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/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/driver.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 u8 u8_pin2mask(unsigned int pin)
36{
37 return 1 << (8 - 1 - pin);
38}
39
40static int u8_gpio_get(struct gpio_chip *gc, unsigned int gpio)
41{
42 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
43
44 return !!(in_8(mm_gc->regs) & u8_pin2mask(gpio));
45}
46
47static void u8_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
48{
49 struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
50 struct u8_gpio_chip *u8_gc = gpiochip_get_data(gc);
51 unsigned long flags;
52
53 spin_lock_irqsave(&u8_gc->lock, flags);
54
55 if (val)
56 u8_gc->data |= u8_pin2mask(gpio);
57 else
58 u8_gc->data &= ~u8_pin2mask(gpio);
59
60 out_8(mm_gc->regs, u8_gc->data);
61
62 spin_unlock_irqrestore(&u8_gc->lock, flags);
63}
64
65static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
66{
67 return 0;
68}
69
70static int u8_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
71{
72 u8_gpio_set(gc, gpio, val);
73 return 0;
74}
75
76static void u8_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
77{
78 struct u8_gpio_chip *u8_gc = gpiochip_get_data(&mm_gc->gc);
79
80 u8_gc->data = in_8(mm_gc->regs);
81}
82
83static int __init u8_simple_gpiochip_add(struct device_node *np)
84{
85 int ret;
86 struct u8_gpio_chip *u8_gc;
87 struct of_mm_gpio_chip *mm_gc;
88 struct gpio_chip *gc;
89
90 u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL);
91 if (!u8_gc)
92 return -ENOMEM;
93
94 spin_lock_init(&u8_gc->lock);
95
96 mm_gc = &u8_gc->mm_gc;
97 gc = &mm_gc->gc;
98
99 mm_gc->save_regs = u8_gpio_save_regs;
100 gc->ngpio = 8;
101 gc->direction_input = u8_gpio_dir_in;
102 gc->direction_output = u8_gpio_dir_out;
103 gc->get = u8_gpio_get;
104 gc->set = u8_gpio_set;
105
106 ret = of_mm_gpiochip_add_data(np, mm_gc, u8_gc);
107 if (ret)
108 goto err;
109 return 0;
110err:
111 kfree(u8_gc);
112 return ret;
113}
114
115void __init simple_gpiochip_init(const char *compatible)
116{
117 struct device_node *np;
118
119 for_each_compatible_node(np, NULL, compatible) {
120 int ret;
121 struct resource r;
122
123 ret = of_address_to_resource(np, 0, &r);
124 if (ret)
125 goto err;
126
127 switch (resource_size(&r)) {
128 case 1:
129 ret = u8_simple_gpiochip_add(np);
130 if (ret)
131 goto err;
132 break;
133 default:
134 /*
135 * Whenever you need support for GPIO bank width > 1,
136 * please just turn u8_ code into huge macros, and
137 * construct needed uX_ code with it.
138 */
139 ret = -ENOSYS;
140 goto err;
141 }
142 continue;
143err:
144 pr_err("%s: registration failed, status %d\n",
145 np->full_name, ret);
146 }
147}