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3d64de9c AV |
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> | |
3d64de9c AV |
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.h> | |
5a0e3ad6 | 23 | #include <linux/slab.h> |
3d64de9c AV |
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 | ||
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 | ||
40 | static u8 u8_pin2mask(unsigned int pin) | |
41 | { | |
42 | return 1 << (8 - 1 - pin); | |
43 | } | |
44 | ||
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 | ||
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 | ||
70 | static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio) | |
71 | { | |
72 | return 0; | |
73 | } | |
74 | ||
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 | ||
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 | ||
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; | |
3d64de9c AV |
93 | struct gpio_chip *gc; |
94 | ||
95 | u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL); | |
96 | if (!u8_gc) | |
97 | return -ENOMEM; | |
98 | ||
99 | spin_lock_init(&u8_gc->lock); | |
100 | ||
101 | mm_gc = &u8_gc->mm_gc; | |
a19e3da5 | 102 | gc = &mm_gc->gc; |
3d64de9c AV |
103 | |
104 | mm_gc->save_regs = u8_gpio_save_regs; | |
3d64de9c AV |
105 | gc->ngpio = 8; |
106 | gc->direction_input = u8_gpio_dir_in; | |
107 | gc->direction_output = u8_gpio_dir_out; | |
108 | gc->get = u8_gpio_get; | |
109 | gc->set = u8_gpio_set; | |
110 | ||
111 | ret = of_mm_gpiochip_add(np, mm_gc); | |
112 | if (ret) | |
113 | goto err; | |
114 | return 0; | |
115 | err: | |
116 | kfree(u8_gc); | |
117 | return ret; | |
118 | } | |
119 | ||
120 | void __init simple_gpiochip_init(const char *compatible) | |
121 | { | |
122 | struct device_node *np; | |
123 | ||
124 | for_each_compatible_node(np, NULL, compatible) { | |
125 | int ret; | |
126 | struct resource r; | |
127 | ||
128 | ret = of_address_to_resource(np, 0, &r); | |
129 | if (ret) | |
130 | goto err; | |
131 | ||
132 | switch (resource_size(&r)) { | |
133 | case 1: | |
134 | ret = u8_simple_gpiochip_add(np); | |
135 | if (ret) | |
136 | goto err; | |
137 | break; | |
138 | default: | |
139 | /* | |
140 | * Whenever you need support for GPIO bank width > 1, | |
141 | * please just turn u8_ code into huge macros, and | |
142 | * construct needed uX_ code with it. | |
143 | */ | |
144 | ret = -ENOSYS; | |
145 | goto err; | |
146 | } | |
147 | continue; | |
148 | err: | |
149 | pr_err("%s: registration failed, status %d\n", | |
150 | np->full_name, ret); | |
151 | } | |
152 | } |