Reset the transmit and receive FIFOs before enabling the UARTs as part
of open() in order to flush any stale data.
Note that the XR21V141X needs a type-specific implementation due to its
UART Manager registers.
Signed-off-by: Johan Hovold <jo...@kernel.org>
---
drivers/usb/serial/xr_serial.c | 51 ++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c
index 14dbda13ab4d..1b7b3c70a9b3 100644
--- a/drivers/usb/serial/xr_serial.c
+++ b/drivers/usb/serial/xr_serial.c
@@ -95,10 +95,13 @@ struct xr_txrx_clk_mask {
#define XR_GPIO_MODE_TX_TOGGLE 0x100
#define XR_GPIO_MODE_RX_TOGGLE 0x200
+#define XR_FIFO_RESET 0x1
+
#define XR_CUSTOM_DRIVER_ACTIVE 0x1
static int xr21v141x_uart_enable(struct usb_serial_port *port);
static int xr21v141x_uart_disable(struct usb_serial_port *port);
+static int xr21v141x_fifo_reset(struct usb_serial_port *port);
static void xr21v141x_set_line_settings(struct tty_struct *tty,
struct usb_serial_port *port, struct ktermios *old_termios);
@@ -118,6 +121,8 @@ struct xr_type {
u16 gpio_set;
u16 gpio_clear;
u16 gpio_status;
+ u16 tx_fifo_reset;
+ u16 rx_fifo_reset;
u16 custom_driver;
bool have_5_6_bit_mode;
@@ -125,6 +130,7 @@ struct xr_type {
int (*enable)(struct usb_serial_port *port);
int (*disable)(struct usb_serial_port *port);
+ int (*fifo_reset)(struct usb_serial_port *port);
void (*set_line_settings)(struct tty_struct *tty,
struct usb_serial_port *port,
struct ktermios *old_termios);
@@ -158,6 +164,7 @@ static const struct xr_type xr_types[] = {
.enable = xr21v141x_uart_enable,
.disable = xr21v141x_uart_disable,
+ .fifo_reset = xr21v141x_fifo_reset,
.set_line_settings = xr21v141x_set_line_settings,
},
[XR21B142X] = {
@@ -176,6 +183,8 @@ static const struct xr_type xr_types[] = {
.gpio_set = 0x0e,
.gpio_clear = 0x0f,
.gpio_status = 0x10,
+ .tx_fifo_reset = 0x40,
+ .rx_fifo_reset = 0x43,
.custom_driver = 0x60,
.have_5_6_bit_mode = true,
@@ -197,6 +206,8 @@ static const struct xr_type xr_types[] = {
.gpio_set = 0xc0e,
.gpio_clear = 0xc0f,
.gpio_status = 0xc10,
+ .tx_fifo_reset = 0xc80,
+ .rx_fifo_reset = 0xcc0,
.custom_driver = 0x20d,
},
[XR2280X] = {
@@ -215,6 +226,8 @@ static const struct xr_type xr_types[] = {
.gpio_set = 0x4e,
.gpio_clear = 0x4f,
.gpio_status = 0x50,
+ .tx_fifo_reset = 0x60,
+ .rx_fifo_reset = 0x63,
.custom_driver = 0x81,
},
};
@@ -384,6 +397,40 @@ static int xr_uart_disable(struct usb_serial_port *port)
return __xr_uart_disable(port);
}
+static int xr21v141x_fifo_reset(struct usb_serial_port *port)
+{
+ int ret;
+
+ ret = xr_set_reg_um(port, XR21V141X_UM_TX_FIFO_RESET, XR_FIFO_RESET);
+ if (ret)
+ return ret;
+
+ ret = xr_set_reg_um(port, XR21V141X_UM_RX_FIFO_RESET, XR_FIFO_RESET);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int xr_fifo_reset(struct usb_serial_port *port)
+{
+ struct xr_data *data = usb_get_serial_port_data(port);
+ int ret;
+
+ if (data->type->fifo_reset)
+ return data->type->fifo_reset(port);
+
+ ret = xr_set_reg_uart(port, data->type->tx_fifo_reset, XR_FIFO_RESET);
+ if (ret)
+ return ret;
+
+ ret = xr_set_reg_uart(port, data->type->rx_fifo_reset, XR_FIFO_RESET);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
static int xr_tiocmget(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
@@ -781,6 +828,10 @@ static int xr_open(struct tty_struct *tty, struct
usb_serial_port *port)
{
int ret;
+ ret = xr_fifo_reset(port);
+ if (ret)
+ return ret;
+
ret = xr_uart_enable(port);
if (ret) {
dev_err(&port->dev, "Failed to enable UART\n");
--
2.26.3
