serial: st-asc: Provide RTS functionality

#include <linux/of_platform.h>

#include <linux/serial_core.h>

#include <linux/clk.h>

#include <linux/gpio/consumer.h>

#define DRIVER_NAME "st-asc"

#define ASC_SERIAL_NAME "ttyAS"

struct asc_port {

	struct uart_port port;

	struct gpio_desc *rts;

	struct clk *clk;

	unsigned int hw_flow_control:1;

	unsigned int force_m1:1;

static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl)

{

	struct asc_port *ascport = to_asc_port(port);

	/*

	 * This routine is used for seting signals of: DTR, DCD, CTS/RTS

	 * We use ASC's hardware for CTS/RTS, so don't need any for that.

	 * Some boards have DTR and DCD implemented using PIO pins,

	 * code to do this should be hooked in here.

	 * This routine is used for seting signals of: DTR, DCD, CTS and RTS.

	 * We use ASC's hardware for CTS/RTS when hardware flow-control is

	 * enabled, however if the RTS line is required for another purpose,

	 * commonly controlled using HUP from userspace, then we need to toggle

	 * it manually, using GPIO.

	 *

	 * Some boards also have DTR and DCD implemented using PIO pins, code to

	 * do this should be hooked in here.

	 */

	if (!ascport->rts)

		return;

	/* If HW flow-control is enabled, we can't fiddle with the RTS line */

	if (asc_in(port, ASC_CTL) & ASC_CTL_CTSENABLE)

		return;

	gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS);

}

static unsigned int asc_get_mctrl(struct uart_port *port)

							"st,hw-flow-control");

	asc_ports[id].force_m1 =  of_property_read_bool(np, "st,force_m1");

	asc_ports[id].port.line = id;

	asc_ports[id].rts = NULL;

	return &asc_ports[id];

}