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Subject[PATCH 22/31] usb: usbssp: added procedure removing request from transfer ring
Date
Patch adds functionality that allows to remove the request from the
endpoint ring. This may cause the DC to stop USB transfers,
potentially stopping in the middle of a TRB buffer. The DC should
pick up where it left off in the TD, unless a Set Transfer Ring
Dequeue Pointer is issued.

Signed-off-by: Pawel Laszczak <pawell@cadence.com>
---
drivers/usb/usbssp/gadget-ring.c | 331 ++++++++++++++++++++++++++++++-
drivers/usb/usbssp/gadget.c | 49 ++++-
drivers/usb/usbssp/gadget.h | 11 +
3 files changed, 387 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/usbssp/gadget-ring.c b/drivers/usb/usbssp/gadget-ring.c
index 4bb13f9e311a..cfb31120eef8 100644
--- a/drivers/usb/usbssp/gadget-ring.c
+++ b/drivers/usb/usbssp/gadget-ring.c
@@ -102,11 +102,51 @@ static bool link_trb_toggles_cycle(union usbssp_trb *trb)
return le32_to_cpu(trb->link.control) & LINK_TOGGLE;
}

+static bool last_td_in_request(struct usbssp_td *td)
+{
+ struct usbssp_request *req_priv = td->priv_request;
+
+ return req_priv->num_tds_done == req_priv->num_tds;
+}
+
static void inc_td_cnt(struct usbssp_request *priv_req)
{
priv_req->num_tds_done++;
}

+static void trb_to_noop(union usbssp_trb *trb, u32 noop_type)
+{
+ if (trb_is_link(trb)) {
+ /* unchain chained link TRBs */
+ trb->link.control &= cpu_to_le32(~TRB_CHAIN);
+ } else {
+ trb->generic.field[0] = 0;
+ trb->generic.field[1] = 0;
+ trb->generic.field[2] = 0;
+ /* Preserve only the cycle bit of this TRB */
+ trb->generic.field[3] &= cpu_to_le32(TRB_CYCLE);
+ trb->generic.field[3] |= cpu_to_le32(TRB_TYPE(noop_type));
+ }
+}
+
+/*
+ * Updates trb to point to the next TRB in the ring, and updates seg if the next
+ * TRB is in a new segment. This does not skip over link TRBs, and it does not
+ * effect the ring dequeue or enqueue pointers.
+ */
+static void next_trb(struct usbssp_udc *usbssp_data,
+ struct usbssp_ring *ring,
+ struct usbssp_segment **seg,
+ union usbssp_trb **trb)
+{
+ if (trb_is_link(*trb)) {
+ *seg = (*seg)->next;
+ *trb = ((*seg)->trbs);
+ } else {
+ (*trb)++;
+ }
+}
+
/*
* See Cycle bit rules. SW is the consumer for the event ring only.
* Don't make a ring full of link TRBs. That would be dumb and this would loop.
@@ -347,6 +387,157 @@ struct usbssp_ring *usbssp_triad_to_transfer_ring(struct usbssp_udc *usbssp_data
return NULL;
}

