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[72.77.81.136]) by smtp.gmail.com with ESMTPSA id y28-20020a37f61c000000b006fa22f0494bsm2379695qkj.117.2022.11.18.06.26.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Nov 2022 06:26:46 -0800 (PST) Date: Fri, 18 Nov 2022 09:26:44 -0500 From: "Gabriel L. Somlo" To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= Cc: LKML , linux-serial , Greg Kroah-Hartman , Jiri Slaby , kgugala@antmicro.com, mholenko@antmicro.com, joel@jms.id.au, david.abdurachmanov@gmail.com, florent@enjoy-digital.fr, geert@linux-m68k.org Subject: Re: [PATCH v4 12/14] serial: liteuart: add IRQ support for the RX path Message-ID: References: <20221116144908.234154-1-gsomlo@gmail.com> <20221116144908.234154-13-gsomlo@gmail.com> <6629539b-c5a7-4edc-7ab1-5c977f7319@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6629539b-c5a7-4edc-7ab1-5c977f7319@linux.intel.com> X-Clacks-Overhead: GNU Terry Pratchett Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org 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 > > --- > > > > 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 > > #include > > +#include > > #include > > #include > > #include > > @@ -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. > > + port->irq = 0; > > + } > > + } > > > > - /* prepare timer for polling */ > > - timer_setup(&uart->timer, liteuart_timer, 0); > > - mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); > > + spin_lock_irqsave(&port->lock, flags); > > + /* only enabling rx irqs during startup */ > > + liteuart_update_irq_reg(port, true, EV_RX); > > + spin_unlock_irqrestore(&port->lock, flags); > > + > > + if (!port->irq) { > > + timer_setup(&uart->timer, liteuart_timer, 0); > > + mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); > > + } > > > > return 0; > > } > > > > static void liteuart_shutdown(struct uart_port *port) > > { > > + struct liteuart_port *uart = to_liteuart_port(port); > > + unsigned long flags; > > + > > + spin_lock_irqsave(&port->lock, flags); > > + liteuart_update_irq_reg(port, false, EV_RX | EV_TX); > > + spin_unlock_irqrestore(&port->lock, flags); > > + > > + if (port->irq) > > + free_irq(port->irq, port); > > + else > > + del_timer_sync(&uart->timer); > > } > > > > static void liteuart_set_termios(struct uart_port *port, struct ktermios *new, > > @@ -262,6 +317,13 @@ static int liteuart_probe(struct platform_device *pdev) > > goto err_erase_id; > > } > > > > + /* get irq */ > > This comment is unnecessary. Removed in v5. > Other than that, > > Reviewed-by: Ilpo Järvinen Thanks much, I'll send out v5 a bit later today. --Gabriel > -- > i. > > > > + ret = platform_get_irq_optional(pdev, 0); > > + if (ret < 0 && ret != -ENXIO) > > + return ret; > > + if (ret > 0) > > + port->irq = ret; > > + > > /* values not from device tree */ > > port->dev = &pdev->dev; > > port->iotype = UPIO_MEM; > >