sc16is7xx: Add flag to activate IrDA mode

This series of uart controllers is able to work in IrDA mode.
Add per-port flag to the device-tree to enable that feature if needed.

Signed-off-by: Pascal Huerst <[e-mail]>
Signed-off-by: Daniel Mack <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/sc16is7xx.c

···
 	struct kthread_work		tx_work;
 	struct kthread_work		reg_work;
 	struct sc16is7xx_one_config	config;
+	bool				irda_mode;
 };
 
 struct sc16is7xx_port {
···
 
 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;
 
···
 
 	/* Now, initialize the UART */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, SC16IS7XX_LCR_WORD_LEN_8);
+
+	/* Enable IrDA mode if requested in DT */
+	/* This bit must be written with LCR[7] = 0 */
+	sc16is7xx_port_update(port, SC16IS7XX_MCR_REG,
+			      SC16IS7XX_MCR_IRDA_BIT,
+			      one->irda_mode ?
+				SC16IS7XX_MCR_IRDA_BIT : 0);
 
 	/* Enable the Rx and Tx FIFO */
 	sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
···
 
 		/* Go to suspend mode */
 		sc16is7xx_power(&s->p[i].port, 0);
+	}
+
+	if (dev->of_node) {
+		struct property *prop;
+		const __be32 *p;
+		u32 u;
+
+		of_property_for_each_u32(dev->of_node, "irda-mode-ports",
+					 prop, p, u)
+			if (u < devtype->nr_uart)
+				s->p[u].irda_mode = true;
 	}
 
 	/*