linux-kernel - Re: Writing a driver for a legacy serial device

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Message-ID: <d120d5000706191159w29ebd0dajbd6cb9ac78d4faa2@mail.gmail.com>
Date:	Tue, 19 Jun 2007 14:59:34 -0400
From:	"Dmitry Torokhov" <dmitry.torokhov@...il.com>
To:	"Jean Delvare" <khali@...ux-fr.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"Vojtech Pavlik" <vojtech@....cz>
Subject: Re: Writing a driver for a legacy serial device

Hi Jean,

On 6/19/07, Jean Delvare <khali@...ux-fr.org> wrote:
> Hi all,
>
> I want to write a Linux kernel driver for a device which connects to
> the legacy serial port. I started writing a driver, however I am
> already stuck at the very beginning. The .connect function of my serial
> driver is never called, and I just don't get why. I couldn't find any
> documentation about writing such a legacy driver in Documentation nor
> in LDD3. Is there anyone out there which could lend a helping hand?
>
> I know that the device and my serial port both work. I can talk to the
> device using minicom just fine. I have the following drivers loaded:
>
> $ lsmod | grep 8250
> 8250_pnp               11648  0
> 8250                   23464  1 8250_pnp
> serial_core            19392  1 8250
>
> Serial: 8250/16550 driver $Revision: 1.90 $ 2 ports, IRQ sharing disabled
> 00:08: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
>
> But I need to implement my driver in kernel space. My code looks like
> this:
>
> static struct serio_device_id taos_serio_ids[] = {
>        {
>                .type   = SERIO_RS232,
>                .proto  = SERIO_ANY,
>                .id     = SERIO_ANY,
>                .extra  = SERIO_ANY,
>        },
>        { 0 }
> };
> MODULE_DEVICE_TABLE(serio, taos_serio_ids);
>
> static struct serio_driver taos_drv = {
>        .driver         = {
>                .name   = "taos-evm",
>        },
>        .description    = "TAOS evaluation module driver",
>        .id_table       = taos_serio_ids,
>        .connect        = taos_connect,
>        .disconnect     = taos_disconnect,
>        .interrupt      = taos_interrupt,
> };
>
> static int __init taos_init(void)
> {
>        return serio_register_driver(&taos_drv);
> }
>
> static void __exit taos_exit(void)
> {
>        serio_unregister_driver(&taos_drv);
> }
>
> The problem is that taos_connect is never called. I suppose that I need
> different values for .type, .proto or .id, except that I just don't
> know what to put there. I tried a few random values without success.
> What's the trick?
>

You need to load serport modue and play with inputattach utility.

-- 
Dmitry
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