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(unknown [212.185.67.148]) by mail.systec-electronic.com (Postfix) with ESMTPSA id 3626194016AA; Mon, 13 Jan 2025 08:30:32 +0100 (CET) From: Andre Werner To: gregkh@linuxfoundation.org, jirislaby@kernel.org, hvilleneuve@dimonoff.com, andy@kernel.org, devicetree@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, lech.perczak@camlingroup.com, krzk+dt@kernel.org, conor+dt@kernel.org, robh@kernel.org, Andre Werner Subject: [PATCH v6 2/2] serial: sc16is7xx: Add polling mode if no IRQ pin is available Date: Mon, 13 Jan 2025 08:30:30 +0100 Message-ID: <20250113073030.15970-2-andre.werner@systec-electronic.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250113073030.15970-1-andre.werner@systec-electronic.com> References: <20250113073030.15970-1-andre.werner@systec-electronic.com> 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 there is no possibility to connect the interrupt pin. If "interrupts" property is missing in devicetree the driver uses a delayed worker to pull the state of interrupt status registers. Signed-off-by: Andre Werner --- V2: - Change warning for polling mode to debug log entry - Correct typo: Resuse -> Reuse - Format define with missing tabs for SC16IS7XX_POLL_PERIOD - Format struct declaration sc16is7xx_one_config with missing tabs for polling and shutdown - Adapt dtbinding with new polling feature V3: - Use suffix with units and drop a comment SC16IS7XX_POLL_PERIOD_MS. Sorry for that miss. - Make Kernel lowercase. V4: - Reword commit messages for better understanding. - Remove 'shutdown' property for canceling delayed worker. - Rename worker function: sc16is7xx_transmission_poll -> sc16is7xx_poll_proc - Unify argument for worker functions: kthread_work *work -> kthread_work *ws V5: - Replace of_property check with IRQ number check to set polling property. This will add support for usage without device tree definitions. Thanks for that advice. - Add blank line es requested. V6: - Use polling mode for IRQ numbers <= 0 which encounter no valid IRQ were found/defined. --- drivers/tty/serial/sc16is7xx.c | 37 ++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index a3093e09309f..560f45ed19ae 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_MS 10 #define SC16IS7XX_RECONF_MD BIT(0) #define SC16IS7XX_RECONF_IER BIT(1) #define SC16IS7XX_RECONF_RS485 BIT(2) @@ -348,6 +349,8 @@ struct sc16is7xx_port { u8 mctrl_mask; struct kthread_worker kworker; struct task_struct *kworker_task; + struct kthread_delayed_work poll_work; + bool polling; struct sc16is7xx_one p[]; }; @@ -861,6 +864,18 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id) return IRQ_HANDLED; } +static void sc16is7xx_poll_proc(struct kthread_work *ws) +{ + struct sc16is7xx_port *s = container_of(ws, struct sc16is7xx_port, poll_work.work); + + /* Reuse standard IRQ handler. Interrupt ID is unused in this context. */ + sc16is7xx_irq(0, s); + + /* Setup delay based on SC16IS7XX_POLL_PERIOD_MS */ + kthread_queue_delayed_work(&s->kworker, &s->poll_work, + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS)); +} + static void sc16is7xx_tx_proc(struct kthread_work *ws) { struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port); @@ -1149,6 +1164,7 @@ 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; @@ -1211,6 +1227,10 @@ static int sc16is7xx_startup(struct uart_port *port) sc16is7xx_enable_ms(port); uart_port_unlock_irqrestore(port, flags); + if (s->polling) + kthread_queue_delayed_work(&s->kworker, &s->poll_work, + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS)); + return 0; } @@ -1232,6 +1252,9 @@ static void sc16is7xx_shutdown(struct uart_port *port) sc16is7xx_power(port, 0); + if (s->polling) + kthread_cancel_delayed_work_sync(&s->poll_work); + kthread_flush_worker(&s->kworker); } @@ -1538,6 +1561,11 @@ 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 = (irq <= 0); + if (s->polling) + dev_dbg(dev, + "No interrupt pin definition, falling back to polling mode\n"); + s->clk = devm_clk_get_optional(dev, NULL); if (IS_ERR(s->clk)) return PTR_ERR(s->clk); @@ -1665,6 +1693,12 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, goto out_ports; #endif + if (s->polling) { + /* Initialize kernel thread for polling */ + kthread_init_delayed_work(&s->poll_work, sc16is7xx_poll_proc); + return 0; + } + /* * Setup interrupt. We first try to acquire the IRQ line as level IRQ. * If that succeeds, we can allow sharing the interrupt as well. @@ -1724,6 +1758,9 @@ 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);