firmware: arm_scmi: Refactor xfer in-flight registration routines

Move the whole xfer in-flight registration process out of scmi_xfer_get
and while at that, split the sequence number selection steps from the
in-flight registration procedure itself.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-2-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 50267ee..3400bd1 100644 (file)
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -411,8 +411,6 @@ static int scmi_xfer_token_set(struct scmi_xfers_info *minfo,
        if (xfer_id != next_token)
                atomic_add((int)(xfer_id - next_token), &transfer_last_id);
 
-       /* Set in-flight */
-       set_bit(xfer_id, minfo->xfer_alloc_table);
        xfer->hdr.seq = (u16)xfer_id;
 
        return 0;
@@ -431,32 +429,76 @@ static inline void scmi_xfer_token_clear(struct scmi_xfers_info *minfo,
 }
 
 /**
+ * scmi_xfer_inflight_register_unlocked  - Register the xfer as in-flight
+ *
+ * @xfer: The xfer to register
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ *
+ * Note that this helper assumes that the xfer to be registered as in-flight
+ * had been built using an xfer sequence number which still corresponds to a
+ * free slot in the xfer_alloc_table.
+ *
+ * Context: Assumes to be called with @xfer_lock already acquired.
+ */
+static inline void
+scmi_xfer_inflight_register_unlocked(struct scmi_xfer *xfer,
+                                    struct scmi_xfers_info *minfo)
+{
+       /* Set in-flight */
+       set_bit(xfer->hdr.seq, minfo->xfer_alloc_table);
+       hash_add(minfo->pending_xfers, &xfer->node, xfer->hdr.seq);
+       xfer->pending = true;
+}
+
+/**
+ * scmi_xfer_pending_set  - Pick a proper sequence number and mark the xfer
+ * as pending in-flight
+ *
+ * @xfer: The xfer to act upon
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ *
+ * Return: 0 on Success or error otherwise
+ */
+static inline int scmi_xfer_pending_set(struct scmi_xfer *xfer,
+                                       struct scmi_xfers_info *minfo)
+{
+       int ret;
+       unsigned long flags;
+
+       spin_lock_irqsave(&minfo->xfer_lock, flags);
+       /* Set a new monotonic token as the xfer sequence number */
+       ret = scmi_xfer_token_set(minfo, xfer);
+       if (!ret)
+               scmi_xfer_inflight_register_unlocked(xfer, minfo);
+       spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+
+       return ret;
+}
+
+/**
  * scmi_xfer_get() - Allocate one message
  *
  * @handle: Pointer to SCMI entity handle
  * @minfo: Pointer to Tx/Rx Message management info based on channel type
- * @set_pending: If true a monotonic token is picked and the xfer is added to
- *              the pending hash table.
  *
  * Helper function which is used by various message functions that are
  * exposed to clients of this driver for allocating a message traffic event.
  *
- * Picks an xfer from the free list @free_xfers (if any available) and, if
- * required, sets a monotonically increasing token and stores the inflight xfer
- * into the @pending_xfers hashtable for later retrieval.
+ * Picks an xfer from the free list @free_xfers (if any available) and perform
+ * a basic initialization.
+ *
+ * Note that, at this point, still no sequence number is assigned to the
+ * allocated xfer, nor it is registered as a pending transaction.
  *
  * The successfully initialized xfer is refcounted.
  *
- * Context: Holds @xfer_lock while manipulating @xfer_alloc_table and
- *         @free_xfers.
+ * Context: Holds @xfer_lock while manipulating @free_xfers.
  *
- * Return: 0 if all went fine, else corresponding error.
+ * Return: An initialized xfer if all went fine, else pointer error.
  */
 static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
-                                      struct scmi_xfers_info *minfo,
-                                      bool set_pending)
+                                      struct scmi_xfers_info *minfo)
 {
-       int ret;
        unsigned long flags;
        struct scmi_xfer *xfer;
 
@@ -476,25 +518,8 @@ static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
         */
        xfer->transfer_id = atomic_inc_return(&transfer_last_id);
 
-       if (set_pending) {
-               /* Pick and set monotonic token */
-               ret = scmi_xfer_token_set(minfo, xfer);
-               if (!ret) {
-                       hash_add(minfo->pending_xfers, &xfer->node,
-                                xfer->hdr.seq);
-                       xfer->pending = true;
-               } else {
-                       dev_err(handle->dev,
-                               "Failed to get monotonic token %d\n", ret);
-                       hlist_add_head(&xfer->node, &minfo->free_xfers);
-                       xfer = ERR_PTR(ret);
-               }
-       }
-
-       if (!IS_ERR(xfer)) {
-               refcount_set(&xfer->users, 1);
-               atomic_set(&xfer->busy, SCMI_XFER_FREE);
-       }
+       refcount_set(&xfer->users, 1);
+       atomic_set(&xfer->busy, SCMI_XFER_FREE);
        spin_unlock_irqrestore(&minfo->xfer_lock, flags);
 
        return xfer;
@@ -752,7 +777,7 @@ static void scmi_handle_notification(struct scmi_chan_info *cinfo,
        ktime_t ts;
 
        ts = ktime_get_boottime();
-       xfer = scmi_xfer_get(cinfo->handle, minfo, false);
+       xfer = scmi_xfer_get(cinfo->handle, minfo);
        if (IS_ERR(xfer)) {
                dev_err(dev, "failed to get free message slot (%ld)\n",
                        PTR_ERR(xfer));
@@ -1143,13 +1168,22 @@ static int xfer_get_init(const struct scmi_protocol_handle *ph,
            tx_size > info->desc->max_msg_size)
                return -ERANGE;
 
-       xfer = scmi_xfer_get(pi->handle, minfo, true);
+       xfer = scmi_xfer_get(pi->handle, minfo);
        if (IS_ERR(xfer)) {
                ret = PTR_ERR(xfer);
                dev_err(dev, "failed to get free message slot(%d)\n", ret);
                return ret;
        }
 
+       /* Pick a sequence number and register this xfer as in-flight */
+       ret = scmi_xfer_pending_set(xfer, minfo);
+       if (ret) {
+               dev_err(pi->handle->dev,
+                       "Failed to get monotonic token %d\n", ret);
+               __scmi_xfer_put(minfo, xfer);
+               return ret;
+       }
+
        xfer->tx.len = tx_size;
        xfer->rx.len = rx_size ? : info->desc->max_msg_size;
        xfer->hdr.type = MSG_TYPE_COMMAND;