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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 
to_u8_gpio_chip(struct of_mm_gpio_chip * mm_gc)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 
u8_pin2mask(unsigned int pin)40 static u8 u8_pin2mask(unsigned int pin)
41 {
42 	return 1 << (8 - 1 - pin);
43 }
44 
u8_gpio_get(struct gpio_chip * gc,unsigned int gpio)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 
u8_gpio_set(struct gpio_chip * gc,unsigned int gpio,int val)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 
u8_gpio_dir_in(struct gpio_chip * gc,unsigned int gpio)70 static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
71 {
72 	return 0;
73 }
74 
u8_gpio_dir_out(struct gpio_chip * gc,unsigned int gpio,int val)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 
u8_gpio_save_regs(struct of_mm_gpio_chip * mm_gc)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 
u8_simple_gpiochip_add(struct device_node * np)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 
simple_gpiochip_init(const char * compatible)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 }
153