serial: Refactor uart_flush_buffer() from uart_close()
In the context of the final tty & port close, flushing the tx
ring buffer after the hardware has already been shutdown and
the ring buffer freed is neither required nor desirable.
uart_flush_buffer() performs 3 operations:
1. Resets tx ring buffer indices, but the tx ring buffer has
already been freed and the indices are reset if the port is
re-opened.
2. Calls uart driver's flush_buffer() method
5 in-tree uart drivers define flush_buffer() methods:
amba-pl011, atmel-serial, imx, serial-tegra, timbuart
These have been refactored into the shutdown() method, if
required.
3. Kicks the ldisc for more writing, but this is undesirable.
The file handle is being released; any waiting writer will
will be kicked out by tty_release() with a warning. Further,
the N_TTY ldisc may generate SIGIO for a file handle which
is no longer valid.
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 02016fc..8469b66 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1689,6 +1689,7 @@
plat->exit();
}
+ pl011_dma_flush_buffer(port);
}
static void
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index edde3ec..8a84034 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1802,6 +1802,20 @@
}
/*
+ * Flush any TX data submitted for DMA. Called when the TX circular
+ * buffer is reset.
+ */
+static void atmel_flush_buffer(struct uart_port *port)
+{
+ struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+ if (atmel_use_pdc_tx(port)) {
+ UART_PUT_TCR(port, 0);
+ atmel_port->pdc_tx.ofs = 0;
+ }
+}
+
+/*
* Disable the port
*/
static void atmel_shutdown(struct uart_port *port)
@@ -1852,20 +1866,8 @@
atmel_free_gpio_irq(port);
atmel_port->ms_irq_enabled = false;
-}
-/*
- * Flush any TX data submitted for DMA. Called when the TX circular
- * buffer is reset.
- */
-static void atmel_flush_buffer(struct uart_port *port)
-{
- struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
-
- if (atmel_use_pdc_tx(port)) {
- UART_PUT_TCR(port, 0);
- atmel_port->pdc_tx.ofs = 0;
- }
+ atmel_flush_buffer(port);
}
/*
diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 53d7c31..78a5cf6 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -1034,6 +1034,20 @@
return ret;
}
+/*
+ * Flush any TX data submitted for DMA and PIO. Called when the
+ * TX circular buffer is reset.
+ */
+static void tegra_uart_flush_buffer(struct uart_port *u)
+{
+ struct tegra_uart_port *tup = to_tegra_uport(u);
+
+ tup->tx_bytes = 0;
+ if (tup->tx_dma_chan)
+ dmaengine_terminate_all(tup->tx_dma_chan);
+ return;
+}
+
static void tegra_uart_shutdown(struct uart_port *u)
{
struct tegra_uart_port *tup = to_tegra_uport(u);
@@ -1046,6 +1060,8 @@
tegra_uart_dma_channel_free(tup, true);
tegra_uart_dma_channel_free(tup, false);
free_irq(u->irq, tup);
+
+ tegra_uart_flush_buffer(u);
}
static void tegra_uart_enable_ms(struct uart_port *u)
@@ -1174,20 +1190,6 @@
return;
}
-/*
- * Flush any TX data submitted for DMA and PIO. Called when the
- * TX circular buffer is reset.
- */
-static void tegra_uart_flush_buffer(struct uart_port *u)
-{
- struct tegra_uart_port *tup = to_tegra_uport(u);
-
- tup->tx_bytes = 0;
- if (tup->tx_dma_chan)
- dmaengine_terminate_all(tup->tx_dma_chan);
- return;
-}
-
static const char *tegra_uart_type(struct uart_port *u)
{
return TEGRA_UART_TYPE;
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 1166c52..787d67f 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1361,7 +1361,6 @@
mutex_lock(&port->mutex);
uart_shutdown(tty, state);
- uart_flush_buffer(tty);
tty_ldisc_flush(tty);
diff --git a/drivers/tty/serial/timbuart.c b/drivers/tty/serial/timbuart.c
index 0d11d50..e9e2523 100644
--- a/drivers/tty/serial/timbuart.c
+++ b/drivers/tty/serial/timbuart.c
@@ -273,6 +273,8 @@
dev_dbg(port->dev, "%s\n", __func__);
free_irq(port->irq, uart);
iowrite32(0, port->membase + TIMBUART_IER);
+
+ timbuart_flush_buffer(port);
}
static int get_bindex(int baud)