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