usb: dwc2: gadget: add mutex to serialize init/deinit calls

This patch adds mutex, which protects initialization and
deinitialization procedures against suspend/resume methods. This mutex
will be needed by the updated suspend/resume calls, which tracks gadget
state.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc2/core.h

@@ -576,6 +576,7 @@ struct dwc2_hsotg {
 	struct regulator_bulk_data supplies[ARRAY_SIZE(s3c_hsotg_supply_names)];
 
 	spinlock_t lock;
+	struct mutex init_mutex;
 	void *priv;
 	int     irq;
 	struct clk *clk;

drivers/usb/dwc2/gadget.c

@@ -21,6 +21,7 @@
 #include <linux/platform_device.h>
 #include <linux/dma-mapping.h>
 #include <linux/debugfs.h>
+#include <linux/mutex.h>
 #include <linux/seq_file.h>
 #include <linux/delay.h>
 #include <linux/io.h>
@@ -2866,6 +2867,7 @@ static int s3c_hsotg_udc_start(struct usb_gadget *gadget,
 		return -EINVAL;
 	}
 
+	mutex_lock(&hsotg->init_mutex);
 	WARN_ON(hsotg->driver);
 
 	driver->driver.bus = NULL;
@@ -2891,9 +2893,12 @@ static int s3c_hsotg_udc_start(struct usb_gadget *gadget,
 
 	dev_info(hsotg->dev, "bound driver %s\n", driver->driver.name);
 
+	mutex_unlock(&hsotg->init_mutex);
+
 	return 0;
 
 err:
+	mutex_unlock(&hsotg->init_mutex);
 	hsotg->driver = NULL;
 	return ret;
 }
@@ -2914,6 +2919,8 @@ static int s3c_hsotg_udc_stop(struct usb_gadget *gadget)
 	if (!hsotg)
 		return -ENODEV;
 
+	mutex_lock(&hsotg->init_mutex);
+
 	/* all endpoints should be shutdown */
 	for (ep = 1; ep < hsotg->num_of_eps; ep++)
 		s3c_hsotg_ep_disable(&hsotg->eps[ep].ep);
@@ -2931,6 +2938,8 @@ static int s3c_hsotg_udc_stop(struct usb_gadget *gadget)
 
 	clk_disable(hsotg->clk);
 
+	mutex_unlock(&hsotg->init_mutex);
+
 	return 0;
 }
 
@@ -2959,6 +2968,7 @@ static int s3c_hsotg_pullup(struct usb_gadget *gadget, int is_on)
 
 	dev_dbg(hsotg->dev, "%s: is_on: %d\n", __func__, is_on);
 
+	mutex_lock(&hsotg->init_mutex);
 	spin_lock_irqsave(&hsotg->lock, flags);
 	if (is_on) {
 		clk_enable(hsotg->clk);
@@ -2970,6 +2980,7 @@ static int s3c_hsotg_pullup(struct usb_gadget *gadget, int is_on)
 
 	hsotg->gadget.speed = USB_SPEED_UNKNOWN;
 	spin_unlock_irqrestore(&hsotg->lock, flags);
+	mutex_unlock(&hsotg->init_mutex);
 
 	return 0;
 }
@@ -3572,6 +3583,8 @@ int s3c_hsotg_suspend(struct dwc2_hsotg *hsotg)
 	unsigned long flags;
 	int ret = 0;
 
+	mutex_lock(&hsotg->init_mutex);
+
 	if (hsotg->driver)
 		dev_info(hsotg->dev, "suspending usb gadget %s\n",
 			 hsotg->driver->driver.name);
@@ -3594,6 +3607,8 @@ int s3c_hsotg_suspend(struct dwc2_hsotg *hsotg)
 		clk_disable(hsotg->clk);
 	}
 
+	mutex_unlock(&hsotg->init_mutex);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(s3c_hsotg_suspend);
@@ -3603,6 +3618,8 @@ int s3c_hsotg_resume(struct dwc2_hsotg *hsotg)
 	unsigned long flags;
 	int ret = 0;
 
+	mutex_lock(&hsotg->init_mutex);
+
 	if (hsotg->driver) {
 		dev_info(hsotg->dev, "resuming usb gadget %s\n",
 			 hsotg->driver->driver.name);
@@ -3619,6 +3636,8 @@ int s3c_hsotg_resume(struct dwc2_hsotg *hsotg)
 	s3c_hsotg_core_connect(hsotg);
 	spin_unlock_irqrestore(&hsotg->lock, flags);
 
+	mutex_unlock(&hsotg->init_mutex);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(s3c_hsotg_resume);

drivers/usb/dwc2/platform.c

@@ -40,6 +40,7 @@
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/of_device.h>
+#include <linux/mutex.h>
 #include <linux/platform_device.h>
 
 #include <linux/usb/of.h>
@@ -212,6 +213,7 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	hsotg->dr_mode = of_usb_get_dr_mode(dev->dev.of_node);
 
 	spin_lock_init(&hsotg->lock);
+	mutex_init(&hsotg->init_mutex);
 	retval = dwc2_gadget_init(hsotg, irq);
 	if (retval)
 		return retval;