usb: dwc3: implement runtime PM

this patch implements the most basic pm_runtime
support for dwc3. Whenever USB cable is dettached,
then we will allow core to runtime_suspend.

Runtime suspending will involve completely tearing
down event buffers and require a full soft-reset of
the IP.

Note that a further optimization could be
implemented once we decide to support hibernation,
which is to allow runtime_suspend with cable
connected when bus is in U3. That's subject to a
separate patch, however.

Tested-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

3 files changed, 174 insertions, 15 deletions

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 80e9affd3d77..bf1789f134ac 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -48,7 +48,7 @@
 
 #include "debug.h"
 
-/* -------------------------------------------------------------------------- */
+#define DWC3_DEFAULT_AUTOSUSPEND_DELAY	5000 /* ms */
 
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
 {
@@ -996,6 +996,9 @@ static int dwc3_probe(struct platform_device *pdev)
 		dma_set_coherent_mask(dev, dev->parent->coherent_dma_mask);
 	}
 
+	pm_runtime_set_active(dev);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_autosuspend_delay(dev, DWC3_DEFAULT_AUTOSUSPEND_DELAY);
 	pm_runtime_enable(dev);
 	pm_runtime_get_sync(dev);
 	pm_runtime_forbid(dev);
@@ -1057,7 +1060,7 @@ static int dwc3_probe(struct platform_device *pdev)
 		goto err3;
 
 	dwc3_debugfs_init(dwc);
-	pm_runtime_allow(dev);
+	pm_runtime_put(dev);
 
 	return 0;
 
@@ -1087,6 +1090,7 @@ static int dwc3_remove(struct platform_device *pdev)
 	struct dwc3	*dwc = platform_get_drvdata(pdev);
 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
+	pm_runtime_get_sync(&pdev->dev);
 	/*
 	 * restore res->start back to its original value so that, in case the
 	 * probe is deferred, we don't end up getting error in request the
@@ -1100,24 +1104,27 @@ static int dwc3_remove(struct platform_device *pdev)
 	dwc3_core_exit(dwc);
 	dwc3_ulpi_exit(dwc);
 
-	dwc3_free_event_buffers(dwc);
-	dwc3_free_scratch_buffers(dwc);
-
 	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_allow(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
+	dwc3_free_event_buffers(dwc);
+	dwc3_free_scratch_buffers(dwc);
+
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int dwc3_suspend(struct device *dev)
+#ifdef CONFIG_PM
+static int dwc3_suspend_common(struct dwc3 *dwc)
 {
-	struct dwc3	*dwc = dev_get_drvdata(dev);
+	unsigned long	flags;
 
 	switch (dwc->dr_mode) {
 	case USB_DR_MODE_PERIPHERAL:
 	case USB_DR_MODE_OTG:
+		spin_lock_irqsave(&dwc->lock, flags);
 		dwc3_gadget_suspend(dwc);
+		spin_unlock_irqrestore(&dwc->lock, flags);
 		break;
 	case USB_DR_MODE_HOST:
 	default:
@@ -1127,18 +1134,14 @@ static int dwc3_suspend(struct device *dev)
 
 	dwc3_core_exit(dwc);
 
-	pinctrl_pm_select_sleep_state(dev);
-
 	return 0;
 }
 
-static int dwc3_resume(struct device *dev)
+static int dwc3_resume_common(struct dwc3 *dwc)
 {
-	struct dwc3	*dwc = dev_get_drvdata(dev);
+	unsigned long	flags;
 	int		ret;
 
-	pinctrl_pm_select_default_state(dev);
-
 	ret = dwc3_core_init(dwc);
 	if (ret)
 		return ret;
@@ -1146,7 +1149,9 @@ static int dwc3_resume(struct device *dev)
 	switch (dwc->dr_mode) {
 	case USB_DR_MODE_PERIPHERAL:
 	case USB_DR_MODE_OTG:
+		spin_lock_irqsave(&dwc->lock, flags);
 		dwc3_gadget_resume(dwc);
+		spin_unlock_irqrestore(&dwc->lock, flags);
 		/* FALLTHROUGH */
 	case USB_DR_MODE_HOST:
 	default:
@@ -1154,6 +1159,119 @@ static int dwc3_resume(struct device *dev)
 		break;
 	}
 
