Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
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 =
79 container_of(mm_gc, struct u8_gpio_chip, mm_gc);
80
81 u8_gc->data = in_8(mm_gc->regs);
82}
83
84static int __init u8_simple_gpiochip_add(struct device_node *np)
85{
86 int ret;
87 struct u8_gpio_chip *u8_gc;
88 struct of_mm_gpio_chip *mm_gc;
89 struct gpio_chip *gc;
90
91 u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL);
92 if (!u8_gc)
93 return -ENOMEM;
94
95 spin_lock_init(&u8_gc->lock);
96
97 mm_gc = &u8_gc->mm_gc;
98 gc = &mm_gc->gc;
99
100 mm_gc->save_regs = u8_gpio_save_regs;
101 gc->ngpio = 8;
102 gc->direction_input = u8_gpio_dir_in;
103 gc->direction_output = u8_gpio_dir_out;
104 gc->get = u8_gpio_get;
105 gc->set = u8_gpio_set;
106
107 ret = of_mm_gpiochip_add_data(np, mm_gc, u8_gc);
108 if (ret)
109 goto err;
110 return 0;
111err:
112 kfree(u8_gc);
113 return ret;
114}
115
116void __init simple_gpiochip_init(const char *compatible)
117{
118 struct device_node *np;
119
120 for_each_compatible_node(np, NULL, compatible) {
121 int ret;
122 struct resource r;
123
124 ret = of_address_to_resource(np, 0, &r);
125 if (ret)
126 goto err;
127
128 switch (resource_size(&r)) {
129 case 1:
130 ret = u8_simple_gpiochip_add(np);
131 if (ret)
132 goto err;
133 break;
134 default:
135 /*
136 * Whenever you need support for GPIO bank width > 1,
137 * please just turn u8_ code into huge macros, and
138 * construct needed uX_ code with it.
139 */
140 ret = -ENOSYS;
141 goto err;
142 }
143 continue;
144err:
145 pr_err("%pOF: registration failed, status %d\n", np, ret);
146 }
147}