linux-kernel - Re: [PATCH v3] serial: 8250: add gpio support to exar

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Message-ID: <20151220164131.46fb25ee@lxorguk.ukuu.org.uk>
Date:	Sun, 20 Dec 2015 16:41:31 +0000
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v3] serial: 8250: add gpio support to exar

On Sun, 20 Dec 2015 20:17:22 +0530
Sudip Mukherjee <sudipm.mukherjee@...il.com> wrote:

> On Sun, Dec 20, 2015 at 04:18:17PM +0200, Andy Shevchenko wrote:
> > On Sun, Dec 20, 2015 at 3:24 PM, Sudip Mukherjee
> > <sudipm.mukherjee@...il.com> wrote:
> > > Exar XR17V352/354/358 chips have 16 multi-purpose inputs/outputs which
> > > can be controlled using gpio interface.
> > > Add support to use these pins and select GPIO_SYSFS also so that these
> > > pins can be used from the userspace through sysfs.
> > >
> > > Tested-by: Rob Groner <rgroner@....com>
> > > Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
> > 
> Hi Andy,
> Thanks for the review. Just a few doubts below.
> 
> > > @@ -0,0 +1,261 @@
> > > +/*
> > > + * GPIO driver for Exar XR17V35X chip
> > > + *
> > > + * Copyright (C) 2015 Sudip Mukherjee <sudipm.mukherjee@...il.com>
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License version 2 as
> > > + * published by the Free Software Foundation.
> > > + */
> <snip>
> > > +
> > > +err_destroy:
> > > +       mutex_unlock(&exar_mtx);
> > > +       mutex_destroy(&exar_gpio->lock);
> > > +err_unmap:
> > > +       iounmap(p);
> > 
> > pci_iounmap?
> 
> I thought about pci_iounmap but I saw that most of the code in
> 8250_pci.c is using iounmap, so i went in favor of the majority.
> Will change it.
> 
> > 
> > > +       return ret;
> > > +}
> > > +EXPORT_SYMBOL(xr17v35x_gpio_init);
> > > +
> > 
> > > +static void __exit exar_gpio_exit(void)
> > > +{
> > > +}
> > > +
> > > +module_exit(exar_gpio_exit);
> > > +
> > > +static int __init exar_gpio_init(void)
> > > +{
> > > +       return 0;
> > > +}
> > > +
> > > +module_init(exar_gpio_init);
> > > +
> > 
> > Useless for now. You are using it as a library.
> 
> Main doubt here. If I do not give the module_init() and module_exit()
> then what entry do i keep in the Kconfig? In this v3, it is kept as
> tristate. Should that be bool then? 

If you are linking it into the driver you don't need the module_init/exit
gpio_init/exit methods. Your Kconfig becomes a bool and you combine the
file into the driver based upon that bool.

Alan
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