Patchwork [3/7] i2c: Add the ability to match device to compatible string without an of_node

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Submitter Lee Jones
Date June 4, 2014, 12:09 p.m.
Message ID <1401883796-17841-4-git-send-email-lee.jones@linaro.org>
Download mbox | patch
Permalink /patch/355881/
State Superseded
Headers show

Comments

Lee Jones - June 4, 2014, 12:09 p.m.
A great deal of I2C devices are currently matched via DT node name, and
as such the compatible naming convention of '<vendor>,<device>' has gone
somewhat awry - some nodes don't supply one, some supply an arbitrary
string and others the correct device name with an arbitrary vendor prefix.

In an effort to correct this problem we have to supply a mechanism to
match a device by compatible string AND by simple device name.  This
function strips off the '<vendor>,' part of a supplied compatible string
and attempts to match without it.

The plan is to remove this function once all of the compatible strings
for each device have been brought into line.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/i2c/i2c-core.c | 25 +++++++++++++++++++++++++
 include/linux/i2c.h    | 10 ++++++++++
 2 files changed, 35 insertions(+)
Rob Herring - June 4, 2014, 5:29 p.m.
On Wed, Jun 4, 2014 at 7:09 AM, Lee Jones <lee.jones@linaro.org> wrote:
> A great deal of I2C devices are currently matched via DT node name, and
> as such the compatible naming convention of '<vendor>,<device>' has gone
> somewhat awry - some nodes don't supply one, some supply an arbitrary
> string and others the correct device name with an arbitrary vendor prefix.
>
> In an effort to correct this problem we have to supply a mechanism to
> match a device by compatible string AND by simple device name.  This
> function strips off the '<vendor>,' part of a supplied compatible string
> and attempts to match without it.
>
> The plan is to remove this function once all of the compatible strings
> for each device have been brought into line.

Then should you add a warning for cases needing to be fixed?

Rob

>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/i2c/i2c-core.c | 25 +++++++++++++++++++++++++
>  include/linux/i2c.h    | 10 ++++++++++
>  2 files changed, 35 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index d3802dc..7dcd5c3 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -1090,6 +1090,31 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>         return i2c_verify_adapter(dev);
>  }
>  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> +
> +const struct of_device_id
> +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> +                                 struct device *dev)
> +{
> +       const struct i2c_client *client = i2c_verify_client(dev);
> +       const char *name;
> +
> +       if (!(client && matches))
> +               return NULL;
> +
> +       for (; matches->compatible[0]; matches++) {
> +               name = strchr(matches->compatible, ',');
> +               if (!name)
> +                       name = matches->compatible;
> +               else
> +                       name++;
> +
> +               if (!strncmp(client->name, name, strlen(client->name)))
> +                       return matches;
> +       }
> +
> +       return NULL;
> +}
> +EXPORT_SYMBOL_GPL(i2c_of_match_device_strip_vendor);
>  #else
>  static void of_i2c_register_devices(struct i2c_adapter *adap) { }
>  #endif /* CONFIG_OF */
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index b556e0a..f7ec75b 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -564,6 +564,9 @@ extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
>  /* must call put_device() when done with returned i2c_adapter device */
>  extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
>
> +extern const struct of_device_id
> +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> +                                 struct device *dev);
>  #else
>
>  static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
> @@ -575,6 +578,13 @@ static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node
>  {
>         return NULL;
>  }
> +
> +const struct of_device_id
> +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> +                                 struct device *dev)
> +{
> +       return NULL;
> +}
>  #endif /* CONFIG_OF */
>
>  #endif /* _LINUX_I2C_H */
> --
> 1.8.3.2
>
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Lee Jones - June 4, 2014, 5:55 p.m.
On Wed, 04 Jun 2014, Rob Herring wrote:

> On Wed, Jun 4, 2014 at 7:09 AM, Lee Jones <lee.jones@linaro.org> wrote:
> > A great deal of I2C devices are currently matched via DT node name, and
> > as such the compatible naming convention of '<vendor>,<device>' has gone
> > somewhat awry - some nodes don't supply one, some supply an arbitrary
> > string and others the correct device name with an arbitrary vendor prefix.
> >
> > In an effort to correct this problem we have to supply a mechanism to
> > match a device by compatible string AND by simple device name.  This
> > function strips off the '<vendor>,' part of a supplied compatible string
> > and attempts to match without it.
> >
> > The plan is to remove this function once all of the compatible strings
> > for each device have been brought into line.
> 
> Then should you add a warning for cases needing to be fixed?