+	return 0;
+}
+
+static int dwc3_runtime_checks(struct dwc3 *dwc)
+{
+	switch (dwc->dr_mode) {
+	case USB_DR_MODE_PERIPHERAL:
+	case USB_DR_MODE_OTG:
+		if (dwc->connected)
+			return -EBUSY;
+		break;
+	case USB_DR_MODE_HOST:
+	default:
+		/* do nothing */
+		break;
+	}
+
+	return 0;
+}
+
+static int dwc3_runtime_suspend(struct device *dev)
+{
+	struct dwc3     *dwc = dev_get_drvdata(dev);
+	int		ret;
+
+	if (dwc3_runtime_checks(dwc))
+		return -EBUSY;
+
+	ret = dwc3_suspend_common(dwc);
+	if (ret)
+		return ret;
+
+	device_init_wakeup(dev, true);
+
+	return 0;
+}
+
+static int dwc3_runtime_resume(struct device *dev)
+{
+	struct dwc3     *dwc = dev_get_drvdata(dev);
+	int		ret;
+
+	device_init_wakeup(dev, false);
+
+	ret = dwc3_resume_common(dwc);
+	if (ret)
+		return ret;
+
+	switch (dwc->dr_mode) {
+	case USB_DR_MODE_PERIPHERAL:
+	case USB_DR_MODE_OTG:
+		dwc3_gadget_process_pending_events(dwc);
+		break;
+	case USB_DR_MODE_HOST:
+	default:
+		/* do nothing */
+		break;
+	}
+
+	pm_runtime_mark_last_busy(dev);
+
+	return 0;
+}
+
+static int dwc3_runtime_idle(struct device *dev)
+{
+	struct dwc3     *dwc = dev_get_drvdata(dev);
+
+	switch (dwc->dr_mode) {
+	case USB_DR_MODE_PERIPHERAL:
+	case USB_DR_MODE_OTG:
+		if (dwc3_runtime_checks(dwc))
+			return -EBUSY;
+		break;
+	case USB_DR_MODE_HOST:
+	default:
+		/* do nothing */
+		break;
+	}
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_autosuspend(dev);
+
+	return 0;
+}
+#endif /* CONFIG_PM */
+
+#ifdef CONFIG_PM_SLEEP
+static int dwc3_suspend(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+	int		ret;
+
+	ret = dwc3_suspend_common(dwc);
+	if (ret)
+		return ret;
+
+	pinctrl_pm_select_sleep_state(dev);
+
+	return 0;
+}
+
+static int dwc3_resume(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+	int		ret;
+
+	pinctrl_pm_select_default_state(dev);
+
+	ret = dwc3_resume_common(dwc);
+	if (ret)
+		return ret;
+
 	pm_runtime_disable(dev);
 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);
@@ -1164,6 +1282,8 @@ static int dwc3_resume(struct device *dev)
 
 static const struct dev_pm_ops dwc3_dev_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
+	SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
+			dwc3_runtime_idle)
 };
 
 #ifdef CONFIG_OF
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 5148c563167e..94b9fd2d583e 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -763,6 +763,7 @@ struct dwc3_scratchpad_array {
  * @lpm_nyet_threshold: LPM NYET response threshold
  * @hird_threshold: HIRD threshold
  * @hsphy_interface: "utmi" or "ulpi"
+ * @connected: true when we're connected to a host, false otherwise
  * @delayed_status: true when gadget driver asks for delayed status
  * @ep0_bounced: true when we used bounce buffer
  * @ep0_expect_in: true when we expect a DATA IN transfer
@@ -773,6 +774,7 @@ struct dwc3_scratchpad_array {
  * 	0	- utmi_sleep_n
  * 	1	- utmi_l1_suspend_n
  * @is_fpga: true when we are using the FPGA board
+ * @pending_events: true when we have pending IRQs to be handled
  * @pullups_connected: true when Run/Stop bit is set
  * @setup_packet_pending: true when there's a Setup Packet in FIFO. Workaround
  * @start_config_issued: true when StartConfig command has been issued
@@ -907,6 +909,7 @@ struct dwc3 {
 
 	const char		*hsphy_interface;
 
