usb: dwc3: core: add power management support

Add support for basic power management on
the dwc3 driver. While there is still lots
to improve for full PM support, this minimal
patch will already make sure that we survive
suspend-to-ram and suspend-to-disk without
major issues.

Cc: Vikas C Sajjan <vikas.sajjan@linaro.org>
Tested-by: Vivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

3 files changed, 212 insertions, 0 deletions

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 47435086058b..75a9f88a5ad6 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -591,6 +591,123 @@ static int dwc3_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int dwc3_prepare(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+	unsigned long	flags;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+
+	switch (dwc->mode) {
+	case DWC3_MODE_DEVICE:
+	case DWC3_MODE_DRD:
+		dwc3_gadget_prepare(dwc);
+		/* FALLTHROUGH */
+	case DWC3_MODE_HOST:
+	default:
+		dwc3_event_buffers_cleanup(dwc);
+		break;
+	}
+
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	return 0;
+}
+
+static void dwc3_complete(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+	unsigned long	flags;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+
+	switch (dwc->mode) {
+	case DWC3_MODE_DEVICE:
+	case DWC3_MODE_DRD:
+		dwc3_gadget_complete(dwc);
+		/* FALLTHROUGH */
+	case DWC3_MODE_HOST:
+	default:
+		dwc3_event_buffers_setup(dwc);
+		break;
+	}
+
+	spin_unlock_irqrestore(&dwc->lock, flags);
+}
+
+static int dwc3_suspend(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+	unsigned long	flags;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+
+	switch (dwc->mode) {
+	case DWC3_MODE_DEVICE:
+	case DWC3_MODE_DRD:
+		dwc3_gadget_suspend(dwc);
+		/* FALLTHROUGH */
+	case DWC3_MODE_HOST:
+	default:
+		/* do nothing */
+		break;
+	}
+
+	dwc->gctl = dwc3_readl(dwc->regs, DWC3_GCTL);
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	usb_phy_shutdown(dwc->usb3_phy);
+	usb_phy_shutdown(dwc->usb2_phy);
+
+	return 0;
+}
+
+static int dwc3_resume(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+	unsigned long	flags;
+
+	usb_phy_init(dwc->usb3_phy);
+	usb_phy_init(dwc->usb2_phy);
+	msleep(100);
+
+	spin_lock_irqsave(&dwc->lock, flags);
+
+	dwc3_writel(dwc->regs, DWC3_GCTL, dwc->gctl);
+
+	switch (dwc->mode) {
+	case DWC3_MODE_DEVICE:
+	case DWC3_MODE_DRD:
+		dwc3_gadget_resume(dwc);
+		/* FALLTHROUGH */
+	case DWC3_MODE_HOST:
+	default:
+		/* do nothing */
+		break;
+	}
+
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	pm_runtime_disable(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops dwc3_dev_pm_ops = {
+	.prepare	= dwc3_prepare,
+	.complete	= dwc3_complete,
+
+	SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
+};
+
+#define DWC3_PM_OPS	&(dwc3_dev_pm_ops)
+#else
+#define DWC3_PM_OPS	NULL
+#endif
+
 #ifdef CONFIG_OF
 static const struct of_device_id of_dwc3_match[] = {
 	{
@@ -607,6 +724,7 @@ static struct platform_driver dwc3_driver = {
 	.driver		= {
 		.name	= "dwc3",
 		.of_match_table	= of_match_ptr(of_dwc3_match),
+		.pm	= DWC3_PM_OPS,
 	},
 };
 
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 35e4d3c01ed0..52e48e21c82f 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -626,6 +626,8 @@ struct dwc3_scratchpad_array {
  * @mode: mode of operation
  * @usb2_phy: pointer to USB2 PHY
  * @usb3_phy: pointer to USB3 PHY
+ * @dcfg: saved contents of DCFG register
+ * @gctl: saved contents of GCTL register
  * @is_selfpowered: true when we are selfpowered
  * @three_stage_setup: set if we perform a three phase setup
  * @ep0_bounced: true when we used bounce buffer
@@ -675,6 +677,10 @@ struct dwc3 {
 	void __iomem		*regs;
 	size_t			regs_size;
 
