The patch titled
gpio: <linux/gpio.h> and "no GPIO support here" stubs
has been added to the -mm tree. Its filename is
gpio-linux-gpioh-and-no-gpio-support-here-stubs.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: gpio: <linux/gpio.h> and "no GPIO support here" stubs
From: David Brownell <david-b@xxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/gpio.txt | 16 ++++--
include/linux/gpio.h | 95 +++++++++++++++++++++++++++++++++++++++
2 files changed, 107 insertions(+), 4 deletions(-)
diff -puN Documentation/gpio.txt~gpio-linux-gpioh-and-no-gpio-support-here-stubs Documentation/gpio.txt
--- a/Documentation/gpio.txt~gpio-linux-gpioh-and-no-gpio-support-here-stubs
+++ a/Documentation/gpio.txt
@@ -2,6 +2,9 @@ GPIO Interfaces
This provides an overview of GPIO access conventions on Linux.
+These calls use the gpio_* naming prefix. No other calls should use that
+prefix, or the related __gpio_* prefix.
+
What is a GPIO?
===============
@@ -69,11 +72,13 @@ in this document, but drivers acting as
not care how it's implemented.)
That said, if the convention is supported on their platform, drivers should
-use it when possible. Platforms should declare GENERIC_GPIO support in
-Kconfig (boolean true), which multi-platform drivers can depend on when
-using the include file:
+use it when possible. Platforms must declare GENERIC_GPIO support in their
+Kconfig (boolean true), and provide an <asm/gpio.h> file. Drivers that can't
+work without standard GPIO calls should have Kconfig entries which depend
+on GENERIC_GPIO. The GPIO calls are available, either as "real code" or as
+optimized-away stubs, when drivers use the include file:
- #include <asm/gpio.h>
+ #include <linux/gpio.h>
If you stick to this convention then it'll be easier for other developers to
see what your code is doing, and help maintain it.
@@ -326,6 +331,9 @@ pulldowns integrated on some platforms.
or support them in the same way; and any given board might use external
pullups (or pulldowns) so that the on-chip ones should not be used.
(When a circuit needs 5 kOhm, on-chip 100 kOhm resistors won't do.)
+Likewise drive strength (2 mA vs 20 mA) and voltage (1.8V vs 3.3V) is a
+platform-specific issue, as are models like (not) having a one-to-one
+correspondence between configurable pins and GPIOs.
There are other system-specific mechanisms that are not specified here,
like the aforementioned options for input de-glitching and wire-OR output.
diff -puN /dev/null include/linux/gpio.h
--- /dev/null
+++ a/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 */
_
Patches currently in -mm which might be from david-b@xxxxxxxxxxx are
rtc-add-support-for-the-s-35390a-rtc-chip.patch
git-acpi.patch
at91-correct-at91sam9263ek-lcd-power-gpio-pin.patch
git-avr32.patch
usb-net-asix-does-not-really-need-10-100mbit.patch
mpc5200-fix-build-error-on-mpc52xx_psc_spi-device-driver.patch
spi-pxa2xx_spi-sparse-fixes.patch
rtc-avoid-legacy-drivers-with-generic-framework.patch
rtc-isl1208-new-style-conversion-and-minor-bug-fixes.patch
rtc-isl1208-new-style-conversion-and-minor-bug-fixes-checkpatch-fixes.patch
rtc-pcf8563-new-style-conversion.patch
rtc-pcf8563-new-style-conversion-checkpatch-fixes.patch
rtc-pcf8563-new-style-conversion-checkpatch-fixes-fix.patch
rtc-x1205-new-style-conversion.patch
rtc-x1205-new-style-conversion-checkpatch-fixes.patch
rtc-silence-section-mismatch-warning-in-rtc-test.patch
make-ds1511_rtc_readset_time-static.patch
gpio-linux-gpioh-and-no-gpio-support-here-stubs.patch
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