pinctrl: core: Fix regression caused by delayed work for hogs

Commit df61b366af26 ("pinctrl: core: Use delayed work for hogs") caused a
regression at least with sh-pfc that is also a GPIO controller as
noted by Geert Uytterhoeven <geert@linux-m68k.org>.

As the original pinctrl_register() has issues calling pin controller
driver functions early before the controller has finished registering,
we can't just revert commit df61b366af26. That would break the drivers
using GENERIC_PINCTRL_GROUPS or GENERIC_PINMUX_FUNCTIONS.

So let's fix the issue with the following steps as a single patch:

1. Revert the late_init parts of commit df61b366af26.

   The late_init clearly won't work and we have to just give up
   on fixing pinctrl_register() for GENERIC_PINCTRL_GROUPS and
   GENERIC_PINMUX_FUNCTIONS.

2. Split pinctrl_register() into two parts

   By splitting pinctrl_register() into pinctrl_init_controller()
   and pinctrl_create_and_start() we have better control over when
   it's safe to call pinctrl_create().

3. Introduce a new pinctrl_register_and_init() function

   As suggested by Linus Walleij <linus.walleij@linaro.org>, we
   can just introduce a new function for the controllers that need
   pinctrl_create() called later.

4. Convert the four known problem cases to use new function

   Let's convert pinctrl-imx, pinctrl-single, sh-pfc and ti-iodelay
   to use the new function to fix the issues. The rest of the drivers
   can be converted later. Let's also update Documentation/pinctrl.txt
   accordingly because of the known issues with pinctrl_register().

Fixes: df61b366af26 ("pinctrl: core: Use delayed work for hogs")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/pinctrl/pinctrl.h b/include/linux/pinctrl/pinctrl.h
index a42e57da270d..8ce2d87a238b 100644
--- a/include/linux/pinctrl/pinctrl.h
+++ b/include/linux/pinctrl/pinctrl.h
@@ -141,12 +141,27 @@ struct pinctrl_desc {
 };
 
 /* External interface to pin controller */
+
+extern int pinctrl_register_and_init(struct pinctrl_desc *pctldesc,
+				     struct device *dev, void *driver_data,
+				     struct pinctrl_dev **pctldev);
+
+/* Please use pinctrl_register_and_init() instead */
 extern struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
 				struct device *dev, void *driver_data);
+
 extern void pinctrl_unregister(struct pinctrl_dev *pctldev);
+
+extern int devm_pinctrl_register_and_init(struct device *dev,
+				struct pinctrl_desc *pctldesc,
+				void *driver_data,
+				struct pinctrl_dev **pctldev);
+
+/* Please use devm_pinctrl_register_and_init() instead */
 extern struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
 				struct pinctrl_desc *pctldesc,
 				void *driver_data);
+
 extern void devm_pinctrl_unregister(struct device *dev,
 				struct pinctrl_dev *pctldev);