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
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
u8_pin2mask(unsigned int pin)35 static u8 u8_pin2mask(unsigned int pin)
36 {
37 return 1 << (8 - 1 - pin);
38 }
39
u8_gpio_get(struct gpio_chip * gc,unsigned int gpio)40 static 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
u8_gpio_set(struct gpio_chip * gc,unsigned int gpio,int val)47 static 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
u8_gpio_dir_in(struct gpio_chip * gc,unsigned int gpio)65 static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
66 {
67 return 0;
68 }
69
u8_gpio_dir_out(struct gpio_chip * gc,unsigned int gpio,int val)70 static 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
u8_gpio_save_regs(struct of_mm_gpio_chip * mm_gc)76 static 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
u8_simple_gpiochip_add(struct device_node * np)84 static 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;
111 err:
112 kfree(u8_gc);
113 return ret;
114 }
115
simple_gpiochip_init(const char * compatible)116 void __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;
144 err:
145 pr_err("%pOF: registration failed, status %d\n", np, ret);
146 }
147 }
148
