Subject: Re: [PATCH 2/3] serial: st-asc: Provide RTS functionality
To: Lee Jones <lee.jones@linaro.org>, <gregkh@linuxfoundation.org>,
        <jslaby@suse.com>
References: <20161202141146.31281-1-lee.jones@linaro.org>
 <20161202141146.31281-2-lee.jones@linaro.org>
CC: <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <kernel@stlinux.com>, <linux-serial@vger.kernel.org>
From: Patrice Chotard <patrice.chotard@st.com>
Message-ID: <5e652529-8dcb-568e-a748-0ec745099211@st.com>
Date: Mon, 5 Dec 2016 15:11:49 +0100
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Hi Lee

On 12/02/2016 03:11 PM, Lee Jones wrote:
> Until this point, it has not been possible for serial applications
> to toggle the UART RTS line.  This can be useful with certain
> configurations. For example, when using a Mezzanine on a Linaro
> 96board, RTS line is used to take the the on-board microcontroller

typo "the the on"

> in and out of reset.
> 
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/tty/serial/st-asc.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
> index 379e5bd..ce46898 100644
> --- a/drivers/tty/serial/st-asc.c
> +++ b/drivers/tty/serial/st-asc.c
> @@ -30,6 +30,7 @@
>  #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"
> @@ -38,6 +39,7 @@
>  
>  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;
> @@ -381,12 +383,16 @@ static unsigned int asc_tx_empty(struct uart_port *port)
>  
>  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.
>  	 */
> +
> +	gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS);
>  }
>  
>  static unsigned int asc_get_mctrl(struct uart_port *port)
> @@ -731,12 +737,20 @@ MODULE_DEVICE_TABLE(of, asc_match);
>  static int asc_serial_probe(struct platform_device *pdev)
>  {
>  	int ret;
> +	struct device_node *np = pdev->dev.of_node;
>  	struct asc_port *ascport;
> +	struct gpio_desc *gpiod;
>  
>  	ascport = asc_of_get_asc_port(pdev);
>  	if (!ascport)
>  		return -ENODEV;
>  
> +	gpiod = devm_get_gpiod_from_child(&pdev->dev, "rts", &np->fwnode);
> +	if (!IS_ERR(gpiod)) {
> +		gpiod_direction_output(gpiod, 0);
> +		ascport->rts = gpiod;
> +	}
> +
>  	ret = asc_init_port(ascport, pdev);
>  	if (ret)
>  		return ret;
>