arch/powerpc/sysdev/simple_gpio.c

   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
  27 struct 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
  35 static 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
  40 static u8 u8_pin2mask(unsigned int pin)
  41 {
  42         return 1 << (8 - 1 - pin);
  43 }
  44
  45 static 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
  52 static 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
  70 static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
  71 {
  72         return 0;
  73 }
  74
  75 static 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
  81 static 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
  88 static 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;
 115 err:
 116         kfree(u8_gc);
 117         return ret;
 118 }
 119
 120 void __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;
 148 err:
 149                 pr_err("%s: registration failed, status %d\n",
 150                        np->full_name, ret);
 151         }
 152 }