[PATCH v2 0/2] base: soc: soc_device_match() improvements

[PATCH v2 0/2] base: soc: soc_device_match() improvements

[Geert Uytterhoeven]

	Hi Arnd, Greg, Kevin, Magnus, Olof, Simon,

This patch series contains two improvements for the SoC bus and
soc_device_match().  The second one is a dependency for handling
different SoC revisions in the Renesas R-Car SYSC driver, which manages
PM Domains and thus needs to be initialized from an early_initcall[*].

Changes compared to v1:
  - Drop RFC state,
  - Add more explanation,
  - Add Acked-by.

Due to the dependency, and as changes for the Renesas R-Car SYSC driver
typically go in through the renesas and arm-soc trees, and if you agree,
I would like to send a pull request for these changes, to be pulled by
all of the driver core, renesas, and arm-soc trees.  This is similar to
how soc_device_match() was integrated earlier.
Then the Renesas R-Car SYSC driver changes can easily be queued on top
in the renesas tree afterwards.

Do you agree?
Thanks for your answer!

P.S. If you think it's already too late in the cycle to queue Renesas
R-Car SYSC driver changes for v4.12 on top, please say so.  Then the
dependency is relaxed, and this series can just go in through the
driver core tree, with the Renesas part to follow for v4.13.

[*] "[PATCH 0/3] soc: renesas: rcar-sysc: Add support for R-Car H3
     ES2.0" (https://lkml.org/lkml/2017/3/13/833), will send v2 with
     patch description changes only soon.

Geert Uytterhoeven (2):
  base: soc: Let soc_device_match() return no match when called too
    early
  base: soc: Allow early registration of a single SoC device

 drivers/base/soc.c | 52 ++++++++++++++++++++++++++++++++++------------------
 1 file changed, 34 insertions(+), 18 deletions(-)

-- 
2.7.4

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

[PATCH v2 0/2] base: soc: soc_device_match() improvements

[Geert Uytterhoeven]

	Hi Arnd, Greg, Kevin, Magnus, Olof, Simon,

This patch series contains two improvements for the SoC bus and
soc_device_match().  The second one is a dependency for handling
different SoC revisions in the Renesas R-Car SYSC driver, which manages
PM Domains and thus needs to be initialized from an early_initcall[*].

Changes compared to v1:
  - Drop RFC state,
  - Add more explanation,
  - Add Acked-by.

Due to the dependency, and as changes for the Renesas R-Car SYSC driver
typically go in through the renesas and arm-soc trees, and if you agree,
I would like to send a pull request for these changes, to be pulled by
all of the driver core, renesas, and arm-soc trees.  This is similar to
how soc_device_match() was integrated earlier.
Then the Renesas R-Car SYSC driver changes can easily be queued on top
in the renesas tree afterwards.

Do you agree?
Thanks for your answer!

P.S. If you think it's already too late in the cycle to queue Renesas
R-Car SYSC driver changes for v4.12 on top, please say so.  Then the
dependency is relaxed, and this series can just go in through the
driver core tree, with the Renesas part to follow for v4.13.

[*] "[PATCH 0/3] soc: renesas: rcar-sysc: Add support for R-Car H3
     ES2.0" (https://lkml.org/lkml/2017/3/13/833), will send v2 with
     patch description changes only soon.

Geert Uytterhoeven (2):
  base: soc: Let soc_device_match() return no match when called too
    early
  base: soc: Allow early registration of a single SoC device

 drivers/base/soc.c | 52 ++++++++++++++++++++++++++++++++++------------------
 1 file changed, 34 insertions(+), 18 deletions(-)

-- 
2.7.4

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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

[PATCH v2 1/2] base: soc: Let soc_device_match() return no match when called too early

[Geert Uytterhoeven]

If soc_device_match() is called before the SoC bus has been registered,
bus_for_each_dev() returns -EINVAL, which is considered a match, as it
is non-zero.

While calling soc_device_match() too early can be considered an
integration mistake, returning a match is counter-intuitive:
soc_device_match() is typically used to handle quirks, i.e. to deviate
from the default path.  Hence add a check to abort checking and return
no match instead.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
v2:
  - Drop RFC state,
  - Add Acked-by,
  - Add missing "too early" to second paragraph of description.
---
 drivers/base/soc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/soc.c b/drivers/base/soc.c
index dc26e5949a320223..50033081834a9ccd 100644
--- a/drivers/base/soc.c
+++ b/drivers/base/soc.c
@@ -230,6 +230,8 @@ const struct soc_device_attribute *soc_device_match(
 			break;
 		ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches,
 				       soc_device_match_one);
+		if (ret < 0)
+			return NULL;
 		if (!ret)
 			matches++;
 		else
-- 
2.7.4

[PATCH v2 1/2] base: soc: Let soc_device_match() return no match when called too early

[Geert Uytterhoeven]

If soc_device_match() is called before the SoC bus has been registered,
bus_for_each_dev() returns -EINVAL, which is considered a match, as it
is non-zero.

