On Fri, 18 Nov 2022, Gabriel L. Somlo wrote:
> On Fri, Nov 18, 2022 at 03:58:47PM +0200, Ilpo Järvinen wrote:
> > On Wed, 16 Nov 2022, Gabriel Somlo wrote:
> >
> > > Add support for IRQ-driven RX. Support for the TX path will be added
> > > in a separate commit.
> > >
> > > Signed-off-by: Gabriel Somlo <gsomlo@xxxxxxxxx>
> > > ---
> > >
> > > Changes from v3:
> > > - add shadow irq register to support polling mode and avoid reading
> > > hardware mmio irq register to learn which irq flags are enabled
> > > - this also simplifies both liteuart_interrupt() and liteuart_startup()
> > >
> > > drivers/tty/serial/liteuart.c | 76 +++++++++++++++++++++++++++++++----
> > > 1 file changed, 69 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
> > > index 8a6e176be08e..fad778578986 100644
> > > --- a/drivers/tty/serial/liteuart.c
> > > +++ b/drivers/tty/serial/liteuart.c
> > > @@ -7,6 +7,7 @@
> > >
> > > #include <linux/bits.h>
> > > #include <linux/console.h>
> > > +#include <linux/interrupt.h>
> > > #include <linux/litex.h>
> > > #include <linux/module.h>
> > > #include <linux/of.h>
> > > @@ -46,6 +47,7 @@ struct liteuart_port {
> > > struct uart_port port;
> > > struct timer_list timer;
> > > u32 id;
> > > + u8 irq_reg;
> > > };
> > >
> > > #define to_liteuart_port(port) container_of(port, struct liteuart_port, port)
> > > @@ -76,6 +78,19 @@ static void liteuart_putchar(struct uart_port *port, unsigned char ch)
> > > litex_write8(port->membase + OFF_RXTX, ch);
> > > }
> > >
> > > +static void liteuart_update_irq_reg(struct uart_port *port, bool set, u8 mask)
> > > +{
> > > + struct liteuart_port *uart = to_liteuart_port(port);
> > > +
> > > + if (set)
> > > + uart->irq_reg |= mask;
> > > + else
> > > + uart->irq_reg &= ~mask;
> > > +
> > > + if (port->irq)
> > > + litex_write8(port->membase + OFF_EV_ENABLE, uart->irq_reg);
> > > +}
> > > +
> > > static void liteuart_stop_tx(struct uart_port *port)
> > > {
> > > }
> > > @@ -129,13 +144,27 @@ static void liteuart_rx_chars(struct uart_port *port)
> > > tty_flip_buffer_push(&port->state->port);
> > > }
> > >
> > > +static irqreturn_t liteuart_interrupt(int irq, void *data)
> > > +{
> > > + struct liteuart_port *uart = data;
> > > + struct uart_port *port = &uart->port;
> > > + u8 isr;
> > > +
> > > + spin_lock(&port->lock);
> > > + isr = litex_read8(port->membase + OFF_EV_PENDING) & uart->irq_reg;
> > > + if (isr & EV_RX)
> > > + liteuart_rx_chars(port);
> > > + spin_unlock(&port->lock);
> > > +
> > > + return IRQ_RETVAL(isr);
> > > +}
> > > +
> > > static void liteuart_timer(struct timer_list *t)
> > > {
> > > struct liteuart_port *uart = from_timer(uart, t, timer);
> > > struct uart_port *port = &uart->port;
> > >
> > > - liteuart_rx_chars(port);
> > > -
> > > + liteuart_interrupt(0, port);
> > > mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
> > > }
> > >
> > > @@ -161,19 +190,45 @@ static unsigned int liteuart_get_mctrl(struct uart_port *port)
> > > static int liteuart_startup(struct uart_port *port)
> > > {
> > > struct liteuart_port *uart = to_liteuart_port(port);
> > > + unsigned long flags;
> > > + int ret;
> > >
> > > - /* disable events */
> > > - litex_write8(port->membase + OFF_EV_ENABLE, 0);
> > > + if (port->irq) {
> > > + ret = request_irq(port->irq, liteuart_interrupt, 0,
> > > + KBUILD_MODNAME, uart);
> > > + if (ret) {
> > > + pr_err(pr_fmt("line %d irq %d failed: using polling\n"),
> > > + port->line, port->irq);
> >
> > dev_err() seems more appropriate here.
>
> Makes sense, good thing `struct uart_port` has a `dev` field :)
> I've made the change, and lined it up for the upcoming v5 of the
> series.
Also that pr_fmt() should be dropped (in case you didn't already). It was
in my mind ealier but should have stated it explicitly.
--
i.
