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
 28struct 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
 36static 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
 41static u8 u8_pin2mask(unsigned int pin)
 42{
 43	return 1 << (8 - 1 - pin);
 44}
 45
 46static 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
 53static 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
 71static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
 72{
 73	return 0;
 74}
 75
 76static 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
 82static 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
 89static 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;
116err:
117	kfree(u8_gc);
118	return ret;
119}
120
121void __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;
149err:
150		pr_err("%s: registration failed, status %d\n",
151		       np->full_name, ret);
152	}
153}