gpiolib: split character device into gpiolib-cdev

Split the cdev specific functionality out of gpiolib.c and into gpiolib-cdev.c. This improves the readability and maintainability of both the cdev and core gpiolib code.

---

Changed in v4:
- rebased onto the latest gpio/devel (v5.8-rc1)
- squashed the "gpiolib: cdev: fix -Wmissing-prototypes warnings" patch so my "gpiolib: cdev: fixes for split from gpiolib.c" patch set can be disregarded.

Changes in v3:
- updated the gpiolib-cdev.c file comment.
- rebased to latest gpio/devel (no changes impacted this patch)
- dropped the patch commentary as the points mentioned are mostly resolved - there still remain a couple of commits in gpio/fixes that will conflict...

 drivers/gpio/Makefile       |    1 +
 drivers/gpio/gpiolib-cdev.c | 1154 +++++++++++++++++++++++++++++++++++
 drivers/gpio/gpiolib-cdev.h |   11 +
 drivers/gpio/gpiolib.c      | 1119 +--------------------------------
 4 files changed, 1170 insertions(+), 1115 deletions(-)
 create mode 100644 drivers/gpio/gpiolib-cdev.c
 create mode 100644 drivers/gpio/gpiolib-cdev.h

index 1e4894e0bf0f..ef666cfef9d0 100644
@@ -7,6 +7,7 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-devres.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-legacy.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-devprop.o
+obj-$(CONFIG_GPIOLIB)		+= gpiolib-cdev.o
 obj-$(CONFIG_OF_GPIO)		+= gpiolib-of.o
 obj-$(CONFIG_GPIO_SYSFS)	+= gpiolib-sysfs.o
 obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o

new file mode 100644
index 000000000000..973578e7ad10
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef GPIOLIB_CDEV_H
+#define GPIOLIB_CDEV_H
+
+#include <linux/device.h>
+
+int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt);
+void gpiolib_cdev_unregister(struct gpio_device *gdev);
+
+#endif /* GPIOLIB_CDEV_H */

base-commit: b3a9e3b9622ae10064826dccb4f7a52bd88c7407

2.27.0

This v4 version applied for v5.9.

Yours,
Linus Walleij