usb:hsotg:samsung: Cable disconnection recovery code

This code allows Samsung SoC's to recover its state when
device is disconnected and connected during transfer.

It is necessary, in such a scenario, to reinitialize the USB core
to assure correct initial state of the driver.
This operation is needed since the disconnect interrupt is only
available at HOST mode, which is not supported by this driver.

A simple mechanism with jiffies has been used to perform core reset
only once.

Tested with:
- DFU gadget (various size of the sent data - also packet = MPS)
- Ethernet gadget (CDC and RNDIS)
- Multi Function Gadget (g_multi)

HW:
- Samsung's C210 Universal rev.0

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/s3c-hsotg.c

@@ -148,6 +148,7 @@ struct s3c_hsotg_ep {
  * @ctrl_buff: Buffer for EP0 control requests.
  * @ctrl_req: Request for EP0 control packets.
  * @setup: NAK management for EP0 SETUP
+ * @last_rst: Time of last reset
  * @eps: The endpoints being supplied to the gadget framework
  */
 struct s3c_hsotg {
@@ -175,6 +176,7 @@ struct s3c_hsotg {
 
 	struct usb_gadget	gadget;
 	unsigned int		setup;
+	unsigned long           last_rst;
 	struct s3c_hsotg_ep	eps[];
 };
 
@@ -2377,23 +2379,26 @@ static irqreturn_t s3c_hsotg_irq(int irq, void *pw)
 	}
 
 	if (gintsts & S3C_GINTSTS_USBRst) {
+
+		u32 usb_status = readl(hsotg->regs + S3C_GOTGCTL);
+
 		dev_info(hsotg->dev, "%s: USBRst\n", __func__);
 		dev_dbg(hsotg->dev, "GNPTXSTS=%08x\n",
 			readl(hsotg->regs + S3C_GNPTXSTS));
 
 		writel(S3C_GINTSTS_USBRst, hsotg->regs + S3C_GINTSTS);
 
-		kill_all_requests(hsotg, &hsotg->eps[0], -ECONNRESET, true);
+		if (usb_status & S3C_GOTGCTL_BSESVLD) {
+			if (time_after(jiffies, hsotg->last_rst +
+				       msecs_to_jiffies(200))) {
 
-		/* it seems after a reset we can end up with a situation
-		 * where the TXFIFO still has data in it... the docs
-		 * suggest resetting all the fifos, so use the init_fifo
-		 * code to relayout and flush the fifos.
-		 */
+				kill_all_requests(hsotg, &hsotg->eps[0],
+							  -ECONNRESET, true);
 
-		s3c_hsotg_init_fifo(hsotg);
-
-		s3c_hsotg_enqueue_setup(hsotg);
+				s3c_hsotg_core_init(hsotg);
+				hsotg->last_rst = jiffies;
+			}
+		}
 	}
 
 	/* check both FIFOs */
@@ -2436,6 +2441,7 @@ static irqreturn_t s3c_hsotg_irq(int irq, void *pw)
 		writel(S3C_GINTSTS_USBSusp, hsotg->regs + S3C_GINTSTS);
 
 		call_gadget(hsotg, suspend);
+		s3c_hsotg_disconnect(hsotg);
 	}
 
 	if (gintsts & S3C_GINTSTS_WkUpInt) {
@@ -2448,6 +2454,8 @@ static irqreturn_t s3c_hsotg_irq(int irq, void *pw)
 	if (gintsts & S3C_GINTSTS_ErlySusp) {
 		dev_dbg(hsotg->dev, "S3C_GINTSTS_ErlySusp\n");
 		writel(S3C_GINTSTS_ErlySusp, hsotg->regs + S3C_GINTSTS);
+
+		s3c_hsotg_disconnect(hsotg);
 	}
 
 	/* these next two seem to crop-up occasionally causing the core
@@ -2823,7 +2831,7 @@ static int s3c_hsotg_start(struct usb_gadget_driver *driver,
 	}
 
 	s3c_hsotg_core_init(hsotg);
-
+	hsotg->last_rst = jiffies;
 	dev_info(hsotg->dev, "bound driver %s\n", driver->driver.name);
 	return 0;