[PATCH v2 00/11] gpiolib: work towards removing gpiochip_find()

[PATCH v2 00/11] gpiolib: work towards removing gpiochip_find()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

This is a reduced subset of patches from the initial sumbission[1]
limited only to changes inside GPIOLIB. Once this is upstream, we can
then slowly merge patches for other subsystems (like HTE) and then
eventually remove gpiochip_find() entirely.

The GPIO subsystem does not handle hot-unplug events very well. We have
recently patched the user-space part of it so that at least a rouge user
cannot crash the kernel but in-kernel users are still affected by a lot of
issues: from incorrect locking or lack thereof to using structures that are
private to GPIO drivers. Since almost all GPIO controllers can be unbound,
not to mention that we have USB devices registering GPIO expanders as well as
I2C-on-USB HID devices on which I2C GPIO expanders can live, various media
gadgets etc., we really need to make GPIO hotplug/unplug friendly.

Before we can even get to fixing the locking, we need to address a serious
abuse of the GPIO driver API - accessing struct gpio_chip by anyone who isn't
the driver owning this object. This structure is owned by the GPIO provider
and its lifetime is tied to that of that provider. It is destroyed when the
device is unregistered and this may happen at any moment. struct gpio_device
is the opaque, reference counted interface to struct gpio_chip (which is the
low-level implementation) and all access should pass through it.

The end-goal is to make all gpio_device manipulators check the existence of
gdev->chip and then lock it for the duration of any of the calls using SRCU.
Before we can get there, we need to first provide a set of functions that will
replace any gpio_chip functions and convert all in-kernel users.

This series adds several new helpers to the public GPIO API and uses
them across the core GPIO code.

Note that this does not make everything correct just yet. Especially the
GPIOLIB internal users release the reference returned by the lookup function
after getting the descriptor of interest but before requesting it. This will
eventually be addressed. This is not a regression either.

[1] https://lore.kernel.org/lkml/20230905185309.131295-1-brgl@bgdev.pl/T/

v1 -> v2:
- drop all non-GPIOLIB patches
- collect tags
- fix kernel docs
- use gpio_device_get_chip() and gpio_device_get_desc() where applicable

Bartosz Golaszewski (11):
  gpiolib: make gpio_device_get() and gpio_device_put() public
  gpiolib: add support for scope-based management to gpio_device
  gpiolib: provide gpio_device_find()
  gpiolib: provide gpio_device_find_by_label()
  gpiolib: provide gpio_device_get_desc()
  gpiolib: reluctantly provide gpio_device_get_chip()
  gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()
  gpio: of: replace gpiochip_find_* with gpio_device_find_*
  gpio: acpi: replace gpiochip_find() with gpio_device_find()
  gpio: swnode: replace gpiochip_find() with gpio_device_find_by_label()
  gpio: sysfs: drop the mention of gpiochip_find() from sysfs code

 drivers/gpio/gpiolib-acpi.c   |  12 +-
 drivers/gpio/gpiolib-of.c     |  32 +++---
 drivers/gpio/gpiolib-swnode.c |  33 +++---
 drivers/gpio/gpiolib-sysfs.c  |   2 +-
 drivers/gpio/gpiolib.c        | 201 ++++++++++++++++++++++++++--------
 drivers/gpio/gpiolib.h        |  10 --
 include/linux/gpio/driver.h   |  13 +++
 7 files changed, 211 insertions(+), 92 deletions(-)

-- 
2.39.2

[PATCH v2 01/11] gpiolib: make gpio_device_get() and gpio_device_put() public

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

In order to start migrating away from accessing struct gpio_chip by
users other than their owners, let's first make the reference management
functions for the opaque struct gpio_device public in the driver.h
header.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c      | 24 ++++++++++++++++++++++++
 drivers/gpio/gpiolib.h      | 10 ----------
 include/linux/gpio/driver.h |  3 +++
 3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index edffa0d2acaa..f84ad54d8dbd 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1058,6 +1058,30 @@ static struct gpio_chip *find_chip_by_name(const char *name)
 	return gpiochip_find((void *)name, gpiochip_match_name);
 }
 
+/**
+ * gpio_device_get() - Increase the reference count of this GPIO device
+ * @gdev: GPIO device to increase the refcount for
+ *
+ * Returns:
+ * Pointer to @gdev.
+ */
+struct gpio_device *gpio_device_get(struct gpio_device *gdev)
+{
+	return to_gpio_device(get_device(&gdev->dev));
+}
+EXPORT_SYMBOL_GPL(gpio_device_get);
+
+/**
+ * gpio_device_put() - Decrease the reference count of this GPIO device and
+ *                     possibly free all resources associated with it.
+ * @gdev: GPIO device to decrease the reference count for
+ */
+void gpio_device_put(struct gpio_device *gdev)
+{
+	put_device(&gdev->dev);
+}
+EXPORT_SYMBOL_GPL(gpio_device_put);
+
 #ifdef CONFIG_GPIOLIB_IRQCHIP
 
 /*
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 9bff5c2cf720..3ccacf3c1288 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -86,16 +86,6 @@ static inline struct gpio_device *to_gpio_device(struct device *dev)
 	return container_of(dev, struct gpio_device, dev);
 }
 
-static inline struct gpio_device *gpio_device_get(struct gpio_device *gdev)
-{
-	return to_gpio_device(get_device(&gdev->dev));
-}
-
-static inline void gpio_device_put(struct gpio_device *gdev)
-{
-	put_device(&gdev->dev);
-}
-
 /* gpio suffixes used for ACPI and device tree lookup */
 static __maybe_unused const char * const gpio_suffixes[] = { "gpios", "gpio" };
 
