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>

diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
index b01774e..58dd444 100644 (file)
--- 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)) {