I was just going to go and fix them all, but I could do that as well?

> > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > ---
> >  drivers/i2c/i2c-core.c | 25 +++++++++++++++++++++++++
> >  include/linux/i2c.h    | 10 ++++++++++
> >  2 files changed, 35 insertions(+)
> >
> > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> > index d3802dc..7dcd5c3 100644
> > --- a/drivers/i2c/i2c-core.c
> > +++ b/drivers/i2c/i2c-core.c
> > @@ -1090,6 +1090,31 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
> >         return i2c_verify_adapter(dev);
> >  }
> >  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> > +
> > +const struct of_device_id
> > +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> > +                                 struct device *dev)
> > +{
> > +       const struct i2c_client *client = i2c_verify_client(dev);
> > +       const char *name;
> > +
> > +       if (!(client && matches))
> > +               return NULL;
> > +
> > +       for (; matches->compatible[0]; matches++) {
> > +               name = strchr(matches->compatible, ',');
> > +               if (!name)
> > +                       name = matches->compatible;
> > +               else
> > +                       name++;
> > +
> > +               if (!strncmp(client->name, name, strlen(client->name)))
> > +                       return matches;
> > +       }
> > +
> > +       return NULL;
> > +}
> > +EXPORT_SYMBOL_GPL(i2c_of_match_device_strip_vendor);
> >  #else
> >  static void of_i2c_register_devices(struct i2c_adapter *adap) { }
> >  #endif /* CONFIG_OF */
> > diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> > index b556e0a..f7ec75b 100644
> > --- a/include/linux/i2c.h
> > +++ b/include/linux/i2c.h
> > @@ -564,6 +564,9 @@ extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
> >  /* must call put_device() when done with returned i2c_adapter device */
> >  extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
> >
> > +extern const struct of_device_id
> > +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> > +                                 struct device *dev);
> >  #else
> >
> >  static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
> > @@ -575,6 +578,13 @@ static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node
> >  {
> >         return NULL;
> >  }
> > +
> > +const struct of_device_id
> > +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> > +                                 struct device *dev)
> > +{
> > +       return NULL;
> > +}
> >  #endif /* CONFIG_OF */
> >
> >  #endif /* _LINUX_I2C_H */
> >
Grant Likely - June 5, 2014, 5:36 p.m.
On Wed,  4 Jun 2014 13:09:52 +0100, Lee Jones <lee.jones@linaro.org> wrote:
> A great deal of I2C devices are currently matched via DT node name, and
> as such the compatible naming convention of '<vendor>,<device>' has gone
> somewhat awry - some nodes don't supply one, some supply an arbitrary
> string and others the correct device name with an arbitrary vendor prefix.
> 
> In an effort to correct this problem we have to supply a mechanism to
> match a device by compatible string AND by simple device name.  This
> function strips off the '<vendor>,' part of a supplied compatible string
> and attempts to match without it.
> 
> The plan is to remove this function once all of the compatible strings
> for each device have been brought into line.
> 
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/i2c/i2c-core.c | 25 +++++++++++++++++++++++++
>  include/linux/i2c.h    | 10 ++++++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index d3802dc..7dcd5c3 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -1090,6 +1090,31 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>  	return i2c_verify_adapter(dev);
>  }
>  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> +
> +const struct of_device_id
> +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> +				  struct device *dev)
> +{
> +	const struct i2c_client *client = i2c_verify_client(dev);
> +	const char *name;
> +
> +	if (!(client && matches))
> +		return NULL;
> +
> +	for (; matches->compatible[0]; matches++) {
> +		name = strchr(matches->compatible, ',');
> +		if (!name)
> +			name = matches->compatible;
> +		else
> +			name++;
> +
> +		if (!strncmp(client->name, name, strlen(client->name)))
> +			return matches;
> +	}

Is it actually necessary to strip off the vendor name? It would be fine
to make users include the vendor prefix when creating the device in
sysfs. In fact that would be preferrable for new drivers so that vendor
prefixes start getting used correctly.

