The USB Controller does not support ID pin change interrupts. So we have
to use a polling function to detect changes of A/B device state
(otg_timer). This poll function has to check in several states if a
other device type might be connected to the USB port. This check is
triggered by manually starting/stopping a USB Session.
So in A mode, we cancel the currently running session which also
disables the possibility to detect new devices via interrupt. In B mode,
we start a session to check for ID-Pin and possibly connected devices.
Whenever a real USB session ends, we have to trigger the otg_timer poll
function again.
Signed-off-by: Markus Pargmann <mpa@xxxxxxxxxxxxxx>
---
drivers/usb/musb/musb_dsps.c | 84 ++++++++++++++++++++++++++++++++++++++++----
1 file changed, 78 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
index b24b697..0245e8d 100644
--- a/drivers/usb/musb/musb_dsps.c
+++ b/drivers/usb/musb/musb_dsps.c
@@ -178,6 +178,43 @@ static const struct file_operations musb_regdump_fops = {
#endif /* IS_ENABLED(CONFIG_DEBUG_FS) */
+/*
+ * Compare driver and hardware mode and update driver state if necessary.
+ * Not all hardware changes actually reach the driver through interrupts.
+ */
+static void dsps_update_mode(struct musb *musb)
+{
+ u8 devctl;
+
+ devctl = dsps_readb(musb->mregs, MUSB_DEVCTL);
+
+ switch (musb->xceiv->state) {
+ case OTG_STATE_A_IDLE:
+ if (devctl & MUSB_DEVCTL_BDEVICE) {
+ dev_dbg(musb->controller, "detected controller state B, software state A\n");
+ musb->xceiv->state = OTG_STATE_B_IDLE;
+ }
+ break;
+ case OTG_STATE_B_IDLE:
+ if (!(devctl & MUSB_DEVCTL_BDEVICE)) {
+ dev_dbg(musb->controller, "detected controller state A, software state B\n");
+ musb->xceiv->state = OTG_STATE_A_IDLE;
+ }
+ break;
+ default:
+ if (!(devctl & MUSB_DEVCTL_SESSION)) {
+ dev_dbg(musb->controller, "detected controller out of session (%x), software state %s\n",
+ devctl,
+ usb_otg_state_string(musb->xceiv->state));
+ if (devctl & MUSB_DEVCTL_BDEVICE)
+ musb->xceiv->state = OTG_STATE_B_IDLE;
+ else
+ musb->xceiv->state = OTG_STATE_A_IDLE;
+ }
+ break;
+ }
+}
+
/**
* dsps_musb_enable - enable interrupts
*/
@@ -229,6 +266,8 @@ static void otg_timer(unsigned long _musb)
u8 devctl;
unsigned long flags;
+ dsps_update_mode(musb);
+
/*
* We poll because DSPS IP's won't expose several OTG-critical
* status change events (from the transceiver) otherwise.
@@ -239,6 +278,16 @@ static void otg_timer(unsigned long _musb)
spin_lock_irqsave(&musb->lock, flags);
switch (musb->xceiv->state) {
+ case OTG_STATE_A_IDLE:
+ case OTG_STATE_A_WAIT_VRISE:
+ /*
+ * Poll the devctl register to know when the controller switches
+ * back to B state.
+ */
+ musb_writeb(mregs, MUSB_DEVCTL,
+ devctl & (~MUSB_DEVCTL_SESSION));
+ mod_timer(&glue->timer, jiffies + wrp->poll_seconds * HZ);
+ break;
case OTG_STATE_A_WAIT_BCON:
devctl &= ~MUSB_DEVCTL_SESSION;
dsps_writeb(musb->mregs, MUSB_DEVCTL, devctl);
@@ -251,6 +300,8 @@ static void otg_timer(unsigned long _musb)
musb->xceiv->state = OTG_STATE_A_IDLE;
MUSB_HST_MODE(musb);
}
+ mod_timer(&glue->timer,
+ jiffies + wrp->poll_seconds * HZ);
break;
case OTG_STATE_A_WAIT_VFALL:
musb->xceiv->state = OTG_STATE_A_WAIT_VRISE;
@@ -258,12 +309,24 @@ static void otg_timer(unsigned long _musb)
MUSB_INTR_VBUSERROR << wrp->usb_shift);
break;
case OTG_STATE_B_IDLE:
+ /*
+ * There's no ID-changed IRQ, so we have no good way to tell
+ * when to switch to the A-Default state machine (by setting
+ * the DEVCTL.Session bit).
+ *
+ * Workaround: whenever we're in B_IDLE, try setting the
+ * session flag every few seconds. If it works, ID was
+ * grounded and we're now in the A-Default state machine.
+ *
+ * NOTE: setting the session flag is _supposed_ to trigger
+ * SRP but clearly it doesn't.
+ */
+ musb_writeb(mregs, MUSB_DEVCTL, devctl | MUSB_DEVCTL_SESSION);
devctl = dsps_readb(mregs, MUSB_DEVCTL);
- if (devctl & MUSB_DEVCTL_BDEVICE)
- mod_timer(&glue->timer,
- jiffies + wrp->poll_seconds * HZ);
- else
+ if (!(devctl & MUSB_DEVCTL_BDEVICE))
musb->xceiv->state = OTG_STATE_A_IDLE;
+ mod_timer(&glue->timer,
+ jiffies + wrp->poll_seconds * HZ);
break;
default:
break;
@@ -376,7 +439,6 @@ static irqreturn_t dsps_interrupt(int irq, void *hci)
MUSB_HST_MODE(musb);
musb->xceiv->otg->default_a = 1;
musb->xceiv->state = OTG_STATE_A_WAIT_VRISE;
- del_timer(&glue->timer);
} else {
musb->is_active = 0;
MUSB_DEV_MODE(musb);
@@ -397,8 +459,16 @@ static irqreturn_t dsps_interrupt(int irq, void *hci)
ret |= musb_interrupt(musb);
/* Poll for ID change */
- if (musb->xceiv->state == OTG_STATE_B_IDLE)
+ switch (musb->xceiv->state) {
+ case OTG_STATE_A_IDLE:
+ case OTG_STATE_A_WAIT_BCON:
+ case OTG_STATE_A_WAIT_VRISE:
+ case OTG_STATE_B_IDLE:
mod_timer(&glue->timer, jiffies + wrp->poll_seconds * HZ);
+ break;
+ default:
+ break;
+ }
out:
spin_unlock_irqrestore(&musb->lock, flags);
@@ -479,6 +549,8 @@ static int dsps_musb_init(struct musb *musb)
dev_info(dev, "%s:%d %s: OK\n", __FILE__, __LINE__, __func__);
+ musb->xceiv->otg->default_a = 0;
+
return 0;
}
--
1.8.4.rc3
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