rpmsg: smd: Perform handshake during open

Validate the the remote side is opening the channel that we've found by
performing a handshake when opening the channel.

Tested-by: Will Newton <will.newton@gmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
index b01774e9fac0..58dd44493420 100644
--- a/drivers/rpmsg/qcom_smd.c
+++ b/drivers/rpmsg/qcom_smd.c
@@ -200,6 +200,7 @@ struct qcom_smd_channel {
         char *name;
         enum smd_channel_state state;
         enum smd_channel_state remote_state;
+        wait_queue_head_t state_change_event;
 
         struct smd_channel_info_pair *info;
         struct smd_channel_info_word_pair *info_word;
@@ -570,6 +571,8 @@ static bool qcom_smd_channel_intr(struct qcom_smd_channel *channel)
         if (remote_state != channel->remote_state) {
                 channel->remote_state = remote_state;
                 need_state_scan = true;
+
+                wake_up_interruptible_all(&channel->state_change_event);
         }
         /* Indicate that we have seen any state change */
         SET_RX_CHANNEL_FLAG(channel, fSTATE, 0);
@@ -786,7 +789,9 @@ out:
 static int qcom_smd_channel_open(struct qcom_smd_channel *channel,
                                  rpmsg_rx_cb_t cb)
 {
+        struct qcom_smd_edge *edge = channel->edge;
         size_t bb_size;
+        int ret;
 
         /*
          * Packets are maximum 4k, but reduce if the fifo is smaller
@@ -798,9 +803,33 @@ static int qcom_smd_channel_open(struct qcom_smd_channel *channel,
 
         qcom_smd_channel_set_callback(channel, cb);
         qcom_smd_channel_set_state(channel, SMD_CHANNEL_OPENING);
+
+        /* Wait for remote to enter opening or opened */
+        ret = wait_event_interruptible_timeout(channel->state_change_event,
+                        channel->remote_state == SMD_CHANNEL_OPENING ||
+                        channel->remote_state == SMD_CHANNEL_OPENED,
+                        HZ);
+        if (!ret) {
+                dev_err(&edge->dev, "remote side did not enter opening state\n");
+                goto out_close_timeout;
+        }
+
         qcom_smd_channel_set_state(channel, SMD_CHANNEL_OPENED);
 
+        /* Wait for remote to enter opened */
+        ret = wait_event_interruptible_timeout(channel->state_change_event,
+                        channel->remote_state == SMD_CHANNEL_OPENED,
+                        HZ);
+        if (!ret) {
+                dev_err(&edge->dev, "remote side did not enter open state\n");
+                goto out_close_timeout;
+        }
+
         return 0;
+
+out_close_timeout:
+        qcom_smd_channel_set_state(channel, SMD_CHANNEL_CLOSED);
+        return -ETIMEDOUT;
 }
 
 /*
@@ -1055,6 +1084,7 @@ static struct qcom_smd_channel *qcom_smd_create_channel(struct qcom_smd_edge *ed
         mutex_init(&channel->tx_lock);
         spin_lock_init(&channel->recv_lock);
         init_waitqueue_head(&channel->fblockread_event);
+        init_waitqueue_head(&channel->state_change_event);
 
         info = qcom_smem_get(edge->remote_pid, smem_info_item, &info_size);
         if (IS_ERR(info)) {