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 8f0859ba7065..a2060dc3344b 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -606,6 +606,9 @@ int devm_gpiochip_add_data_with_key(struct device *dev, struct gpio_chip *gc,
 struct gpio_chip *gpiochip_find(void *data,
 				int (*match)(struct gpio_chip *gc, void *data));
 
+struct gpio_device *gpio_device_get(struct gpio_device *gdev);
+void gpio_device_put(struct gpio_device *gdev);
+
 bool gpiochip_line_is_irq(struct gpio_chip *gc, unsigned int offset);
 int gpiochip_reqres_irq(struct gpio_chip *gc, unsigned int offset);
 void gpiochip_relres_irq(struct gpio_chip *gc, unsigned int offset);
-- 
2.39.2

[PATCH v2 02/11] gpiolib: add support for scope-based management to gpio_device

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

As the few users that need to get the reference to the GPIO device often
release it right after inspecting its properties, let's add support for
the automatic reference release to struct gpio_device.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 include/linux/gpio/driver.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index a2060dc3344b..a52c6cc5162b 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -609,6 +609,8 @@ struct gpio_chip *gpiochip_find(void *data,
 struct gpio_device *gpio_device_get(struct gpio_device *gdev);
 void gpio_device_put(struct gpio_device *gdev);
 
+DEFINE_FREE(gpio_device_put, struct gpio_device *, if (_T) gpio_device_put(_T));
+
 bool gpiochip_line_is_irq(struct gpio_chip *gc, unsigned int offset);
 int gpiochip_reqres_irq(struct gpio_chip *gc, unsigned int offset);
 void gpiochip_relres_irq(struct gpio_chip *gc, unsigned int offset);
-- 
2.39.2

[PATCH v2 03/11] gpiolib: provide gpio_device_find()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

gpiochip_find() is wrong and its kernel doc is misleading as the
function doesn't return a reference to the gpio_chip but just a raw
pointer. The chip itself is not guaranteed to stay alive, in fact it can
be deleted at any point. Also: other than GPIO drivers themselves,
nobody else has any business accessing gpio_chip structs.

Provide a new gpio_device_find() function that returns a real reference
to the opaque gpio_device structure that is guaranteed to stay alive for
as long as there are active users of it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c      | 71 +++++++++++++++++++++++++++----------
 include/linux/gpio/driver.h |  3 ++
 2 files changed, 56 insertions(+), 18 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index f84ad54d8dbd..0371d23f0a46 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1014,16 +1014,10 @@ void gpiochip_remove(struct gpio_chip *gc)
 }
 EXPORT_SYMBOL_GPL(gpiochip_remove);
 
-/**
- * gpiochip_find() - iterator for locating a specific gpio_chip
- * @data: data to pass to match function
- * @match: Callback function to check gpio_chip
+/*
+ * FIXME: This will be removed soon.
  *
- * Similar to bus_find_device.  It returns a reference to a gpio_chip as
- * determined by a user supplied @match callback.  The callback should return
- * 0 if the device doesn't match and non-zero if it does.  If the callback is
- * non-zero, this function will return to the caller and not iterate over any
- * more gpio_chips.
+ * This function is depracated, don't use.
  */
 struct gpio_chip *gpiochip_find(void *data,
 				int (*match)(struct gpio_chip *gc,
@@ -1031,21 +1025,62 @@ struct gpio_chip *gpiochip_find(void *data,
 {
 	struct gpio_device *gdev;
 	struct gpio_chip *gc = NULL;
-	unsigned long flags;
 
-	spin_lock_irqsave(&gpio_lock, flags);
-	list_for_each_entry(gdev, &gpio_devices, list)
-		if (gdev->chip && match(gdev->chip, data)) {
-			gc = gdev->chip;
-			break;
-		}
-
-	spin_unlock_irqrestore(&gpio_lock, flags);
+	gdev = gpio_device_find(data, match);
+	if (gdev) {
+		gc = gdev->chip;
+		gpio_device_put(gdev);
+	}
 
 	return gc;
 }
 EXPORT_SYMBOL_GPL(gpiochip_find);
 
+/**
+ * gpio_device_find() - find a specific GPIO device
+ * @data: data to pass to match function
+ * @match: Callback function to check gpio_chip
+ *
+ * Returns:
+ * New reference to struct gpio_device.
+ *
+ * Similar to bus_find_device(). It returns a reference to a gpio_device as
+ * determined by a user supplied @match callback. The callback should return
+ * 0 if the device doesn't match and non-zero if it does. If the callback
+ * returns non-zero, this function will return to the caller and not iterate
+ * over any more gpio_devices.
+ *
+ * The callback takes the GPIO chip structure as argument. During the execution
+ * of the callback function the chip is protected from being freed. TODO: This
+ * actually has yet to be implemented.
+ *
+ * If the function returns non-NULL, the returned reference must be freed by
+ * the caller using gpio_device_put().
+ */
+struct gpio_device *gpio_device_find(void *data,
+				     int (*match)(struct gpio_chip *gc,
+						  void *data))
+{
+	struct gpio_device *gdev;
+
+	/*
+	 * Not yet but in the future the spinlock below will become a mutex.
+	 * Annotate this function before anyone tries to use it in interrupt
+	 * context like it happened with gpiochip_find().
+	 */
+	might_sleep();
+
+	guard(spinlock_irqsave)(&gpio_lock);
+
+	list_for_each_entry(gdev, &gpio_devices, list) {
+		if (gdev->chip && match(gdev->chip, data))
+			return gpio_device_get(gdev);
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(gpio_device_find);
+
 static int gpiochip_match_name(struct gpio_chip *gc, void *data)
 {
 	const char *name = data;
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index a52c6cc5162b..bf27cc8392fb 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -606,6 +606,9 @@ int devm_gpiochip_add_data_with_key(struct device *dev, struct gpio_chip *gc,
 struct gpio_chip *gpiochip_find(void *data,
 				int (*match)(struct gpio_chip *gc, void *data));
 
