[PATCH] i2c: Add i2c_get_match_data()

[PATCH] i2c: Add i2c_get_match_data()

[Biju Das]

Add i2c_get_match_data() similar to of_device_get_match_data(),
so that we can optimize the driver code that uses both I2C and
DT-based matching.

Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
eg:
The RTC 1208 driver code [1] can be optimized with [2], which is planned
to mainline once [3] is accepted.

[1]
if (client->dev.of_node) {
	isl1208->config = of_device_get_match_data(&client->dev);
	if (!isl1208->config)
		return -ENODEV;
} else {
	const struct i2c_device_id *id = i2c_match_id(isl1208_id, client);

	if (!id)
		return -ENODEV;
	isl1208->config = (struct isl1208_config *)id->driver_data;
}

[2]
if (client->dev.of_node)
	isl1208->config = of_device_get_match_data(&client->dev);
else
	isl1208->config = i2c_get_match_data(isl1208_id, client);

if (!isl1208->config)
	return -ENODEV;

[3]
https://lore.kernel.org/linux-renesas-soc/20230522101849.297499-1-biju.das.jz@bp.renesas.com/T/#t
---
 drivers/i2c/i2c-core-base.c | 24 ++++++++++++++++++++++--
 include/linux/i2c.h         |  3 +++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 3442aa80290f..1ab639b2693c 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32 bus_freq_hz)
 }
 EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
 
-const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
-						const struct i2c_client *client)
+static const struct i2c_device_id *i2c_match_device_id(const struct i2c_device_id *id,
+						       const struct i2c_client *client)
 {
 	if (!(id && client))
 		return NULL;
@@ -110,10 +110,30 @@ const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
 			return id;
 		id++;
 	}
+
 	return NULL;
 }
+
+const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
+					 const struct i2c_client *client)
+{
+	return i2c_match_device_id(id, client);
+}
 EXPORT_SYMBOL_GPL(i2c_match_id);
 
+const void *i2c_get_match_data(const struct i2c_device_id *id,
+			       const struct i2c_client *client)
+{
+	const struct i2c_device_id *match;
+
+	match = i2c_match_device_id(id, client);
+	if (!match)
+		return NULL;
+
+	return (const void *)match->driver_data;
+}
+EXPORT_SYMBOL(i2c_get_match_data);
+
 static int i2c_device_match(struct device *dev, struct device_driver *drv)
 {
 	struct i2c_client	*client = i2c_verify_client(dev);
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 0ce344724209..ddfe842b8f24 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -367,6 +367,9 @@ struct i2c_adapter *i2c_verify_adapter(struct device *dev);
 const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
 					 const struct i2c_client *client);
 
+const void *i2c_get_match_data(const struct i2c_device_id *id,
+			       const struct i2c_client *client);
+
 static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
 {
 	struct device * const dev = kobj_to_dev(kobj);
-- 
2.25.1

Re: [PATCH] i2c: Add i2c_get_match_data()

[Geert Uytterhoeven]

Hi Biju,

On Mon, May 22, 2023 at 12:42 PM Biju Das <biju.das.jz@bp.renesas.com> wrote:
> Add i2c_get_match_data() similar to of_device_get_match_data(),
> so that we can optimize the driver code that uses both I2C and
> DT-based matching.
>
> Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>

Thanks for your patch!

> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32 bus_freq_hz)
>  }
>  EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
>
> -const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
> -                                               const struct i2c_client *client)
> +static const struct i2c_device_id *i2c_match_device_id(const struct i2c_device_id *id,
> +                                                      const struct i2c_client *client)
>  {
>         if (!(id && client))
>                 return NULL;
> @@ -110,10 +110,30 @@ const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
>                         return id;
>                 id++;
>         }
> +
>         return NULL;
>  }
> +
> +const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
> +                                        const struct i2c_client *client)
> +{
> +       return i2c_match_device_id(id, client);
> +}
>  EXPORT_SYMBOL_GPL(i2c_match_id);

Is there any reason why you're adding a new intermediate?

>
> +const void *i2c_get_match_data(const struct i2c_device_id *id,
> +                              const struct i2c_client *client)

I think this should take the id table from the i2c_driver, as pointed to
by client->dev.driver, instead of from an explicitly passed parameter.

> +{
> +       const struct i2c_device_id *match;
> +
> +       match = i2c_match_device_id(id, client);
> +       if (!match)
> +               return NULL;
> +
> +       return (const void *)match->driver_data;

One can discuss about the returned type: personally, I won't mind
"const void *" for consistency with other subsystems (e.g. DT), but
as i2c_device_id.driver_data has type "kernel_ulong_t", other people
might prefer the latter.

