tegra: hv_comm: update driver for ivc reset

Update the virtual serial driver to implement support for
ivc channel resets. Use of ivc under the previous (non-reset)
model has been deprecated.

Bug 1597821

Change-Id: Icbe2914d66628f0e604808fa8fafa5778edc866b
Signed-off-by: Dennis Kou <dkou@nvidia.com>
Reviewed-on: http://git-master/r/1314799
Signed-off-by: Bo Kim <bok@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1527785
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/drivers/tty/serial/tegra_hv_comm.c b/drivers/tty/serial/tegra_hv_comm.c
index 301a53197..5a08c8bfe 100644
--- a/drivers/tty/serial/tegra_hv_comm.c
+++ b/drivers/tty/serial/tegra_hv_comm.c
@@ -1,7 +1,7 @@
 /*
  * tegra_hv_comm.c: TTY over Tegra HV
  *
- * Copyright (c) 2014 NVIDIA CORPORATION. All rights reserved.
+ * Copyright (c) 2014-2015 NVIDIA CORPORATION. All rights reserved.
  *
  * Very loosely based on altera_jtaguart.c
  *
@@ -323,11 +323,14 @@ static irqreturn_t tegra_hv_comm_interrupt(int irq, void *data)
 
         spin_lock(&port->lock);
 
-        if (pp->rx_en && tegra_hv_ivc_can_read(pp->ivck))
-                tegra_hv_comm_rx_chars(pp);
+        /* until this function returns 0, the channel is unusable */
+        if (tegra_hv_ivc_channel_notified(pp->ivck) == 0) {
+                if (pp->rx_en && tegra_hv_ivc_can_read(pp->ivck))
+                        tegra_hv_comm_rx_chars(pp);
 
-        tegra_hv_comm_tx_chars(pp);
-        xmit_timer_setup(pp, 0);
+                tegra_hv_comm_tx_chars(pp);
+                xmit_timer_setup(pp, 0);
+        }
 
         spin_unlock(&port->lock);
 
@@ -543,6 +546,13 @@ static int tegra_hv_comm_probe(struct platform_device *pdev)
         port->ops = &tegra_hv_comm_ops;
         port->flags = UPF_BOOT_AUTOCONF;
 
+        /*
+         * start the channel reset process asynchronously. until the reset
+         * process completes, any attempt to use the ivc channel will return
+         * an error (e.g., all transmits will fail.)
+         */
+        tegra_hv_ivc_channel_reset(pp->ivck);
+
         ret = uart_add_one_port(&tegra_hv_comm_driver, port);
         if (ret != 0) {
                 dev_err(dev, "uart_add_one_port failed\n");