fotg210-udc: Handle PCLK

This adds optional handling of the peripheral clock PCLK.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221114115201.302887-3-linus.walleij@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/fotg210/fotg210-udc.c

@@ -15,6 +15,7 @@
 #include <linux/platform_device.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
+#include <linux/clk.h>
 #include <linux/usb/otg.h>
 #include <linux/usb/phy.h>
 
@@ -1132,6 +1133,10 @@ int fotg210_udc_remove(struct platform_device *pdev)
 	fotg210_ep_free_request(&fotg210->ep[0]->ep, fotg210->ep0_req);
 	for (i = 0; i < FOTG210_MAX_NUM_EP; i++)
 		kfree(fotg210->ep[i]);
+
+	if (!IS_ERR(fotg210->pclk))
+		clk_disable_unprepare(fotg210->pclk);
+
 	kfree(fotg210);
 
 	return 0;
@@ -1167,17 +1172,34 @@ int fotg210_udc_probe(struct platform_device *pdev)
 
 	fotg210->dev = dev;
 
+	/* It's OK not to supply this clock */
+	fotg210->pclk = devm_clk_get(dev, "PCLK");
+	if (!IS_ERR(fotg210->pclk)) {
+		ret = clk_prepare_enable(fotg210->pclk);
+		if (ret) {
+			dev_err(dev, "failed to enable PCLK\n");
+			return ret;
+		}
+	} else if (PTR_ERR(fotg210->pclk) == -EPROBE_DEFER) {
+		/*
+		 * Percolate deferrals, for anything else,
+		 * just live without the clocking.
+		 */
+		ret = -EPROBE_DEFER;
+		goto err;
+	}
+
 	fotg210->phy = devm_usb_get_phy_by_phandle(dev->parent, "usb-phy", 0);
 	if (IS_ERR(fotg210->phy)) {
 		ret = PTR_ERR(fotg210->phy);
 		if (ret == -EPROBE_DEFER)
-			goto err;
+			goto err_pclk;
 		dev_info(dev, "no PHY found\n");
 		fotg210->phy = NULL;
 	} else {
 		ret = usb_phy_init(fotg210->phy);
 		if (ret)
-			goto err;
+			goto err_pclk;
 		dev_info(dev, "found and initialized PHY\n");
 	}
 
@@ -1277,6 +1299,10 @@ int fotg210_udc_probe(struct platform_device *pdev)
 err_alloc:
 	for (i = 0; i < FOTG210_MAX_NUM_EP; i++)
 		kfree(fotg210->ep[i]);
+err_pclk:
+	if (!IS_ERR(fotg210->pclk))
+		clk_disable_unprepare(fotg210->pclk);
+
 	kfree(fotg210);
 
 err:

drivers/usb/fotg210/fotg210-udc.h

@@ -231,6 +231,7 @@ struct fotg210_ep {
 struct fotg210_udc {
 	spinlock_t		lock; /* protect the struct */
 	void __iomem		*reg;
+	struct clk		*pclk;
 
 	unsigned long		irq_trigger;