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/driver.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 u8 u8_pin2mask(unsigned int pin)
  36 {
  37         return 1 << (8 - 1 - pin);
  38 }
  39
  40 static 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
  47 static 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
  65 static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
  66 {
  67         return 0;
  68 }
  69
  70 static 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
  76 static 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
  83 static 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;
 110 err:
 111         kfree(u8_gc);
 112         return ret;
 113 }
 114
 115 void __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;
 143 err:
 144                 pr_err("%s: registration failed, status %d\n",
 145                        np->full_name, ret);
 146         }
 147 }