While calling soc_device_match() too early can be considered an
integration mistake, returning a match is counter-intuitive:
soc_device_match() is typically used to handle quirks, i.e. to deviate
from the default path.  Hence add a check to abort checking and return
no match instead.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
v2:
  - Drop RFC state,
  - Add Acked-by,
  - Add missing "too early" to second paragraph of description.
---
 drivers/base/soc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/soc.c b/drivers/base/soc.c
index dc26e5949a320223..50033081834a9ccd 100644
--- a/drivers/base/soc.c
+++ b/drivers/base/soc.c
@@ -230,6 +230,8 @@ const struct soc_device_attribute *soc_device_match(
 			break;
 		ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches,
 				       soc_device_match_one);
+		if (ret < 0)
+			return NULL;
 		if (!ret)
 			matches++;
 		else
-- 
2.7.4

[PATCH v2 2/2] base: soc: Allow early registration of a single SoC device

[Geert Uytterhoeven]

Commit 1da1b3628df34a2a ("base: soc: Early register bus when needed")
added support for early registration of SoC devices from a
core_initcall().  However, some drivers need to check the SoC revision
from an early_initcall(), which is even earlier.

A specific example is the Renesas R-Car SYSC driver, which manages PM
Domains and thus needs to be initialized from an early_initcall.
Preproduction versions of the R-Car H3 SoC have an additional power
area, which no longer exists on H3 ES2.0, so the R-Car SYSC driver needs
to check the exact SoC revision before instantiating a PM Domain for
that power area.

While registering the SoC bus and device, and using soc_device_match(),
from an early_initcall() do work, the "soc" directory and the "soc0"
file end up wrongly in the sysfs root, as the "bus" resp. "devices"
directories haven't been created yet.

To fix this, allow to register a single SoC device early on.
As long as the SoC bus isn't registered, soc_device_match() just
matches against this early device.
When the SoC bus is registered later, the early device is registered for
real.

Note that soc_device_register() returns NULL (no error, but also not a
valid pointer) when registering an early device.  Hence platform devices
cannot be instantiated as children of the "soc0" node representing an
early SoC device.  This should not be an issue, as that practice has
been deprecated for new platforms.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
v2:
  - Drop RFC state,
  - Add more explanation,
  - Add Acked-by.
---
 drivers/base/soc.c | 50 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/drivers/base/soc.c b/drivers/base/soc.c
index 50033081834a9ccd..909dedae4c4e1d48 100644
--- a/drivers/base/soc.c
+++ b/drivers/base/soc.c
@@ -109,15 +109,18 @@ static void soc_release(struct device *dev)
 	kfree(soc_dev);
 }
 
+static struct soc_device_attribute *early_soc_dev_attr;
+
 struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
 {
 	struct soc_device *soc_dev;
 	int ret;
 
 	if (!soc_bus_type.p) {
-		ret = bus_register(&soc_bus_type);
-		if (ret)
-			goto out1;
+		if (early_soc_dev_attr)
+			return ERR_PTR(-EBUSY);
+		early_soc_dev_attr = soc_dev_attr;
+		return NULL;
 	}
 
 	soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);
@@ -159,45 +162,53 @@ void soc_device_unregister(struct soc_device *soc_dev)
 	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
 
 	device_unregister(&soc_dev->dev);
+	early_soc_dev_attr = NULL;
 }
 
 static int __init soc_bus_register(void)
 {
-	if (soc_bus_type.p)
-		return 0;
+	int ret;
 
-	return bus_register(&soc_bus_type);
+	ret = bus_register(&soc_bus_type);
+	if (ret)
+		return ret;
+
+	if (early_soc_dev_attr)
+		return PTR_ERR(soc_device_register(early_soc_dev_attr));
+
+	return 0;
 }
 core_initcall(soc_bus_register);
 