+/*
+ * Get the hw dequeue pointer DC stopped on, either directly from the
+ * endpoint context, or if streams are in use from the stream context.
+ * The returned hw_dequeue contains the lowest four bits with cycle state
+ * and possbile stream context type.
+ */
+u64 usbssp_get_hw_deq(struct usbssp_udc *usbssp_data,
+ struct usbssp_device *dev,
+ unsigned int ep_index,
+ unsigned int stream_id)
+{
+ struct usbssp_ep_ctx *ep_ctx;
+ struct usbssp_stream_ctx *st_ctx;
+ struct usbssp_ep *ep;
+
+ ep = &dev->eps[ep_index];
+
+ if (ep->ep_state & EP_HAS_STREAMS) {
+ st_ctx = &ep->stream_info->stream_ctx_array[stream_id];
+ return le64_to_cpu(st_ctx->stream_ring);
+ }
+ ep_ctx = usbssp_get_ep_ctx(usbssp_data, dev->out_ctx, ep_index);
+ return le64_to_cpu(ep_ctx->deq);
+}
+
+/*
+ * Move the DC endpoint ring dequeue pointer past cur_td.
+ * Record the new state of the DC endpoint ring dequeue segment,
+ * dequeue pointer, and new consumer cycle state in state.
+ * Update our internal representation of the ring's dequeue pointer.
+ *
+ * We do this in three jumps:
+ * - First we update our new ring state to be the same as when the DC stopped.
+ * - Then we traverse the ring to find the segment that contains
+ * the last TRB in the TD. We toggle the DC new cycle state when we pass
+ * any link TRBs with the toggle cycle bit set.
+ * - Finally we move the dequeue state one TRB further, toggling the cycle bit
+ * if we've moved it past a link TRB with the toggle cycle bit set.
+ */
+void usbssp_find_new_dequeue_state(struct usbssp_udc *usbssp_data,
+ unsigned int ep_index,
+ unsigned int stream_id,
+ struct usbssp_td *cur_td,
+ struct usbssp_dequeue_state *state)
+{
+ struct usbssp_device *dev_priv = &usbssp_data->devs;
+ struct usbssp_ep *ep_priv = &dev_priv->eps[ep_index];
+ struct usbssp_ring *ep_ring;
+ struct usbssp_segment *new_seg;
+ union usbssp_trb *new_deq;
+ dma_addr_t addr;
+ u64 hw_dequeue;
+ bool cycle_found = false;
+ bool td_last_trb_found = false;
+
+ ep_ring = usbssp_triad_to_transfer_ring(usbssp_data,
+ ep_index, stream_id);
+ if (!ep_ring) {
+ dev_warn(usbssp_data->dev, "WARN can't find new dequeue state "
+ "for invalid stream ID %u.\n",
+ stream_id);
+ return;
+ }
+
+ /* Dig out the cycle state saved by the DC during the stop ep cmd */
+ usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_cancel_request,
+ "Finding endpoint context");
+
+ hw_dequeue = usbssp_get_hw_deq(usbssp_data, dev_priv,
+ ep_index, stream_id);
+ new_seg = ep_ring->deq_seg;
+ new_deq = ep_ring->dequeue;
+ state->new_cycle_state = hw_dequeue & 0x1;
+ state->stream_id = stream_id;