+struct gpio_device *gpio_device_find(void *data,
+				int (*match)(struct gpio_chip *gc, void *data));
+
 struct gpio_device *gpio_device_get(struct gpio_device *gdev);
 void gpio_device_put(struct gpio_device *gdev);
 
-- 
2.39.2

[PATCH v2 04/11] gpiolib: provide gpio_device_find_by_label()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

By far the most common way of looking up GPIO devices is using their
label. Provide a helpers for that to avoid every user implementing their
own matching function.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c      | 21 +++++++++++++++++++++
 include/linux/gpio/driver.h |  1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 0371d23f0a46..9f20311e4c1a 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -20,6 +20,7 @@
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/string.h>
 
 #include <linux/gpio.h>
 #include <linux/gpio/driver.h>
@@ -1081,6 +1082,26 @@ struct gpio_device *gpio_device_find(void *data,
 }
 EXPORT_SYMBOL_GPL(gpio_device_find);
 
+static int gpio_chip_match_by_label(struct gpio_chip *gc, void *label)
+{
+	return gc->label && !strcmp(gc->label, label);
+}
+
+/**
+ * gpio_device_find_by_label() - wrapper around gpio_device_find() finding the
+ *                               GPIO device by its backing chip's label
+ * @label: Label to lookup
+ *
+ * Returns:
+ * Reference to the GPIO device or NULL. Reference must be released with
+ * gpio_device_put().
+ */
+struct gpio_device *gpio_device_find_by_label(const char *label)
+{
+	return gpio_device_find((void *)label, gpio_chip_match_by_label);
+}
+EXPORT_SYMBOL_GPL(gpio_device_find_by_label);
+
 static int gpiochip_match_name(struct gpio_chip *gc, void *data)
 {
 	const char *name = data;
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index bf27cc8392fb..bcf418441ef2 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -608,6 +608,7 @@ struct gpio_chip *gpiochip_find(void *data,
 
 struct gpio_device *gpio_device_find(void *data,
 				int (*match)(struct gpio_chip *gc, void *data));
+struct gpio_device *gpio_device_find_by_label(const char *label);
 
 struct gpio_device *gpio_device_get(struct gpio_device *gdev);
 void gpio_device_put(struct gpio_device *gdev);
-- 
2.39.2

[PATCH v2 05/11] gpiolib: provide gpio_device_get_desc()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Getting the GPIO descriptor directly from the gpio_chip struct is
dangerous as we don't take the reference to the underlying GPIO device.
In order to start working towards removing gpiochip_get_desc(), let's
provide a safer variant that works with an existing reference to struct
gpio_device.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c      | 45 +++++++++++++++++++++++++++----------
 include/linux/gpio/driver.h |  2 ++
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 9f20311e4c1a..e413136d1566 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -147,27 +147,48 @@ struct gpio_desc *gpio_to_desc(unsigned gpio)
 }
 EXPORT_SYMBOL_GPL(gpio_to_desc);
 
-/**
- * gpiochip_get_desc - get the GPIO descriptor corresponding to the given
- *                     hardware number for this chip
- * @gc: GPIO chip
- * @hwnum: hardware number of the GPIO for this chip
- *
- * Returns:
- * A pointer to the GPIO descriptor or ``ERR_PTR(-EINVAL)`` if no GPIO exists
- * in the given chip for the specified hardware number.
- */
+/* This function is deprecated and will be removed soon, don't use. */
 struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc,
 				    unsigned int hwnum)
 {
-	struct gpio_device *gdev = gc->gpiodev;
+	return gpio_device_get_desc(gc->gpiodev, hwnum);
+}
+EXPORT_SYMBOL_GPL(gpiochip_get_desc);
+
+/**
+ * gpio_device_get_desc() - get the GPIO descriptor corresponding to the given
+ *                          hardware number for this GPIO device
+ * @gdev: GPIO device to get the descriptor from
+ * @hwnum: hardware number of the GPIO for this chip
+ *
+ * Returns:
+ * A pointer to the GPIO descriptor or %EINVAL if no GPIO exists in the given
+ * chip for the specified hardware number or %ENODEV if the underlying chip
+ * already vanished.
+ *
+ * The reference count of struct gpio_device is *NOT* increased like when the
+ * GPIO is being requested for exclusive usage. It's up to the caller to make
+ * sure the GPIO device will stay alive together with the descriptor returned
+ * by this function.
+ */
+struct gpio_desc *
+gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum)
+{
+	struct gpio_chip *gc = gdev->chip;
+
+	/*
+	 * FIXME: This will be locked once we protect gdev->chip everywhere
+	 * with SRCU.
+	 */
+	if (!gc)
+		return ERR_PTR(-ENODEV);
 
 	if (hwnum >= gdev->ngpio)
 		return ERR_PTR(-EINVAL);
 
 	return &gdev->descs[hwnum];
 }
-EXPORT_SYMBOL_GPL(gpiochip_get_desc);
+EXPORT_SYMBOL_GPL(gpio_device_get_desc);
 
