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Subject[PATCH v2 1/5] pinctrl: Allow modules to use pinctrl_[un]register_mappings
Date
Currently only the drivers/pinctrl/devicetree.c code allows registering
pinctrl-mappings which may later be unregistered, all other mappings
are assumed to be permanent.

Non-dt platforms may also want to register pinctrl mappings from code which
is build as a module, which requires being able to unregister the mapping
when the module is unloaded to avoid dangling pointers.

To allow unregistering the mappings the devicetree code uses 2 internal
functions: pinctrl_register_map and pinctrl_unregister_map.

pinctrl_register_map allows the devicetree code to tell the core to
not memdup the mappings as it retains ownership of them and
pinctrl_unregister_map does the unregistering, note this only works
when the mappings where not memdupped.

The only code relying on the memdup/shallow-copy done by
pinctrl_register_mappings is arch/arm/mach-u300/core.c this commit
replaces the __initdata with const, so that the shallow-copy is no
longer necessary.

After that we can get rid of the internal pinctrl_unregister_map function
and just use pinctrl_register_mappings directly everywhere.

This commit also renames pinctrl_unregister_map to
pinctrl_unregister_mappings so that its naming matches its
pinctrl_register_mappings counter-part and exports it.

Together these 2 changes will allow non-dt platform code to
register pinctrl-mappings from modules without breaking things on
module unload (as they can now unregister the mapping on unload).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
-Drop __initdata from arch/arm/mach-u300/core.c pinctrl-map, so
that we can drop the dup behavior for non device-tree callers
-Stop memdupping the pinctrl-maps in some cases, remove all code for
dealing with dupped maps, including the extra coded added for this in v1
of this patch
-Drop the private (non-dupping) pinctrl_register_map function, now that
our public pinctrl_register_mappings does not dup we can simply use it
everywhere
---
arch/arm/mach-u300/core.c | 2 +-
drivers/pinctrl/core.c | 41 +++++++++++++--------------------
drivers/pinctrl/core.h | 4 ----
drivers/pinctrl/devicetree.c | 4 ++--
include/linux/pinctrl/machine.h | 5 ++++
5 files changed, 24 insertions(+), 32 deletions(-)

diff --git a/arch/arm/mach-u300/core.c b/arch/arm/mach-u300/core.c
index a79fa3b0c8ed..a1694d977ec9 100644
--- a/arch/arm/mach-u300/core.c
+++ b/arch/arm/mach-u300/core.c
@@ -201,7 +201,7 @@ static unsigned long pin_highz_conf[] = {
};

/* Pin control settings */
-static struct pinctrl_map __initdata u300_pinmux_map[] = {
+static const struct pinctrl_map u300_pinmux_map[] = {
/* anonymous maps for chip power and EMIFs */
PIN_MAP_MUX_GROUP_HOG_DEFAULT("pinctrl-u300", NULL, "power"),
PIN_MAP_MUX_GROUP_HOG_DEFAULT("pinctrl-u300", NULL, "emif0"),
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 2bbd8ee93507..b0eea728455d 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1376,8 +1376,15 @@ void devm_pinctrl_put(struct pinctrl *p)
}
EXPORT_SYMBOL_GPL(devm_pinctrl_put);

-int pinctrl_register_map(const struct pinctrl_map *maps, unsigned num_maps,
- bool dup)
+/**
+ * pinctrl_register_mappings() - register a set of pin controller mappings
+ * @maps: the pincontrol mappings table to register. Note the pinctrl-core
+ * keeps a reference to the passed in maps, so they should _not_ be
+ * marked with __initdata.
+ * @num_maps: the number of maps in the mapping table
+ */
+int pinctrl_register_mappings(const struct pinctrl_map *maps,
+ unsigned num_maps)
{
int i, ret;
struct pinctrl_maps *maps_node;
@@ -1430,17 +1437,8 @@ int pinctrl_register_map(const struct pinctrl_map *maps, unsigned num_maps,
if (!maps_node)
return -ENOMEM;

