From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] i2c: export bit-banging algo functions Date: Wed, 29 Feb 2012 20:48:18 +0100 Message-ID: <20120229194818.GC28941@phenom.ffwll.local> References: <20120227225223.GB1050@phenom.ffwll.local> <1330385979-19406-1-git-send-email-daniel.vetter@ffwll.ch> <20120228090817.1a95c28b@endymion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120228090817.1a95c28b-R0o5gVi9kd7kN2dkZ6Wm7A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jean Delvare Cc: Daniel Vetter , Intel Graphics Development , DRI Development , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org On Tue, Feb 28, 2012 at 09:08:17AM +0100, Jean Delvare wrote: > On Tue, 28 Feb 2012 00:39:39 +0100, Daniel Vetter wrote: > > i915 has a hw i2c controller (gmbus) but for a bunch of stupid reasons > > we need to be able to fall back to the bit-banging algo on gpio pins. > > > > The current code sets up a 2nd i2c controller for the same i2c bus using > > the bit-banging algo. This has a bunch of issues, the major one being > > that userspace can directly access this fallback i2c adaptor behind > > the drivers back. > > > > But we need to frob a few registers before and after using fallback > > gpio bit-banging, so this horribly fails. > > > > The new plan is to only set up one i2c adaptor and transparently fall > > back to bit-banging by directly calling the xfer function of the bit- > > banging algo in the i2c core. > > > > To make that possible, export the 2 i2c algo functions. > > > > v2: As suggested by Jean Delvare, simply export the i2c_bit_algo > > vtable instead of the individual functions. > > > > Signed-off-by: Daniel Vetter > > --- > > drivers/i2c/algos/i2c-algo-bit.c | 3 ++- > > include/linux/i2c-algo-bit.h | 1 + > > 2 files changed, 3 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c > > index 525c734..ad0459c 100644 > > --- a/drivers/i2c/algos/i2c-algo-bit.c > > +++ b/drivers/i2c/algos/i2c-algo-bit.c > > @@ -610,10 +610,11 @@ static u32 bit_func(struct i2c_adapter *adap) > > > > /* -----exported algorithm data: ------------------------------------- */ > > > > -static const struct i2c_algorithm i2c_bit_algo = { > > +const struct i2c_algorithm i2c_bit_algo = { > > .master_xfer = bit_xfer, > > .functionality = bit_func, > > }; > > +EXPORT_SYMBOL(i2c_bit_algo); > > > > /* > > * registering functions to load algorithms at runtime > > diff --git a/include/linux/i2c-algo-bit.h b/include/linux/i2c-algo-bit.h > > index 4f98148..584ffa0 100644 > > --- a/include/linux/i2c-algo-bit.h > > +++ b/include/linux/i2c-algo-bit.h > > @@ -49,5 +49,6 @@ struct i2c_algo_bit_data { > > > > int i2c_bit_add_bus(struct i2c_adapter *); > > int i2c_bit_add_numbered_bus(struct i2c_adapter *); > > +extern const struct i2c_algorithm i2c_bit_algo; > > > > #endif /* _LINUX_I2C_ALGO_BIT_H */ > > Acked-by: Jean Delvare I've applied this patch to drm-intel-next, thanks for the feedback. -Daniel -- Daniel Vetter Mail: daniel-/w4YWyX8dFk@public.gmane.org Mobile: +41 (0)79 365 57 48