 /**
  * desc_to_gpio - convert a GPIO descriptor to the integer namespace
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index bcf418441ef2..5c0f2ccfd51b 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -767,6 +767,8 @@ struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc,
 void gpiochip_free_own_desc(struct gpio_desc *desc);
 
 struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum);
+struct gpio_desc *
+gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum);
 
 #ifdef CONFIG_GPIOLIB
 
-- 
2.39.2

[PATCH v2 06/11] gpiolib: reluctantly provide gpio_device_get_chip()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

The process of converting all unauthorized users of struct gpio_chip to
using dedicated struct gpio_device function will be long so in the
meantime we must provide a way of retrieving the pointer to struct
gpio_chip from a GPIO device.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c      | 21 +++++++++++++++++++++
 include/linux/gpio/driver.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e413136d1566..224e0d330009 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -219,6 +219,27 @@ struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_to_chip);
 
+/**
+ * gpio_device_get_chip() - Get the gpio_chip implementation of this GPIO device
+ * @gdev: GPIO device
+ *
+ * Returns:
+ * Address of the GPIO chip backing this device.
+ *
+ * Until we can get rid of all non-driver users of struct gpio_chip, we must
+ * provide a way of retrieving the pointer to it from struct gpio_device. This
+ * is *NOT* safe as the GPIO API is considered to be hot-unpluggable and the
+ * chip can dissapear at any moment (unlike reference-counted struct
+ * gpio_device).
+ *
+ * Use at your own risk.
+ */
+struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)
+{
+	return gdev->chip;
+}
+EXPORT_SYMBOL_GPL(gpio_device_get_chip);
+
 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
 static int gpiochip_find_base(int ngpio)
 {
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 5c0f2ccfd51b..a583e539263e 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -770,6 +770,8 @@ struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum);
 struct gpio_desc *
 gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum);
 
+struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev);
+
 #ifdef CONFIG_GPIOLIB
 
 /* lock/unlock as IRQ */
-- 
2.39.2

[PATCH v2 07/11] gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Remove all remaining uses of find_chip_by_name() (and subsequently:
gpiochip_find()) from gpiolib.c and use the new
gpio_device_find_by_label() instead.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c | 33 ++++++++++++---------------------
 1 file changed, 12 insertions(+), 21 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 224e0d330009..a10d1d663524 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1144,18 +1144,6 @@ struct gpio_device *gpio_device_find_by_label(const char *label)
 }
 EXPORT_SYMBOL_GPL(gpio_device_find_by_label);
 
-static int gpiochip_match_name(struct gpio_chip *gc, void *data)
-{
-	const char *name = data;
-
-	return !strcmp(gc->label, name);
-}
-
-static struct gpio_chip *find_chip_by_name(const char *name)
-{
-	return gpiochip_find((void *)name, gpiochip_match_name);
-}
-
 /**
  * gpio_device_get() - Increase the reference count of this GPIO device
  * @gdev: GPIO device to increase the refcount for
@@ -3907,21 +3895,22 @@ EXPORT_SYMBOL_GPL(gpiod_remove_lookup_table);
  */
 void gpiod_add_hogs(struct gpiod_hog *hogs)
 {
-	struct gpio_chip *gc;
 	struct gpiod_hog *hog;
 
 	mutex_lock(&gpio_machine_hogs_mutex);
 
 	for (hog = &hogs[0]; hog->chip_label; hog++) {
+		struct gpio_device *gdev __free(gpio_device_put) = NULL;
+
 		list_add_tail(&hog->list, &gpio_machine_hogs);
 
 		/*
 		 * The chip may have been registered earlier, so check if it
 		 * exists and, if so, try to hog the line now.
 		 */
-		gc = find_chip_by_name(hog->chip_label);
-		if (gc)
-			gpiochip_machine_hog(gc, hog);
+		gdev = gpio_device_find_by_label(hog->chip_label);
+		if (gdev)
+			gpiochip_machine_hog(gpio_device_get_chip(gdev), hog);
 	}
 
 	mutex_unlock(&gpio_machine_hogs_mutex);
@@ -3976,13 +3965,16 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 	struct gpio_desc *desc = ERR_PTR(-ENOENT);
 	struct gpiod_lookup_table *table;
 	struct gpiod_lookup *p;
+	struct gpio_chip *gc;
 
 	table = gpiod_find_lookup_table(dev);
 	if (!table)
 		return desc;
 
 	for (p = &table->table[0]; p->key; p++) {
-		struct gpio_chip *gc;
+		struct gpio_device *gdev __free(gpio_device_put) = NULL;
+
+		gc = gpio_device_get_chip(gdev);
 
 		/* idx must always match exactly */
 		if (p->idx != idx)
@@ -4004,9 +3996,8 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 			return ERR_PTR(-EPROBE_DEFER);
 		}
 
-		gc = find_chip_by_name(p->key);
-
-		if (!gc) {
+		gdev = gpio_device_find_by_label(p->key);
+		if (!gdev) {
 			/*
 			 * As the lookup table indicates a chip with
 			 * p->key should exist, assume it may
@@ -4022,7 +4013,7 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 		if (gc->ngpio <= p->chip_hwnum) {
 			dev_err(dev,
 				"requested GPIO %u (%u) is out of range [0..%u] for chip %s\n",
-				idx, p->chip_hwnum, gc->ngpio - 1,
+				idx, p->chip_hwnum, gdev->chip->ngpio - 1,
 				gc->label);
 			return ERR_PTR(-EINVAL);
 		}
-- 
2.39.2

