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Date:   Tue, 9 Jul 2019 16:22:21 +0100
From:   Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To:     Martin =?UTF-8?B?SHVuZGViw7hsbA==?= <martin@geanix.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>, linux-kernel@vger.kernel.org,
        Sean =?UTF-8?B?Tnlla2o=?= =?UTF-8?B?w6Zy?= <sean@geanix.com>,
        Esben Haabendal <esben@geanix.com>
Subject: Re: [PATCH 4/4] tty: n_gsm: add ioctl to map serial device to
 mux'ed tty
Message-ID: <20190709162221.623f99ce@alans-desktop>
In-Reply-To: <20190708190252.24628-4-martin@geanix.com>
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        <20190708190252.24628-4-martin@geanix.com>
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On Mon,  8 Jul 2019 21:02:52 +0200
Martin Hundebøll <martin@geanix.com> wrote:

> Guessing the base tty for a gsm0710 multiplexed serial device is not
> currently possible, which makes it racy to use with multiple modems.
> 
> Add a way to map the physical serial tty to its related mux devices
> using a ioctl.

That looks very sensible

> +	int base;
>  
>  	/* open the serial port connected to the modem */
>  	fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
> @@ -58,6 +61,11 @@ Major parts of the initialization program :
>  	c.mtu = 127;
>  	/* set the new configuration */
>  	ioctl(fd, GSMIOC_SETCONF, &c);
> +	/* get and print base gsmtty device node */
> +	ioctl(fd, GSMIOC_GETBASE, &base);

Can we at least use a specific sized type ? uint32_t or whatever is fine.

Alan