+
+ /*
+ * We want to find the pointer, segment and cycle state of the new trb
+ * (the one after current TD's last_trb). We know the cycle state at
+ * hw_dequeue, so walk the ring until both hw_dequeue and last_trb are
+ * found.
+ */
+ do {
+ if (!cycle_found && usbssp_trb_virt_to_dma(new_seg, new_deq)
+ == (dma_addr_t)(hw_dequeue & ~0xf)) {
+ cycle_found = true;
+ if (td_last_trb_found)
+ break;
+ }
+
+ if (new_deq == cur_td->last_trb)
+ td_last_trb_found = true;
+
+ if (cycle_found && trb_is_link(new_deq) &&
+ link_trb_toggles_cycle(new_deq))
+ state->new_cycle_state ^= 0x1;
+
+ next_trb(usbssp_data, ep_ring, &new_seg, &new_deq);
+
+ /* Search wrapped around, bail out */
+ if (new_deq == ep_priv->ring->dequeue) {
+ dev_err(usbssp_data->dev,
+ "Error: Failed finding new dequeue state\n");
+ state->new_deq_seg = NULL;
+ state->new_deq_ptr = NULL;
+ return;
+ }
+
+ } while (!cycle_found || !td_last_trb_found);
+
+ state->new_deq_seg = new_seg;
+ state->new_deq_ptr = new_deq;
+
+ /* Don't update the ring cycle state for the producer (us). */
+ usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_cancel_request,
+ "Cycle state = 0x%x", state->new_cycle_state);
+
+ usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_cancel_request,
+ "New dequeue segment = %p (virtual)",
+ state->new_deq_seg);
+ addr = usbssp_trb_virt_to_dma(state->new_deq_seg, state->new_deq_ptr);
+ usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_cancel_request,
+ "New dequeue pointer = 0x%llx (DMA)",
+ (unsigned long long) addr);
+}
+
+/*
+ * flip_cycle means flip the cycle bit of all but the first and last TRB.
+ * (The last TRB actually points to the ring enqueue pointer, which is not part
+ * of this TD.) This is used to remove partially enqueued isoc TDs from a ring.
+ */
+static void td_to_noop(struct usbssp_udc *usbssp_data,
+ struct usbssp_ring *ep_ring,
+ struct usbssp_td *td, bool flip_cycle)
+{
+ struct usbssp_segment *seg = td->start_seg;
+ union usbssp_trb *trb = td->first_trb;
+
+ while (1) {
+ trb_to_noop(trb, TRB_TR_NOOP);
+
+ /* flip cycle if asked to */
+ if (flip_cycle && trb != td->first_trb && trb != td->last_trb)
+ trb->generic.field[3] ^= cpu_to_le32(TRB_CYCLE);
+
+ if (trb == td->last_trb)
+ break;
+
+ next_trb(usbssp_data, ep_ring, &seg, &trb);
+ }
+}
+
/* Must be called with usbssp_data->lock held in interrupt context
* or usbssp_data->irq_thread_lock from thread conext (defered interrupt)
*/
@@ -365,6 +556,139 @@ void usbssp_giveback_request_in_irq(struct usbssp_udc *usbssp_data,
usbssp_gadget_giveback(req_priv->dep, req_priv, status);
}