If you're worried about preserving exisiting ABI, then I would make
striping the prefix an option that drivers can enable, but by default
only match on the full string.

g.
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Lee Jones - June 6, 2014, 8:10 a.m.
On Thu, 05 Jun 2014, Grant Likely wrote:

> On Wed,  4 Jun 2014 13:09:52 +0100, Lee Jones <lee.jones@linaro.org> wrote:
> > A great deal of I2C devices are currently matched via DT node name, and
> > as such the compatible naming convention of '<vendor>,<device>' has gone
> > somewhat awry - some nodes don't supply one, some supply an arbitrary
> > string and others the correct device name with an arbitrary vendor prefix.
> > 
> > In an effort to correct this problem we have to supply a mechanism to
> > match a device by compatible string AND by simple device name.  This
> > function strips off the '<vendor>,' part of a supplied compatible string
> > and attempts to match without it.
> > 
> > The plan is to remove this function once all of the compatible strings
> > for each device have been brought into line.
> > 
> > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > ---
> >  drivers/i2c/i2c-core.c | 25 +++++++++++++++++++++++++
> >  include/linux/i2c.h    | 10 ++++++++++
> >  2 files changed, 35 insertions(+)
> > 
> > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> > index d3802dc..7dcd5c3 100644
> > --- a/drivers/i2c/i2c-core.c
> > +++ b/drivers/i2c/i2c-core.c
> > @@ -1090,6 +1090,31 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
> >  	return i2c_verify_adapter(dev);
> >  }
> >  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> > +
> > +const struct of_device_id
> > +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> > +				  struct device *dev)
> > +{
> > +	const struct i2c_client *client = i2c_verify_client(dev);
> > +	const char *name;
> > +
> > +	if (!(client && matches))
> > +		return NULL;
> > +
> > +	for (; matches->compatible[0]; matches++) {
> > +		name = strchr(matches->compatible, ',');
> > +		if (!name)
> > +			name = matches->compatible;
> > +		else
> > +			name++;
> > +
> > +		if (!strncmp(client->name, name, strlen(client->name)))
> > +			return matches;
> > +	}
> 
> Is it actually necessary to strip off the vendor name? It would be fine
> to make users include the vendor prefix when creating the device in
> sysfs. In fact that would be preferrable for new drivers so that vendor
> prefixes start getting used correctly.

I see a few issues with this strategy.  Firstly, there are already
users registering their devices via sysfs, some are taking their
device names from an EEPROM which would require reprogramming in order
to prefix the vendor ID.  I'm keen not to break existing systems -
which not stripping off the vendor name would inevitably do.
Secondly, I'm not sure how Wolfram would feel about the client->name
containing a DT compatible string. And finally, other than looking
at the kernel source, there is no real way for a user to know if the
device supports ACPI or OF, or neither and if an i2c_device_table is
supplied or not.

Remember that the idea of this set is to remove i2c_device_table's,
doing so will break any devices which are still registering via sysfs
with only the model number of the device.  I think the sysfs
interface should be a black-box.  I think requiring users to have
kernel knowledge is a sub-optimal idea.

