linux-kernel - Re: [PATCH 2/2] iio: light: bh1750: Add device tree support

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Date:   Sat, 22 Sep 2018 16:22:14 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     r yang <decatf@...il.com>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] iio: light: bh1750: Add device tree support

On Mon, 17 Sep 2018 21:57:33 -0400
r yang <decatf@...il.com> wrote:

> On Sun, Sep 16, 2018 at 10:45:26AM +0100, Jonathan Cameron wrote:
> > On Sat, 15 Sep 2018 13:42:14 -0400
> > ryang <decatf@...il.com> wrote:
> >   
> > > Add device tree support for ROHM BH1750 series ambient light sensors.
> > > 
> > > Signed-off-by: ryang <decatf@...il.com>  
> > Just to check, how is it picking up on the enum value which is provided
> > in the i2c_device_id entries?
> > 
> > i.e. What is setting id->driver_data in the probe?
> > There may be something in the i2c core that I'm missing that will do the
> > association but I don't remember anything trying to do this.
> > 
> > Jonathan
> >  
> 
> I've looked through it and it is indeed in the i2c core.
> The i2c core probe function picks the id entry based on the i2c client
> name.
> 
> The i2c client name is assigned based on the device tree compatible
> string.
> 
>   of_i2c_register_device()
>     of_i2c_get_board_info()
>       of_modalias_node()
> 
> During probe the i2c_device_id is picked by matching the i2c
> client->name to i2c_device_id->name in the i2c_match_id() function.
> 
>   i2c_device_probe()
>     driver->probe(client, i2c_match_id(driver->id_table, client));
> 
Great!  Thanks for tracking that down.  I'll pick this up once
you've added the MODULE_DEVICE_TABLE as Tomasz suggested.


> I've tested this on device. It's Samsung Galaxy Tab 10.1. It has a
> BH1721.
> 
> > > ---
> > >  drivers/iio/light/bh1750.c | 10 ++++++++++
> > >  1 file changed, 10 insertions(+)
> > > 
> > > diff --git a/drivers/iio/light/bh1750.c b/drivers/iio/light/bh1750.c
> > > index a814828e69f5..50b599abb383 100644
> > > --- a/drivers/iio/light/bh1750.c
> > > +++ b/drivers/iio/light/bh1750.c
> > > @@ -315,9 +315,19 @@ static const struct i2c_device_id bh1750_id[] = {
> > >  };
> > >  MODULE_DEVICE_TABLE(i2c, bh1750_id);
> > >  
> > > +static const struct of_device_id bh1750_of_match[] = {
> > > +	{ .compatible = "rohm,bh1710", },
> > > +	{ .compatible = "rohm,bh1715", },
> > > +	{ .compatible = "rohm,bh1721", },
> > > +	{ .compatible = "rohm,bh1750", },
> > > +	{ .compatible = "rohm,bh1751", },
> > > +	{ }
> > > +};
> > > +
> > >  static struct i2c_driver bh1750_driver = {
> > >  	.driver = {
> > >  		.name = "bh1750",
> > > +		.of_match_table = of_match_ptr(bh1750_of_match),
> > >  		.pm = BH1750_PM_OPS,
> > >  	},
> > >  	.probe = bh1750_probe,  
> >