phy: qcom-snps: Add runtime suspend and resume handlers

Allow for the PHY to be put into a powered down state when possible.
Add the required suspend and resume callbacks, which will determine
what resources can be turned off depending on the cable status.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/20200625195444.15130-2-wcheng@codeaurora.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/qualcomm/phy-qcom-snps-femto-v2.c

@@ -104,6 +104,63 @@ static inline void qcom_snps_hsphy_write_mask(void __iomem *base, u32 offset,
 	readl_relaxed(base + offset);
 }
 
+static int qcom_snps_hsphy_suspend(struct qcom_snps_hsphy *hsphy)
+{
+	dev_dbg(&hsphy->phy->dev, "Suspend QCOM SNPS PHY\n");
+
+	if (hsphy->mode == PHY_MODE_USB_HOST) {
+		/* Enable auto-resume to meet remote wakeup timing */
+		qcom_snps_hsphy_write_mask(hsphy->base,
+					   USB2_PHY_USB_PHY_HS_PHY_CTRL2,
+					   USB2_AUTO_RESUME,
+					   USB2_AUTO_RESUME);
+		usleep_range(500, 1000);
+		qcom_snps_hsphy_write_mask(hsphy->base,
+					   USB2_PHY_USB_PHY_HS_PHY_CTRL2,
+					   0, USB2_AUTO_RESUME);
+	}
+
+	clk_disable_unprepare(hsphy->cfg_ahb_clk);
+	return 0;
+}
+
+static int qcom_snps_hsphy_resume(struct qcom_snps_hsphy *hsphy)
+{
+	int ret;
+
+	dev_dbg(&hsphy->phy->dev, "Resume QCOM SNPS PHY, mode\n");
+
+	ret = clk_prepare_enable(hsphy->cfg_ahb_clk);
+	if (ret) {
+		dev_err(&hsphy->phy->dev, "failed to enable cfg ahb clock\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused qcom_snps_hsphy_runtime_suspend(struct device *dev)
+{
+	struct qcom_snps_hsphy *hsphy = dev_get_drvdata(dev);
+
+	if (!hsphy->phy_initialized)
+		return 0;
+
+	qcom_snps_hsphy_suspend(hsphy);
+	return 0;
+}
+
+static int __maybe_unused qcom_snps_hsphy_runtime_resume(struct device *dev)
+{
+	struct qcom_snps_hsphy *hsphy = dev_get_drvdata(dev);
+
+	if (!hsphy->phy_initialized)
+		return 0;
+
+	qcom_snps_hsphy_resume(hsphy);
+	return 0;
+}
+
 static int qcom_snps_hsphy_init(struct phy *phy)
 {
 	struct qcom_snps_hsphy *hsphy = phy_get_drvdata(phy);
@@ -212,6 +269,11 @@ static const struct of_device_id qcom_snps_hsphy_of_match_table[] = {
 };
 MODULE_DEVICE_TABLE(of, qcom_snps_hsphy_of_match_table);
 
+static const struct dev_pm_ops qcom_snps_hsphy_pm_ops = {
+	SET_RUNTIME_PM_OPS(qcom_snps_hsphy_runtime_suspend,
+			   qcom_snps_hsphy_runtime_resume, NULL)
+};
+
 static int qcom_snps_hsphy_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -255,6 +317,14 @@ static int qcom_snps_hsphy_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	/*
+	 * Prevent runtime pm from being ON by default. Users can enable
+	 * it using power/control in sysfs.
+	 */
+	pm_runtime_forbid(dev);
+
 	generic_phy = devm_phy_create(dev, NULL, &qcom_snps_hsphy_gen_ops);
 	if (IS_ERR(generic_phy)) {
 		ret = PTR_ERR(generic_phy);
@@ -269,6 +339,8 @@ static int qcom_snps_hsphy_probe(struct platform_device *pdev)
 	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
 	if (!IS_ERR(phy_provider))
 		dev_dbg(dev, "Registered Qcom-SNPS HS phy\n");
+	else
+		pm_runtime_disable(dev);
 
 	return PTR_ERR_OR_ZERO(phy_provider);
 }
@@ -277,6 +349,7 @@ static struct platform_driver qcom_snps_hsphy_driver = {
 	.probe		= qcom_snps_hsphy_probe,
 	.driver = {
 		.name	= "qcom-snps-hs-femto-v2-phy",
+		.pm = &qcom_snps_hsphy_pm_ops,
 		.of_match_table = qcom_snps_hsphy_of_match_table,
 	},
 };