+/**
+ * spi_pump_messages - kthread work function which processes spi message queue
+ * @work: pointer to kthread work struct contained in the master struct
+ *
+ * This function checks if there is any spi message in the queue that
+ * needs processing and if so call out to the driver to initialize hardware
+ * and transfer each message.
+ *
+ */
+static void spi_pump_messages(struct kthread_work *work)
+{
+ struct spi_master *master =
+ container_of(work, struct spi_master, pump_messages);
+ unsigned long flags;
+ bool was_busy = false;
+ int ret;
+
+ /* Lock queue and check for queue work */
+ spin_lock_irqsave(&master->queue_lock, flags);
+ if (list_empty(&master->queue) || !master->running) {
+ if (master->busy) {
+ ret = master->unprepare_transfer_hardware(master);
+ if (ret) {
+ dev_err(&master->dev,
+ "failed to unprepare transfer hardware\n");
+ return;
+ }
+ }
+ master->busy = false;
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return;
+ }
+
+ /* Make sure we are not already running a message */
+ if (master->cur_msg) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return;
+ }
+ /* Extract head of queue */
+ master->cur_msg =
+ list_entry(master->queue.next, struct spi_message, queue);
+
+ list_del_init(&master->cur_msg->queue);
+ if (master->busy)
+ was_busy = true;
+ else
+ master->busy = true;
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ if (!was_busy) {
+ ret = master->prepare_transfer_hardware(master);
+ if (ret) {
+ dev_err(&master->dev,
+ "failed to prepare transfer hardware\n");
+ return;
+ }
+ }
+
+ ret = master->transfer_one_message(master, master->cur_msg);
+ if (ret) {
+ dev_err(&master->dev,
+ "failed to transfer one message from queue\n");
+ return;
+ }
+}
+
+static int spi_init_queue(struct spi_master *master)
+{
+ struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
+
+ INIT_LIST_HEAD(&master->queue);
+ spin_lock_init(&master->queue_lock);
+
+ master->running = false;
+ master->busy = false;
+
+ init_kthread_worker(&master->kworker);
+ master->kworker_task = kthread_run(kthread_worker_fn,
+ &master->kworker,
+ dev_name(&master->dev));
+ if (IS_ERR(master->kworker_task)) {
+ dev_err(&master->dev, "failed to create message pump task\n");
+ return -ENOMEM;
+ }
+ init_kthread_work(&master->pump_messages, spi_pump_messages);
+
+ /*
+ * Master config will indicate if this controller should run the
+ * message pump with high (realtime) priority to reduce the transfer
+ * latency on the bus by minimising the delay between a transfer
+ * request and the scheduling of the message pump thread. Without this
+ * setting the message pump thread will remain at default priority.
+ */
+ if (master->rt) {
+ dev_info(&master->dev,
+ "will run message pump with realtime priority\n");
+ sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
+ }
+
+ return 0;
+}
+
+/**
+ * spi_get_next_queued_message() - called by driver to check for queued
+ * messages
+ * @master: the master to check for queued messages
+ *
+ * If there are more messages in the queue, the next message is returned from
+ * this call.
+ */
+struct spi_message *spi_get_next_queued_message(struct spi_master *master)
+{
+ struct spi_message *next;
+ unsigned long flags;
+
+ /* get a pointer to the next message, if any */
+ spin_lock_irqsave(&master->queue_lock, flags);
+ if (list_empty(&master->queue))
+ next = NULL;
+ else
+ next = list_entry(master->queue.next,
+ struct spi_message, queue);
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ return next;
+}
+EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
+
+/**
+ * spi_finalize_current_message() - the current message is complete
+ * @master: the master to return the message to
+ *
+ * Called by the driver to notify the core that the message in the front of the
+ * queue is complete and can be removed from the queue.
+ */
+void spi_finalize_current_message(struct spi_master *master)
+{
+ struct spi_message *mesg;
+ unsigned long flags;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+ mesg = master->cur_msg;
+ master->cur_msg = NULL;
+
+ queue_kthread_work(&master->kworker, &master->pump_messages);
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ mesg->state = NULL;
+ if (mesg->complete)
+ mesg->complete(mesg->context);
+}
+EXPORT_SYMBOL_GPL(spi_finalize_current_message);
+
+static int spi_start_queue(struct spi_master *master)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+
+ if (master->running || master->busy) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return -EBUSY;
+ }
+
+ master->running = true;
+ master->cur_msg = NULL;
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ queue_kthread_work(&master->kworker, &master->pump_messages);
+
+ return 0;
+}
+
+static int spi_stop_queue(struct spi_master *master)
+{
+ unsigned long flags;
+ unsigned limit = 500;
+ int ret = 0;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+
+ /*
+ * This is a bit lame, but is optimized for the common execution path.
+ * A wait_queue on the master->busy could be used, but then the common
+ * execution path (pump_messages) would be required to call wake_up or
+ * friends on every SPI message. Do this instead.
+ */
+ while ((!list_empty(&master->queue) || master->busy) && limit--) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ msleep(10);
+ spin_lock_irqsave(&master->queue_lock, flags);
+ }
+
+ if (!list_empty(&master->queue) || master->busy)
+ ret = -EBUSY;
+ else
+ master->running = false;
+
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+
+ if (ret) {
+ dev_warn(&master->dev,
+ "could not stop message queue\n");
+ return ret;
+ }
+ return ret;
+}
+
+static int spi_destroy_queue(struct spi_master *master)
+{
+ int ret;
+
+ ret = spi_stop_queue(master);
+
+ /*
+ * flush_kthread_worker will block until all work is done.
+ * If the reason that stop_queue timed out is that the work will never
+ * finish, then it does no good to call flush/stop thread, so
+ * return anyway.
+ */
+ if (ret) {
+ dev_err(&master->dev, "problem destroying queue\n");
+ return ret;
+ }
+
+ flush_kthread_worker(&master->kworker);
+ kthread_stop(master->kworker_task);
+
+ return 0;
+}
+
+/**
+ * spi_queued_transfer - transfer function for queued transfers
+ * @spi: spi device which is requesting transfer
+ * @msg: spi message which is to handled is queued to driver queue
+ */
+static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
+{
+ struct spi_master *master = spi->master;
+ unsigned long flags;
+
+ spin_lock_irqsave(&master->queue_lock, flags);
+
+ if (!master->running) {
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return -ESHUTDOWN;
+ }
+ msg->actual_length = 0;
+ msg->status = -EINPROGRESS;
+
+ list_add_tail(&msg->queue, &master->queue);
+ if (master->running && !master->busy)
+ queue_kthread_work(&master->kworker, &master->pump_messages);
+
+ spin_unlock_irqrestore(&master->queue_lock, flags);
+ return 0;
+}
+
+static int spi_master_initialize_queue(struct spi_master *master)
+{
+ int ret;
+
+ master->queued = true;
+ master->transfer = spi_queued_transfer;
+
+ /* Initialize and start queue */
+ ret = spi_init_queue(master);
+ if (ret) {
+ dev_err(&master->dev, "problem initializing queue\n");
+ goto err_init_queue;
+ }
+ ret = spi_start_queue(master);
+ if (ret) {
+ dev_err(&master->dev, "problem starting queue\n");
+ goto err_start_queue;
+ }
+
+ return 0;
+
+err_start_queue:
+err_init_queue:
+ spi_destroy_queue(master);
+ return ret;
+}
+
+/*-------------------------------------------------------------------------*/
+