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/driver.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 u8 u8_pin2mask(unsigned int pin)
  36{
  37        return 1 << (8 - 1 - pin);
  38}
  39
  40static int u8_gpio_get(struct gpio_chip *gc, unsigned int gpio)
  41{
  42        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  43
  44        return !!(in_8(mm_gc->regs) & u8_pin2mask(gpio));
  45}
  46
  47static void u8_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
  48{
  49        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  50        struct u8_gpio_chip *u8_gc = gpiochip_get_data(gc);
  51        unsigned long flags;
  52
  53        spin_lock_irqsave(&u8_gc->lock, flags);
  54
  55        if (val)
  56                u8_gc->data |= u8_pin2mask(gpio);
  57        else
  58                u8_gc->data &= ~u8_pin2mask(gpio);
  59
  60        out_8(mm_gc->regs, u8_gc->data);
  61
  62        spin_unlock_irqrestore(&u8_gc->lock, flags);
  63}
  64
  65static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
  66{
  67        return 0;
  68}
  69
  70static int u8_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
  71{
  72        u8_gpio_set(gc, gpio, val);
  73        return 0;
  74}
  75
  76static void u8_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
  77{
  78        struct u8_gpio_chip *u8_gc = gpiochip_get_data(&mm_gc->gc);
  79
  80        u8_gc->data = in_8(mm_gc->regs);
  81}
  82
  83static int __init u8_simple_gpiochip_add(struct device_node *np)
  84{
  85        int ret;
  86        struct u8_gpio_chip *u8_gc;
  87        struct of_mm_gpio_chip *mm_gc;
  88        struct gpio_chip *gc;
  89
  90        u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL);
  91        if (!u8_gc)
  92                return -ENOMEM;
  93
  94        spin_lock_init(&u8_gc->lock);
  95
  96        mm_gc = &u8_gc->mm_gc;
  97        gc = &mm_gc->gc;
  98
  99        mm_gc->save_regs = u8_gpio_save_regs;
 100        gc->ngpio = 8;
 101        gc->direction_input = u8_gpio_dir_in;
 102        gc->direction_output = u8_gpio_dir_out;
 103        gc->get = u8_gpio_get;
 104        gc->set = u8_gpio_set;
 105
 106        ret = of_mm_gpiochip_add_data(np, mm_gc, u8_gc);
 107        if (ret)
 108                goto err;
 109        return 0;
 110err:
 111        kfree(u8_gc);
 112        return ret;
 113}
 114
 115void __init simple_gpiochip_init(const char *compatible)
 116{
 117        struct device_node *np;
 118
 119        for_each_compatible_node(np, NULL, compatible) {
 120                int ret;
 121                struct resource r;
 122
 123                ret = of_address_to_resource(np, 0, &r);
 124                if (ret)
 125                        goto err;
 126
 127                switch (resource_size(&r)) {
 128                case 1:
 129                        ret = u8_simple_gpiochip_add(np);
 130                        if (ret)
 131                                goto err;
 132                        break;
 133                default:
 134                        /*
 135                         * Whenever you need support for GPIO bank width > 1,
 136                         * please just turn u8_ code into huge macros, and
 137                         * construct needed uX_ code with it.
 138                         */
 139                        ret = -ENOSYS;
 140                        goto err;
 141                }
 142                continue;
 143err:
 144                pr_err("%s: registration failed, status %d\n",
 145                       np->full_name, ret);
 146        }
 147}
 148