+	unsigned		connected:1;
 	unsigned		delayed_status:1;
 	unsigned		ep0_bounced:1;
 	unsigned		ep0_expect_in:1;
@@ -914,6 +917,7 @@ struct dwc3 {
 	unsigned		has_lpm_erratum:1;
 	unsigned		is_utmi_l1_suspend:1;
 	unsigned		is_fpga:1;
+	unsigned		pending_events:1;
 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;
@@ -1139,6 +1143,7 @@ static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 #if !IS_ENABLED(CONFIG_USB_DWC3_HOST)
 int dwc3_gadget_suspend(struct dwc3 *dwc);
 int dwc3_gadget_resume(struct dwc3 *dwc);
+void dwc3_gadget_process_pending_events(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_suspend(struct dwc3 *dwc)
 {
@@ -1149,6 +1154,10 @@ static inline int dwc3_gadget_resume(struct dwc3 *dwc)
 {
 	return 0;
 }
+
+static inline void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
+{
+}
 #endif /* !IS_ENABLED(CONFIG_USB_DWC3_HOST) */
 
 #if IS_ENABLED(CONFIG_USB_DWC3_ULPI)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index b59893c3093a..194775184a58 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -199,6 +199,9 @@ void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
 	spin_unlock(&dwc->lock);
 	usb_gadget_giveback_request(&dep->endpoint, &req->request);
 	spin_lock(&dwc->lock);
+
+	if (dep->number > 1)
+		pm_runtime_put(dwc->dev);
 }
 
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned cmd, u32 param)
@@ -1081,6 +1084,8 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 		return -EINVAL;
 	}
 
+	pm_runtime_get(dwc->dev);
+
 	req->request.actual	= 0;
 	req->request.status	= -EINPROGRESS;
 	req->direction		= dep->direction;
@@ -1509,6 +1514,9 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
 	u32			reg;
 	u32			timeout = 500;
 
+	if (pm_runtime_suspended(dwc->dev))
+		return 0;
+
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 	if (is_on) {
 		if (dwc->revision <= DWC3_REVISION_187A) {
@@ -1766,7 +1774,9 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 
 	dwc->gadget_driver	= driver;
 
-	__dwc3_gadget_start(dwc);
+	if (pm_runtime_active(dwc->dev))
+		__dwc3_gadget_start(dwc);
+
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;
@@ -2355,12 +2365,16 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
 	dwc->gadget.speed = USB_SPEED_UNKNOWN;
 	dwc->setup_packet_pending = false;
 	usb_gadget_set_state(&dwc->gadget, USB_STATE_NOTATTACHED);
+
+	dwc->connected = false;
 }
 
 static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
 {
 	u32			reg;
 
+	dwc->connected = true;
+
 	/*
 	 * WORKAROUND: DWC3 revisions <1.88a have an issue which
 	 * would cause a missing Disconnect Event if there's a
@@ -2822,6 +2836,13 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
 	u32 count;
 	u32 reg;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pm_runtime_get(dwc->dev);
+		disable_irq_nosync(dwc->irq_gadget);
+		dwc->pending_events = true;
+		return IRQ_HANDLED;
+	}
+
 	count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
 	count &= DWC3_GEVNTCOUNT_MASK;
 	if (!count)
@@ -3028,3 +3049,12 @@ err1:
 err0:
 	return ret;
 }
+
+void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
+{
+	if (dwc->pending_events) {
+		dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
+		dwc->pending_events = false;
+		enable_irq(dwc->irq_gadget);
+	}
+}