Subject: [PATCH RESEND 3/5] tty/serial: Add GPIOLIB helpers for controlling modem lines

From: [email-masked] (Greg Kroah-Hartman)
Date: Wed, 28 May 2014 12:45:50 -0700

On Tue, May 13, 2014 at 08:20:43PM +0200, Richard Genoud wrote:
> This patch add some helpers to control modem lines (CTS/RTS/DSR...) via
> GPIO.
> This will be useful for many boards which have a serial controller that
> only handle CTS/RTS pins (or even just RX/TX).
> 
> Signed-off-by: Richard Genoud <[email-masked]>
> Tested-by: Yegor Yefremov <[email-masked]>
> ---
>  Documentation/serial/driver            |   25 ++++++
>  drivers/tty/serial/Kconfig             |    3 +
>  drivers/tty/serial/Makefile            |    3 +
>  drivers/tty/serial/serial_mctrl_gpio.c |  143 ++++++++++++++++++++++++++++++++
>  drivers/tty/serial/serial_mctrl_gpio.h |  110 ++++++++++++++++++++++++
>  5 files changed, 284 insertions(+)
>  create mode 100644 drivers/tty/serial/serial_mctrl_gpio.c
>  create mode 100644 drivers/tty/serial/serial_mctrl_gpio.h
> 
> diff --git a/Documentation/serial/driver b/Documentation/serial/driver
> index c3a7689..3bba1ae 100644
> --- a/Documentation/serial/driver
> +++ b/Documentation/serial/driver
> @@ -429,3 +429,28 @@ thus:
>  		struct uart_port	port;
>  		int			my_stuff;
>  	};
> +
> +Modem control lines via GPIO
> +----------------------------
> +
> +Some helpers are provided in order to set/get modem control lines via GPIO.
> +
> +mctrl_gpio_init(dev, idx):
> +	This will get the {cts,rts,...}-gpios from device tree if they are
> +	present and request them, set direction etc, and return an
> +	allocated structure. devm_* functions are used, so there's no need
> +	to call mctrl_gpio_free().
> +
> +mctrl_gpio_free(dev, gpios):
> +	This will free the requested gpios in mctrl_gpio_init().
> +	As devm_* function are used, there's generally no need to call
> +	this function.
> +
> +mctrl_gpio_to_gpiod(gpios, gidx)
> +	This returns the gpio structure associated to the modem line index.
> +
> +mctrl_gpio_set(gpios, mctrl):
> +	This will sets the gpios according to the mctrl state.
> +
> +mctrl_gpio_get(gpios, mctrl):
> +	This will update mctrl with the gpios values.
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 5d9b01a..95afd31 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1510,4 +1510,7 @@ config SERIAL_ST_ASC_CONSOLE
>  
>  endmenu
>  
> +config SERIAL_MCTRL_GPIO
> +	tristate

Why is this added here?  Who is going to use it?

> +
>  endif # TTY
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index 3680854..bcf31da 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -87,3 +87,6 @@ obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
>  obj-$(CONFIG_SERIAL_ARC)	+= arc_uart.o
>  obj-$(CONFIG_SERIAL_RP2)	+= rp2.o
>  obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o
> +
> +# GPIOLIB helpers for modem control lines
> +obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o

This chunk doesn't apply anymore :(