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authorDavid Brownell <david-b@pacbell.net>2008-03-05 01:28:27 +0300
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-03-05 03:35:10 +0300
commit7560fa60fcdcdb0da662f6a9fad9064b554ef46c (patch)
tree2089d826b0b9230752f318b20884dca20b3847d5 /include/linux/gpio.h
parent83c7c693ed3e61535ad6a097ad991a88aafc54b8 (diff)
downloadlinux-7560fa60fcdcdb0da662f6a9fad9064b554ef46c.tar.xz
gpio: <linux/gpio.h> and "no GPIO support here" stubs
Add a <linux/gpio.h> defining fail/warn stubs for GPIO calls on platforms that don't support the GPIO programming interface. That includes the arch-specific implementation glue otherwise. This facilitates a new model for GPIO usage: drivers that can use GPIOs if they're available, but don't require them. One example of such a driver is NAND driver for various FreeScale chips. On platforms update with GPIO support, they can be used instead of a worst-case delay to verify that the BUSY signal is off. (Also includes a couple minor unrelated doc updates.) Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/gpio.h')
-rw-r--r--include/linux/gpio.h95
1 files changed, 95 insertions, 0 deletions
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
new file mode 100644
index 000000000000..4987a84078ef
--- /dev/null
+++ b/include/linux/gpio.h
@@ -0,0 +1,95 @@
+#ifndef __LINUX_GPIO_H
+#define __LINUX_GPIO_H
+
+/* see Documentation/gpio.txt */
+
+#ifdef CONFIG_GENERIC_GPIO
+#include <asm/gpio.h>
+
+#else
+
+/*
+ * Some platforms don't support the GPIO programming interface.
+ *
+ * In case some driver uses it anyway (it should normally have
+ * depended on GENERIC_GPIO), these routines help the compiler
+ * optimize out much GPIO-related code ... or trigger a runtime
+ * warning when something is wrongly called.
+ */
+
+static inline int gpio_is_valid(int number)
+{
+ return 0;
+}
+
+static inline int gpio_request(unsigned gpio, const char *label)
+{
+ return -ENOSYS;
+}
+
+static inline void gpio_free(unsigned gpio)
+{
+ /* GPIO can never have been requested */
+ WARN_ON(1);
+}
+
+static inline int gpio_direction_input(unsigned gpio)
+{
+ return -ENOSYS;
+}
+
+static inline int gpio_direction_output(unsigned gpio, int value)
+{
+ return -ENOSYS;
+}
+
+static inline int gpio_get_value(unsigned gpio)
+{
+ /* GPIO can never have been requested or set as {in,out}put */
+ WARN_ON(1);
+ return 0;
+}
+
+static inline void gpio_set_value(unsigned gpio, int value)
+{
+ /* GPIO can never have been requested or set as output */
+ WARN_ON(1);
+}
+
+static inline int gpio_cansleep(unsigned gpio)
+{
+ /* GPIO can never have been requested or set as {in,out}put */
+ WARN_ON(1);
+ return 0;
+}
+
+static inline int gpio_get_value_cansleep(unsigned gpio)
+{
+ /* GPIO can never have been requested or set as {in,out}put */
+ WARN_ON(1);
+ return 0;
+}
+
+static inline void gpio_set_value_cansleep(unsigned gpio, int value)
+{
+ /* GPIO can never have been requested or set as output */
+ WARN_ON(1);
+}
+
+static inline int gpio_to_irq(unsigned gpio)
+{
+ /* GPIO can never have been requested or set as input */
+ WARN_ON(1);
+ return -EINVAL;
+}
+
+static inline int irq_to_gpio(unsigned irq)
+{
+ /* irq can never have been returned from gpio_to_irq() */
+ WARN_ON(1);
+ return -EINVAL;
+}
+
+#endif
+
+#endif /* __LINUX_GPIO_H */