+void usbssp_unmap_td_bounce_buffer(struct usbssp_udc *usbssp_data,
+ struct usbssp_ring *ring,
+ struct usbssp_td *td)
+{
+ /*TODO: ??? */
+}
+
+void usbssp_remove_request(struct usbssp_udc *usbssp_data,
+ struct usbssp_request *req_priv, int ep_index)
+{
+ int i = 0;
+ struct usbssp_ring *ep_ring;
+ struct usbssp_ep *ep;
+ struct usbssp_td *cur_td = NULL;
+ struct usbssp_ep_ctx *ep_ctx;
+ struct usbssp_device *priv_dev;
+ u64 hw_deq;
+ struct usbssp_dequeue_state deq_state;
+
+ memset(&deq_state, 0, sizeof(deq_state));
+ ep = &usbssp_data->devs.eps[ep_index];
+
+ priv_dev = &usbssp_data->devs;
+ ep_ctx = usbssp_get_ep_ctx(usbssp_data, priv_dev->out_ctx, ep_index);
+ trace_usbssp_remove_request(ep_ctx);
+
+ i = req_priv->num_tds_done;
+
+ for (; i < req_priv->num_tds; i++) {
+ cur_td = &req_priv->td[i];
+ usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_cancel_request,
+ "Removing canceled TD starting at 0x%llx (dma).",
+ (unsigned long long)usbssp_trb_virt_to_dma(
+ cur_td->start_seg,
+ cur_td->first_trb));
+
+ ep_ring = usbssp_request_to_transfer_ring(usbssp_data,
+ cur_td->priv_request);
+
+ if (!ep_ring) {
+ /*
+ * This shouldn't happen unless a driver is mucking
+ * with the stream ID after submission. This will
+ * leave the TD on the hardware ring, and the hardware
+ * will try to execute it, and may access a buffer
+ * that has already been freed. In the best case, the
+ * hardware will execute it, and the event handler will
+ * ignore the completion event for that TD, since it was
+ * removed from the td_list for that endpoint. In
+ * short, don't muck with the stream ID after
+ * submission.
+ */
+ dev_warn(usbssp_data->dev, "WARN Cancelled USB Request %p"
+ " has invalid stream ID %u.\n",
+ cur_td->priv_request,
+ cur_td->priv_request->request.stream_id);
+ goto remove_finished_td;
+ }
+
+ if (!(ep->ep_state & USBSSP_EP_ENABLED) ||
+ ep->ep_state & USBSSP_EP_DISABLE_PENDING) {
+ goto remove_finished_td;
+ }
+
+ /*
+ * If we stopped on the TD we need to cancel, then we have to
+ * move the DC endpoint ring dequeue pointer past this TD.
+ */
+ hw_deq = usbssp_get_hw_deq(usbssp_data, priv_dev, ep_index,
+ cur_td->priv_request->request.stream_id);
+ hw_deq &= ~0xf;
+
+ if (usbssp_trb_in_td(usbssp_data, cur_td->start_seg,
+ cur_td->first_trb, cur_td->last_trb, hw_deq, false)) {
+ usbssp_find_new_dequeue_state(usbssp_data, ep_index,
+ cur_td->priv_request->request.stream_id,
+ cur_td, &deq_state);
+ } else {
+ td_to_noop(usbssp_data, ep_ring, cur_td, false);
+ }
+
+remove_finished_td:
+ /*
+ * The event handler won't see a completion for this TD anymore,
+ * so remove it from the endpoint ring's TD list.
+ */
+ list_del_init(&cur_td->td_list);
+ }
+
+ ep->ep_state &= ~EP_STOP_CMD_PENDING;
+
+ if (!(ep->ep_state & USBSSP_EP_DISABLE_PENDING) &&
+ ep->ep_state & USBSSP_EP_ENABLED) {
+ /* If necessary, queue a Set Transfer Ring Dequeue Pointer command*/
+ if (deq_state.new_deq_ptr && deq_state.new_deq_seg) {
+ usbssp_queue_new_dequeue_state(usbssp_data, ep_index,
+ &deq_state);
+ usbssp_ring_cmd_db(usbssp_data);
+ } else {
+ /*
+ * Otherwise ring the doorbell(s) to restart queued
+ * transfers
+ */
+ ring_doorbell_for_active_rings(usbssp_data, ep_index);
+ }
+ }
+
+ /*
+ * Complete the cancellation of USB request.
+ */
+ i = req_priv->num_tds_done;
+ for (; i < req_priv->num_tds; i++) {
+ cur_td = &req_priv->td[i];
+
+ /*
+ * Clean up the cancelled USB Request
+ * Doesn't matter what we pass for status, since the core will
+ * just overwrite it.
+ */
+ ep_ring = usbssp_request_to_transfer_ring(usbssp_data,
+ cur_td->priv_request);
+
+ usbssp_unmap_td_bounce_buffer(usbssp_data, ep_ring, cur_td);
+
+ inc_td_cnt(cur_td->priv_request);
+ if (last_td_in_request(cur_td)) {
+ usbssp_giveback_request_in_irq(usbssp_data,
+ cur_td, -ECONNRESET);
+ }
+ }
+}
+
+
/*
* When we get a command completion for a Stop Endpoint Command, we need to
* stop timer and clear EP_STOP_CMD_PENDING flag.
@@ -385,7 +709,6 @@ static void usbssp_handle_cmd_stop_ep(struct usbssp_udc *usbssp_data,
"CMD stop endpoint completion for ep index: %d - %s\n",
ep_index, ep->name);