[PATCH v2 08/11] gpio: of: replace gpiochip_find_* with gpio_device_find_*

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We're porting all users of gpiochip_find() to using gpio_device_find().
Update the OF GPIO code.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib-of.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 5515f32cf19b..ff13aa079a22 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -127,10 +127,10 @@ static int of_gpiochip_match_node_and_xlate(struct gpio_chip *chip, void *data)
 				chip->of_xlate(chip, gpiospec, NULL) >= 0;
 }
 
-static struct gpio_chip *of_find_gpiochip_by_xlate(
-					struct of_phandle_args *gpiospec)
+static struct gpio_device *
+of_find_gpio_device_by_xlate(struct of_phandle_args *gpiospec)
 {
-	return gpiochip_find(gpiospec, of_gpiochip_match_node_and_xlate);
+	return gpio_device_find(gpiospec, of_gpiochip_match_node_and_xlate);
 }
 
 static struct gpio_desc *of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
@@ -362,8 +362,8 @@ static void of_gpio_flags_quirks(const struct device_node *np,
 static struct gpio_desc *of_get_named_gpiod_flags(const struct device_node *np,
 		     const char *propname, int index, enum of_gpio_flags *flags)
 {
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
 	struct of_phandle_args gpiospec;
-	struct gpio_chip *chip;
 	struct gpio_desc *desc;
 	int ret;
 
@@ -375,13 +375,13 @@ static struct gpio_desc *of_get_named_gpiod_flags(const struct device_node *np,
 		return ERR_PTR(ret);
 	}
 
-	chip = of_find_gpiochip_by_xlate(&gpiospec);
-	if (!chip) {
+	gdev = of_find_gpio_device_by_xlate(&gpiospec);
+	if (!gdev) {
 		desc = ERR_PTR(-EPROBE_DEFER);
 		goto out;
 	}
 
-	desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, flags);
+	desc = of_xlate_and_get_gpiod_flags(gdev->chip, &gpiospec, flags);
 	if (IS_ERR(desc))
 		goto out;
 
@@ -813,16 +813,16 @@ static int of_gpiochip_match_node(struct gpio_chip *chip, void *data)
 	return device_match_of_node(&chip->gpiodev->dev, data);
 }
 
-static struct gpio_chip *of_find_gpiochip_by_node(struct device_node *np)
+static struct gpio_device *of_find_gpio_device_by_node(struct device_node *np)
 {
-	return gpiochip_find(np, of_gpiochip_match_node);
+	return gpio_device_find(np, of_gpiochip_match_node);
 }
 
 static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 			  void *arg)
 {
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
 	struct of_reconfig_data *rd = arg;
-	struct gpio_chip *chip;
 	int ret;
 
 	/*
@@ -839,11 +839,11 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED))
 			return NOTIFY_DONE;
 
-		chip = of_find_gpiochip_by_node(rd->dn->parent);
-		if (chip == NULL)
+		gdev = of_find_gpio_device_by_node(rd->dn->parent);
+		if (!gdev)
 			return NOTIFY_DONE;	/* not for us */
 
-		ret = of_gpiochip_add_hog(chip, rd->dn);
+		ret = of_gpiochip_add_hog(gpio_device_get_chip(gdev), rd->dn);
 		if (ret < 0) {
 			pr_err("%s: failed to add hogs for %pOF\n", __func__,
 			       rd->dn);
@@ -856,11 +856,11 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 		if (!of_node_check_flag(rd->dn, OF_POPULATED))
 			return NOTIFY_DONE;	/* already depopulated */
 
-		chip = of_find_gpiochip_by_node(rd->dn->parent);
-		if (chip == NULL)
+		gdev = of_find_gpio_device_by_node(rd->dn->parent);
+		if (!gdev)
 			return NOTIFY_DONE;	/* not for us */
 
-		of_gpiochip_remove_hog(chip, rd->dn);
+		of_gpiochip_remove_hog(gpio_device_get_chip(gdev), rd->dn);
 		of_node_clear_flag(rd->dn, OF_POPULATED);
 		return NOTIFY_OK;
 	}
-- 
2.39.2

[PATCH v2 09/11] gpio: acpi: replace gpiochip_find() with gpio_device_find()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We're porting all users of gpiochip_find() to using gpio_device_find().
Update the ACPI GPIO code.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib-acpi.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 17a86bdd9609..ec618962a5cb 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -143,7 +143,7 @@ static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
  */
 static struct gpio_desc *acpi_get_gpiod(char *path, unsigned int pin)
 {
-	struct gpio_chip *chip;
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
 	acpi_handle handle;
 	acpi_status status;
 
@@ -151,11 +151,15 @@ static struct gpio_desc *acpi_get_gpiod(char *path, unsigned int pin)
 	if (ACPI_FAILURE(status))
 		return ERR_PTR(-ENODEV);
 
-	chip = gpiochip_find(handle, acpi_gpiochip_find);
-	if (!chip)
+	gdev = gpio_device_find(handle, acpi_gpiochip_find);
+	if (!gdev)
 		return ERR_PTR(-EPROBE_DEFER);
 
-	return gpiochip_get_desc(chip, pin);
+	/*
+	 * FIXME: keep track of this reference somehow instead of putting it
+	 * here.
+	 */
+	return gpio_device_get_desc(gdev, pin);
 }
 
 /**
-- 
2.39.2

[PATCH v2 10/11] gpio: swnode: replace gpiochip_find() with gpio_device_find_by_label()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We're porting all users of gpiochip_find() to using gpio_device_find().
Update the swnode GPIO code.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib-swnode.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-swnode.c
index b5a6eaf3729b..33c4b1a6c3c1 100644
--- a/drivers/gpio/gpiolib-swnode.c
+++ b/drivers/gpio/gpiolib-swnode.c
@@ -31,31 +31,26 @@ static void swnode_format_propname(const char *con_id, char *propname,
 		strscpy(propname, "gpios", max_size);
 }
 
