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, 84 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index c0929d938ced..c4919966453d 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -712,3 +712,87 @@ void acpi_gpiochip_remove(struct gpio_chip *chip)
         acpi_detach_data(handle, acpi_gpio_chip_dh);
         kfree(acpi_gpio);
 }
+
+static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
+{
+        const union acpi_object *element = obj->package.elements;
+        const union acpi_object *end = element + obj->package.count;
+        unsigned int count = 0;
+
+        while (element < end) {
+                if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
+                        count++;
+
+                element++;
+        }
+        return count;
+}
+
+static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
+{
+        unsigned int *count = data;
+
+        if (ares->type == ACPI_RESOURCE_TYPE_GPIO)
+                *count += ares->data.gpio.pin_table_length;
+
+        return 1;
+}
+
+/**
+ * acpi_gpio_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 acpi_gpio_count(struct device *dev, const char *con_id)
+{
+        struct acpi_device *adev = ACPI_COMPANION(dev);
+        const union acpi_object *obj;
+        const struct acpi_gpio_mapping *gm;
+        int count = -ENOENT;
+        int ret;
+        char propname[32];
+        unsigned int i;
+
+        /* Try first from _DSD */
+        for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+                if (con_id && strcmp(con_id, "gpios"))
+                        snprintf(propname, sizeof(propname), "%s-%s",
+                                 con_id, gpio_suffixes[i]);
+                else
+                        snprintf(propname, sizeof(propname), "%s",
+                                 gpio_suffixes[i]);
+
+                ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
+                                            &obj);
+                if (ret == 0) {
+                        if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
+                                count = 1;
+                        else if (obj->type == ACPI_TYPE_PACKAGE)
+                                count = acpi_gpio_package_count(obj);
+                } else if (adev->driver_gpios) {
+                        for (gm = adev->driver_gpios; gm->name; gm++)
+                                if (strcmp(propname, gm->name) == 0) {
+                                        count = gm->size;
+                                        break;
+                                }
+                }
+                if (count >= 0)
+                        break;
+        }
+
+        /* Then from plain _CRS GPIOs */
+        if (count < 0) {
+                struct list_head resource_list;
+                unsigned int crs_count = 0;
+
+                INIT_LIST_HEAD(&resource_list);
+                acpi_dev_get_resources(adev, &resource_list,
+                                       acpi_find_gpio_count, &crs_count);
+                acpi_dev_free_resource_list(&resource_list);
+                if (crs_count > 0)
+                        count = crs_count;
+        }
+        return count;
+}