-static int soc_device_match_one(struct device *dev, void *arg)
+static int soc_device_match_attr(const struct soc_device_attribute *attr,
+				 const struct soc_device_attribute *match)
 {
-	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
-	const struct soc_device_attribute *match = arg;
-
 	if (match->machine &&
-	    (!soc_dev->attr->machine ||
-	     !glob_match(match->machine, soc_dev->attr->machine)))
+	    (!attr->machine || !glob_match(match->machine, attr->machine)))
 		return 0;
 
 	if (match->family &&
-	    (!soc_dev->attr->family ||
-	     !glob_match(match->family, soc_dev->attr->family)))
+	    (!attr->family || !glob_match(match->family, attr->family)))
 		return 0;
 
 	if (match->revision &&
-	    (!soc_dev->attr->revision ||
-	     !glob_match(match->revision, soc_dev->attr->revision)))
+	    (!attr->revision || !glob_match(match->revision, attr->revision)))
 		return 0;
 
 	if (match->soc_id &&
-	    (!soc_dev->attr->soc_id ||
-	     !glob_match(match->soc_id, soc_dev->attr->soc_id)))
+	    (!attr->soc_id || !glob_match(match->soc_id, attr->soc_id)))
 		return 0;
 
 	return 1;
 }
 
+static int soc_device_match_one(struct device *dev, void *arg)
+{
+	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
+
+	return soc_device_match_attr(soc_dev->attr, arg);
+}
+
 /*
  * soc_device_match - identify the SoC in the machine
  * @matches: zero-terminated array of possible matches
@@ -230,6 +241,9 @@ const struct soc_device_attribute *soc_device_match(
 			break;
 		ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches,
 				       soc_device_match_one);
+		if (ret < 0 && early_soc_dev_attr)
+			ret = soc_device_match_attr(early_soc_dev_attr,
+						    matches);
 		if (ret < 0)
 			return NULL;
 		if (!ret)
-- 
2.7.4

[PATCH v2 2/2] base: soc: Allow early registration of a single SoC device

[Geert Uytterhoeven]

Commit 1da1b3628df34a2a ("base: soc: Early register bus when needed")
added support for early registration of SoC devices from a
core_initcall().  However, some drivers need to check the SoC revision
from an early_initcall(), which is even earlier.

A specific example is the Renesas R-Car SYSC driver, which manages PM
Domains and thus needs to be initialized from an early_initcall.
Preproduction versions of the R-Car H3 SoC have an additional power
area, which no longer exists on H3 ES2.0, so the R-Car SYSC driver needs
to check the exact SoC revision before instantiating a PM Domain for
that power area.

While registering the SoC bus and device, and using soc_device_match(),
from an early_initcall() do work, the "soc" directory and the "soc0"
file end up wrongly in the sysfs root, as the "bus" resp. "devices"
directories haven't been created yet.

To fix this, allow to register a single SoC device early on.
As long as the SoC bus isn't registered, soc_device_match() just
matches against this early device.
When the SoC bus is registered later, the early device is registered for
real.

Note that soc_device_register() returns NULL (no error, but also not a
valid pointer) when registering an early device.  Hence platform devices
cannot be instantiated as children of the "soc0" node representing an
early SoC device.  This should not be an issue, as that practice has
been deprecated for new platforms.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
v2:
  - Drop RFC state,
  - Add more explanation,
  - Add Acked-by.
---
 drivers/base/soc.c | 50 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/drivers/base/soc.c b/drivers/base/soc.c
index 50033081834a9ccd..909dedae4c4e1d48 100644
--- a/drivers/base/soc.c
+++ b/drivers/base/soc.c
@@ -109,15 +109,18 @@ static void soc_release(struct device *dev)
 	kfree(soc_dev);
 }
 
+static struct soc_device_attribute *early_soc_dev_attr;
+
 struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
 {
 	struct soc_device *soc_dev;
 	int ret;
 
 	if (!soc_bus_type.p) {
-		ret = bus_register(&soc_bus_type);
-		if (ret)
-			goto out1;
+		if (early_soc_dev_attr)
+			return ERR_PTR(-EBUSY);
+		early_soc_dev_attr = soc_dev_attr;
+		return NULL;
 	}
 
 	soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);
@@ -159,45 +162,53 @@ void soc_device_unregister(struct soc_device *soc_dev)
 	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
 
 	device_unregister(&soc_dev->dev);
+	early_soc_dev_attr = NULL;
 }
 
 static int __init soc_bus_register(void)
 {
-	if (soc_bus_type.p)
-		return 0;
+	int ret;
 
