| Message ID | 20221112212125.448824-1-gsomlo@gmail.com |
|---|---|
| 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 >
Add IRQ support to the LiteX LiteUART serial interface Changes from v2: - further split out "separate RX loop from poll timer" into dedicated patches highlighting additional changes explicitly: - factoring out tty_flip_buffer_push() (6/14) - ack only RX events in RX loop (7/14) - pass constant flag to uart_insert_char() directly (8/14) - fix variable types in rx loop (9/14) - separating RX loop from poll timer (10/14) - added patch (11/14) to move function definitions to a more convenient location, making subsequent changes easier to read in diff patch form. - fixes and clarifications for RX path IRQ support patch (now 12/14): - only return IRQ_HANDLED for RX events - use pr_fmt() to improve style of irq setup error message - remove unnecessary locking from around single-register access - modify TX path to support both IRQ-mode and polling (13/14) - move polling-only liteuart_putchar() behind same conditional (CONFIG_SERIAL_LITEUART_CONSOLE) as the rest of the code that's still using it. > Changes from v1: > - split minor cosmetic changes out into individual patches > (1/3 became 1..5/7) > - patches 6/7 and 7/7 unchanged (used to be 2/3 and 3/3) Gabriel Somlo (14): serial: liteuart: use KBUILD_MODNAME as driver name serial: liteuart: use bit number macros serial: liteuart: remove unused uart_ops stubs serial: liteuart: don't set unused port fields serial: liteuart: minor style fix in liteuart_init() serial: liteuart: move tty_flip_buffer_push() out of rx loop serial: liteuart: rx loop should only ack rx events serial: liteuart: simplify passing of uart_insert_char() flag serial: liteuart: fix rx loop variable types serial: liteuart: separate rx loop from poll timer serial: liteuart: move function definitions serial: liteuart: add IRQ support for the RX path serial: liteuart: add IRQ support for the TX path serial: liteuart: move polling putchar() function drivers/tty/serial/liteuart.c | 226 +++++++++++++++++++++------------- 1 file changed, 142 insertions(+), 84 deletions(-)