+	/* used for suspend/resume */
+	u32			dcfg;
+	u32			gctl;
+
 	u32			num_event_buffers;
 	u32			u1u2;
 	u32			maximum_speed;
@@ -885,4 +891,31 @@ static inline void dwc3_gadget_exit(struct dwc3 *dwc)
 { }
 #endif
 
+/* power management interface */
+#if !IS_ENABLED(CONFIG_USB_DWC3_HOST)
+int dwc3_gadget_prepare(struct dwc3 *dwc);
+void dwc3_gadget_complete(struct dwc3 *dwc);
+int dwc3_gadget_suspend(struct dwc3 *dwc);
+int dwc3_gadget_resume(struct dwc3 *dwc);
+#else
+static inline int dwc3_gadget_prepare(struct dwc3 *dwc)
+{
+	return 0;
+}
+
+static inline void dwc3_gadget_complete(struct dwc3 *dwc)
+{
+}
+
+static inline int dwc3_gadget_suspend(struct dwc3 *dwc)
+{
+	return 0;
+}
+
+static inline int dwc3_gadget_resume(struct dwc3 *dwc)
+{
+	return 0;
+}
+#endif /* !IS_ENABLED(CONFIG_USB_DWC3_HOST) */
+
 #endif /* __DRIVERS_USB_DWC3_CORE_H */
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 04e4812fe2f9..73b0b7fc77f1 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2594,6 +2594,8 @@ err0:
 	return ret;
 }
 
+/* -------------------------------------------------------------------------- */
+
 void dwc3_gadget_exit(struct dwc3 *dwc)
 {
 	usb_del_gadget_udc(&dwc->gadget);
@@ -2611,3 +2613,62 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
 	dma_free_coherent(dwc->dev, sizeof(*dwc->ctrl_req),
 			dwc->ctrl_req, dwc->ctrl_req_addr);
 }
+
+int dwc3_gadget_prepare(struct dwc3 *dwc)
+{
+	if (dwc->pullups_connected)
+		dwc3_gadget_disable_irq(dwc);
+
+	return 0;
+}
+
+void dwc3_gadget_complete(struct dwc3 *dwc)
+{
+	if (dwc->pullups_connected) {
+		dwc3_gadget_enable_irq(dwc);
+		dwc3_gadget_run_stop(dwc, true);
+	}
+}
+
+int dwc3_gadget_suspend(struct dwc3 *dwc)
+{
+	__dwc3_gadget_ep_disable(dwc->eps[0]);
+	__dwc3_gadget_ep_disable(dwc->eps[1]);
+
+	dwc->dcfg = dwc3_readl(dwc->regs, DWC3_DCFG);
+
+	return 0;
+}
+
+int dwc3_gadget_resume(struct dwc3 *dwc)
+{
+	struct dwc3_ep		*dep;
+	int			ret;
+
+	/* Start with SuperSpeed Default */
+	dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
+
+	dep = dwc->eps[0];
+	ret = __dwc3_gadget_ep_enable(dep, &dwc3_gadget_ep0_desc, NULL, false);
+	if (ret)
+		goto err0;
+
+	dep = dwc->eps[1];
+	ret = __dwc3_gadget_ep_enable(dep, &dwc3_gadget_ep0_desc, NULL, false);
+	if (ret)
+		goto err1;
+
+	/* begin to receive SETUP packets */
+	dwc->ep0state = EP0_SETUP_PHASE;
+	dwc3_ep0_out_start(dwc);
+
+	dwc3_writel(dwc->regs, DWC3_DCFG, dwc->dcfg);
+
+	return 0;
+
+err1:
+	__dwc3_gadget_ep_disable(dwc->eps[0]);
+
+err0:
+	return ret;
+}