation of sending the PME_Turn_Off
message using a dummy MMIO write cannot be used. Use the previous method to
kick off PME_TURN_OFF message for these platforms.

The System Reset Control (SRC) interface is used to toggle 'turnoff_reset'
to send PME_TURN_OFF and since the DWC implementation is used, it is not
needed now.

Replace the imx_pcie_stop_link() and imx_pcie_host_exit() by
dw_pcie_suspend_noirq() in imx_pcie_suspend_noirq().

Since dw_pcie_suspend_noirq() already does these, see below call stack:

  dw_pcie_suspend_noirq()
    dw_pcie_stop_link()
      imx_pcie_stop_link()
    pci->pp.ops->deinit()
      imx_pcie_host_exit()

Replace the imx_pcie_host_init(), dw_pcie_setup_rc() and
imx_pcie_start_link() by dw_pcie_resume_noirq() in imx_pcie_resume_noirq().

Since dw_pcie_resume_noirq() already does these, see below call stack:

  dw_pcie_resume_noirq()
    pci->pp.ops->init()
      imx_pcie_host_init()
    dw_pcie_setup_rc()
    dw_pcie_start_link()
      imx_pcie_start_link(;

Link: https://lore.kernel.org/r/20241126075702.4099164-9-hongxing.zhu@nxp.com
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

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

@@ -33,6 +33,7 @@
 #include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 #define IMX8MQ_GPR_PCIE_REF_USE_PAD		BIT(9)
@@ -111,19 +112,18 @@ struct imx_pcie_drvdata {
 	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);
+	const struct dw_pcie_host_ops *ops;
 };
 
 struct imx_pcie {
 	struct dw_pcie		*pci;
 	struct gpio_desc	*reset_gpiod;
-	bool			link_is_up;
 	struct clk_bulk_data	clks[IMX_PCIE_MAX_CLKS];
 	struct regmap		*iomuxc_gpr;
 	u16			msi_ctrl;
 	u32			controller_id;
 	struct reset_control	*pciephy_reset;
 	struct reset_control	*apps_reset;
-	struct reset_control	*turnoff_reset;
 	u32			tx_deemph_gen1;
 	u32			tx_deemph_gen2_3p5db;
 	u32			tx_deemph_gen2_6db;
@@ -908,13 +908,11 @@ static int imx_pcie_start_link(struct dw_pcie *pci)
 		dev_info(dev, "Link: Only Gen1 is enabled\n");
 	}
 
-	imx_pcie->link_is_up = true;
 	tmp = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
 	dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS);
 	return 0;
 
 err_reset_phy:
-	imx_pcie->link_is_up = false;
 	dev_dbg(dev, "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n",
 		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
 		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
@@ -1033,9 +1031,31 @@ static u64 imx_pcie_cpu_addr_fixup(struct dw_pcie *pcie, u64 cpu_addr)
 	return cpu_addr - entry->offset;
 }
 
+/*
+ * In old DWC implementations, PCIE_ATU_INHIBIT_PAYLOAD in iATU Ctrl2
+ * register is reserved, so the generic DWC implementation of sending the
+ * PME_Turn_Off message using a dummy MMIO write cannot be used.
+ */
+static void imx_pcie_pme_turn_off(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct imx_pcie *imx_pcie = to_imx_pcie(pci);
+
+	regmap_set_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12, IMX6SX_GPR12_PCIE_PM_TURN_OFF);
+	regmap_clear_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12, IMX6SX_GPR12_PCIE_PM_TURN_OFF);
+
+	usleep_range(PCIE_PME_TO_L2_TIMEOUT_US/10, PCIE_PME_TO_L2_TIMEOUT_US);
+}
+
 static const struct dw_pcie_host_ops imx_pcie_host_ops = {
 	.init = imx_pcie_host_init,
 	.deinit = imx_pcie_host_exit,
+	.pme_turn_off = imx_pcie_pme_turn_off,
+};
+
+static const struct dw_pcie_host_ops imx_pcie_host_dw_pme_ops = {
+	.init = imx_pcie_host_init,
+	.deinit = imx_pcie_host_exit,
 };
 
 static const struct dw_pcie_ops dw_pcie_ops = {
@@ -1176,43 +1196,6 @@ static int imx_add_pcie_ep(struct imx_pcie *imx_pcie,
 	return 0;
 }
 
