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