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(unknown [212.185.67.148]) by mail.systec-electronic.com (Postfix) with ESMTPSA id 1897C94016B2; Thu, 19 Dec 2024 09:46:40 +0100 (CET) From: Andre Werner To: gregkh@linuxfoundation.org, jirislaby@kernel.org, hvilleneuve@dimonoff.com, andy@kernel.org Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, lech.perczak@camlingroup.com, Andre Werner Subject: [PATCH] serial: sc16is7xx: Add polling feature if no IRQ usage possible Date: Thu, 19 Dec 2024 09:46:38 +0100 Message-ID: <20241219084638.960253-1-andre.werner@systec-electronic.com> X-Mailer: git-send-email 2.47.1 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Fall back to polling mode if no interrupt is configured because not possible. If "interrupts" property is missing in devicetree the driver uses a delayed worker to pull state of interrupt status registers. Signed-off-by: Andre Werner --- This driver was tested on Linux 5.10. We had a custom board that was not able to connect the interrupt port. Only I2C was available. --- --- drivers/tty/serial/sc16is7xx.c | 40 ++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index a3093e09309f..31962fdca178 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -314,6 +314,7 @@ #define SC16IS7XX_FIFO_SIZE (64) #define SC16IS7XX_GPIOS_PER_BANK 4 +#define SC16IS7XX_POLL_PERIOD 10 /*ms*/ #define SC16IS7XX_RECONF_MD BIT(0) #define SC16IS7XX_RECONF_IER BIT(1) #define SC16IS7XX_RECONF_RS485 BIT(2) @@ -348,6 +349,9 @@ struct sc16is7xx_port { u8 mctrl_mask; struct kthread_worker kworker; struct task_struct *kworker_task; + struct kthread_delayed_work poll_work; + bool polling; + bool shutdown; struct sc16is7xx_one p[]; }; @@ -861,6 +865,19 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id) return IRQ_HANDLED; } +static void sc16is7xx_transmission_poll(struct kthread_work *work) +{ + struct sc16is7xx_port *s = container_of(work, struct sc16is7xx_port, poll_work.work); + + /* Resuse standard IRQ handler. Interrupt ID is unused in this context. */ + sc16is7xx_irq(0, s); + + /* setup delay based on SC16IS7XX_POLL_PERIOD */ + if (!s->shutdown) + kthread_queue_delayed_work(&s->kworker, &s->poll_work, + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD)); +} + static void sc16is7xx_tx_proc(struct kthread_work *ws) { struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port); @@ -1149,6 +1166,7 @@ static int sc16is7xx_config_rs485(struct uart_port *port, struct ktermios *termi static int sc16is7xx_startup(struct uart_port *port) { struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); + struct sc16is7xx_port *s = dev_get_drvdata(port->dev); unsigned int val; unsigned long flags; @@ -1210,6 +1228,11 @@ static int sc16is7xx_startup(struct uart_port *port) uart_port_lock_irqsave(port, &flags); sc16is7xx_enable_ms(port); uart_port_unlock_irqrestore(port, flags); + if (s->polling) { + s->shutdown = false; + kthread_queue_delayed_work(&s->kworker, &s->poll_work, + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD)); + } return 0; } @@ -1232,6 +1255,10 @@ static void sc16is7xx_shutdown(struct uart_port *port) sc16is7xx_power(port, 0); + if (s->polling) { + s->shutdown = true; + kthread_cancel_delayed_work_sync(&s->poll_work); + } kthread_flush_worker(&s->kworker); } @@ -1537,7 +1564,13 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, /* Always ask for fixed clock rate from a property. */ device_property_read_u32(dev, "clock-frequency", &uartclk); + s->polling = !device_property_present(dev, "interrupts"); + if (s->polling) { + dev_warn(dev, + "No interrupt definition found. Falling back to polling mode.\n"); + irq = 0; + } s->clk = devm_clk_get_optional(dev, NULL); if (IS_ERR(s->clk)) return PTR_ERR(s->clk); @@ -1664,6 +1697,11 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, if (ret) goto out_ports; #endif + if (s->polling) { + /* Initialize Kernel timer for polling */ + kthread_init_delayed_work(&s->poll_work, sc16is7xx_transmission_poll); + return 0; + } /* * Setup interrupt. We first try to acquire the IRQ line as level IRQ. @@ -1724,6 +1762,8 @@ void sc16is7xx_remove(struct device *dev) sc16is7xx_power(&s->p[i].port, 0); } + if (s->polling) + kthread_cancel_delayed_work_sync(&s->poll_work); kthread_flush_worker(&s->kworker); kthread_stop(s->kworker_task);