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 <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 of_gpio_chip *of_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 of_gc = &mm_gc->of_gc;
104 gc = &of_gc->gc;
105
106 mm_gc->save_regs = u8_gpio_save_regs;
107 of_gc->gpio_cells = 2;
108 gc->ngpio = 8;
109 gc->direction_input = u8_gpio_dir_in;
110 gc->direction_output = u8_gpio_dir_out;
111 gc->get = u8_gpio_get;
112 gc->set = u8_gpio_set;
113
114 ret = of_mm_gpiochip_add(np, mm_gc);
115 if (ret)
116 goto err;
117 return 0;
118 err:
119 kfree(u8_gc);
120 return ret;
121 }
122
simple_gpiochip_init(const char * compatible)123 void __init simple_gpiochip_init(const char *compatible)
124 {
125 struct device_node *np;
126
127 for_each_compatible_node(np, NULL, compatible) {
128 int ret;
129 struct resource r;
130
131 ret = of_address_to_resource(np, 0, &r);
132 if (ret)
133 goto err;
134
135 switch (resource_size(&r)) {
136 case 1:
137 ret = u8_simple_gpiochip_add(np);
138 if (ret)
139 goto err;
140 break;
141 default:
142 /*
143 * Whenever you need support for GPIO bank width > 1,
144 * please just turn u8_ code into huge macros, and
145 * construct needed uX_ code with it.
146 */
147 ret = -ENOSYS;
148 goto err;
149 }
150 continue;
151 err:
152 pr_err("%s: registration failed, status %d\n",
153 np->full_name, ret);
154 }
155 }
156