gpio: move sysfs support to its own file

sysfs support is currently entangled within the core GPIO support, while
it should relly just be a (privileged) user of the integer GPIO API.
This patch is a first step towards making the gpiolib code more readable
by splitting it into logical parts.

Move all sysfs support to their own source file, and share static
members of gpiolib that need to be in the private gpiolib.h file. In
the future we will want to put some of them back into gpiolib.c, but this
first patch let us at least identify them.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Makefile

@@ -5,6 +5,7 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
 obj-$(CONFIG_GPIO_DEVRES)	+= devres.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 obj-$(CONFIG_OF_GPIO)		+= gpiolib-of.o
+obj-$(CONFIG_GPIO_SYSFS)	+= gpiolib-sysfs.o
 obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 
 # Device drivers. Generally keep list sorted alphabetically

drivers/gpio/gpiolib.h

@@ -51,4 +51,95 @@ void gpiochip_free_own_desc(struct gpio_desc *desc);
 struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 		   const char *list_name, int index, enum of_gpio_flags *flags);
 
+extern struct spinlock gpio_lock;
+extern struct list_head gpio_chips;
+
+struct gpio_desc {
+	struct gpio_chip	*chip;
+	unsigned long		flags;
+/* flag symbols are bit numbers */
+#define FLAG_REQUESTED	0
+#define FLAG_IS_OUT	1
+#define FLAG_EXPORT	2	/* protected by sysfs_lock */
+#define FLAG_SYSFS	3	/* exported via /sys/class/gpio/control */
+#define FLAG_TRIG_FALL	4	/* trigger on falling edge */
+#define FLAG_TRIG_RISE	5	/* trigger on rising edge */
+#define FLAG_ACTIVE_LOW	6	/* value has active low */
+#define FLAG_OPEN_DRAIN	7	/* Gpio is open drain type */
+#define FLAG_OPEN_SOURCE 8	/* Gpio is open source type */
+#define FLAG_USED_AS_IRQ 9	/* GPIO is connected to an IRQ */
+
+#define ID_SHIFT	16	/* add new flags before this one */
+
+#define GPIO_FLAGS_MASK		((1 << ID_SHIFT) - 1)
+#define GPIO_TRIGGER_MASK	(BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
+
+	const char		*label;
+};
+
+int gpiod_request(struct gpio_desc *desc, const char *label);
+void gpiod_free(struct gpio_desc *desc);
+
+/*
+ * Return the GPIO number of the passed descriptor relative to its chip
+ */
+static int __maybe_unused gpio_chip_hwgpio(const struct gpio_desc *desc)
+{
+	return desc - &desc->chip->desc[0];
+}
+
+/* With descriptor prefix */
+
+#define gpiod_emerg(desc, fmt, ...)					       \
+	pr_emerg("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\
+		 ##__VA_ARGS__)
+#define gpiod_crit(desc, fmt, ...)					       \
+	pr_crit("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
+		 ##__VA_ARGS__)
+#define gpiod_err(desc, fmt, ...)					       \
+	pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",  \
+		 ##__VA_ARGS__)
+#define gpiod_warn(desc, fmt, ...)					       \
+	pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
+		 ##__VA_ARGS__)
+#define gpiod_info(desc, fmt, ...)					       \
+	pr_info("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
+		 ##__VA_ARGS__)
+#define gpiod_dbg(desc, fmt, ...)					       \
+	pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\
+		 ##__VA_ARGS__)
+
+/* With chip prefix */
+
+#define chip_emerg(chip, fmt, ...)					\
+	pr_emerg("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
+#define chip_crit(chip, fmt, ...)					\
+	pr_crit("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
+#define chip_err(chip, fmt, ...)					\
+	pr_err("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
+#define chip_warn(chip, fmt, ...)					\
+	pr_warn("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
+#define chip_info(chip, fmt, ...)					\
+	pr_info("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
+#define chip_dbg(chip, fmt, ...)					\
+	pr_debug("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
+
+#ifdef CONFIG_GPIO_SYSFS
+
+int gpiochip_export(struct gpio_chip *chip);
+void gpiochip_unexport(struct gpio_chip *chip);
+
+#else
+
+static inline int gpiochip_export(struct gpio_chip *chip)
+{
+	return 0;
+}
+
+static inline void gpiochip_unexport(struct gpio_chip *chip)
+{
+}
+
+#endif /* CONFIG_GPIO_SYSFS */
+
 #endif /* GPIOLIB_H */