1 /* linux/drivers/char/nsc_gpio.c
2
3 National Semiconductor common GPIO device-file/VFS methods.
4 Allows a user space process to control the GPIO pins.
5
6 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
7 Copyright (c) 2005 Jim Cromie <jim.cromie@gmail.com>
8 */
9
10 #include <linux/fs.h>
11 #include <linux/module.h>
12 #include <linux/errno.h>
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/nsc_gpio.h>
16 #include <linux/platform_device.h>
17 #include <asm/uaccess.h>
18 #include <asm/io.h>
19
20 #define NAME "nsc_gpio"
21
22 void nsc_gpio_dump(struct nsc_gpio_ops *amp, unsigned index)
23 {
24 /* retrieve current config w/o changing it */
25 u32 config = amp->gpio_config(index, ~0, 0);
26
27 /* user requested via 'v' command, so its INFO */
28 dev_info(amp->dev, "io%02u: 0x%04x %s %s %s %s %s %s %s\tio:%d/%d\n",
29 index, config,
30 (config & 1) ? "OE" : "TS", /* output-enabled/tristate */
31 (config & 2) ? "PP" : "OD", /* push pull / open drain */
32 (config & 4) ? "PUE" : "PUD", /* pull up enabled/disabled */
33 (config & 8) ? "LOCKED" : "", /* locked / unlocked */
34 (config & 16) ? "LEVEL" : "EDGE",/* level/edge input */
35 (config & 32) ? "HI" : "LO", /* trigger on rise/fall edge */
36 (config & 64) ? "DEBOUNCE" : "", /* debounce */
37
38 amp->gpio_get(index), amp->gpio_current(index));
39 }
40
41 ssize_t nsc_gpio_write(struct file *file, const char __user *data,
42 size_t len, loff_t *ppos)
43 {
44 unsigned m = iminor(file->f_path.dentry->d_inode);
45 struct nsc_gpio_ops *amp = file->private_data;
46 struct device *dev = amp->dev;
47 size_t i;
48 int err = 0;
49
50 for (i = 0; i < len; ++i) {
51 char c;
52 if (get_user(c, data + i))
53 return -EFAULT;
54 switch (c) {
55 case '':
56 amp->gpio_set(m, 0);
57 break;
58 case '1':
59 amp->gpio_set(m, 1);
60 break;
61 case 'O':
62 dev_dbg(dev, "GPIO%d output enabled\n", m);
63 amp->gpio_config(m, ~1, 1);
64 break;
65 case 'o':
66 dev_dbg(dev, "GPIO%d output disabled\n", m);
67 amp->gpio_config(m, ~1, 0);
68 break;
69 case 'T':
70 dev_dbg(dev, "GPIO%d output is push pull\n", m);
71 amp->gpio_config(m, ~2, 2);
72 break;
73 case 't':
74 dev_dbg(dev, "GPIO%d output is open drain\n", m);
75 amp->gpio_config(m, ~2, 0);
76 break;
77 case 'P':
78 dev_dbg(dev, "GPIO%d pull up enabled\n", m);
79 amp->gpio_config(m, ~4, 4);
80 break;
81 case 'p':
82 dev_dbg(dev, "GPIO%d pull up disabled\n", m);
83 amp->gpio_config(m, ~4, 0);
84 break;
85 case 'v':
86 /* View Current pin settings */
87 amp->gpio_dump(amp, m);
88 break;
89 case '\n':
90 /* end of settings string, do nothing */
91 break;
92 default:
93 dev_err(dev, "io%2d bad setting: chr<0x%2x>\n",
94 m, (int)c);
95 err++;
96 }
97 }
98 if (err)
99 return -EINVAL; /* full string handled, report error */
100
101 return len;
102 }
103
104 ssize_t nsc_gpio_read(struct file *file, char __user * buf,
105 size_t len, loff_t * ppos)
106 {
107 unsigned m = iminor(file->f_path.dentry->d_inode);
108 int value;
109 struct nsc_gpio_ops *amp = file->private_data;
110
111 value = amp->gpio_get(m);
112 if (put_user(value ? '1' : '', buf))
113 return -EFAULT;
114
115 return 1;
116 }
117
118 /* common file-ops routines for both scx200_gpio and pc87360_gpio */
119 EXPORT_SYMBOL(nsc_gpio_write);
120 EXPORT_SYMBOL(nsc_gpio_read);
121 EXPORT_SYMBOL(nsc_gpio_dump);
122
123 static int __init nsc_gpio_init(void)
124 {
125 printk(KERN_DEBUG NAME " initializing\n");
126 return 0;
127 }
128
129 static void __exit nsc_gpio_cleanup(void)
130 {
131 printk(KERN_DEBUG NAME " cleanup\n");
132 }
133
134 module_init(nsc_gpio_init);
135 module_exit(nsc_gpio_cleanup);
136
137 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
138 MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
139 MODULE_LICENSE("GPL");
140
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