Notorious OF GPIO API support

This patch implements various helpers to support OF bindings for
the GPIO LIB API.

Previously this was PowerPC specific, but it seems this code isn't arch-dependent anyhow, so let's place it into of/.

SPARC will not see this addition yet, real hardware seem to not use GPIOs at all. But this might change:

http://www.leox.org/docs/faq_MLleon.html

"16-bit I/O port" sounds promising. :-)

Signed-off-by Anton Vorontsov <[email protected]>

This patch implements support for the GPIO LIB API. Two calls
unimplemented though: irq_to_gpio and gpio_to_irq.

Signed-off-by Anton Vorontsov <[email protected]>

---

  Documentation/powerpc/booting-without-of.txt |   52 ++++++++++++++++++++++++
  arch/powerpc/Kconfig                         |    5 ++
  include/asm-powerpc/gpio.h                   |   56 ++++++++++++++++++++++++++
  3 files changed, 113 insertions(+), 0 deletions(-)

create mode 100644 include/asm-powerpc/gpio.h

diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index b506245..e9e0c2f 100644
--- a/Documentation/powerpc/booting-without-of.txt
+++ b/Documentation/powerpc/booting-without-of.txt
@@ -66,6 +66,10 @@ Table of Contents
3) OpenPIC Interrupt Controllers
4) ISA Interrupt Controllers

+ VIII - Specifying GPIO information for devices
+ 1) gpios property
+ 2) gpio-controller nodes
+
Appendix A - Sample SOC node for MPC8540

@@ -2925,6 +2929,54 @@ encodings listed below:
2 = high to low edge sensitive type enabled 3 = low to high edge sensitive type enabled

+VIII - Specifying GPIO information for devices
+==============================================
+
+1) gpios property
+-----------------
+
+Nodes that makes use of GPIOs should define them using `gpios' property, +format of which is: <&gpio-controller1-phandle gpio1-specifier

 +                    &gpio-controller2-phandle gpio2-specifier
 +                    0 /* holes are permitted, means no GPIO 3 */
 +                    &gpio-controller4-phandle gpio4-specifier
 +                    ...>;
 +
 +Note that gpio-specifier length is controller dependent.
 +
 +gpio-specifier may encode: bank, pin position inside the bank,
 +whether pin is open-drain and whether pin is logically inverted.
 +
 +Example of the node using GPIOs:
 +
 +       node {
 +               gpios = <&qe_pio_e 18 0>;
 +       };
 +
 +In this example gpio-specifier is "18 0" and encodes GPIO pin number,
 +and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller.
 +
 +2) gpio-controller nodes
 +------------------------
 +
 +Every GPIO controller node must have #gpio-cells property defined,
 +this information will be used to translate gpio-specifiers.
 +
 +Example of two SOC GPIO banks defined as gpio-controller nodes:
 +
 +       qe_pio_a: gpio-controller@1400 {
 +               #gpio-cells = <2>;
 +               compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
 +               reg = <0x1400 0x18>;
 +               gpio-controller;
 +       };
 +
 +       qe_pio_e: gpio-controller@1460 {
 +               #gpio-cells = <2>;
 +               compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
 +               reg = <0x1460 0x18>;
 +               gpio-controller;

+ };

Appendix A - Sample SOC node for MPC8540
========================================
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 0b27cbd..f328509 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -81,6 +81,11 @@ config GENERIC_FIND_NEXT_BIT
bool
default y

+config GENERIC_GPIO
+ bool
+ help
+ Generic GPIO API support
+
config ARCH_NO_VIRT_TO_BUS
def_bool PPC64

diff --git a/include/asm-powerpc/gpio.h b/include/asm-powerpc/gpio.h new file mode 100644
index 0000000..77ad3a8
--- /dev/null
+++ b/include/asm-powerpc/gpio.h
@@ -0,0 +1,56 @@
+/*
+ * Generic GPIO API implementation for PowerPC.
+ *
+ * Copyright (c) 2007-2008 MontaVista Software, Inc.
+ *
+ * Author: Anton Vorontsov <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __ASM_POWERPC_GPIO_H
+#define __ASM_POWERPC_GPIO_H
+
+#include <linux/errno.h>
+#include <asm-generic/gpio.h>
+
+#ifdef CONFIG_HAVE_GPIO_LIB
+
+/*
+ * We don't (yet) implement inlined/rapid versions for on-chip gpios.
+ * Just call gpiolib.
+ */
+static inline int gpio_get_value(unsigned int gpio)
+{
+ return __gpio_get_value(gpio);
+}
+
+static inline void gpio_set_value(unsigned int gpio, int value) +{
+ __gpio_set_value(gpio, value);
+}
+
+static inline int gpio_cansleep(unsigned int gpio)
+{
+ return __gpio_cansleep(gpio);
+}
+
+/*
+ * Not implemented, yet.
+ */
+static inline int gpio_to_irq(unsigned int gpio)
+{
+ return -ENOSYS;
+}
+
+static inline int irq_to_gpio(unsigned int irq)
+{
+ return -EINVAL;
+}
+
+#endif /* CONFIG_HAVE_GPIO_LIB */
+
+#endif /* __ASM_POWERPC_GPIO_H */
--
1.5.4.5
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