-static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
+static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
 {
-	return !strcmp(chip->label, data);
-}
+	const struct software_node *gdev_node;
+	struct gpio_device *gdev;
 
-static struct gpio_chip *swnode_get_chip(struct fwnode_handle *fwnode)
-{
-	const struct software_node *chip_node;
-	struct gpio_chip *chip;
-
-	chip_node = to_software_node(fwnode);
-	if (!chip_node || !chip_node->name)
+	gdev_node = to_software_node(fwnode);
+	if (!gdev_node || !gdev_node->name)
 		return ERR_PTR(-EINVAL);
 
-	chip = gpiochip_find((void *)chip_node->name, swnode_gpiochip_match_name);
-	return chip ?: ERR_PTR(-EPROBE_DEFER);
+	gdev = gpio_device_find_by_label((void *)gdev_node->name);
+	return gdev ?: ERR_PTR(-EPROBE_DEFER);
 }
 
 struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
 				   const char *con_id, unsigned int idx,
 				   unsigned long *flags)
 {
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
 	const struct software_node *swnode;
 	struct fwnode_reference_args args;
-	struct gpio_chip *chip;
 	struct gpio_desc *desc;
 	char propname[32]; /* 32 is max size of property name */
 	int error;
@@ -77,12 +72,16 @@ struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
 		return ERR_PTR(error);
 	}
 
-	chip = swnode_get_chip(args.fwnode);
+	gdev = swnode_get_gpio_device(args.fwnode);
 	fwnode_handle_put(args.fwnode);
-	if (IS_ERR(chip))
-		return ERR_CAST(chip);
+	if (IS_ERR(gdev))
+		return ERR_CAST(gdev);
 
-	desc = gpiochip_get_desc(chip, args.args[0]);
+	/*
+	 * FIXME: The GPIO device reference is put at return but the descriptor
+	 * is passed on. Find a proper solution.
+	 */
+	desc = gpio_device_get_desc(gdev, args.args[0]);
 	*flags = args.args[1]; /* We expect native GPIO flags */
 
 	pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
-- 
2.39.2

[PATCH v2 11/11] gpio: sysfs: drop the mention of gpiochip_find() from sysfs code

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We have removed all callers of gpiochip_find() so don't mention it in
gpiolib-sysfs.c.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 50503a4525eb..6f309a3b2d9a 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -814,7 +814,7 @@ static int __init gpiolib_sysfs_init(void)
 		 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
 		 * and needs to be fixed.
 		 *
-		 * Also it would be nice to use gpiochip_find() here so we
+		 * Also it would be nice to use gpio_device_find() here so we
 		 * can keep gpio_chips local to gpiolib.c, but the yield of
 		 * gpio_lock prevents us from doing this.
 		 */
-- 
2.39.2

Re: [PATCH v2 04/11] gpiolib: provide gpio_device_find_by_label()

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:20PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> By far the most common way of looking up GPIO devices is using their
> label. Provide a helpers for that to avoid every user implementing their
> own matching function.

...

> +static int gpio_chip_match_by_label(struct gpio_chip *gc, void *label)
> +{
> +	return gc->label && !strcmp(gc->label, label);

When gc->label can be NULL?

> +}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 05/11] gpiolib: provide gpio_device_get_desc()

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:21PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Getting the GPIO descriptor directly from the gpio_chip struct is
> dangerous as we don't take the reference to the underlying GPIO device.
> In order to start working towards removing gpiochip_get_desc(), let's
> provide a safer variant that works with an existing reference to struct
> gpio_device.

...

> +struct gpio_desc *
> +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum)
> +{
> +	struct gpio_chip *gc = gdev->chip;

I prefer

	struct gpio_chip *gc;

> +	/*
> +	 * FIXME: This will be locked once we protect gdev->chip everywhere
> +	 * with SRCU.
> +	 */

	gc = gdev->chip;

as it is more robust against changes in between and easier to read and
understand in the code what's going on. With decoupled assignment in this case
it's harder to see at the flash glance if the gc is parameter of the function
or being derived from somewhere else.

> +	if (!gc)
> +		return ERR_PTR(-ENODEV);
>  
>  	if (hwnum >= gdev->ngpio)
>  		return ERR_PTR(-EINVAL);
>  
>  	return &gdev->descs[hwnum];
>  }

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 07/11] gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:23PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Remove all remaining uses of find_chip_by_name() (and subsequently:
> gpiochip_find()) from gpiolib.c and use the new
> gpio_device_find_by_label() instead.

...

>  	for (hog = &hogs[0]; hog->chip_label; hog++) {
> +		struct gpio_device *gdev __free(gpio_device_put) = NULL;

In the loop?! How does it work when loop goes second iteration and so on?

>  		list_add_tail(&hog->list, &gpio_machine_hogs);
>  
>  		/*
>  		 * The chip may have been registered earlier, so check if it
>  		 * exists and, if so, try to hog the line now.
>  		 */
> -		gc = find_chip_by_name(hog->chip_label);
> -		if (gc)
> -			gpiochip_machine_hog(gc, hog);
> +		gdev = gpio_device_find_by_label(hog->chip_label);
> +		if (gdev)
> +			gpiochip_machine_hog(gpio_device_get_chip(gdev), hog);

So, do we expect the chip_label be different between hogs? Ah, seems so
as it covers _all_ hogs in the system.

