mei: bus: Synchronous API for the data transmission

Define a truly synchronous API for the bus Tx path by putting all pending
request to the write list and wait for the interrupt tx handler to wake
us up.
The ___mei_cl_send() out path is also slightly reworked to make it look more
like main.c:mei_write().

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 30 insertions, 10 deletions

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index c626dc9937eb..2b4b5b3f639f 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -222,7 +222,8 @@ void mei_cl_driver_unregister(struct mei_cl_driver *driver)
 }
 EXPORT_SYMBOL_GPL(mei_cl_driver_unregister);
 
-int __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length)
+static int ___mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length,
+                        bool blocking)
 {
         struct mei_device *dev;
         struct mei_msg_hdr mei_hdr;
@@ -273,11 +274,8 @@ int __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length)
                 cb->buf_idx = 0;
                 mei_hdr.msg_complete = 0;
                 cl->writing_state = MEI_WRITING;
-                list_add_tail(&cb->list, &dev->write_list.list);
-
-                mutex_unlock(&dev->device_lock);
 
-                return length;
+                goto out;
         }
 
         dev->hbuf_is_ready = false;
@@ -303,19 +301,30 @@ int __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length)
         cl->writing_state = MEI_WRITING;
         cb->buf_idx = mei_hdr.length;
 
-        if (!mei_hdr.msg_complete) {
-                list_add_tail(&cb->list, &dev->write_list.list);
-        } else {
+out:
+        if (mei_hdr.msg_complete) {
                 if (mei_cl_flow_ctrl_reduce(cl)) {
-                        err = -EIO;
+                        err = -ENODEV;
                         goto out_err;
                 }
-
                 list_add_tail(&cb->list, &dev->write_waiting_list.list);
+        } else {
+                list_add_tail(&cb->list, &dev->write_list.list);
         }
 
         mutex_unlock(&dev->device_lock);
 
+        if (blocking && cl->writing_state != MEI_WRITE_COMPLETE) {
+                if (wait_event_interruptible(cl->tx_wait,
+                        cl->writing_state == MEI_WRITE_COMPLETE)) {
+                                if (signal_pending(current))
+                                        err = -EINTR;
+                        err = -ERESTARTSYS;
+                        mutex_lock(&dev->device_lock);
+                        goto out_err;
+                }
+        }
+
         return mei_hdr.length;
 
 out_err:
@@ -382,6 +391,16 @@ out:
         return r_length;
 }
 
+inline int __mei_cl_async_send(struct mei_cl *cl, u8 *buf, size_t length)
+{
+        return ___mei_cl_send(cl, buf, length, 0);
+}
+
+inline int __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length)
+{
+        return ___mei_cl_send(cl, buf, length, 1);
+}
+
 int mei_cl_send(struct mei_cl_device *device, u8 *buf, size_t length)
 {
         struct mei_cl *cl = device->cl;
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index 7d594bedc685..325f71abeb7a 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -273,6 +273,7 @@ struct mei_cl_device *mei_cl_add_device(struct mei_device *dev,
                                   uuid_le uuid, char *name);
 void mei_cl_remove_device(struct mei_cl_device *device);
 
+int __mei_cl_async_send(struct mei_cl *cl, u8 *buf, size_t length);
 int __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length);
 int __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length);