-
priv_dev = &usbssp_data->devs;
ep_ctx = usbssp_get_ep_ctx(usbssp_data, priv_dev->out_ctx, ep_index);
trace_usbssp_handle_cmd_stop_ep(ep_ctx);
@@ -2273,7 +2596,8 @@ void usbssp_queue_new_dequeue_state(struct usbssp_udc *usbssp_data,
(unsigned long long)deq_state->new_deq_seg->dma,
deq_state->new_deq_ptr,
(unsigned long long)usbssp_trb_virt_to_dma(
- deq_state->new_deq_seg, deq_state->new_deq_ptr),
+ deq_state->new_deq_seg,
+ deq_state->new_deq_ptr),
deq_state->new_cycle_state);

addr = usbssp_trb_virt_to_dma(deq_state->new_deq_seg,
@@ -2284,6 +2608,7 @@ void usbssp_queue_new_dequeue_state(struct usbssp_udc *usbssp_data,
deq_state->new_deq_seg, deq_state->new_deq_ptr);
return;
}
+
ep_priv = &usbssp_data->devs.eps[ep_index];
if ((ep_priv->ep_state & SET_DEQ_PENDING)) {
dev_warn(usbssp_data->dev, "WARN Cannot submit Set TR Deq Ptr\n");
@@ -2304,10 +2629,12 @@ void usbssp_queue_new_dequeue_state(struct usbssp_udc *usbssp_data,
ep_priv->queued_deq_ptr = deq_state->new_deq_ptr;
if (deq_state->stream_id)
trb_sct = SCT_FOR_TRB(SCT_PRI_TR);
+
ret = queue_command(usbssp_data, cmd,
lower_32_bits(addr) | trb_sct | deq_state->new_cycle_state,
upper_32_bits(addr), trb_stream_id,
trb_slot_id | trb_ep_index | type, false);
+
if (ret < 0) {
usbssp_free_command(usbssp_data, cmd);
return;
diff --git a/drivers/usb/usbssp/gadget.c b/drivers/usb/usbssp/gadget.c
index e2751693404d..fe373a7b7198 100644
--- a/drivers/usb/usbssp/gadget.c
+++ b/drivers/usb/usbssp/gadget.c
@@ -545,8 +545,53 @@ int usbssp_enqueue(struct usbssp_ep *dep, struct usbssp_request *req_priv)
*/
int usbssp_dequeue(struct usbssp_ep *ep_priv, struct usbssp_request *req_priv)
{
- /*TODO: this function must be implemented*/
- return 0;
+ int ret = 0, i;
+ struct usbssp_udc *usbssp_data;
+ unsigned int ep_index;
+ struct usbssp_ring *ep_ring;
+ struct usbssp_device *priv_dev;
+ struct usbssp_ep_ctx *ep_ctx;
+
+ usbssp_data = ep_priv->usbssp_data;
+ trace_usbssp_request_dequeue(&req_priv->request);
+
+ priv_dev = &usbssp_data->devs;
+ ep_index = usbssp_get_endpoint_index(req_priv->dep->endpoint.desc);
+ ep_priv = &usbssp_data->devs.eps[ep_index];
+ ep_ring = usbssp_request_to_transfer_ring(usbssp_data, req_priv);
+
+ if (!ep_ring)
+ goto err_giveback;
+
+ i = req_priv->num_tds_done;
+
+ if (i < req_priv->num_tds)
+ usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_cancel_request,
+ "Cancel request %p, dev %s, ep 0x%x, "
+ "starting at offset 0x%llx",
+ &req_priv->request, usbssp_data->gadget.name,
+ req_priv->dep->endpoint.desc->bEndpointAddress,
+ (unsigned long long) usbssp_trb_virt_to_dma(
+ req_priv->td[i].start_seg,
+ req_priv->td[i].first_trb));
+
+ /* Queue a stop endpoint command, but only if it is
+ * in EP_STATE_RUNNING state.
+ */
+ ep_ctx = usbssp_get_ep_ctx(usbssp_data, priv_dev->out_ctx, ep_index);
+ if (GET_EP_CTX_STATE(ep_ctx) == EP_STATE_RUNNING) {
+ ret = usbssp_cmd_stop_ep(usbssp_data, &usbssp_data->gadget,
+ ep_priv);
+ if (ret)
+ return ret;
+ }
+
+ usbssp_remove_request(usbssp_data, req_priv, ep_index);
+ return ret;
+
+err_giveback:
+ usbssp_giveback_request_in_irq(usbssp_data, req_priv->td, -ESHUTDOWN);
+ return ret;
}

int usbssp_halt_endpoint(struct usbssp_udc *usbssp_data, struct usbssp_ep *dep,
diff --git a/drivers/usb/usbssp/gadget.h b/drivers/usb/usbssp/gadget.h
index 0477eb0f354c..000f2cb93723 100644
--- a/drivers/usb/usbssp/gadget.h
+++ b/drivers/usb/usbssp/gadget.h
@@ -1780,6 +1780,14 @@ int usbssp_queue_halt_endpoint(struct usbssp_udc *usbssp_data,
unsigned int ep_index);
int usbssp_queue_reset_device(struct usbssp_udc *usbssp_data,
struct usbssp_command *cmd);
+void usbssp_find_new_dequeue_state(struct usbssp_udc *usbssp_data,
+ unsigned int ep_index,
+ unsigned int stream_id,
+ struct usbssp_td *cur_td,
+ struct usbssp_dequeue_state *state);
+void usbssp_queue_new_dequeue_state(struct usbssp_udc *usbssp_data,
+ unsigned int ep_index,
+ struct usbssp_dequeue_state *deq_state);
void usbssp_handle_command_timeout(struct work_struct *work);

void usbssp_cleanup_command_queue(struct usbssp_udc *usbssp_data);
@@ -2313,4 +2321,7 @@ __le32 __iomem *usbssp_get_port_io_addr(struct usbssp_udc *usbssp_data);
void usbssp_giveback_request_in_irq(struct usbssp_udc *usbssp_data,
struct usbssp_td *cur_td, int status);

+void usbssp_remove_request(struct usbssp_udc *usbssp_data,
+ struct usbssp_request *req_priv, int ep_index);
+
#endif /* __LINUX_USBSSP_GADGET_H */
--
2.17.1
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