>  	}

Even if the __free() scope works fine, I think this algorithm should be
revisited to make sure we have iterating only on hogs of the same chip.
Hence, the hogs should be placed into tree structure with a label being
the key in it.

...

> +		struct gpio_device *gdev __free(gpio_device_put) = NULL;

> +		gc = gpio_device_get_chip(gdev);

Similar wish here, perhaps maple tree can be utilized in the future for both of them.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 07/11] gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:23PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Remove all remaining uses of find_chip_by_name() (and subsequently:
> gpiochip_find()) from gpiolib.c and use the new
> gpio_device_find_by_label() instead.

...

>  	for (p = &table->table[0]; p->key; p++) {
> -		struct gpio_chip *gc;
> +		struct gpio_device *gdev __free(gpio_device_put) = NULL;

> +		gc = gpio_device_get_chip(gdev);

What the heck is this, btw? You have gdev NULL here.

>  		/* idx must always match exactly */
>  		if (p->idx != idx)
> @@ -4004,9 +3996,8 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
>  			return ERR_PTR(-EPROBE_DEFER);
>  		}
>  
> -		gc = find_chip_by_name(p->key);
> -
> -		if (!gc) {
> +		gdev = gpio_device_find_by_label(p->key);
> +		if (!gdev) {

...

>  		if (gc->ngpio <= p->chip_hwnum) {
>  			dev_err(dev,
>  				"requested GPIO %u (%u) is out of range [0..%u] for chip %s\n",
> -				idx, p->chip_hwnum, gc->ngpio - 1,
> +				idx, p->chip_hwnum, gdev->chip->ngpio - 1,

In other patch you use wrapper to get gdev->chip, why not here?

>  				gc->label);

Is this gc is different to gdev->chip?

>  			return ERR_PTR(-EINVAL);
>  		}

...

Sorry, but this patch seems to me as WIP. Please, revisit it, make sure all
things are done consistently.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 08/11] gpio: of: replace gpiochip_find_* with gpio_device_find_*

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:24PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> We're porting all users of gpiochip_find() to using gpio_device_find().
> Update the OF GPIO code.

...

> +	desc = of_xlate_and_get_gpiod_flags(gdev->chip, &gpiospec, flags);

> +		ret = of_gpiochip_add_hog(gpio_device_get_chip(gdev), rd->dn);

> +		of_gpiochip_remove_hog(gpio_device_get_chip(gdev), rd->dn);

Find the difference in the first parameter in all three.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 09/11] gpio: acpi: replace gpiochip_find() with gpio_device_find()

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:25PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> We're porting all users of gpiochip_find() to using gpio_device_find().
> Update the ACPI GPIO code.

...

> +	/*
> +	 * FIXME: keep track of this reference somehow instead of putting it
> +	 * here.

Under "this" you meant gdev? Please, spell it explicitly, I spent a couple of
minutes to get what exactly this comment is about.

> +	 */
> +	return gpio_device_get_desc(gdev, pin);
>  }

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 02/11] gpiolib: add support for scope-based management to gpio_device

[Andy Shevchenko]

On Tue, Sep 12, 2023 at 12:07:18PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> As the few users that need to get the reference to the GPIO device often
> release it right after inspecting its properties, let's add support for
> the automatic reference release to struct gpio_device.

...

> +DEFINE_FREE(gpio_device_put, struct gpio_device *, if (_T) gpio_device_put(_T));

Looks like this should be

	if (!IS_ERR_OR_NULL(_T))

(with linux/err.h included).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 07/11] gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()

[Bartosz Golaszewski]

On Tue, Sep 12, 2023 at 1:08 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Tue, Sep 12, 2023 at 12:07:23PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > Remove all remaining uses of find_chip_by_name() (and subsequently:
> > gpiochip_find()) from gpiolib.c and use the new
> > gpio_device_find_by_label() instead.
>
> ...
>
> >       for (hog = &hogs[0]; hog->chip_label; hog++) {
> > +             struct gpio_device *gdev __free(gpio_device_put) = NULL;
>
> In the loop?! How does it work when loop goes second iteration and so on?
>

This works fine, the variable goes out of scope (reference is put) on
every iteration.

Bart

> >               list_add_tail(&hog->list, &gpio_machine_hogs);
> >
> >               /*
> >                * The chip may have been registered earlier, so check if it
> >                * exists and, if so, try to hog the line now.
> >                */
> > -             gc = find_chip_by_name(hog->chip_label);
> > -             if (gc)
> > -                     gpiochip_machine_hog(gc, hog);
> > +             gdev = gpio_device_find_by_label(hog->chip_label);
> > +             if (gdev)
> > +                     gpiochip_machine_hog(gpio_device_get_chip(gdev), hog);
>
> So, do we expect the chip_label be different between hogs? Ah, seems so
> as it covers _all_ hogs in the system.
>
> >       }
>
> Even if the __free() scope works fine, I think this algorithm should be
> revisited to make sure we have iterating only on hogs of the same chip.
> Hence, the hogs should be placed into tree structure with a label being
> the key in it.
>
> ...
>
> > +             struct gpio_device *gdev __free(gpio_device_put) = NULL;
>
> > +             gc = gpio_device_get_chip(gdev);
>
> Similar wish here, perhaps maple tree can be utilized in the future for both of them.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Re: [PATCH v2 07/11] gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()

[Bartosz Golaszewski]

On Tue, Sep 12, 2023 at 1:16 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Tue, Sep 12, 2023 at 12:07:23PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > Remove all remaining uses of find_chip_by_name() (and subsequently:
> > gpiochip_find()) from gpiolib.c and use the new
> > gpio_device_find_by_label() instead.
>
> ...
>
> >       for (p = &table->table[0]; p->key; p++) {
> > -             struct gpio_chip *gc;
> > +             struct gpio_device *gdev __free(gpio_device_put) = NULL;
>
> > +             gc = gpio_device_get_chip(gdev);
>
> What the heck is this, btw? You have gdev NULL here.
>

Gah! Thanks. I relied on tests succeeding and no KASAN warnings, I
need to go through this line-by-line again.

