PCI: brcmstb: Disable/enable regulators in suspend/resume

If we found power regulators for a device below the Root Port, disable them
during suspend and re-enable them during resume.

If any downstream device can be a wakeup device, do not turn off the
regulators as the device will need them on.

[bhelgaas: drop unused regulator_oops, skip wrapping of .add_bus()/
.remove_bus(), move brcm_pcie_start_link() to .add_bus() in previous patch,
squash WOL checking into this patch]
Link: https://lore.kernel.org/r/20220725151258.42574-6-jim2101024@gmail.com
Link: https://lore.kernel.org/r/20220725151258.42574-7-jim2101024@gmail.com
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>

drivers/pci/controller/pcie-brcmstb.c

@@ -262,6 +262,7 @@ struct brcm_pcie {
 	void			(*perst_set)(struct brcm_pcie *pcie, u32 val);
 	void			(*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
 	struct subdev_regulators *sr;
+	bool			ep_wakeup_capable;
 };
 
 static inline bool is_bmips(const struct brcm_pcie *pcie)
@@ -1244,9 +1245,21 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
 	pcie->bridge_sw_init_set(pcie, 1);
 }
 
-static int brcm_pcie_suspend(struct device *dev)
+static int pci_dev_may_wakeup(struct pci_dev *dev, void *data)
+{
+	bool *ret = data;
+
+	if (device_may_wakeup(&dev->dev)) {
+		*ret = true;
+		dev_info(&dev->dev, "Possible wake-up device; regulators will not be disabled\n");
+	}
+	return (int) *ret;
+}
+
+static int brcm_pcie_suspend_noirq(struct device *dev)
 {
 	struct brcm_pcie *pcie = dev_get_drvdata(dev);
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
 	int ret;
 
 	brcm_pcie_turn_off(pcie);
@@ -1264,12 +1277,31 @@ static int brcm_pcie_suspend(struct device *dev)
 		return ret;
 	}
 
+	if (pcie->sr) {
+		/*
+		 * Now turn off the regulators, but if at least one
+		 * downstream device is enabled as a wake-up source, do not
+		 * turn off regulators.
+		 */
+		pcie->ep_wakeup_capable = false;
+		pci_walk_bus(bridge->bus, pci_dev_may_wakeup,
+			     &pcie->ep_wakeup_capable);
+		if (!pcie->ep_wakeup_capable) {
+			ret = regulator_bulk_disable(pcie->sr->num_supplies,
+						     pcie->sr->supplies);
+			if (ret) {
+				dev_err(dev, "Could not turn off regulators\n");
+				reset_control_reset(pcie->rescal);
+				return ret;
+			}
+		}
+	}
 	clk_disable_unprepare(pcie->clk);
 
 	return 0;
 }
 
-static int brcm_pcie_resume(struct device *dev)
+static int brcm_pcie_resume_noirq(struct device *dev)
 {
 	struct brcm_pcie *pcie = dev_get_drvdata(dev);
 	void __iomem *base;
@@ -1304,15 +1336,37 @@ static int brcm_pcie_resume(struct device *dev)
 	if (ret)
 		goto err_reset;
 
+	if (pcie->sr) {
+		if (pcie->ep_wakeup_capable) {
+			/*
+			 * We are resuming from a suspend.  In the suspend we
+			 * did not disable the power supplies, so there is
+			 * no need to enable them (and falsely increase their
+			 * usage count).
+			 */
+			pcie->ep_wakeup_capable = false;
+		} else {
+			ret = regulator_bulk_enable(pcie->sr->num_supplies,
+						    pcie->sr->supplies);
+			if (ret) {
+				dev_err(dev, "Could not turn on regulators\n");
+				goto err_reset;
+			}
+		}
+	}
+
 	ret = brcm_pcie_start_link(pcie);
 	if (ret)
-		goto err_reset;
+		goto err_regulator;
 
 	if (pcie->msi)
 		brcm_msi_set_regs(pcie->msi);
 
 	return 0;
 
+err_regulator:
+	if (pcie->sr)
+		regulator_bulk_disable(pcie->sr->num_supplies, pcie->sr->supplies);
 err_reset:
 	reset_control_rearm(pcie->rescal);
 err_disable_clk:
@@ -1541,8 +1595,8 @@ fail:
 MODULE_DEVICE_TABLE(of, brcm_pcie_match);
 
 static const struct dev_pm_ops brcm_pcie_pm_ops = {
-	.suspend = brcm_pcie_suspend,
+	.suspend_noirq = brcm_pcie_suspend_noirq,
-	.resume = brcm_pcie_resume,
+	.resume_noirq = brcm_pcie_resume_noirq,
 };
 
 static struct platform_driver brcm_pcie_driver = {