[PATCH 1/4] OF helpers for the GPIO API
Anton Vorontsov
avorontsov at ru.mvista.com
Wed Mar 12 05:42:10 EST 2008
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 <avorontsov at ru.mvista.com>
---
drivers/of/Kconfig | 6 ++
drivers/of/Makefile | 1 +
drivers/of/gpio.c | 202 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of_gpio.h | 96 ++++++++++++++++++++++
4 files changed, 305 insertions(+), 0 deletions(-)
create mode 100644 drivers/of/gpio.c
create mode 100644 include/linux/of_gpio.h
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index c03072b..3354ad7 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -1,3 +1,9 @@
config OF_DEVICE
def_bool y
depends on OF && (SPARC || PPC_OF)
+
+config OF_GPIO
+ def_bool y
+ depends on OF && PPC_OF && HAVE_GPIO_LIB
+ help
+ OpenFirmware GPIO accessors
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index ab9be5d..5a61f70 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -1,2 +1,3 @@
obj-y = base.o
obj-$(CONFIG_OF_DEVICE) += device.o platform.o
+obj-$(CONFIG_OF_GPIO) += gpio.o
diff --git a/drivers/of/gpio.c b/drivers/of/gpio.c
new file mode 100644
index 0000000..ed1c161
--- /dev/null
+++ b/drivers/of/gpio.c
@@ -0,0 +1,202 @@
+/*
+ * OF helpers for the GPIO API
+ *
+ * Copyright (c) 2007-2008 MontaVista Software, Inc.
+ *
+ * Author: Anton Vorontsov <avorontsov at ru.mvista.com>
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <asm/prom.h>
+
+int of_get_gpio(struct device_node *np, int index)
+{
+ int ret = -EINVAL;
+ struct device_node *gc;
+ struct of_gpio_chip *of_gc = NULL;
+ int size;
+ const u32 *gpios;
+ u32 nr_cells;
+ int i;
+ const void *gpio_spec;
+ const u32 *gpio_cells;
+ int gpio_index = 0;
+
+ gpios = of_get_property(np, "gpios", &size);
+ if (!gpios) {
+ ret = -ENOENT;
+ goto err0;
+ }
+ nr_cells = size / sizeof(u32);
+
+ for (i = 0; i < nr_cells; gpio_index++) {
+ const phandle *gpio_phandle;
+
+ gpio_phandle = gpios + i;
+ gpio_spec = gpio_phandle + 1;
+
+ /* one cell hole in the gpios = <>; */
+ if (!*gpio_phandle) {
+ if (gpio_index == index)
+ return -ENOENT;
+ i++;
+ continue;
+ }
+
+ gc = of_find_node_by_phandle(*gpio_phandle);
+ if (!gc) {
+ pr_debug("%s: could not find phandle for gpios\n",
+ np->full_name);
+ goto err0;
+ }
+
+ of_gc = gc->data;
+ if (!of_gc) {
+ pr_debug("%s: gpio controller %s isn't registered\n",
+ np->full_name, gc->full_name);
+ goto err1;
+ }
+
+ gpio_cells = of_get_property(gc, "#gpio-cells", &size);
+ if (!gpio_cells || size != sizeof(*gpio_cells) ||
+ *gpio_cells != of_gc->gpio_cells) {
+ pr_debug("%s: wrong #gpio-cells for %s\n",
+ np->full_name, gc->full_name);
+ goto err1;
+ }
+
+ /* Next phandle is at phandle cells + #gpio-cells */
+ i += sizeof(*gpio_phandle) / sizeof(u32) + *gpio_cells;
+ if (i >= nr_cells + 1) {
+ pr_debug("%s: insufficient gpio-spec length\n",
+ np->full_name);
+ goto err1;
+ }
+
+ if (gpio_index == index)
+ break;
+
+ of_gc = NULL;
+ of_node_put(gc);
+ }
+
+ if (!of_gc) {
+ ret = -ENOENT;
+ goto err0;
+ }
+
+ ret = of_gc->xlate(of_gc, np, gpio_spec);
+ if (ret < 0)
+ goto err1;
+
+ ret += of_gc->gc.base;
+err1:
+ of_node_put(gc);
+err0:
+ pr_debug("%s exited with status %d\n", __func__, ret);
+ return ret;
+}
+EXPORT_SYMBOL(of_get_gpio);
+
+static int of_gpio_simple_xlate(struct of_gpio_chip *of_gc,
+ struct device_node *np,
+ const void *gpio_spec)
+{
+ const u32 *gpio = gpio_spec;
+
+ if (*gpio > of_gc->gc.ngpio)
+ return -EINVAL;
+
+ return *gpio;
+}
+
+/* Should be sufficient for now, later we'll use dynamic bases. */
+#if defined(CONFIG_PPC32) || defined(CONFIG_SPARC32)
+#define GPIOS_PER_CHIP 32
+#else
+#define GPIOS_PER_CHIP 64
+#endif
+
+static int of_get_gpiochip_base(struct device_node *np)
+{
+ struct device_node *gc = NULL;
+ int gpiochip_base = 0;
+
+ while ((gc = of_find_all_nodes(gc))) {
+ if (!of_get_property(gc, "gpio-controller", NULL))