-	return bus_register(&soc_bus_type);
+	ret = bus_register(&soc_bus_type);
+	if (ret)
+		return ret;
+
+	if (early_soc_dev_attr)
+		return PTR_ERR(soc_device_register(early_soc_dev_attr));
+
+	return 0;
 }
 core_initcall(soc_bus_register);
 
-static int soc_device_match_one(struct device *dev, void *arg)
+static int soc_device_match_attr(const struct soc_device_attribute *attr,
+				 const struct soc_device_attribute *match)
 {
-	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
-	const struct soc_device_attribute *match = arg;
-
 	if (match->machine &&
-	    (!soc_dev->attr->machine ||
-	     !glob_match(match->machine, soc_dev->attr->machine)))
+	    (!attr->machine || !glob_match(match->machine, attr->machine)))
 		return 0;
 
 	if (match->family &&
-	    (!soc_dev->attr->family ||
-	     !glob_match(match->family, soc_dev->attr->family)))
+	    (!attr->family || !glob_match(match->family, attr->family)))
 		return 0;
 
 	if (match->revision &&
-	    (!soc_dev->attr->revision ||
-	     !glob_match(match->revision, soc_dev->attr->revision)))
+	    (!attr->revision || !glob_match(match->revision, attr->revision)))
 		return 0;
 
 	if (match->soc_id &&
-	    (!soc_dev->attr->soc_id ||
-	     !glob_match(match->soc_id, soc_dev->attr->soc_id)))
+	    (!attr->soc_id || !glob_match(match->soc_id, attr->soc_id)))
 		return 0;
 
 	return 1;
 }
 
+static int soc_device_match_one(struct device *dev, void *arg)
+{
+	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
+
+	return soc_device_match_attr(soc_dev->attr, arg);
+}
+
 /*
  * soc_device_match - identify the SoC in the machine
  * @matches: zero-terminated array of possible matches
@@ -230,6 +241,9 @@ const struct soc_device_attribute *soc_device_match(
 			break;
 		ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches,
 				       soc_device_match_one);
+		if (ret < 0 && early_soc_dev_attr)
+			ret = soc_device_match_attr(early_soc_dev_attr,
+						    matches);
 		if (ret < 0)
 			return NULL;
 		if (!ret)
-- 
2.7.4

Re: [PATCH v2 0/2] base: soc: soc_device_match() improvements

[Arnd Bergmann]

On Wed, Mar 29, 2017 at 9:38 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
>         Hi Arnd, Greg, Kevin, Magnus, Olof, Simon,
>
> This patch series contains two improvements for the SoC bus and
> soc_device_match().  The second one is a dependency for handling
> different SoC revisions in the Renesas R-Car SYSC driver, which manages
> PM Domains and thus needs to be initialized from an early_initcall[*].
>
> Changes compared to v1:
>   - Drop RFC state,
>   - Add more explanation,
>   - Add Acked-by.
>
> Due to the dependency, and as changes for the Renesas R-Car SYSC driver
> typically go in through the renesas and arm-soc trees, and if you agree,
> I would like to send a pull request for these changes, to be pulled by
> all of the driver core, renesas, and arm-soc trees.  This is similar to
> how soc_device_match() was integrated earlier.
> Then the Renesas R-Car SYSC driver changes can easily be queued on top
> in the renesas tree afterwards.
>
> Do you agree?
> Thanks for your answer!

Merging this through arm-soc is fine with me.

> P.S. If you think it's already too late in the cycle to queue Renesas
> R-Car SYSC driver changes for v4.12 on top, please say so.  Then the
> dependency is relaxed, and this series can just go in through the
> driver core tree, with the Renesas part to follow for v4.13.

We can take it for 4.12.

      Arnd

[PATCH v2 0/2] base: soc: soc_device_match() improvements

[Arnd Bergmann]

On Wed, Mar 29, 2017 at 9:38 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
>         Hi Arnd, Greg, Kevin, Magnus, Olof, Simon,
>
> This patch series contains two improvements for the SoC bus and
> soc_device_match().  The second one is a dependency for handling
> different SoC revisions in the Renesas R-Car SYSC driver, which manages
> PM Domains and thus needs to be initialized from an early_initcall[*].
>
> Changes compared to v1:
>   - Drop RFC state,
>   - Add more explanation,
>   - Add Acked-by.
>
> Due to the dependency, and as changes for the Renesas R-Car SYSC driver
> typically go in through the renesas and arm-soc trees, and if you agree,
> I would like to send a pull request for these changes, to be pulled by
> all of the driver core, renesas, and arm-soc trees.  This is similar to
> how soc_device_match() was integrated earlier.
> Then the Renesas R-Car SYSC driver changes can easily be queued on top
> in the renesas tree afterwards.
>
> Do you agree?
> Thanks for your answer!

