tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 of_gpio_chip *of_gc;
95 struct gpio_chip *gc;
96
97 u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL);
98 if (!u8_gc)
99 return -ENOMEM;
100
101 spin_lock_init(&u8_gc->lock);
102
103 mm_gc = &u8_gc->mm_gc;
104 of_gc = &mm_gc->of_gc;
105 gc = &of_gc->gc;
106
107 mm_gc->save_regs = u8_gpio_save_regs;
108 of_gc->gpio_cells = 2;
109 gc->ngpio = 8;
110 gc->direction_input = u8_gpio_dir_in;
111 gc->direction_output = u8_gpio_dir_out;
112 gc->get = u8_gpio_get;
113 gc->set = u8_gpio_set;
114
115 ret = of_mm_gpiochip_add(np, mm_gc);
116 if (ret)
117 goto err;
118 return 0;
119err:
120 kfree(u8_gc);
121 return ret;
122}
123
124void __init simple_gpiochip_init(const char *compatible)
125{
126 struct device_node *np;
127
128 for_each_compatible_node(np, NULL, compatible) {
129 int ret;
130 struct resource r;
131
132 ret = of_address_to_resource(np, 0, &r);
133 if (ret)
134 goto err;
135
136 switch (resource_size(&r)) {
137 case 1:
138 ret = u8_simple_gpiochip_add(np);
139 if (ret)
140 goto err;
141 break;
142 default:
143 /*
144 * Whenever you need support for GPIO bank width > 1,
145 * please just turn u8_ code into huge macros, and
146 * construct needed uX_ code with it.
147 */
148 ret = -ENOSYS;
149 goto err;
150 }
151 continue;
152err:
153 pr_err("%s: registration failed, status %d\n",
154 np->full_name, ret);
155 }
156}