+ maps_node->maps = maps;
maps_node->num_maps = num_maps;
- if (dup) {
- maps_node->maps = kmemdup(maps, sizeof(*maps) * num_maps,
- GFP_KERNEL);
- if (!maps_node->maps) {
- kfree(maps_node);
- return -ENOMEM;
- }
- } else {
- maps_node->maps = maps;
- }

mutex_lock(&pinctrl_maps_mutex);
list_add_tail(&maps_node->node, &pinctrl_maps);
@@ -1448,22 +1446,14 @@ int pinctrl_register_map(const struct pinctrl_map *maps, unsigned num_maps,

return 0;
}
+EXPORT_SYMBOL_GPL(pinctrl_register_mappings);

/**
- * pinctrl_register_mappings() - register a set of pin controller mappings
- * @maps: the pincontrol mappings table to register. This should probably be
- * marked with __initdata so it can be discarded after boot. This
- * function will perform a shallow copy for the mapping entries.
- * @num_maps: the number of maps in the mapping table
+ * pinctrl_unregister_mappings() - unregister a set of pin controller mappings
+ * @maps: the pincontrol mappings table passed to pinctrl_register_mappings()
+ * when registering the mappings.
*/
-int pinctrl_register_mappings(const struct pinctrl_map *maps,
- unsigned num_maps)
-{
- return pinctrl_register_map(maps, num_maps, true);
-}
-EXPORT_SYMBOL_GPL(pinctrl_register_mappings);
-
-void pinctrl_unregister_map(const struct pinctrl_map *map)
+void pinctrl_unregister_mappings(const struct pinctrl_map *map)
{
struct pinctrl_maps *maps_node;

@@ -1478,6 +1468,7 @@ void pinctrl_unregister_map(const struct pinctrl_map *map)
}
mutex_unlock(&pinctrl_maps_mutex);
}
+EXPORT_SYMBOL_GPL(pinctrl_unregister_mappings);

/**
* pinctrl_force_sleep() - turn a given controller device into sleep state
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index 7f34167a0405..840103c40c14 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -236,10 +236,6 @@ extern struct pinctrl_gpio_range *
pinctrl_find_gpio_range_from_pin_nolock(struct pinctrl_dev *pctldev,
unsigned int pin);

-int pinctrl_register_map(const struct pinctrl_map *maps, unsigned num_maps,
- bool dup);
-void pinctrl_unregister_map(const struct pinctrl_map *map);
-
extern int pinctrl_force_sleep(struct pinctrl_dev *pctldev);
extern int pinctrl_force_default(struct pinctrl_dev *pctldev);

diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index 674920daac26..9357f7c46cf3 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -51,7 +51,7 @@ void pinctrl_dt_free_maps(struct pinctrl *p)
struct pinctrl_dt_map *dt_map, *n1;

list_for_each_entry_safe(dt_map, n1, &p->dt_maps, node) {
- pinctrl_unregister_map(dt_map->map);
+ pinctrl_unregister_mappings(dt_map->map);
list_del(&dt_map->node);
dt_free_map(dt_map->pctldev, dt_map->map,
dt_map->num_maps);
@@ -92,7 +92,7 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename,
dt_map->num_maps = num_maps;
list_add_tail(&dt_map->node, &p->dt_maps);

- return pinctrl_register_map(map, num_maps, false);
+ return pinctrl_register_mappings(map, num_maps);

err_free_map:
dt_free_map(pctldev, map, num_maps);
diff --git a/include/linux/pinctrl/machine.h b/include/linux/pinctrl/machine.h
index ddd1b2773431..e987dc9fd2af 100644
--- a/include/linux/pinctrl/machine.h
+++ b/include/linux/pinctrl/machine.h
@@ -153,6 +153,7 @@ struct pinctrl_map {

extern int pinctrl_register_mappings(const struct pinctrl_map *map,
unsigned num_maps);
+extern void pinctrl_unregister_mappings(const struct pinctrl_map *map);
extern void pinctrl_provide_dummies(void);
#else

@@ -162,6 +163,10 @@ static inline int pinctrl_register_mappings(const struct pinctrl_map *map,
return 0;
}

+static inline void pinctrl_unregister_mappings(const struct pinctrl_map *map)
+{
+}
+
static inline void pinctrl_provide_dummies(void)
{
}
--
2.23.0
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