USB: imx_udc: Fix IMX UDC gadget general irq handling

Workaround of hw bug in IMX UDC.
This bug causes wrong handling of CFG_CHG interrupt.
Workaround is documented inline source code.

Signed-off-by: Darius Augulis <augulis.darius@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 94 insertions, 65 deletions

diff --git a/drivers/usb/gadget/imx_udc.c b/drivers/usb/gadget/imx_udc.c
index e590464c3a50..8d3c6a960988 100644
--- a/drivers/usb/gadget/imx_udc.c
+++ b/drivers/usb/gadget/imx_udc.c
@@ -28,6 +28,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/timer.h>
 
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
@@ -1013,70 +1014,32 @@ static void udc_stop_activity(struct imx_udc_struct *imx_usb,
  *******************************************************************************
  */
 
-static irqreturn_t imx_udc_irq(int irq, void *dev)
+/*
+ * Called when timer expires.
+ * Timer is started when CFG_CHG is received.
+ */
+static void handle_config(unsigned long data)
 {
-        struct imx_udc_struct *imx_usb = dev;
+        struct imx_udc_struct *imx_usb = (void *)data;
         struct usb_ctrlrequest u;
         int temp, cfg, intf, alt;
-        int intr = __raw_readl(imx_usb->base + USB_INTR);
-
-        if (intr & (INTR_WAKEUP | INTR_SUSPEND | INTR_RESUME | INTR_RESET_START
-                        | INTR_RESET_STOP | INTR_CFG_CHG)) {
-                                dump_intr(__func__, intr, imx_usb->dev);
-                                dump_usb_stat(__func__, imx_usb);
-        }
-
-        if (!imx_usb->driver)
-                goto end_irq;
-
-        if (intr & INTR_WAKEUP) {
-                if (imx_usb->gadget.speed == USB_SPEED_UNKNOWN
-                        && imx_usb->driver && imx_usb->driver->resume)
-                                imx_usb->driver->resume(&imx_usb->gadget);
-                imx_usb->set_config = 0;
-                imx_usb->gadget.speed = USB_SPEED_FULL;
-        }
-
-        if (intr & INTR_SUSPEND) {
-                if (imx_usb->gadget.speed != USB_SPEED_UNKNOWN
-                        && imx_usb->driver && imx_usb->driver->suspend)
-                                imx_usb->driver->suspend(&imx_usb->gadget);
-                imx_usb->set_config = 0;
-                imx_usb->gadget.speed = USB_SPEED_UNKNOWN;
-        }
 
-        if (intr & INTR_RESET_START) {
-                __raw_writel(intr, imx_usb->base + USB_INTR);
-                udc_stop_activity(imx_usb, imx_usb->driver);
-                imx_usb->set_config = 0;
-                imx_usb->gadget.speed = USB_SPEED_UNKNOWN;
-        }
-
-        if (intr & INTR_RESET_STOP)
-                imx_usb->gadget.speed = USB_SPEED_FULL;
+        local_irq_disable();
 
-        if (intr & INTR_CFG_CHG) {
-                __raw_writel(INTR_CFG_CHG, imx_usb->base + USB_INTR);
-                temp = __raw_readl(imx_usb->base + USB_STAT);
-                cfg  = (temp & STAT_CFG) >> 5;
-                intf = (temp & STAT_INTF) >> 3;
-                alt  =  temp & STAT_ALTSET;
+        temp = __raw_readl(imx_usb->base + USB_STAT);
+        cfg  = (temp & STAT_CFG) >> 5;
+        intf = (temp & STAT_INTF) >> 3;
+        alt  =  temp & STAT_ALTSET;
 
-                D_REQ(imx_usb->dev,
-                        "<%s> orig config C=%d, I=%d, A=%d / "
-                        "req config C=%d, I=%d, A=%d\n",
-                        __func__, imx_usb->cfg, imx_usb->intf, imx_usb->alt,
-                        cfg, intf, alt);
+        D_REQ(imx_usb->dev,
+                "<%s> orig config C=%d, I=%d, A=%d / "
+                "req config C=%d, I=%d, A=%d\n",
+                __func__, imx_usb->cfg, imx_usb->intf, imx_usb->alt,
+                cfg, intf, alt);
 
-                if (cfg != 1 && cfg != 2)
-                        goto end_irq;
+        if (cfg == 1 || cfg == 2) {
 
-                imx_usb->set_config = 0;
-
-                /* Config setup */
                 if (imx_usb->cfg != cfg) {
-                        D_REQ(imx_usb->dev,
-                                        "<%s> Change config start\n", __func__);
                         u.bRequest = USB_REQ_SET_CONFIGURATION;
                         u.bRequestType = USB_DIR_OUT |
                                         USB_TYPE_STANDARD |
@@ -1085,16 +1048,10 @@ static irqreturn_t imx_udc_irq(int irq, void *dev)
                         u.wIndex = 0;
                         u.wLength = 0;
                         imx_usb->cfg = cfg;
-                        imx_usb->set_config = 1;
                         imx_usb->driver->setup(&imx_usb->gadget, &u);
-                        imx_usb->set_config = 0;
-                        D_REQ(imx_usb->dev,
-                                        "<%s> Change config done\n", __func__);
 
