phy: usb: Leave some clocks running during suspend

The PHY client driver does a phy_exit() call on suspend or rmmod and
the PHY driver needs to know the difference because some clocks need
to be kept running for suspend but can be shutdown on unbind/rmmod
(or if there are no PHY clients at all).

The fix is to use a PM notifier so the driver can tell if a PHY
client is calling exit() because of a system suspend or a driver
unbind/rmmod.
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20211201180653.35097-2-alcooperx@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/broadcom/phy-brcm-usb.c

@@ -18,6 +18,7 @@
 #include <linux/soc/brcmstb/brcmstb.h>
 #include <dt-bindings/phy/phy.h>
 #include <linux/mfd/syscon.h>
+#include <linux/suspend.h>
 
 #include "phy-brcm-usb-init.h"
 
@@ -70,12 +71,35 @@ struct brcm_usb_phy_data {
 	int			init_count;
 	int			wake_irq;
 	struct brcm_usb_phy	phys[BRCM_USB_PHY_ID_MAX];
+	struct notifier_block	pm_notifier;
+	bool			pm_active;
 };
 
 static s8 *node_reg_names[BRCM_REGS_MAX] = {
 	"crtl", "xhci_ec", "xhci_gbl", "usb_phy", "usb_mdio", "bdc_ec"
 };
 
+static int brcm_pm_notifier(struct notifier_block *notifier,
+			    unsigned long pm_event,
+			    void *unused)
+{
+	struct brcm_usb_phy_data *priv =
+		container_of(notifier, struct brcm_usb_phy_data, pm_notifier);
+
+	switch (pm_event) {
+	case PM_HIBERNATION_PREPARE:
+	case PM_SUSPEND_PREPARE:
+		priv->pm_active = true;
+		break;
+	case PM_POST_RESTORE:
+	case PM_POST_HIBERNATION:
+	case PM_POST_SUSPEND:
+		priv->pm_active = false;
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
 static irqreturn_t brcm_usb_phy_wake_isr(int irq, void *dev_id)
 {
 	struct phy *gphy = dev_id;
@@ -91,6 +115,9 @@ static int brcm_usb_phy_init(struct phy *gphy)
 	struct brcm_usb_phy_data *priv =
 		container_of(phy, struct brcm_usb_phy_data, phys[phy->id]);
 
+	if (priv->pm_active)
+		return 0;
+
 	/*
 	 * Use a lock to make sure a second caller waits until
 	 * the base phy is inited before using it.
@@ -120,6 +147,9 @@ static int brcm_usb_phy_exit(struct phy *gphy)
 	struct brcm_usb_phy_data *priv =
 		container_of(phy, struct brcm_usb_phy_data, phys[phy->id]);
 
+	if (priv->pm_active)
+		return 0;
+
 	dev_dbg(&gphy->dev, "EXIT\n");
 	if (phy->id == BRCM_USB_PHY_2_0)
 		brcm_usb_uninit_eohci(&priv->ini);
@@ -488,6 +518,9 @@ static int brcm_usb_phy_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
+	priv->pm_notifier.notifier_call = brcm_pm_notifier;
+	register_pm_notifier(&priv->pm_notifier);
+
 	mutex_init(&priv->mutex);
 
 	/* make sure invert settings are correct */
@@ -528,7 +561,10 @@ static int brcm_usb_phy_probe(struct platform_device *pdev)
 
 static int brcm_usb_phy_remove(struct platform_device *pdev)
 {
+	struct brcm_usb_phy_data *priv = dev_get_drvdata(&pdev->dev);
+
 	sysfs_remove_group(&pdev->dev.kobj, &brcm_usb_phy_group);
+	unregister_pm_notifier(&priv->pm_notifier);
 
 	return 0;
 }
@@ -539,6 +575,7 @@ static int brcm_usb_phy_suspend(struct device *dev)
 	struct brcm_usb_phy_data *priv = dev_get_drvdata(dev);
 
 	if (priv->init_count) {
+		dev_dbg(dev, "SUSPEND\n");
 		priv->ini.wake_enabled = device_may_wakeup(dev);
 		if (priv->phys[BRCM_USB_PHY_3_0].inited)
 			brcm_usb_uninit_xhci(&priv->ini);
@@ -578,6 +615,7 @@ static int brcm_usb_phy_resume(struct device *dev)
 	 * Uninitialize anything that wasn't previously initialized.
 	 */
 	if (priv->init_count) {
+		dev_dbg(dev, "RESUME\n");
 		if (priv->wake_irq >= 0)
 			disable_irq_wake(priv->wake_irq);
 		brcm_usb_init_common(&priv->ini);