Many Linux drivers use [devm_]gpiod_get to get appropriately configured
GPIO descriptors out with little code. Make porting such Linux code
easier by providing a semi-compatible gpiod_get function. Main
differences:
- It returns a gpio index, so it can be passed to any gpio_ function
- It's device-tree only, so it should only be used from drivers
that themselves probe from device tree.
Signed-off-by: Ahmad Fatoum <ahmad@xxxxxx>
---
drivers/gpio/gpiolib.c | 43 ++++++++++++++++++++++++++++++++++++++++++
include/gpiod.h | 26 +++++++++++++++++++++++++
2 files changed, 69 insertions(+)
create mode 100644 include/gpiod.h
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 6088cadd8a18..7b7261d01f24 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -6,6 +6,7 @@
#include <complete.h>
#include <gpio.h>
#include <of_gpio.h>
+#include <gpiod.h>
#include <errno.h>
#include <malloc.h>
@@ -554,6 +555,48 @@ static int of_gpiochip_scan_hogs(struct gpio_chip *chip)
return 0;
}
+/* Linux compatibility helper: Get a GPIO descriptor from device tree */
+int gpiod_get(struct device_d *dev, const char *_con_id, enum gpiod_flags flags)
+{
+ struct device_node *np = dev->device_node;
+ enum of_gpio_flags of_flags;
+ const char *con_id = "gpios", *label = dev_name(dev);
+ char *buf = NULL;
+ int gpio;
+ int ret;
+
+ if (!IS_ENABLED(CONFIG_OFDEVICE) || !dev->device_node)
+ return -ENODEV;
+
+ if (_con_id) {
+ con_id = buf = basprintf("%s-gpios", _con_id);
+ if (!buf)
+ return -ENOMEM;
+ }
+
+ gpio = of_get_named_gpio_flags(np, con_id, 0, &of_flags);
+ free(buf);
+
+ if (!gpio_is_valid(gpio))
+ return gpio < 0 ? gpio : -EINVAL;
+
+ if (of_flags & OF_GPIO_ACTIVE_LOW)
+ flags |= GPIOF_ACTIVE_LOW;
+
+ buf = NULL;
+
+ if (_con_id) {
+ label = buf = basprintf("%s-%s", dev_name(dev), _con_id);
+ if (!label)
+ return -ENOMEM;
+ }
+
+ ret = gpio_request_one(gpio, flags, label);
+ free(buf);
+
+ return ret ?: gpio;
+}
+
int gpiochip_add(struct gpio_chip *chip)
{
int base, i;
diff --git a/include/gpiod.h b/include/gpiod.h
new file mode 100644
index 000000000000..c8b2cd47a3cb
--- /dev/null
+++ b/include/gpiod.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __GPIOD_H_
+#define __GPIOD_H_
+
+#include <gpio.h>
+#include <of_gpio.h>
+
+/**
+ * Optional flags that can be passed to one of gpiod_* to configure direction
+ * and output value. These values cannot be OR'd.
+ */
+enum gpiod_flags {
+ GPIOD_ASIS = 0,
+ GPIOD_IN = GPIOF_IN,
+ /*
+ * To change this later to a different logic level (i.e. taking
+ * active low into account), use gpio_direction_active()
+ */
+ GPIOD_OUT_LOW = GPIOF_OUT_INIT_INACTIVE,
+ GPIOD_OUT_HIGH = GPIOF_OUT_INIT_ACTIVE,
+};
+
+/* returned gpio descriptor can be passed to any normal gpio_* function */
+int gpiod_get(struct device_d *dev, const char *_con_id, enum gpiod_flags flags);
+
+#endif
--
2.30.0
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