> If you're worried about preserving exisiting ABI, then I would make
> striping the prefix an option that drivers can enable, but by default
> only match on the full string.
> 
> g.
Grant Likely - June 6, 2014, 11:39 p.m.
On Fri, 6 Jun 2014 09:10:26 +0100, Lee Jones <lee.jones@linaro.org> wrote:
> On Thu, 05 Jun 2014, Grant Likely wrote:
> 
> > On Wed,  4 Jun 2014 13:09:52 +0100, Lee Jones <lee.jones@linaro.org> wrote:
> > > A great deal of I2C devices are currently matched via DT node name, and
> > > as such the compatible naming convention of '<vendor>,<device>' has gone
> > > somewhat awry - some nodes don't supply one, some supply an arbitrary
> > > string and others the correct device name with an arbitrary vendor prefix.
> > > 
> > > In an effort to correct this problem we have to supply a mechanism to
> > > match a device by compatible string AND by simple device name.  This
> > > function strips off the '<vendor>,' part of a supplied compatible string
> > > and attempts to match without it.
> > > 
> > > The plan is to remove this function once all of the compatible strings
> > > for each device have been brought into line.
> > > 
> > > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > > ---
> > >  drivers/i2c/i2c-core.c | 25 +++++++++++++++++++++++++
> > >  include/linux/i2c.h    | 10 ++++++++++
> > >  2 files changed, 35 insertions(+)
> > > 
> > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> > > index d3802dc..7dcd5c3 100644
> > > --- a/drivers/i2c/i2c-core.c
> > > +++ b/drivers/i2c/i2c-core.c
> > > @@ -1090,6 +1090,31 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
> > >  	return i2c_verify_adapter(dev);
> > >  }
> > >  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> > > +
> > > +const struct of_device_id
> > > +*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> > > +				  struct device *dev)
> > > +{
> > > +	const struct i2c_client *client = i2c_verify_client(dev);
> > > +	const char *name;
> > > +
> > > +	if (!(client && matches))
> > > +		return NULL;
> > > +
> > > +	for (; matches->compatible[0]; matches++) {
> > > +		name = strchr(matches->compatible, ',');
> > > +		if (!name)
> > > +			name = matches->compatible;
> > > +		else
> > > +			name++;
> > > +
> > > +		if (!strncmp(client->name, name, strlen(client->name)))
> > > +			return matches;
> > > +	}
> > 
> > Is it actually necessary to strip off the vendor name? It would be fine
> > to make users include the vendor prefix when creating the device in
> > sysfs. In fact that would be preferrable for new drivers so that vendor
> > prefixes start getting used correctly.
> 
> I see a few issues with this strategy.  Firstly, there are already
> users registering their devices via sysfs, some are taking their
> device names from an EEPROM which would require reprogramming in order
> to prefix the vendor ID.  I'm keen not to break existing systems -
> which not stripping off the vendor name would inevitably do.
> Secondly, I'm not sure how Wolfram would feel about the client->name
> containing a DT compatible string. And finally, other than looking
> at the kernel source, there is no real way for a user to know if the
> device supports ACPI or OF, or neither and if an i2c_device_table is
> supplied or not.

I just went and looked at the code. I2C_NAME_SIZE is fixed to 20
characters. Compatible strings can be larger than that, so you're right.
Stuffing it into the name field isn't a good solution.

g.
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Patch

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index d3802dc..7dcd5c3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1090,6 +1090,31 @@  struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
 	return i2c_verify_adapter(dev);
 }
 EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
+
+const struct of_device_id
+*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
+				  struct device *dev)
+{
+	const struct i2c_client *client = i2c_verify_client(dev);
+	const char *name;
+
+	if (!(client && matches))
+		return NULL;
+
+	for (; matches->compatible[0]; matches++) {
+		name = strchr(matches->compatible, ',');
+		if (!name)
+			name = matches->compatible;
+		else
+			name++;
+
+		if (!strncmp(client->name, name, strlen(client->name)))
+			return matches;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(i2c_of_match_device_strip_vendor);
 #else
 static void of_i2c_register_devices(struct i2c_adapter *adap) { }
 #endif /* CONFIG_OF */
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index b556e0a..f7ec75b 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -564,6 +564,9 @@  extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
 /* must call put_device() when done with returned i2c_adapter device */
 extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
 
+extern const struct of_device_id
+*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
+				  struct device *dev);
 #else
 
 static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
@@ -575,6 +578,13 @@  static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node
 {
 	return NULL;
 }
+
+const struct of_device_id
+*i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
+				  struct device *dev)
+{
+	return NULL;
+}
 #endif /* CONFIG_OF */
 
 #endif /* _LINUX_I2C_H */