* [PATCH] serial: amba-pl011: Add basic rs485 support
@ 2017-08-01 12:52 ` Ladislav Michl
0 siblings, 0 replies; 2+ messages in thread
From: Ladislav Michl @ 2017-08-01 12:52 UTC (permalink / raw)
To: linux-arm-kernel, linux-serial; +Cc: Russell King
Currently RS485 mode can be selected only via DT bindings.
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
---
Notes: this change was sitting in my tree for a year and now with
"serial: Add common rs485 device tree parsing function" et al.
patches being submitted is time to move forward a bit.
Although rpi with this patched driver is working for months I do not
like mdelay in interrupt while waiting for last bit to leave tx wire.
If anyone has better idea, I'll happily implement it. Thank you.
drivers/tty/serial/amba-pl011.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8a857bb34fbb..44016840f5df 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1319,9 +1319,22 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
static void pl011_stop_tx(struct uart_port *port)
{
+ unsigned int cr;
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
+ /* Handle RS-485 */
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
+ mdelay(1);
+ cr = readw(uap->port.membase + UART011_CR);
+ if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
+ cr &= ~UART011_CR_RTS;
+ else
+ cr |= UART011_CR_RTS;
+ writew(cr, uap->port.membase + UART011_CR);
+ }
+
uap->im &= ~UART011_TXIM;
pl011_write(uap->im, uap, REG_IMSC);
pl011_dma_tx_stop(uap);
@@ -1340,9 +1353,20 @@ static void pl011_start_tx_pio(struct uart_amba_port *uap)
static void pl011_start_tx(struct uart_port *port)
{
+ unsigned int cr;
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
+ /* Handle RS-485 */
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ cr = readw(uap->port.membase + UART011_CR);
+ if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
+ cr |= UART011_CR_RTS;
+ else
+ cr &= ~UART011_CR_RTS;
+ writew(cr, uap->port.membase + UART011_CR);
+ }
+
if (!pl011_dma_tx_start(uap))
pl011_start_tx_pio(uap);
}
@@ -2588,6 +2612,7 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
return PTR_ERR(base);
index = pl011_probe_dt_alias(index, dev);
+ of_get_rs485_mode(dev->of_node, &uap->port.rs485);
uap->old_cr = 0;
uap->port.dev = dev;
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH] serial: amba-pl011: Add basic rs485 support
@ 2017-08-01 12:52 ` Ladislav Michl
0 siblings, 0 replies; 2+ messages in thread
From: Ladislav Michl @ 2017-08-01 12:52 UTC (permalink / raw)
To: linux-arm-kernel
Currently RS485 mode can be selected only via DT bindings.
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
---
Notes: this change was sitting in my tree for a year and now with
"serial: Add common rs485 device tree parsing function" et al.
patches being submitted is time to move forward a bit.
Although rpi with this patched driver is working for months I do not
like mdelay in interrupt while waiting for last bit to leave tx wire.
If anyone has better idea, I'll happily implement it. Thank you.
drivers/tty/serial/amba-pl011.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8a857bb34fbb..44016840f5df 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1319,9 +1319,22 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
static void pl011_stop_tx(struct uart_port *port)
{
+ unsigned int cr;
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
+ /* Handle RS-485 */
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
+ mdelay(1);
+ cr = readw(uap->port.membase + UART011_CR);
+ if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
+ cr &= ~UART011_CR_RTS;
+ else
+ cr |= UART011_CR_RTS;
+ writew(cr, uap->port.membase + UART011_CR);
+ }
+
uap->im &= ~UART011_TXIM;
pl011_write(uap->im, uap, REG_IMSC);
pl011_dma_tx_stop(uap);
@@ -1340,9 +1353,20 @@ static void pl011_start_tx_pio(struct uart_amba_port *uap)
static void pl011_start_tx(struct uart_port *port)
{
+ unsigned int cr;
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
+ /* Handle RS-485 */
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ cr = readw(uap->port.membase + UART011_CR);
+ if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
+ cr |= UART011_CR_RTS;
+ else
+ cr &= ~UART011_CR_RTS;
+ writew(cr, uap->port.membase + UART011_CR);
+ }
+
if (!pl011_dma_tx_start(uap))
pl011_start_tx_pio(uap);
}
@@ -2588,6 +2612,7 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
return PTR_ERR(base);
index = pl011_probe_dt_alias(index, dev);
+ of_get_rs485_mode(dev->of_node, &uap->port.rs485);
uap->old_cr = 0;
uap->port.dev = dev;
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
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2017-08-01 12:52 ` Ladislav Michl
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