| Message ID | 20221112212125.448824-14-gsomlo@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | serial: liteuart: add IRQ support | expand |
On Sat, Nov 12, 2022 at 04:21:24PM -0500, Gabriel Somlo wrote: > Modify the TX path to operate in an IRQ-compatible way, while > maintaining support for polling mode via the poll timer. > > Signed-off-by: Gabriel Somlo <gsomlo@gmail.com> > --- > drivers/tty/serial/liteuart.c | 67 ++++++++++++++++++++++++----------- > 1 file changed, 47 insertions(+), 20 deletions(-) > > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c > index e30adb30277f..307c27398e30 100644 > --- a/drivers/tty/serial/liteuart.c > +++ b/drivers/tty/serial/liteuart.c > @@ -46,6 +46,7 @@ struct liteuart_port { > struct uart_port port; > struct timer_list timer; > u32 id; > + bool poll_tx_started; > }; > > #define to_liteuart_port(port) container_of(port, struct liteuart_port, port) > @@ -78,29 +79,24 @@ static void liteuart_putchar(struct uart_port *port, unsigned char ch) > > static void liteuart_stop_tx(struct uart_port *port) > { > - /* not used in LiteUART, but called unconditionally from serial_core */ > + if (port->irq) { > + u8 irq_mask = litex_read8(port->membase + OFF_EV_ENABLE); > + litex_write8(port->membase + OFF_EV_ENABLE, irq_mask & ~EV_TX); > + } else { > + struct liteuart_port *uart = to_liteuart_port(port); > + uart->poll_tx_started = false; > + } > } > > static void liteuart_start_tx(struct uart_port *port) > { > - struct circ_buf *xmit = &port->state->xmit; > - unsigned char ch; > - > - if (unlikely(port->x_char)) { > - litex_write8(port->membase + OFF_RXTX, port->x_char); > - port->icount.tx++; > - port->x_char = 0; > - } else if (!uart_circ_empty(xmit)) { > - while (xmit->head != xmit->tail) { > - ch = xmit->buf[xmit->tail]; I just realized that this: > - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); > - port->icount.tx++; ... conflicts with another accepted patch (by Ilpo) that's currently making its way to being released: https://lore.kernel.org/all/20221019091151.6692-20-ilpo.jarvinen@linux.intel.com/ > - liteuart_putchar(port, ch); > - } > + if (port->irq) { > + u8 irq_mask = litex_read8(port->membase + OFF_EV_ENABLE); > + litex_write8(port->membase + OFF_EV_ENABLE, irq_mask | EV_TX); > + } else { > + struct liteuart_port *uart = to_liteuart_port(port); > + uart->poll_tx_started = true; > } > - > - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) > - uart_write_wakeup(port); > } > > static void liteuart_stop_rx(struct uart_port *port) > @@ -131,18 +127,47 @@ static void liteuart_rx_chars(struct uart_port *port) > tty_flip_buffer_push(&port->state->port); > } > > +static void liteuart_tx_chars(struct uart_port *port) > +{ > + struct circ_buf *xmit = &port->state->xmit; > + > + if (unlikely(port->x_char)) { > + litex_write8(port->membase + OFF_RXTX, port->x_char); > + port->x_char = 0; > + port->icount.tx++; > + return; > + } > + > + while (!litex_read8(port->membase + OFF_TXFULL)) { > + if (xmit->head == xmit->tail) > + break; > + litex_write8(port->membase + OFF_RXTX, xmit->buf[xmit->tail]); Also, this: > + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); > + port->icount.tx++; should now be `uart_xmit_advance(port, 1);` instead. I'm going to take that into account in v4, in addition to any extra feedback I'll receive. Thanks! > + } > + > + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) > + uart_write_wakeup(port); > + > + if (uart_circ_empty(xmit)) > + liteuart_stop_tx(port); > +} > + > static irqreturn_t liteuart_interrupt(int irq, void *data) > { > struct liteuart_port *uart = data; > struct uart_port *port = &uart->port; > u8 isr = litex_read8(port->membase + OFF_EV_PENDING); > > - /* for now, only rx path triggers interrupts */ > - isr &= EV_RX; > + if (!(port->irq || uart->poll_tx_started)) > + isr &= ~EV_TX; /* polling mode with tx stopped */ > > spin_lock(&port->lock); > if (isr & EV_RX) > liteuart_rx_chars(port); > + if (isr & EV_TX) { > + liteuart_tx_chars(port); > + } > spin_unlock(&port->lock); > > return IRQ_RETVAL(isr); > @@ -196,6 +221,7 @@ static int liteuart_startup(struct uart_port *port) > } > > if (!port->irq) { > + uart->poll_tx_started = false; > timer_setup(&uart->timer, liteuart_timer, 0); > mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); > } > @@ -210,6 +236,7 @@ static void liteuart_shutdown(struct uart_port *port) > struct liteuart_port *uart = to_liteuart_port(port); > > litex_write8(port->membase + OFF_EV_ENABLE, 0); > + uart->poll_tx_started = false; > > if (port->irq) > free_irq(port->irq, port); > -- > 2.37.3 >
diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c index e30adb30277f..307c27398e30 100644 --- a/drivers/tty/serial/liteuart.c +++ b/drivers/tty/serial/liteuart.c @@ -46,6 +46,7 @@ struct liteuart_port { struct uart_port port; struct timer_list timer; u32 id; + bool poll_tx_started; }; #define to_liteuart_port(port) container_of(port, struct liteuart_port, port) @@ -78,29 +79,24 @@ static void liteuart_putchar(struct uart_port *port, unsigned char ch) static void liteuart_stop_tx(struct uart_port *port) { - /* not used in LiteUART, but called unconditionally from serial_core */ + if (port->irq) { + u8 irq_mask = litex_read8(port->membase + OFF_EV_ENABLE); + litex_write8(port->membase + OFF_EV_ENABLE, irq_mask & ~EV_TX); + } else { + struct liteuart_port *uart = to_liteuart_port(port); + uart->poll_tx_started = false; + } } static void liteuart_start_tx(struct uart_port *port) { - struct circ_buf *xmit = &port->state->xmit; - unsigned char ch; - - if (unlikely(port->x_char)) { - litex_write8(port->membase + OFF_RXTX, port->x_char); - port->icount.tx++; - port->x_char = 0; - } else if (!uart_circ_empty(xmit)) { - while (xmit->head != xmit->tail) { - ch = xmit->buf[xmit->tail]; - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); - port->icount.tx++; - liteuart_putchar(port, ch); - } + if (port->irq) { + u8 irq_mask = litex_read8(port->membase + OFF_EV_ENABLE); + litex_write8(port->membase + OFF_EV_ENABLE, irq_mask | EV_TX); + } else { + struct liteuart_port *uart = to_liteuart_port(port); + uart->poll_tx_started = true; } - - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) - uart_write_wakeup(port); } static void liteuart_stop_rx(struct uart_port *port) @@ -131,18 +127,47 @@ static void liteuart_rx_chars(struct uart_port *port) tty_flip_buffer_push(&port->state->port); } +static void liteuart_tx_chars(struct uart_port *port) +{ + struct circ_buf *xmit = &port->state->xmit; + + if (unlikely(port->x_char)) { + litex_write8(port->membase + OFF_RXTX, port->x_char); + port->x_char = 0; + port->icount.tx++; + return; + } + + while (!litex_read8(port->membase + OFF_TXFULL)) { + if (xmit->head == xmit->tail) + break; + litex_write8(port->membase + OFF_RXTX, xmit->buf[xmit->tail]); + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + port->icount.tx++; + } + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); + + if (uart_circ_empty(xmit)) + liteuart_stop_tx(port); +} + static irqreturn_t liteuart_interrupt(int irq, void *data) { struct liteuart_port *uart = data; struct uart_port *port = &uart->port; u8 isr = litex_read8(port->membase + OFF_EV_PENDING); - /* for now, only rx path triggers interrupts */ - isr &= EV_RX; + if (!(port->irq || uart->poll_tx_started)) + isr &= ~EV_TX; /* polling mode with tx stopped */ spin_lock(&port->lock); if (isr & EV_RX) liteuart_rx_chars(port); + if (isr & EV_TX) { + liteuart_tx_chars(port); + } spin_unlock(&port->lock); return IRQ_RETVAL(isr); @@ -196,6 +221,7 @@ static int liteuart_startup(struct uart_port *port) } if (!port->irq) { + uart->poll_tx_started = false; timer_setup(&uart->timer, liteuart_timer, 0); mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); } @@ -210,6 +236,7 @@ static void liteuart_shutdown(struct uart_port *port) struct liteuart_port *uart = to_liteuart_port(port); litex_write8(port->membase + OFF_EV_ENABLE, 0); + uart->poll_tx_started = false; if (port->irq) free_irq(port->irq, port);
Modify the TX path to operate in an IRQ-compatible way, while maintaining support for polling mode via the poll timer. Signed-off-by: Gabriel Somlo <gsomlo@gmail.com> --- drivers/tty/serial/liteuart.c | 67 ++++++++++++++++++++++++----------- 1 file changed, 47 insertions(+), 20 deletions(-)