> +}
> +EXPORT_SYMBOL(i2c_get_match_data);

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

RE: [PATCH] i2c: Add i2c_get_match_data()

[Biju Das]

Hi Geert,

Thanks for the feedback.

> -----Original Message-----
> From: Geert Uytterhoeven <geert@linux-m68k.org>
> Sent: Monday, May 22, 2023 12:29 PM
> To: Biju Das <biju.das.jz@bp.renesas.com>
> Cc: Wolfram Sang <wsa@kernel.org>; linux-i2c@vger.kernel.org; Alessandro
> Zummo <a.zummo@towertech.it>; Alexandre Belloni
> <alexandre.belloni@bootlin.com>; Prabhakar Mahadev Lad
> <prabhakar.mahadev-lad.rj@bp.renesas.com>; linux-renesas-
> soc@vger.kernel.org
> Subject: Re: [PATCH] i2c: Add i2c_get_match_data()
> 
> Hi Biju,
> 
> On Mon, May 22, 2023 at 12:42 PM Biju Das <biju.das.jz@bp.renesas.com>
> wrote:
> > Add i2c_get_match_data() similar to of_device_get_match_data(), so
> > that we can optimize the driver code that uses both I2C and DT-based
> > matching.
> >
> > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/i2c/i2c-core-base.c
> > +++ b/drivers/i2c/i2c-core-base.c
> > @@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32 bus_freq_hz)  }
> > EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
> >
> > -const struct i2c_device_id *i2c_match_id(const struct i2c_device_id
> *id,
> > -                                               const struct
> i2c_client *client)
> > +static const struct i2c_device_id *i2c_match_device_id(const struct
> i2c_device_id *id,
> > +                                                      const struct
> > +i2c_client *client)
> >  {
> >         if (!(id && client))
> >                 return NULL;
> > @@ -110,10 +110,30 @@ const struct i2c_device_id *i2c_match_id(const
> struct i2c_device_id *id,
> >                         return id;
> >                 id++;
> >         }
> > +
> >         return NULL;
> >  }
> > +
> > +const struct i2c_device_id *i2c_match_id(const struct i2c_device_id
> *id,
> > +                                        const struct i2c_client
> > +*client) {
> > +       return i2c_match_device_id(id, client); }
> >  EXPORT_SYMBOL_GPL(i2c_match_id);
> 
> Is there any reason why you're adding a new intermediate?

The same code is shared between below function.
As discussed below, it is not required.

> 
> >
> > +const void *i2c_get_match_data(const struct i2c_device_id *id,
> > +                              const struct i2c_client *client)
> 
> I think this should take the id table from the i2c_driver, as pointed to
> by client->dev.driver, instead of from an explicitly passed parameter.

You mean const void *i2c_get_match_data(const struct i2c_client *client)??

struct i2c_driver	*driver = client->dev.driver;

And then call

match = i2c_match_id(driver->id_table, client)??

> 
> > +{
> > +       const struct i2c_device_id *match;
> > +
> > +       match = i2c_match_device_id(id, client);
> > +       if (!match)
> > +               return NULL;
> > +
> > +       return (const void *)match->driver_data;
> 
> One can discuss about the returned type: personally, I won't mind "const
> void *" for consistency with other subsystems (e.g. DT), but as
> i2c_device_id.driver_data has type "kernel_ulong_t", other people might
> prefer the latter.

The advantage of void*, is upper layer don't need casting.

eg: with kernel_ulong_t as return parameter:

isl1208->config = (struct isl1208_config *)i2c_get_match_data;

Cheers,
Biju



> 
> > +}
> > +EXPORT_SYMBOL(i2c_get_match_data);
> 

Re: [PATCH] i2c: Add i2c_get_match_data()

[Geert Uytterhoeven]

