LXR linux/arch/powerpc/sysdev/simple

   1/*
   2 * Simple Memory-Mapped GPIOs
   3 *
   4 * Copyright (c) MontaVista Software, Inc. 2008.
   5 *
   6 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
   7 *
   8 * This program is free software; you can redistribute  it and/or modify it
   9 * under  the terms of  the GNU General  Public License as published by the
  10 * Free Software Foundation;  either version 2 of the  License, or (at your
  11 * option) any later version.
  12 */
  13
  14#include <linux/init.h>
  15#include <linux/kernel.h>
  16#include <linux/spinlock.h>
  17#include <linux/types.h>
  18#include <linux/ioport.h>
  19#include <linux/io.h>
  20#include <linux/of.h>
  21#include <linux/of_gpio.h>
  22#include <linux/gpio.h>
  23#include <linux/slab.h>
  24#include <asm/prom.h>
  25#include "simple_gpio.h"
  26
  27struct u8_gpio_chip {
  28        struct of_mm_gpio_chip mm_gc;
  29        spinlock_t lock;
  30
  31        /* shadowed data register to clear/set bits safely */
  32        u8 data;
  33};
  34
  35static struct u8_gpio_chip *to_u8_gpio_chip(struct of_mm_gpio_chip *mm_gc)
  36{
  37        return container_of(mm_gc, struct u8_gpio_chip, mm_gc);
  38}
  39
  40static u8 u8_pin2mask(unsigned int pin)
  41{
  42        return 1 << (8 - 1 - pin);
  43}
  44
  45static int u8_gpio_get(struct gpio_chip *gc, unsigned int gpio)
  46{
  47        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  48
  49        return in_8(mm_gc->regs) & u8_pin2mask(gpio);
  50}
  51
  52static void u8_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
  53{
  54        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  55        struct u8_gpio_chip *u8_gc = to_u8_gpio_chip(mm_gc);
  56        unsigned long flags;
  57
  58        spin_lock_irqsave(&u8_gc->lock, flags);
  59
  60        if (val)
  61                u8_gc->data |= u8_pin2mask(gpio);
  62        else
  63                u8_gc->data &= ~u8_pin2mask(gpio);
  64
  65        out_8(mm_gc->regs, u8_gc->data);
  66
  67        spin_unlock_irqrestore(&u8_gc->lock, flags);
  68}
  69
  70static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
  71{
  72        return 0;
  73}
  74
  75static int u8_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
  76{
  77        u8_gpio_set(gc, gpio, val);
  78        return 0;
  79}
  80
  81static void u8_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
  82{
  83        struct u8_gpio_chip *u8_gc = to_u8_gpio_chip(mm_gc);
  84
  85        u8_gc->data = in_8(mm_gc->regs);
  86}
  87
  88static int __init u8_simple_gpiochip_add(struct device_node *np)
  89{
  90        int ret;
  91        struct u8_gpio_chip *u8_gc;
  92        struct of_mm_gpio_chip *mm_gc;
  93        struct gpio_chip *gc;
  94
  95        u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL);
  96        if (!u8_gc)
  97                return -ENOMEM;
  98
  99        spin_lock_init(&u8_gc->lock);
 100
 101        mm_gc = &u8_gc->mm_gc;
 102        gc = &mm_gc->gc;
 103
 104        mm_gc->save_regs = u8_gpio_save_regs;
 105        gc->ngpio = 8;
 106        gc->direction_input = u8_gpio_dir_in;
 107        gc->direction_output = u8_gpio_dir_out;
 108        gc->get = u8_gpio_get;
 109        gc->set = u8_gpio_set;
 110
 111        ret = of_mm_gpiochip_add(np, mm_gc);
 112        if (ret)
 113                goto err;
 114        return 0;
 115err:
 116        kfree(u8_gc);
 117        return ret;
 118}
 119
 120void __init simple_gpiochip_init(const char *compatible)
 121{
 122        struct device_node *np;
 123
 124        for_each_compatible_node(np, NULL, compatible) {
 125                int ret;
 126                struct resource r;
 127
 128                ret = of_address_to_resource(np, 0, &r);
 129                if (ret)
 130                        goto err;
 131
 132                switch (resource_size(&r)) {
 133                case 1:
 134                        ret = u8_simple_gpiochip_add(np);
 135                        if (ret)
 136                                goto err;
 137                        break;
 138                default:
 139                        /*
 140                         * Whenever you need support for GPIO bank width > 1,
 141                         * please just turn u8_ code into huge macros, and
 142                         * construct needed uX_ code with it.
 143                         */
 144                        ret = -ENOSYS;
 145                        goto err;
 146                }
 147                continue;
 148err:
 149                pr_err("%s: registration failed, status %d\n",
 150                       np->full_name, ret);
 151        }
 152}
 153