musb: support disconnect after HNP roleswitch

Adjust HNP state machines in MUSB driver so that they handle the
case where the cable is disconnected.  The A-side machine was
very wrong (unrecoverable); the B-Side was much less so.

 - A_PERIPHERAL ... as usual, the non-observability of the ID
   pin through Mentor's registers makes trouble.  We can't go
   directly to A_WAIT_VFALL to end the session and start the
   disconnect processing.  We can however sense link suspending,
   go to A_WAIT_BCON, and from there use OTG timeouts to finally
   trigger that A_WAIT_VFALL transition.  (Hoping that nobody
   reconnects quickly to that port and notices the wrong state.)

 - B_HOST ... actually clear the Host Request (HR) bit as the
   messages say, disconnect the peripheral from the root hub,
   and don't detour through a suspend state.  (In some cases
   this would eventually have cleaned up.)

Also adjust the A_SUSPEND transition to respect the A_AIDL_BDIS
timeout, so if HNP doesn't trigger quickly enough the A_WAIT_VFALL
transition happens as it should.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 35 insertions, 12 deletions

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 93dd23a7eb6c..b49859623f8d 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -304,9 +304,11 @@ void musb_otg_timer_func(unsigned long data)
                 musb->xceiv->state = OTG_STATE_B_PERIPHERAL;
                 musb->is_active = 0;
                 break;
+        case OTG_STATE_A_SUSPEND:
         case OTG_STATE_A_WAIT_BCON:
-                DBG(1, "HNP: a_wait_bcon timeout; back to a_host\n");
-                musb_hnp_stop(musb);
+                DBG(1, "HNP: %s timeout\n", otg_state_string(musb));
+                musb_set_vbus(musb, 0);
+                musb->xceiv->state = OTG_STATE_A_WAIT_VFALL;
                 break;
         default:
                 DBG(1, "HNP: Unhandled mode %s\n", otg_state_string(musb));
@@ -324,15 +326,12 @@ void musb_hnp_stop(struct musb *musb)
         void __iomem    *mbase = musb->mregs;
         u8      reg;
 
+        DBG(1, "HNP: stop from %s\n", otg_state_string(musb));
+
         switch (musb->xceiv->state) {
         case OTG_STATE_A_PERIPHERAL:
-        case OTG_STATE_A_WAIT_VFALL:
-        case OTG_STATE_A_WAIT_BCON:
-                DBG(1, "HNP: Switching back to A-host\n");
                 musb_g_disconnect(musb);
-                musb->xceiv->state = OTG_STATE_A_IDLE;
-                MUSB_HST_MODE(musb);
-                musb->is_active = 0;
+                DBG(1, "HNP: back to %s\n", otg_state_string(musb));
                 break;
         case OTG_STATE_B_HOST:
                 DBG(1, "HNP: Disabling HR\n");
@@ -775,7 +774,16 @@ static irqreturn_t musb_stage2_irq(struct musb *musb, u8 int_usb,
 #endif  /* HOST */
 #ifdef CONFIG_USB_MUSB_OTG
                 case OTG_STATE_B_HOST:
-                        musb_hnp_stop(musb);
+                        /* REVISIT this behaves for "real disconnect"
+                         * cases; make sure the other transitions from
+                         * from B_HOST act right too.  The B_HOST code
+                         * in hnp_stop() is currently not used...
+                         */
+                        musb_root_disconnect(musb);
+                        musb_to_hcd(musb)->self.is_b_host = 0;
+                        musb->xceiv->state = OTG_STATE_B_PERIPHERAL;
+                        MUSB_DEV_MODE(musb);
+                        musb_g_disconnect(musb);
                         break;
                 case OTG_STATE_A_PERIPHERAL:
                         musb_hnp_stop(musb);
@@ -807,10 +815,19 @@ static irqreturn_t musb_stage2_irq(struct musb *musb, u8 int_usb,
                 switch (musb->xceiv->state) {
 #ifdef  CONFIG_USB_MUSB_OTG
                 case OTG_STATE_A_PERIPHERAL:
-                        /*
-                         * We cannot stop HNP here, devctl BDEVICE might be
-                         * still set.
+                        /* We also come here if the cable is removed, since
+                         * this silicon doesn't report ID-no-longer-grounded.
+                         *
+                         * We depend on T(a_wait_bcon) to shut us down, and
+                         * hope users don't do anything dicey during this
+                         * undesired detour through A_WAIT_BCON.
                          */
+                        musb_hnp_stop(musb);
+                        usb_hcd_resume_root_hub(musb_to_hcd(musb));
+                        musb_root_disconnect(musb);
+                        musb_platform_try_idle(musb, jiffies
+                                        + msecs_to_jiffies(musb->a_wait_bcon
+                                                ? : OTG_TIME_A_WAIT_BCON));
                         break;
 #endif
                 case OTG_STATE_B_PERIPHERAL:
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index 3c4da75fbc7b..858d005fae6d 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -1962,9 +1962,11 @@ void musb_g_disconnect(struct musb *musb)
                 DBG(2, "Unhandled disconnect %s, setting a_idle\n",
                         otg_state_string(musb));
                 musb->xceiv->state = OTG_STATE_A_IDLE;
+                MUSB_HST_MODE(musb);
                 break;
         case OTG_STATE_A_PERIPHERAL:
                 musb->xceiv->state = OTG_STATE_A_WAIT_BCON;
+                MUSB_HST_MODE(musb);
                 break;
         case OTG_STATE_B_WAIT_ACON:
         case OTG_STATE_B_HOST:
diff --git a/drivers/usb/musb/musb_virthub.c b/drivers/usb/musb/musb_virthub.c
index c85a82a41d5c..bfe5fe4ebfee 100644
--- a/drivers/usb/musb/musb_virthub.c
+++ b/drivers/usb/musb/musb_virthub.c
@@ -83,6 +83,10 @@ static void musb_port_suspend(struct musb *musb, bool do_suspend)
                         musb->xceiv->state = OTG_STATE_A_SUSPEND;
                         musb->is_active = is_otg_enabled(musb)
                                         && musb->xceiv->host->b_hnp_enable;
+                        if (musb->is_active)
+                                mod_timer(&musb->otg_timer, jiffies
+                                        + msecs_to_jiffies(
+                                                OTG_TIME_A_AIDL_BDIS));
                         musb_platform_try_idle(musb, 0);
                         break;
 #ifdef  CONFIG_USB_MUSB_OTG