diff options
| author | Jeremy Kerr <jk@ozlabs.org> | 2018-03-27 05:48:26 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-23 10:16:50 +0200 |
| commit | 989983ea849d9421e8b9cd11f18e072fe00ea0d7 (patch) | |
| tree | 110e76ddfdf12ba344716ce5756a8a423ba092c1 /drivers/tty | |
| parent | serial/8250: export serial8250_read_char (diff) | |
| download | linux-989983ea849d9421e8b9cd11f18e072fe00ea0d7.tar.xz linux-989983ea849d9421e8b9cd11f18e072fe00ea0d7.zip | |
serial/aspeed-vuart: Implement rx throttling
The aspeed VUART runs at LPC bus frequency, rather than being restricted
to a typical UART baud rate. This means that the VUART can receive a lot
of data, which can overrun tty flip buffers, and/or cause a large amount
of interrupt traffic.
This change implements the uart_port->throttle & unthrottle callbacks,
implemented by disabling the receiver line status & received data
available IRQs.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Tested-by: Eddie James <eajames@linux.vnet.ibm.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_aspeed_vuart.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c index 74a408d9db24..cd1bb49dadfe 100644 --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c @@ -179,6 +179,30 @@ static void aspeed_vuart_shutdown(struct uart_port *uart_port) serial8250_do_shutdown(uart_port); } +static void aspeed_vuart_set_throttle(struct uart_port *port, bool throttle) +{ + unsigned char irqs = UART_IER_RLSI | UART_IER_RDI; + struct uart_8250_port *up = up_to_u8250p(port); + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + up->ier &= ~irqs; + if (!throttle) + up->ier |= irqs; + serial_out(up, UART_IER, up->ier); + spin_unlock_irqrestore(&port->lock, flags); +} + +static void aspeed_vuart_throttle(struct uart_port *port) +{ + aspeed_vuart_set_throttle(port, true); +} + +static void aspeed_vuart_unthrottle(struct uart_port *port) +{ + aspeed_vuart_set_throttle(port, false); +} + static int aspeed_vuart_probe(struct platform_device *pdev) { struct uart_8250_port port; @@ -208,6 +232,9 @@ static int aspeed_vuart_probe(struct platform_device *pdev) port.port.mapsize = resource_size(res); port.port.startup = aspeed_vuart_startup; port.port.shutdown = aspeed_vuart_shutdown; + port.port.throttle = aspeed_vuart_throttle; + port.port.unthrottle = aspeed_vuart_unthrottle; + port.port.status = UPSTAT_SYNC_FIFO; port.port.dev = &pdev->dev; rc = sysfs_create_group(&vuart->dev->kobj, &aspeed_vuart_attr_group); |