Merging this through arm-soc is fine with me.

> P.S. If you think it's already too late in the cycle to queue Renesas
> R-Car SYSC driver changes for v4.12 on top, please say so.  Then the
> dependency is relaxed, and this series can just go in through the
> driver core tree, with the Renesas part to follow for v4.13.

We can take it for 4.12.

      Arnd

Re: [PATCH v2 0/2] base: soc: soc_device_match() improvements

[Simon Horman]

On Wed, Mar 29, 2017 at 09:48:48PM +0200, Arnd Bergmann wrote:
> On Wed, Mar 29, 2017 at 9:38 PM, Geert Uytterhoeven
> <geert+renesas@glider.be> wrote:
> >         Hi Arnd, Greg, Kevin, Magnus, Olof, Simon,
> >
> > This patch series contains two improvements for the SoC bus and
> > soc_device_match().  The second one is a dependency for handling
> > different SoC revisions in the Renesas R-Car SYSC driver, which manages
> > PM Domains and thus needs to be initialized from an early_initcall[*].
> >
> > Changes compared to v1:
> >   - Drop RFC state,
> >   - Add more explanation,
> >   - Add Acked-by.
> >
> > Due to the dependency, and as changes for the Renesas R-Car SYSC driver
> > typically go in through the renesas and arm-soc trees, and if you agree,
> > I would like to send a pull request for these changes, to be pulled by
> > all of the driver core, renesas, and arm-soc trees.  This is similar to
> > how soc_device_match() was integrated earlier.
> > Then the Renesas R-Car SYSC driver changes can easily be queued on top
> > in the renesas tree afterwards.
> >
> > Do you agree?
> > Thanks for your answer!
> 
> Merging this through arm-soc is fine with me.

Thanks, in that case I am fine with this plan.

> > P.S. If you think it's already too late in the cycle to queue Renesas
> > R-Car SYSC driver changes for v4.12 on top, please say so.  Then the
> > dependency is relaxed, and this series can just go in through the
> > driver core tree, with the Renesas part to follow for v4.13.
> 
> We can take it for 4.12.

Thanks again. My preference at this time is to deffer the DT changes to v4.13
as it seems somewhat simpler and I'm not aware of any urgency to get them
into v4.12.

[PATCH v2 0/2] base: soc: soc_device_match() improvements

[Simon Horman]

On Wed, Mar 29, 2017 at 09:48:48PM +0200, Arnd Bergmann wrote:
> On Wed, Mar 29, 2017 at 9:38 PM, Geert Uytterhoeven
> <geert+renesas@glider.be> wrote:
> >         Hi Arnd, Greg, Kevin, Magnus, Olof, Simon,
> >
> > This patch series contains two improvements for the SoC bus and
> > soc_device_match().  The second one is a dependency for handling
> > different SoC revisions in the Renesas R-Car SYSC driver, which manages
> > PM Domains and thus needs to be initialized from an early_initcall[*].
> >
> > Changes compared to v1:
> >   - Drop RFC state,
> >   - Add more explanation,
> >   - Add Acked-by.
> >
> > Due to the dependency, and as changes for the Renesas R-Car SYSC driver
> > typically go in through the renesas and arm-soc trees, and if you agree,
> > I would like to send a pull request for these changes, to be pulled by
> > all of the driver core, renesas, and arm-soc trees.  This is similar to
> > how soc_device_match() was integrated earlier.
> > Then the Renesas R-Car SYSC driver changes can easily be queued on top
> > in the renesas tree afterwards.
> >
> > Do you agree?
> > Thanks for your answer!
> 
> Merging this through arm-soc is fine with me.

Thanks, in that case I am fine with this plan.

> > P.S. If you think it's already too late in the cycle to queue Renesas
> > R-Car SYSC driver changes for v4.12 on top, please say so.  Then the
> > dependency is relaxed, and this series can just go in through the
> > driver core tree, with the Renesas part to follow for v4.13.
> 
> We can take it for 4.12.

Thanks again. My preference at this time is to deffer the DT changes to v4.13
as it seems somewhat simpler and I'm not aware of any urgency to get them
into v4.12.