-static void imx_pcie_pm_turnoff(struct imx_pcie *imx_pcie)
-{
-	struct device *dev = imx_pcie->pci->dev;
-
-	/* Some variants have a turnoff reset in DT */
-	if (imx_pcie->turnoff_reset) {
-		reset_control_assert(imx_pcie->turnoff_reset);
-		reset_control_deassert(imx_pcie->turnoff_reset);
-		goto pm_turnoff_sleep;
-	}
-
-	/* Others poke directly at IOMUXC registers */
-	switch (imx_pcie->drvdata->variant) {
-	case IMX6SX:
-	case IMX6QP:
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
-				IMX6SX_GPR12_PCIE_PM_TURN_OFF,
-				IMX6SX_GPR12_PCIE_PM_TURN_OFF);
-		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
-				IMX6SX_GPR12_PCIE_PM_TURN_OFF, 0);
-		break;
-	default:
-		dev_err(dev, "PME_Turn_Off not implemented\n");
-		return;
-	}
-
-	/*
-	 * Components with an upstream port must respond to
-	 * PME_Turn_Off with PME_TO_Ack but we can't check.
-	 *
-	 * The standard recommends a 1-10ms timeout after which to
-	 * proceed anyway as if acks were received.
-	 */
-pm_turnoff_sleep:
-	usleep_range(1000, 10000);
-}
-
 static void imx_pcie_msi_save_restore(struct imx_pcie *imx_pcie, bool save)
 {
 	u8 offset;
@@ -1236,7 +1219,6 @@ static void imx_pcie_msi_save_restore(struct imx_pcie *imx_pcie, bool save)
 static int imx_pcie_suspend_noirq(struct device *dev)
 {
 	struct imx_pcie *imx_pcie = dev_get_drvdata(dev);
-	struct dw_pcie_rp *pp = &imx_pcie->pci->pp;
 
 	if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND))
 		return 0;
@@ -1251,9 +1233,7 @@ static int imx_pcie_suspend_noirq(struct device *dev)
 		imx_pcie_assert_core_reset(imx_pcie);
 		imx_pcie->drvdata->enable_ref_clk(imx_pcie, false);
 	} else {
-		imx_pcie_pm_turnoff(imx_pcie);
+		return dw_pcie_suspend_noirq(imx_pcie->pci);
-		imx_pcie_stop_link(imx_pcie->pci);
-		imx_pcie_host_exit(pp);
 	}
 
 	return 0;
@@ -1263,7 +1243,6 @@ static int imx_pcie_resume_noirq(struct device *dev)
 {
 	int ret;
 	struct imx_pcie *imx_pcie = dev_get_drvdata(dev);
-	struct dw_pcie_rp *pp = &imx_pcie->pci->pp;
 
 	if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND))
 		return 0;
@@ -1283,17 +1262,12 @@ static int imx_pcie_resume_noirq(struct device *dev)
 		ret = dw_pcie_setup_rc(&imx_pcie->pci->pp);
 		if (ret)
 			return ret;
-		imx_pcie_msi_save_restore(imx_pcie, false);
 	} else {
-		ret = imx_pcie_host_init(pp);
+		ret = dw_pcie_resume_noirq(imx_pcie->pci);
 		if (ret)
 			return ret;
-		imx_pcie_msi_save_restore(imx_pcie, false);
-		dw_pcie_setup_rc(pp);
-
-		if (imx_pcie->link_is_up)
-			imx_pcie_start_link(imx_pcie->pci);
 	}
+	imx_pcie_msi_save_restore(imx_pcie, false);
 
 	return 0;
 }
@@ -1325,11 +1299,15 @@ static int imx_pcie_probe(struct platform_device *pdev)
 
 	pci->dev = dev;
 	pci->ops = &dw_pcie_ops;
-	pci->pp.ops = &imx_pcie_host_ops;
 
 	imx_pcie->pci = pci;
 	imx_pcie->drvdata = of_device_get_match_data(dev);
 
+	if (imx_pcie->drvdata->ops)
+		pci->pp.ops = imx_pcie->drvdata->ops;
+	else
+		pci->pp.ops = &imx_pcie_host_dw_pme_ops;
+
 	/* Find the PHY if one is defined, only imx7d uses it */
 	np = of_parse_phandle(node, "fsl,imx7d-pcie-phy", 0);
 	if (np) {
@@ -1399,13 +1377,6 @@ static int imx_pcie_probe(struct platform_device *pdev)
 		break;
 	}
 
-	/* Grab turnoff reset */
-	imx_pcie->turnoff_reset = devm_reset_control_get_optional_exclusive(dev, "turnoff");
-	if (IS_ERR(imx_pcie->turnoff_reset)) {
-		dev_err(dev, "Failed to get TURNOFF reset control\n");
-		return PTR_ERR(imx_pcie->turnoff_reset);
-	}
-
 	if (imx_pcie->drvdata->gpr) {
 	/* Grab GPR config register range */
 		imx_pcie->iomuxc_gpr =
@@ -1484,6 +1455,7 @@ static int imx_pcie_probe(struct platform_device *pdev)
 		if (ret < 0)
 			return ret;
 	} else {
+		pci->pp.use_atu_msg = true;
 		ret = dw_pcie_host_init(&pci->pp);
 		if (ret < 0)
 			return ret;
@@ -1548,6 +1520,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.init_phy = imx6sx_pcie_init_phy,
 		.enable_ref_clk = imx6sx_pcie_enable_ref_clk,
 		.core_reset = imx6sx_pcie_core_reset,
+		.ops = &imx_pcie_host_ops,
 	},
 	[IMX6QP] = {
 		.variant = IMX6QP,
@@ -1565,6 +1538,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.init_phy = imx_pcie_init_phy,
 		.enable_ref_clk = imx6q_pcie_enable_ref_clk,
 		.core_reset = imx6qp_pcie_core_reset,
+		.ops = &imx_pcie_host_ops,
 	},
 	[IMX7D] = {
 		.variant = IMX7D,