DRD mode is a reduced functionality OTG mode. In this mode
we don't support SRP, HNP and dynamic role-swap.
In DRD operation, the controller mode (Host or Peripheral)
is decided based on the ID pin status. Once a cable plug (Type-A
or Type-B) is attached the controller selects the state
and doesn't change till the cable in unplugged and a different
cable type is inserted.
As we don't need most of the complex OTG states and OTG timers
we implement a lean DRD state machine in usb-otg.c.
The DRD state machine is only interested in 2 hardware inputs
'id' and 'b_sess_vld'.
Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---
drivers/usb/common/usb-otg.c | 178 +++++++++++++++++++++++++++++++++++++++++--
include/linux/usb/otg-fsm.h | 5 ++
include/linux/usb/otg.h | 2 +
3 files changed, 177 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c
index 930c2fe..44b5577 100644
--- a/drivers/usb/common/usb-otg.c
+++ b/drivers/usb/common/usb-otg.c
@@ -519,14 +519,165 @@ int usb_otg_start_gadget(struct otg_fsm *fsm, int on)
}
EXPORT_SYMBOL_GPL(usb_otg_start_gadget);
+/* Change USB protocol when there is a protocol change */
+static int drd_set_protocol(struct otg_fsm *fsm, int protocol)
+{
+ struct usb_otg *otgd = container_of(fsm, struct usb_otg, fsm);
+ int ret = 0;
+
+ if (fsm->protocol != protocol) {
+ dev_dbg(otgd->dev, "otg: changing role fsm->protocol= %d; new protocol= %d\n",
+ fsm->protocol, protocol);
+ /* stop old protocol */
+ if (fsm->protocol == PROTO_HOST)
+ ret = otg_start_host(fsm, 0);
+ else if (fsm->protocol == PROTO_GADGET)
+ ret = otg_start_gadget(fsm, 0);
+ if (ret)
+ return ret;
+
+ /* start new protocol */
+ if (protocol == PROTO_HOST)
+ ret = otg_start_host(fsm, 1);
+ else if (protocol == PROTO_GADGET)
+ ret = otg_start_gadget(fsm, 1);
+ if (ret)
+ return ret;
+
+ fsm->protocol = protocol;
+ return 0;
+ }
+
+ return 0;
+}
+
+/* Called when entering a DRD state */
+static void drd_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state)
+{
+ struct usb_otg *otgd = container_of(fsm, struct usb_otg, fsm);
+
+ if (fsm->otg->state == new_state)
+ return;
+
+ fsm->state_changed = 1;
+ dev_dbg(otgd->dev, "otg: set state: %s\n",
+ usb_otg_state_string(new_state));
+ switch (new_state) {
+ case OTG_STATE_B_IDLE:
+ drd_set_protocol(fsm, PROTO_UNDEF);
+ break;
+ case OTG_STATE_B_PERIPHERAL:
+ drd_set_protocol(fsm, PROTO_GADGET);
+ break;
+ case OTG_STATE_A_HOST:
+ drd_set_protocol(fsm, PROTO_HOST);
+ break;
+ case OTG_STATE_UNDEFINED:
+ case OTG_STATE_B_SRP_INIT:
+ case OTG_STATE_B_WAIT_ACON:
+ case OTG_STATE_B_HOST:
+ case OTG_STATE_A_IDLE:
+ case OTG_STATE_A_WAIT_VRISE:
+ case OTG_STATE_A_WAIT_BCON:
+ case OTG_STATE_A_SUSPEND:
+ case OTG_STATE_A_PERIPHERAL:
+ case OTG_STATE_A_WAIT_VFALL:
+ case OTG_STATE_A_VBUS_ERR:
+ default:
+ dev_warn(otgd->dev, "%s: otg: invalid state: %s\n",
+ __func__, usb_otg_state_string(new_state));
+ break;
+ }
+
+ fsm->otg->state = new_state;
+}
+
/**
- * OTG FSM work function
+ * DRD state change judgement
+ *
+ * For DRD we're only interested in some of the OTG states
+ * i.e. OTG_STATE_B_IDLE: both peripheral and host are stopped
+ * OTG_STATE_B_PERIPHERAL: peripheral active
+ * OTG_STATE_A_HOST: host active
+ * we're only interested in the following inputs
+ * fsm->id, fsm->b_sess_vld
+ */
+static int drd_statemachine(struct otg_fsm *fsm)
+{
+ struct usb_otg *otgd = container_of(fsm, struct usb_otg, fsm);
+ enum usb_otg_state state;
+
+ mutex_lock(&fsm->lock);
+
+ state = fsm->otg->state;
+
+ switch (state) {
+ case OTG_STATE_UNDEFINED:
+ if (!fsm->id)
+ drd_set_state(fsm, OTG_STATE_A_HOST);
+ else if (fsm->id && fsm->b_sess_vld)
+ drd_set_state(fsm, OTG_STATE_B_PERIPHERAL);
+ else
+ drd_set_state(fsm, OTG_STATE_B_IDLE);
+ break;
+ case OTG_STATE_B_IDLE:
+ if (!fsm->id)
+ drd_set_state(fsm, OTG_STATE_A_HOST);
