serial: tegra: add support to ignore read

Add support to ignore read characters if CREAD flag is not set.

Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-2-git-send-email-kyarlagadda@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 82a8d5130cbcb0d8ef772d22472e71627eb8d464..9c15c87fa9e55d4e5a95523eefc44a980b96a515 100644 (file)
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -547,6 +547,9 @@ static void tegra_uart_handle_rx_pio(struct tegra_uart_port *tup,
 
                if (!uart_handle_sysrq_char(&tup->uport, ch) && tty)
                        tty_insert_flip_char(tty, ch, flag);
+
+               if (tup->uport.ignore_status_mask & UART_LSR_DR)
+                       continue;
        } while (1);
 }
 
@@ -565,6 +568,10 @@ static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
                dev_err(tup->uport.dev, "No tty port\n");
                return;
        }
+
+       if (tup->uport.ignore_status_mask & UART_LSR_DR)
+               return;
+
        dma_sync_single_for_cpu(tup->uport.dev, tup->rx_dma_buf_phys,
                                TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
        copied = tty_insert_flip_string(tty,
@@ -1193,6 +1200,11 @@ static void tegra_uart_set_termios(struct uart_port *u,
        tegra_uart_write(tup, tup->ier_shadow, UART_IER);
        tegra_uart_read(tup, UART_IER);
 
+       tup->uport.ignore_status_mask = 0;
+       /* Ignore all characters if CREAD is not set */
+       if ((termios->c_cflag & CREAD) == 0)
+               tup->uport.ignore_status_mask |= UART_LSR_DR;
+
        spin_unlock_irqrestore(&u->lock, flags);
 }