                 }
                 if (imx_usb->intf != intf || imx_usb->alt != alt) {
-                        D_REQ(imx_usb->dev,
-                                "<%s> Change interface start\n", __func__);
                         u.bRequest = USB_REQ_SET_INTERFACE;
                         u.bRequestType = USB_DIR_OUT |
                                           USB_TYPE_STANDARD |
@@ -1104,14 +1061,30 @@ static irqreturn_t imx_udc_irq(int irq, void *dev)
                         u.wLength = 0;
                         imx_usb->intf = intf;
                         imx_usb->alt = alt;
-                        imx_usb->set_config = 1;
                         imx_usb->driver->setup(&imx_usb->gadget, &u);
-                        imx_usb->set_config = 0;
-                        D_REQ(imx_usb->dev,
-                                "<%s> Change interface done\n", __func__);
                 }
         }
 
+        imx_usb->set_config = 0;
+
+        local_irq_enable();
+}
+
+static irqreturn_t imx_udc_irq(int irq, void *dev)
+{
+        struct imx_udc_struct *imx_usb = dev;
+        int intr = __raw_readl(imx_usb->base + USB_INTR);
+        int temp;
+
+        if (intr & (INTR_WAKEUP | INTR_SUSPEND | INTR_RESUME | INTR_RESET_START
+                        | INTR_RESET_STOP | INTR_CFG_CHG)) {
+                                dump_intr(__func__, intr, imx_usb->dev);
+                                dump_usb_stat(__func__, imx_usb);
+        }
+
+        if (!imx_usb->driver)
+                goto end_irq;
+
         if (intr & INTR_SOF) {
                 /* Copy from Freescale BSP.
                    We must enable SOF intr and set CMDOVER.
@@ -1125,6 +1098,55 @@ static irqreturn_t imx_udc_irq(int irq, void *dev)
                 }
         }
 
+        if (intr & INTR_CFG_CHG) {
+                /* A workaround of serious IMX UDC bug.
+                   Handling of CFG_CHG should be delayed for some time, because
+                   IMX does not NACK the host when CFG_CHG interrupt is pending.
+                   There is no time to handle current CFG_CHG
+                   if next CFG_CHG or SETUP packed is send immediately.
+                   We have to clear CFG_CHG, start the timer and
+                   NACK the host by setting CTRL_CMDOVER
+                   if it sends any SETUP packet.
+                   When timer expires, handler is called to handle configuration
+                   changes. While CFG_CHG is not handled (set_config=1),
+                   we must NACK the host to every SETUP packed.
+                   This delay prevents from going out of sync with host.
+                 */
+                __raw_writel(INTR_CFG_CHG, imx_usb->base + USB_INTR);
+                imx_usb->set_config = 1;
+                mod_timer(&imx_usb->timer, jiffies + 5);
+                goto end_irq;
+        }
+
+        if (intr & INTR_WAKEUP) {
+                if (imx_usb->gadget.speed == USB_SPEED_UNKNOWN
+                        && imx_usb->driver && imx_usb->driver->resume)
+                                imx_usb->driver->resume(&imx_usb->gadget);
+                imx_usb->set_config = 0;
+                del_timer(&imx_usb->timer);
+                imx_usb->gadget.speed = USB_SPEED_FULL;
+        }
+
+        if (intr & INTR_SUSPEND) {
+                if (imx_usb->gadget.speed != USB_SPEED_UNKNOWN
+                        && imx_usb->driver && imx_usb->driver->suspend)
+                                imx_usb->driver->suspend(&imx_usb->gadget);
+                imx_usb->set_config = 0;
+                del_timer(&imx_usb->timer);
+                imx_usb->gadget.speed = USB_SPEED_UNKNOWN;
+        }
+
+        if (intr & INTR_RESET_START) {
+                __raw_writel(intr, imx_usb->base + USB_INTR);
+                udc_stop_activity(imx_usb, imx_usb->driver);
+                imx_usb->set_config = 0;
+                del_timer(&imx_usb->timer);
+                imx_usb->gadget.speed = USB_SPEED_UNKNOWN;
+        }
+
+        if (intr & INTR_RESET_STOP)
+                imx_usb->gadget.speed = USB_SPEED_FULL;
+
 end_irq:
         __raw_writel(intr, imx_usb->base + USB_INTR);
         return IRQ_HANDLED;
@@ -1342,6 +1364,7 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 
         udc_stop_activity(imx_usb, driver);
         imx_udc_disable(imx_usb);
+        del_timer(&imx_usb->timer);
 
         driver->unbind(&imx_usb->gadget);
         imx_usb->gadget.dev.driver = NULL;
@@ -1459,6 +1482,10 @@ static int __init imx_udc_probe(struct platform_device *pdev)
         usb_init_data(imx_usb);
         imx_udc_init(imx_usb);
 
+        init_timer(&imx_usb->timer);
+        imx_usb->timer.function = handle_config;
+        imx_usb->timer.data = (unsigned long)imx_usb;
+
         return 0;
 
 fail3:
@@ -1481,6 +1508,7 @@ static int __exit imx_udc_remove(struct platform_device *pdev)
         int i;
 
         imx_udc_disable(imx_usb);
+        del_timer(&imx_usb->timer);
 
         for (i = 0; i < IMX_USB_NB_EP + 1; i++)
                 free_irq(imx_usb->usbd_int[i], imx_usb);
diff --git a/drivers/usb/gadget/imx_udc.h b/drivers/usb/gadget/imx_udc.h
index 6b0b1e3d6fc7..b48ad59603d1 100644
--- a/drivers/usb/gadget/imx_udc.h
+++ b/drivers/usb/gadget/imx_udc.h
@@ -59,6 +59,7 @@ struct imx_udc_struct {
         struct device                           *dev;
         struct imx_ep_struct                    imx_ep[IMX_USB_NB_EP];
         struct clk                              *clk;
+        struct timer_list                       timer;
         enum ep0_state                          ep0state;
         struct resource                         *res;
         void __iomem                            *base;