Bart

> >               /* idx must always match exactly */
> >               if (p->idx != idx)
> > @@ -4004,9 +3996,8 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
> >                       return ERR_PTR(-EPROBE_DEFER);
> >               }
> >
> > -             gc = find_chip_by_name(p->key);
> > -
> > -             if (!gc) {
> > +             gdev = gpio_device_find_by_label(p->key);
> > +             if (!gdev) {
>
> ...
>
> >               if (gc->ngpio <= p->chip_hwnum) {
> >                       dev_err(dev,
> >                               "requested GPIO %u (%u) is out of range [0..%u] for chip %s\n",
> > -                             idx, p->chip_hwnum, gc->ngpio - 1,
> > +                             idx, p->chip_hwnum, gdev->chip->ngpio - 1,
>
> In other patch you use wrapper to get gdev->chip, why not here?
>
> >                               gc->label);
>
> Is this gc is different to gdev->chip?
>
> >                       return ERR_PTR(-EINVAL);
> >               }
>
> ...
>
> Sorry, but this patch seems to me as WIP. Please, revisit it, make sure all
> things are done consistently.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Re: [PATCH v2 02/11] gpiolib: add support for scope-based management to gpio_device

[Bartosz Golaszewski]

On Tue, Sep 12, 2023 at 1:33 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Tue, Sep 12, 2023 at 12:07:18PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > As the few users that need to get the reference to the GPIO device often
> > release it right after inspecting its properties, let's add support for
> > the automatic reference release to struct gpio_device.
>
> ...
>
> > +DEFINE_FREE(gpio_device_put, struct gpio_device *, if (_T) gpio_device_put(_T));
>
> Looks like this should be
>
>         if (!IS_ERR_OR_NULL(_T))
>

Good catch, thanks!

Bart

Re: [PATCH v2 04/11] gpiolib: provide gpio_device_find_by_label()

[Bartosz Golaszewski]

On Tue, Sep 12, 2023 at 12:57 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Tue, Sep 12, 2023 at 12:07:20PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > By far the most common way of looking up GPIO devices is using their
> > label. Provide a helpers for that to avoid every user implementing their
> > own matching function.
>
> ...
>
> > +static int gpio_chip_match_by_label(struct gpio_chip *gc, void *label)
> > +{
> > +     return gc->label && !strcmp(gc->label, label);
>
> When gc->label can be NULL?
>

Whenever the driver doesn't assign it. The copy in gpio_device is set
to "unknown" for display in logs/user-space but not the one in
gpio_chip.

Bart

> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Re: [PATCH v2 07/11] gpiolib: replace find_chip_by_name() with gpio_device_find_by_label()

[Bartosz Golaszewski]

On Tue, Sep 12, 2023 at 1:35 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> On Tue, Sep 12, 2023 at 1:16 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> >
> > On Tue, Sep 12, 2023 at 12:07:23PM +0200, Bartosz Golaszewski wrote:
> > > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> > >
> > > Remove all remaining uses of find_chip_by_name() (and subsequently:
> > > gpiochip_find()) from gpiolib.c and use the new
> > > gpio_device_find_by_label() instead.
> >
> > ...
> >
> > >       for (p = &table->table[0]; p->key; p++) {
> > > -             struct gpio_chip *gc;
> > > +             struct gpio_device *gdev __free(gpio_device_put) = NULL;
> >
> > > +             gc = gpio_device_get_chip(gdev);
> >
> > What the heck is this, btw? You have gdev NULL here.
> >
>
> Gah! Thanks. I relied on tests succeeding and no KASAN warnings, I
> need to go through this line-by-line again.
>

Fortunately, this was just an unused leftover. I fixed it for v3.

Bart

> Bart
>
> > >               /* idx must always match exactly */
> > >               if (p->idx != idx)
> > > @@ -4004,9 +3996,8 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
> > >                       return ERR_PTR(-EPROBE_DEFER);
> > >               }
> > >
> > > -             gc = find_chip_by_name(p->key);
> > > -
> > > -             if (!gc) {
> > > +             gdev = gpio_device_find_by_label(p->key);
> > > +             if (!gdev) {
> >
> > ...
> >
> > >               if (gc->ngpio <= p->chip_hwnum) {
> > >                       dev_err(dev,
> > >                               "requested GPIO %u (%u) is out of range [0..%u] for chip %s\n",
> > > -                             idx, p->chip_hwnum, gc->ngpio - 1,
> > > +                             idx, p->chip_hwnum, gdev->chip->ngpio - 1,
> >
> > In other patch you use wrapper to get gdev->chip, why not here?
> >
> > >                               gc->label);
> >
> > Is this gc is different to gdev->chip?
> >
> > >                       return ERR_PTR(-EINVAL);
> > >               }
> >
> > ...
> >
> > Sorry, but this patch seems to me as WIP. Please, revisit it, make sure all
> > things are done consistently.
> >
> > --
> > With Best Regards,
> > Andy Shevchenko
> >
> >