Hi Biju,

On Mon, May 22, 2023 at 2:38 PM Biju Das <biju.das.jz@bp.renesas.com> wrote:
> > -----Original Message-----
> > From: Geert Uytterhoeven <geert@linux-m68k.org>
> > Sent: Monday, May 22, 2023 12:29 PM
> > To: Biju Das <biju.das.jz@bp.renesas.com>
> > Cc: Wolfram Sang <wsa@kernel.org>; linux-i2c@vger.kernel.org; Alessandro
> > Zummo <a.zummo@towertech.it>; Alexandre Belloni
> > <alexandre.belloni@bootlin.com>; Prabhakar Mahadev Lad
> > <prabhakar.mahadev-lad.rj@bp.renesas.com>; linux-renesas-
> > soc@vger.kernel.org
> > Subject: Re: [PATCH] i2c: Add i2c_get_match_data()
> >
> > Hi Biju,
> >
> > On Mon, May 22, 2023 at 12:42 PM Biju Das <biju.das.jz@bp.renesas.com>
> > wrote:
> > > Add i2c_get_match_data() similar to of_device_get_match_data(), so
> > > that we can optimize the driver code that uses both I2C and DT-based
> > > matching.
> > >
> > > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> >
> > Thanks for your patch!
> >
> > > --- a/drivers/i2c/i2c-core-base.c
> > > +++ b/drivers/i2c/i2c-core-base.c
> > > @@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32 bus_freq_hz)  }
> > > EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
> > >
> > > -const struct i2c_device_id *i2c_match_id(const struct i2c_device_id
> > *id,
> > > -                                               const struct
> > i2c_client *client)
> > > +static const struct i2c_device_id *i2c_match_device_id(const struct
> > i2c_device_id *id,
> > > +                                                      const struct
> > > +i2c_client *client)
> > >  {
> > >         if (!(id && client))
> > >                 return NULL;
> > > @@ -110,10 +110,30 @@ const struct i2c_device_id *i2c_match_id(const
> > struct i2c_device_id *id,
> > >                         return id;
> > >                 id++;
> > >         }
> > > +
> > >         return NULL;
> > >  }
> > > +
> > > +const struct i2c_device_id *i2c_match_id(const struct i2c_device_id
> > *id,
> > > +                                        const struct i2c_client
> > > +*client) {
> > > +       return i2c_match_device_id(id, client); }
> > >  EXPORT_SYMBOL_GPL(i2c_match_id);
> >
> > Is there any reason why you're adding a new intermediate?
>
> The same code is shared between below function.
> As discussed below, it is not required.
>
> >
> > >
> > > +const void *i2c_get_match_data(const struct i2c_device_id *id,
> > > +                              const struct i2c_client *client)
> >
> > I think this should take the id table from the i2c_driver, as pointed to
> > by client->dev.driver, instead of from an explicitly passed parameter.
>
> You mean const void *i2c_get_match_data(const struct i2c_client *client)??
>
> struct i2c_driver       *driver = client->dev.driver;

also needs to_i2c_driver()

>
> And then call
>
> match = i2c_match_id(driver->id_table, client)??

Exactly.

> > > +{
> > > +       const struct i2c_device_id *match;
> > > +
> > > +       match = i2c_match_device_id(id, client);
> > > +       if (!match)
> > > +               return NULL;
> > > +
> > > +       return (const void *)match->driver_data;
> >
> > One can discuss about the returned type: personally, I won't mind "const
> > void *" for consistency with other subsystems (e.g. DT), but as
> > i2c_device_id.driver_data has type "kernel_ulong_t", other people might
> > prefer the latter.
>
> The advantage of void*, is upper layer don't need casting.

Depending on what the driver wants...
Some drivers want integers, other want pointers...

> eg: with kernel_ulong_t as return parameter:
>
> isl1208->config = (struct isl1208_config *)i2c_get_match_data;

I know ;-)
For the isl1208 case, "void *" simplifies the driver...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

RE: [PATCH] i2c: Add i2c_get_match_data()

[Biju Das]

Hi Geert,

Thanks for the feedback.

