usb: bdc: Add support for suspend/resume

Based on a previous commit by Danesh Petigara <dpetigara@broadcom.com>
that added resume to solve the following problem:
"The BDC driver will fail after resuming from S3 suspend and this
will cause any upper layer gadget driver to fail."
This commit also adds support for suspend and manages the clock during
suspend/resume.
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/bdc/bdc.h

@@ -454,6 +454,7 @@ struct bdc {
 	 * Func Wake packet every 2.5 secs. Refer to USB3 spec section 8.5.6.4
 	 */
 	struct delayed_work	func_wake_notify;
+	struct clk		*clk;
 };
 
 static inline u32 bdc_readl(void __iomem *base, u32 offset)

drivers/usb/gadget/udc/bdc/bdc_core.c

@@ -473,6 +473,8 @@ static int bdc_probe(struct platform_device *pdev)
 	if (!bdc)
 		return -ENOMEM;
 
+	bdc->clk = clk;
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	bdc->regs = devm_ioremap_resource(dev, res);
 	if (IS_ERR(bdc->regs)) {
@@ -529,10 +531,43 @@ static int bdc_remove(struct platform_device *pdev)
 	dev_dbg(bdc->dev, "%s ()\n", __func__);
 	bdc_udc_exit(bdc);
 	bdc_hw_exit(bdc);
+	clk_disable_unprepare(bdc->clk);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int bdc_suspend(struct device *dev)
+{
+	struct bdc *bdc = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(bdc->clk);
+	return 0;
+}
+
+static int bdc_resume(struct device *dev)
+{
+	struct bdc *bdc = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(bdc->clk);
+	if (ret) {
+		dev_err(bdc->dev, "err enabling the clock\n");
+		return ret;
+	}
+	ret = bdc_reinit(bdc);
+	if (ret) {
+		dev_err(bdc->dev, "err in bdc reinit\n");
+		return ret;
+	}
 
 	return 0;
 }
 
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(bdc_pm_ops, bdc_suspend,
+		bdc_resume);
+
 static const struct of_device_id bdc_of_match[] = {
 	{ .compatible = "brcm,bdc-v0.16" },
 	{ .compatible = "brcm,bdc" },
@@ -543,6 +578,7 @@ static struct platform_driver bdc_driver = {
 	.driver		= {
 		.name	= BRCM_BDC_NAME,
 		.owner	= THIS_MODULE,
+		.pm = &bdc_pm_ops,
 		.of_match_table	= bdc_of_match,
 	},
 	.probe		= bdc_probe,