usb: chipidea: ci_hdrc_imx: add wakeup clock and keep it always on

Some platform using ChipIdea IP may keep 32KHz wakeup clock always
on without usb driver intervention. And some may need driver to handle
this clock. For now only i.MX93 needs this wakeup clock. This patch will
get wakeup clock and keep it always on to make controller work properly.

Signed-off-by: Xu Yang <[e-mail]>
Acked-by: Peter Chen <[e-mail]>
Tested-by: Stefan Wahren <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/chipidea/ci_hdrc_imx.c

···
 	struct usb_phy *phy;
 	struct platform_device *ci_pdev;
 	struct clk *clk;
+	struct clk *clk_wakeup;
 	struct imx_usbmisc_data *usbmisc_data;
 	bool supports_runtime_pm;
 	bool override_phy_control;
···
 
 	data->clk_ipg = devm_clk_get(dev, "ipg");
 	if (IS_ERR(data->clk_ipg)) {
-		/* If the platform only needs one clocks */
+		/* If the platform only needs one primary clock */
 		data->clk = devm_clk_get(dev, NULL);
 		if (IS_ERR(data->clk)) {
 			ret = PTR_ERR(data->clk);
···
 				PTR_ERR(data->clk), PTR_ERR(data->clk_ipg));
 			return ret;
 		}
+		/* Get wakeup clock. Not all of the platforms need to
+		 * handle this clock. So make it optional.
+		 */
+		data->clk_wakeup = devm_clk_get_optional(dev, "usb_wakeup_clk");
+		if (IS_ERR(data->clk_wakeup))
+			ret = dev_err_probe(dev, PTR_ERR(data->clk_wakeup),
+					"Failed to get wakeup clk\n");
 		return ret;
 	}
 
···
 	if (ret)
 		goto disable_hsic_regulator;
 
+	ret = clk_prepare_enable(data->clk_wakeup);
+	if (ret)
+		goto err_wakeup_clk;
+
 	data->phy = devm_usb_get_phy_by_phandle(dev, "fsl,usbphy", 0);
 	if (IS_ERR(data->phy)) {
 		ret = PTR_ERR(data->phy);
···
 disable_device:
 	ci_hdrc_remove_device(data->ci_pdev);
 err_clk:
+	clk_disable_unprepare(data->clk_wakeup);
+err_wakeup_clk:
 	imx_disable_unprepare_clks(dev);
 disable_hsic_regulator:
 	if (data->hsic_pad_regulator)
···
 		usb_phy_shutdown(data->phy);
 	if (data->ci_pdev) {
 		imx_disable_unprepare_clks(&pdev->dev);
+		clk_disable_unprepare(data->clk_wakeup);
 		if (data->plat_data->flags & CI_HDRC_PMQOS)
 			cpu_latency_qos_remove_request(&data->pm_qos_req);
 		if (data->hsic_pad_regulator)