gpiolib: add gpiod_get_array and gpiod_put_array functions

Introduce new functions for conveniently obtaining and disposing of
an entire array of GPIOs with one function call.

ACPI parts tested by Mika Westerberg, DT parts tested by Rojhalat
Ibrahim.

Change log:
v5: move the ACPI functions to gpiolib-acpi.c
v4: - use shorter names for members of struct gpio_descs
    - rename lut_gpio_count to platform_gpio_count for clarity
    - add check for successful memory allocation
    - use ERR_CAST()
v3: - rebase on current linux-gpio devel branch
    - fix ACPI GPIO counting
    - allow for zero-sized arrays
    - make the flags argument mandatory for the new functions
    - clarify documentation
v2: change interface

Suggested-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Rojhalat Ibrahim <imr@rtschenk.de>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Rojhalat Ibrahim <imr@rtschenk.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 145 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 2f8296c021e5..3d5b85a7dcdf 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1806,6 +1806,70 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 	return desc;
 }
 
+static int dt_gpio_count(struct device *dev, const char *con_id)
+{
+	int ret;
+	char propname[32];
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id)
+			snprintf(propname, sizeof(propname), "%s-%s",
+				 con_id, gpio_suffixes[i]);
+		else
+			snprintf(propname, sizeof(propname), "%s",
+				 gpio_suffixes[i]);
+
+		ret = of_gpio_named_count(dev->of_node, propname);
+		if (ret >= 0)
+			break;
+	}
+	return ret;
+}
+
+static int platform_gpio_count(struct device *dev, const char *con_id)
+{
+	struct gpiod_lookup_table *table;
+	struct gpiod_lookup *p;
+	unsigned int count = 0;
+
+	table = gpiod_find_lookup_table(dev);
+	if (!table)
+		return -ENOENT;
+
+	for (p = &table->table[0]; p->chip_label; p++) {
+		if ((con_id && p->con_id && !strcmp(con_id, p->con_id)) ||
+		    (!con_id && !p->con_id))
+			count++;
+	}
+	if (!count)
+		return -ENOENT;
+
+	return count;
+}
+
+/**
+ * gpiod_count - return the number of GPIOs associated with a device / function
+ *		or -ENOENT if no GPIO has been assigned to the requested function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ */
+int gpiod_count(struct device *dev, const char *con_id)
+{
+	int count = -ENOENT;
+
+	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
+		count = dt_gpio_count(dev, con_id);
+	else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev))
+		count = acpi_gpio_count(dev, con_id);
+
+	if (count < 0)
+		count = platform_gpio_count(dev, con_id);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(gpiod_count);
+
 /**
  * gpiod_get - obtain a GPIO for a given GPIO function
  * @dev:	GPIO consumer, can be NULL for system-global GPIOs
@@ -2090,6 +2154,72 @@ static void gpiochip_free_hogs(struct gpio_chip *chip)
 }
 
 /**
+ * gpiod_get_array - obtain multiple GPIOs from a multi-index GPIO function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This function acquires all the GPIOs defined under a given function.
+ *
+ * Return a struct gpio_descs containing an array of descriptors, -ENOENT if
+ * no GPIO has been assigned to the requested function, or another IS_ERR()
+ * code if an error occurred while trying to acquire the GPIOs.
+ */
+struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
+						const char *con_id,
+						enum gpiod_flags flags)
+{
+	struct gpio_desc *desc;
+	struct gpio_descs *descs;
+	int count;
+
+	count = gpiod_count(dev, con_id);
+	if (count < 0)
+		return ERR_PTR(count);
+
+	descs = kzalloc(sizeof(*descs) + sizeof(descs->desc[0]) * count,
+			GFP_KERNEL);
+	if (!descs)
+		return ERR_PTR(-ENOMEM);
+
+	for (descs->ndescs = 0; descs->ndescs < count; ) {
+		desc = gpiod_get_index(dev, con_id, descs->ndescs, flags);
+		if (IS_ERR(desc)) {
+			gpiod_put_array(descs);
+			return ERR_CAST(desc);
+		}
+		descs->desc[descs->ndescs] = desc;
+		descs->ndescs++;
+	}
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array);
+
+/**
+ * gpiod_get_array_optional - obtain multiple GPIOs from a multi-index GPIO
+ *                            function
+ * @dev:	GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id:	function within the GPIO consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This is equivalent to gpiod_get_array(), except that when no GPIO was
+ * assigned to the requested function it will return NULL.
+ */
+struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
+							const char *con_id,
+							enum gpiod_flags flags)
+{
+	struct gpio_descs *descs;
+
+	descs = gpiod_get_array(dev, con_id, flags);
+	if (IS_ERR(descs) && (PTR_ERR(descs) == -ENOENT))
+		return NULL;
+
+	return descs;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_array_optional);
+
+/**
  * gpiod_put - dispose of a GPIO descriptor
  * @desc:	GPIO descriptor to dispose of
  *
@@ -2101,6 +2231,21 @@ void gpiod_put(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_put);
 
+/**
+ * gpiod_put_array - dispose of multiple GPIO descriptors
+ * @descs:	struct gpio_descs containing an array of descriptors
+ */
+void gpiod_put_array(struct gpio_descs *descs)
+{
+	unsigned int i;
+
+	for (i = 0; i < descs->ndescs; i++)
+		gpiod_put(descs->desc[i]);
+
+	kfree(descs);
+}
+EXPORT_SYMBOL_GPL(gpiod_put_array);
+
 #ifdef CONFIG_DEBUG_FS
 
 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)