> Subject: Re: [PATCH] i2c: Add i2c_get_match_data()
> 
> Hi Biju,
> 
> On Mon, May 22, 2023 at 2:38 PM Biju Das <biju.das.jz@bp.renesas.com>
> wrote:
> > > -----Original Message-----
> > > From: Geert Uytterhoeven <geert@linux-m68k.org>
> > > Sent: Monday, May 22, 2023 12:29 PM
> > > To: Biju Das <biju.das.jz@bp.renesas.com>
> > > Cc: Wolfram Sang <wsa@kernel.org>; linux-i2c@vger.kernel.org;
> > > Alessandro Zummo <a.zummo@towertech.it>; Alexandre Belloni
> > > <alexandre.belloni@bootlin.com>; Prabhakar Mahadev Lad
> > > <prabhakar.mahadev-lad.rj@bp.renesas.com>; linux-renesas-
> > > soc@vger.kernel.org
> > > Subject: Re: [PATCH] i2c: Add i2c_get_match_data()
> > >
> > > Hi Biju,
> > >
> > > On Mon, May 22, 2023 at 12:42 PM Biju Das
> > > <biju.das.jz@bp.renesas.com>
> > > wrote:
> > > > Add i2c_get_match_data() similar to of_device_get_match_data(), so
> > > > that we can optimize the driver code that uses both I2C and
> > > > DT-based matching.
> > > >
> > > > Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > >
> > > Thanks for your patch!
> > >
> > > > --- a/drivers/i2c/i2c-core-base.c
> > > > +++ b/drivers/i2c/i2c-core-base.c
> > > > @@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32
> > > > bus_freq_hz)  } EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
> > > >
> > > > -const struct i2c_device_id *i2c_match_id(const struct
> > > > i2c_device_id
> > > *id,
> > > > -                                               const struct
> > > i2c_client *client)
> > > > +static const struct i2c_device_id *i2c_match_device_id(const
> > > > +struct
> > > i2c_device_id *id,
> > > > +                                                      const
> > > > +struct i2c_client *client)
> > > >  {
> > > >         if (!(id && client))
> > > >                 return NULL;
> > > > @@ -110,10 +110,30 @@ const struct i2c_device_id
> > > > *i2c_match_id(const
> > > struct i2c_device_id *id,
> > > >                         return id;
> > > >                 id++;
> > > >         }
> > > > +
> > > >         return NULL;
> > > >  }
> > > > +
> > > > +const struct i2c_device_id *i2c_match_id(const struct
> > > > +i2c_device_id
> > > *id,
> > > > +                                        const struct i2c_client
> > > > +*client) {
> > > > +       return i2c_match_device_id(id, client); }
> > > >  EXPORT_SYMBOL_GPL(i2c_match_id);
> > >
> > > Is there any reason why you're adding a new intermediate?
> >
> > The same code is shared between below function.
> > As discussed below, it is not required.
> >
> > >
> > > >
> > > > +const void *i2c_get_match_data(const struct i2c_device_id *id,
> > > > +                              const struct i2c_client *client)
> > >
> > > I think this should take the id table from the i2c_driver, as
> > > pointed to by client->dev.driver, instead of from an explicitly
> passed parameter.
> >
> > You mean const void *i2c_get_match_data(const struct i2c_client
> *client)??
> >
> > struct i2c_driver       *driver = client->dev.driver;
> 
> also needs to_i2c_driver()

OK.

> 
> >
> > And then call
> >
> > match = i2c_match_id(driver->id_table, client)??
> 
> Exactly.
> 
> > > > +{
> > > > +       const struct i2c_device_id *match;
> > > > +
> > > > +       match = i2c_match_device_id(id, client);
> > > > +       if (!match)
> > > > +               return NULL;
> > > > +
> > > > +       return (const void *)match->driver_data;
> > >
> > > One can discuss about the returned type: personally, I won't mind
> > > "const void *" for consistency with other subsystems (e.g. DT), but
> > > as i2c_device_id.driver_data has type "kernel_ulong_t", other people
> > > might prefer the latter.
> >
> > The advantage of void*, is upper layer don't need casting.
> 
> Depending on what the driver wants...
> Some drivers want integers, other want pointers...

For integer and enums, already most of the drivers are using like this
chip_id = i2c_match_id(max20730_id, client)->driver_data;

> 
> > eg: with kernel_ulong_t as return parameter:
> >
> > isl1208->config = (struct isl1208_config *)i2c_get_match_data;
> 
> I know ;-)
> For the isl1208 case, "void *" simplifies the driver...

But with return type as "void *" the below drivers can make use of it,
as these drivers never checks return type for "i2c_match_id".

drivers/iio/potentiometer/mcp4018.c:		data->cfg = &mcp4018_cfg[i2c_match_id(mcp4018_id, client)->driver_data];

drivers/iio/accel/adxl313_i2c.c:		chip_data = (const struct adxl313_chip_info *)i2c_match_id(adxl313_i2c_id, client)->driver_data;

drivers/iio/accel/adxl355_i2c.c:		chip_data = (void *)i2c_match_id(adxl355, client)->driver_data;

drivers/rtc/rtc-pcf85063.c-		config = &pcf85063_cfg[type];

drivers/i2c/muxes/i2c-mux-ltc4306.c:		chip = &chips[i2c_match_id(ltc4306_id, client)->driver_data];

drivers/hwmon/sht3x.c-		attribute_groups = sts3x_groups;

drivers/hwmon/pmbus/pmbus.c:	device_info = (struct pmbus_device_info *)i2c_match_id(pmbus_id, client)->driver_data;

I will send next version based on return type as void*,

Based on wider feedback if needed will change return type.

Hope it is ok??

Cheers,
Biju