[PATCH RFC/RFT 1/2] gpio: allow atomic registration of gpio chip with pin ranges

[Jonas Gorski <jogo@xxxxxxxxxxx>]

Allow registering gpio chip with ranges at the same time, so we know
at registration time whether there is an associated pin controller.

This allows us to automatically populate the request/free callbacks,
so that drivers are free to omit the assignment, if they do not need
any special handling.

Signed-off-by: Jonas Gorski <jogo@xxxxxxxxxxx>
---
 drivers/gpio/gpiolib-of.c   |  5 +++++
 drivers/gpio/gpiolib.c      | 43 +++++++++++++++++++++++++++++++++++--------
 drivers/gpio/gpiolib.h      |  9 +++++++++
 include/linux/gpio/driver.h | 10 +++++++++-
 4 files changed, 58 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 5fe34a9..e05f0c2e 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -415,6 +415,11 @@ static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
 	return 0;
 }
 
+bool of_gpiochip_has_pin_range(struct gpio_chip *chip)
+{
+	return !!of_find_property(chip->of_node, "gpio-ranges", NULL);
+}
+
 #else
 static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
 #endif
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 8eba02d..09d87ae 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -280,30 +280,47 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc)
 }
 
 /**
- * gpiochip_add() - register a gpio_chip
+ * gpiochip_add_with_ranges() - register a gpio_chip with pin ranges
  * @chip: the chip to register, with chip->base initialized
+ * @pinctrl_name: the dev_name() of the pin controller to map to
+ * @ranges: the mappings of relative gpio offsets to pins
+ * @nranges: the number of ranges
  * Context: potentially before irqs will work
  *
  * Returns a negative errno if the chip can't be registered, such as
  * because the chip->base is invalid or already associated with a
  * different chip.  Otherwise it returns zero as a success code.
  *
- * When gpiochip_add() is called very early during boot, so that GPIOs
- * can be freely used, the chip->dev device must be registered before
- * the gpio framework's arch_initcall().  Otherwise sysfs initialization
- * for GPIOs will fail rudely.
+ * When gpiochip_add_with_ranges() is called very early during boot, so
+ * that GPIOs can be freely used, the chip->dev device must be
+ * registered before the gpio framework's arch_initcall().  Otherwise
+ * sysfs initialization for GPIOs will fail rudely.
  *
  * If chip->base is negative, this requests dynamic assignment of
  * a range of valid GPIOs.
+ *
+ * If nranges is zero, pinctrl_name and ranges may be NULL.
+ * If nranges is not zero or chip->of_node is populated and has a
+ * "gpio-ranges" property, chip->request and chip->free will be populated
+ * with generic callbacks if not yet set.
  */
-int gpiochip_add(struct gpio_chip *chip)
+int gpiochip_add_with_ranges(struct gpio_chip *chip, const char *pinctl_name,
+			     const struct pinctrl_gpio_range *ranges,
+			     unsigned int nranges)
 {
 	unsigned long	flags;
 	int		status = 0;
-	unsigned	id;
+	unsigned	id, i;
 	int		base = chip->base;
 	struct gpio_desc *descs;
 
+	if ((ranges > 0) || of_gpiochip_has_pin_range(chip)) {
+		if (!chip->request)
+			chip->request = gpiochip_generic_request;
+		if (!chip->free)
+			chip->free = gpiochip_generic_free;
+	}
+
 	descs = kcalloc(chip->ngpio, sizeof(descs[0]), GFP_KERNEL);
 	if (!descs)
 		return -ENOMEM;
@@ -359,6 +376,15 @@ int gpiochip_add(struct gpio_chip *chip)
 	if (status)
 		goto err_remove_chip;
 
+	for (i = 0; i < nranges; i++) {
+		const struct pinctrl_gpio_range *range = &ranges[i];
+
+		status = gpiochip_add_pin_range(chip, pinctl_name, range->base,
+						range->pin_base, range->npins);
+		if (status)
+			goto err_remove_chip;
+	}
+
 	acpi_gpiochip_add(chip);
 
 	status = gpiochip_sysfs_register(chip);
@@ -373,6 +399,7 @@ int gpiochip_add(struct gpio_chip *chip)
 
 err_remove_chip:
 	acpi_gpiochip_remove(chip);
+	gpiochip_remove_pin_ranges(chip);
 	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
 err_remove_from_list:
@@ -389,7 +416,7 @@ err_free_descs:
 		chip->label ? : "generic");
 	return status;
 }
-EXPORT_SYMBOL_GPL(gpiochip_add);
+EXPORT_SYMBOL_GPL(gpiochip_add_with_ranges);
 
 /**
  * gpiochip_remove() - unregister a gpio_chip
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 78e634d..6f49e25 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -72,6 +72,15 @@ struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 
 struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum);
 
+#if defined(CONFIG_OF_GPIO) && defined(CONFIG_PINCTRL)
+bool of_gpiochip_has_pin_range(struct gpio_chip *chip);
+#else
+static inline bool of_gpiochip_has_pin_range(struct gpio_chip *chip)
+{
+	return false;
+}
+#endif
+
 extern struct spinlock gpio_lock;
 extern struct list_head gpio_chips;
 
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index d1baebf..727ae9e 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -166,7 +166,15 @@ extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 			unsigned offset);
 
 /* add/remove chips */
-extern int gpiochip_add(struct gpio_chip *chip);
+int gpiochip_add_with_ranges(struct gpio_chip *chip, const char *pinctl_name,
+			     const struct pinctrl_gpio_range *ranges,
+			     unsigned int nranges);
+
+static inline int gpiochip_add(struct gpio_chip *chip)
+{
+	return gpiochip_add_with_ranges(chip, NULL, NULL, 0);
+}
+
 extern void gpiochip_remove(struct gpio_chip *chip);
 extern struct gpio_chip *gpiochip_find(void *data,
 			      int (*match)(struct gpio_chip *chip, void *data));
-- 
2.1.4
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