+ else if (fsm->b_sess_vld)
+ drd_set_state(fsm, OTG_STATE_B_PERIPHERAL);
+ break;
+ case OTG_STATE_B_PERIPHERAL:
+ if (!fsm->id)
+ drd_set_state(fsm, OTG_STATE_A_HOST);
+ else if (!fsm->b_sess_vld)
+ drd_set_state(fsm, OTG_STATE_B_IDLE);
+ break;
+ case OTG_STATE_A_HOST:
+ if (fsm->id && fsm->b_sess_vld)
+ drd_set_state(fsm, OTG_STATE_B_PERIPHERAL);
+ else if (fsm->id && !fsm->b_sess_vld)
+ drd_set_state(fsm, OTG_STATE_B_IDLE);
+ break;
+
+ /* invalid states for DRD */
+ case OTG_STATE_B_SRP_INIT:
+ case OTG_STATE_B_WAIT_ACON:
+ case OTG_STATE_B_HOST:
+ case OTG_STATE_A_IDLE:
+ case OTG_STATE_A_WAIT_VRISE:
+ case OTG_STATE_A_WAIT_BCON:
+ case OTG_STATE_A_SUSPEND:
+ case OTG_STATE_A_PERIPHERAL:
+ case OTG_STATE_A_WAIT_VFALL:
+ case OTG_STATE_A_VBUS_ERR:
+ dev_err(otgd->dev, "%s: otg: invalid usb-drd state: %s\n",
+ __func__, usb_otg_state_string(state));
+ drd_set_state(fsm, OTG_STATE_UNDEFINED);
+ break;
+ }
+
+ mutex_unlock(&fsm->lock);
+ dev_dbg(otgd->dev, "otg: quit statemachine, changed %d\n",
+ fsm->state_changed);
+
+ return fsm->state_changed;
+}
+
+/**
+ * OTG FSM/DRD work function
*/
static void usb_otg_work(struct work_struct *work)
{
struct usb_otg *otgd = container_of(work, struct usb_otg, work);
- otg_statemachine(&otgd->fsm);
+ /* OTG state machine */
+ if (!otgd->drd_only) {
+ otg_statemachine(&otgd->fsm);
+ return;
+ }
+
+ /* DRD state machine */
+ drd_statemachine(&otgd->fsm);
}
/**
@@ -584,13 +735,22 @@ struct otg_fsm *usb_otg_register(struct device *dev,
goto err_wq;
}
- usb_otg_init_timers(otgd, config->otg_timeouts);
+ if (!(otgd->caps->hnp_support || otgd->caps->srp_support ||
+ otgd->caps->adp_support))
+ otgd->drd_only = true;
/* create copy of original ops */
otgd->fsm_ops = *config->fsm_ops;
- /* FIXME: we ignore caller's timer ops */
- otgd->fsm_ops.add_timer = usb_otg_add_timer;
- otgd->fsm_ops.del_timer = usb_otg_del_timer;
+
+ /* For DRD mode we don't need OTG timers */
+ if (!otgd->drd_only) {
+ usb_otg_init_timers(otgd, config->otg_timeouts);
+
+ /* FIXME: we ignore caller's timer ops */
+ otgd->fsm_ops.add_timer = usb_otg_add_timer;
+ otgd->fsm_ops.del_timer = usb_otg_del_timer;
+ }
+
/* set otg ops */
otgd->fsm.ops = &otgd->fsm_ops;
otgd->fsm.otg = otgd;
@@ -703,8 +863,10 @@ static void usb_otg_stop_fsm(struct otg_fsm *fsm)
otgd->fsm_running = false;
/* Stop state machine / timers */
- for (i = 0; i < ARRAY_SIZE(otgd->timers); i++)
- hrtimer_cancel(&otgd->timers[i].timer);
+ if (!otgd->drd_only) {
+ for (i = 0; i < ARRAY_SIZE(otgd->timers); i++)
+ hrtimer_cancel(&otgd->timers[i].timer);
+ }
flush_workqueue(otgd->wq);
fsm->otg->state = OTG_STATE_UNDEFINED;
diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h
index 75e82cc..48a6aea 100644
--- a/include/linux/usb/otg-fsm.h
+++ b/include/linux/usb/otg-fsm.h
@@ -48,6 +48,11 @@ enum otg_fsm_timer {
/**
* struct otg_fsm - OTG state machine according to the OTG spec
*
+ * DRD mode hardware Inputs
+ *
+ * @id: TRUE for B-device, FALSE for A-device.
+ * @b_sess_vld: VBUS voltage in regulation.
+ *
* OTG hardware Inputs
*
* Common inputs for A and B device
diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h
index 38cabe0..18de812 100644
--- a/include/linux/usb/otg.h
+++ b/include/linux/usb/otg.h
@@ -74,6 +74,7 @@ struct otg_timer {
* @work: otg state machine work
* @wq: otg state machine work queue
* @fsm_running: state machine running/stopped indicator
+ * @drd_only: dual-role mode. no otg features.
*/
struct usb_otg {
u8 default_a;
@@ -102,6 +103,7 @@ struct usb_otg {
struct workqueue_struct *wq;
bool fsm_running;
/* use otg->fsm.lock for serializing access */
+ bool drd_only;
/*------------- deprecated interface -----------------------------*/
/* bind/unbind the host controller */
--
2.1.4
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