+ continue;
+
+ if (gc != np) {
+ gpiochip_base += GPIOS_PER_CHIP;
+ continue;
+ }
+
+ of_node_put(gc);
+
+ if (gpiochip_base >= ARCH_NR_GPIOS)
+ return -ENOSPC;
+
+ return gpiochip_base;
+ }
+
+ return -ENOENT;
+}
+
+int of_mm_gpiochip_add(struct device_node *np,
+ struct of_mm_gpio_chip *mm_gc)
+{
+ int ret = -ENOMEM;
+ struct of_gpio_chip *of_gc = &mm_gc->of_gc;
+ struct gpio_chip *gc = &of_gc->gc;
+
+ gc->label = kstrdup(np->full_name, GFP_KERNEL);
+ if (!gc->label)
+ goto err0;
+
+ mm_gc->regs = of_iomap(np, 0);
+ if (!mm_gc->regs)
+ goto err1;
+
+ gc->base = of_get_gpiochip_base(np);
+ if (gc->base < 0) {
+ ret = gc->base;
+ goto err1;
+ }
+
+ if (!of_gc->xlate)
+ of_gc->xlate = of_gpio_simple_xlate;
+
+ if (mm_gc->save_regs)
+ mm_gc->save_regs(mm_gc);
+
+ np->data = of_gc;
+
+ ret = gpiochip_add(gc);
+ if (ret)
+ goto err2;
+
+ /* We don't want to lose the node and its ->data */
+ of_node_get(np);
+
+ pr_debug("%s: registered as generic GPIO chip, base is %d\n",
+ np->full_name, gc->base);
+ return 0;
+err2:
+ np->data = NULL;
+ iounmap(mm_gc->regs);
+err1:
+ kfree(gc->label);
+err0:
+ pr_err("%s: GPIO chip registration failed with status %d\n",
+ np->full_name, ret);
+ return ret;
+}
+EXPORT_SYMBOL(of_mm_gpiochip_add);
diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h
new file mode 100644
index 0000000..ca313f0
--- /dev/null
+++ b/include/linux/of_gpio.h
@@ -0,0 +1,96 @@
+/*
+ * Generic GPIO API implementation for PowerPC.
+ *
+ * Copyright (c) 2007-2008 MontaVista Software, Inc.
+ *
+ * Author: Anton Vorontsov <avorontsov at ru.mvista.com>
+ *
+ * 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 __LINUX_OF_GPIO_H
+#define __LINUX_OF_GPIO_H
+
+#include <asm/gpio.h>
+
+#ifdef CONFIG_OF_GPIO
+
+/*
+ * Generic OF GPIO chip
+ */
+struct of_gpio_chip {
+ struct gpio_chip gc;
+ int gpio_cells;
+ int (*xlate)(struct of_gpio_chip *of_gc, struct device_node *np,
+ const void *gpio_spec);
+};
+
+static inline struct of_gpio_chip *to_of_gpio_chip(struct gpio_chip *gc)
+{
+ return container_of(gc, struct of_gpio_chip, gc);
+}
+
+/*
+ * OF GPIO chip for memory mapped banks
+ */
+struct of_mm_gpio_chip {
+ struct of_gpio_chip of_gc;
+ void (*save_regs)(struct of_mm_gpio_chip *mm_gc);
+ void __iomem *regs;
+};
+
+static inline struct of_mm_gpio_chip *to_of_mm_gpio_chip(struct gpio_chip *gc)
+{
+ struct of_gpio_chip *of_gc = to_of_gpio_chip(gc);
+
+ return container_of(of_gc, struct of_mm_gpio_chip, of_gc);
+}
+
+/**
+ * of_get_gpio - Get a GPIO number from the device tree to use with GPIO API
+ * @np: device node to get GPIO from
+ * @index: index of the GPIO
+ *
+ * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
+ * value on the error condition.
+ */
+extern int of_get_gpio(struct device_node *np, int index);
+
+/**
+ * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
+ * @np: device node of the GPIO chip
+ * @mm_gc: pointer to the of_mm_gpio_chip allocated structure
+ *
+ * To use this function you should allocate and fill mm_gc with:
+ *
+ * 1) In the gpio_chip structure:
+ * - all the callbacks
+ *
+ * 2) In the of_gpio_chip structure:
+ * - gpio_cells
+ * - xlate callback (optional)
+ *
+ * 3) In the of_mm_gpio_chip structure:
+ * - save_regs callback (optional)
+ *
+ * If succeeded, this function will map bank's memory and will
+ * do all necessary work for you. Then you'll able to use .regs
+ * to manage GPIOs from the callbacks.
+ */
+extern int of_mm_gpiochip_add(struct device_node *np,
+ struct of_mm_gpio_chip *mm_gc);
+
+#else
+
+/* Drivers may not strictly depend on the GPIO support, so let them link. */
+static inline int of_get_gpio(struct device_node *np, int index)
+{
+ return -ENOSYS;
+}
+
+#endif /* CONFIG_OF_GPIO */
+
+#endif /* __LINUX_OF_GPIO_H */
--
1.5.2.2
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