2 files changed, 90 insertions, 6 deletions

diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
index 53a4351aef97..f119a62140ef 100644
--- a/drivers/usb/musb/musb_dsps.c
+++ b/drivers/usb/musb/musb_dsps.c
@@ -144,6 +144,7 @@ struct dsps_glue {
         const struct dsps_musb_wrapper *wrp; /* wrapper register offsets */
         struct timer_list timer;        /* otg_workaround timer */
         unsigned long last_timer;    /* last timer data for each instance */
+        bool sw_babble_enabled;
 
         struct dsps_context context;
         struct debugfs_regset32 regset;
@@ -477,6 +478,19 @@ static int dsps_musb_init(struct musb *musb)
         val &= ~(1 << wrp->otg_disable);
         dsps_writel(musb->ctrl_base, wrp->phy_utmi, val);
 
+        /*
+         *  Check whether the dsps version has babble control enabled.
+         * In latest silicon revision the babble control logic is enabled.
+         * If MUSB_BABBLE_CTL returns 0x4 then we have the babble control
+         * logic enabled.
+         */
+        val = dsps_readb(musb->mregs, MUSB_BABBLE_CTL);
+        if (val == MUSB_BABBLE_RCV_DISABLE) {
+                glue->sw_babble_enabled = true;
+                val |= MUSB_BABBLE_SW_SESSION_CTRL;
+                dsps_writeb(musb->mregs, MUSB_BABBLE_CTL, val);
+        }
+
         ret = dsps_musb_dbg_init(musb, glue);
         if (ret)
                 return ret;
@@ -544,19 +558,82 @@ static int dsps_musb_set_mode(struct musb *musb, u8 mode)
         return 0;
 }
 
+static bool  sw_babble_control(struct musb *musb)
+{
+        u8 babble_ctl;
+        bool session_restart =  false;
+
+        babble_ctl = dsps_readb(musb->mregs, MUSB_BABBLE_CTL);
+        dev_dbg(musb->controller, "babble: MUSB_BABBLE_CTL value %x\n",
+                babble_ctl);
+        /*
+         * check line monitor flag to check whether babble is
+         * due to noise
+         */
+        dev_dbg(musb->controller, "STUCK_J is %s\n",
+                babble_ctl & MUSB_BABBLE_STUCK_J ? "set" : "reset");
+
+        if (babble_ctl & MUSB_BABBLE_STUCK_J) {
+                int timeout = 10;
+
+                /*
+                 * babble is due to noise, then set transmit idle (d7 bit)
+                 * to resume normal operation
+                 */
+                babble_ctl = dsps_readb(musb->mregs, MUSB_BABBLE_CTL);
+                babble_ctl |= MUSB_BABBLE_FORCE_TXIDLE;
+                dsps_writeb(musb->mregs, MUSB_BABBLE_CTL, babble_ctl);
+
+                /* wait till line monitor flag cleared */
+                dev_dbg(musb->controller, "Set TXIDLE, wait J to clear\n");
+                do {
+                        babble_ctl = dsps_readb(musb->mregs, MUSB_BABBLE_CTL);
+                        udelay(1);
+                } while ((babble_ctl & MUSB_BABBLE_STUCK_J) && timeout--);
+
+                /* check whether stuck_at_j bit cleared */
+                if (babble_ctl & MUSB_BABBLE_STUCK_J) {
+                        /*
+                         * real babble condition has occurred
+                         * restart the controller to start the
+                         * session again
+                         */
+                        dev_dbg(musb->controller, "J not cleared, misc (%x)\n",
+                                babble_ctl);
+                        session_restart = true;
+                }
+        } else {
+                session_restart = true;
+        }
+
+        return session_restart;
+}
+
 static int dsps_musb_reset(struct musb *musb)
 {
         struct device *dev = musb->controller;
         struct dsps_glue *glue = dev_get_drvdata(dev->parent);
         const struct dsps_musb_wrapper *wrp = glue->wrp;
+        int session_restart = 0;
 
-        dsps_writel(musb->ctrl_base, wrp->control, (1 << wrp->reset));
-        usleep_range(100, 200);
-        usb_phy_shutdown(musb->xceiv);
-        usleep_range(100, 200);
-        usb_phy_init(musb->xceiv);
+        if (glue->sw_babble_enabled)
+                session_restart = sw_babble_control(musb);
+        /*
+         * In case of new silicon version babble condition can be recovered
+         * without resetting the MUSB. But for older silicon versions, MUSB
+         * reset is needed
+         */
+        if (session_restart || !glue->sw_babble_enabled) {
+                dev_info(musb->controller, "Restarting MUSB to recover from Babble\n");
+                dsps_writel(musb->ctrl_base, wrp->control, (1 << wrp->reset));
+                usleep_range(100, 200);
+                usb_phy_shutdown(musb->xceiv);
+                usleep_range(100, 200);
+                usb_phy_init(musb->xceiv);
+                session_restart = 1;
+        }
 
-        return 0;
+        return !session_restart;
 }
 
 static struct musb_platform_ops dsps_ops = {
diff --git a/drivers/usb/musb/musb_regs.h b/drivers/usb/musb/musb_regs.h
index 03f2655af290..b9bcda5e3945 100644
--- a/drivers/usb/musb/musb_regs.h
+++ b/drivers/usb/musb/musb_regs.h
@@ -72,6 +72,12 @@
 #define MUSB_DEVCTL_HR          0x02
 #define MUSB_DEVCTL_SESSION     0x01
 
+/* BABBLE_CTL */
+#define MUSB_BABBLE_FORCE_TXIDLE        0x80
+#define MUSB_BABBLE_SW_SESSION_CTRL     0x40
+#define MUSB_BABBLE_STUCK_J             0x20
+#define MUSB_BABBLE_RCV_DISABLE         0x04
+
 /* MUSB ULPI VBUSCONTROL */
 #define MUSB_ULPI_USE_EXTVBUS   0x01
 #define MUSB_ULPI_USE_EXTVBUSIND 0x02
@@ -246,6 +252,7 @@
  */
 
 #define MUSB_DEVCTL             0x60    /* 8 bit */
+#define MUSB_BABBLE_CTL         0x61    /* 8 bit */
 
 /* These are always controlled through the INDEX register */
 #define MUSB_TXFIFOSZ           0x62    /* 8-bit (see masks) */