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
22void 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
41ssize_t nsc_gpio_write(struct file *file, const char __user *data,
42		       size_t len, loff_t *ppos)
43{
44	unsigned m = iminor(file_inode(file));
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 '0':
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
104ssize_t nsc_gpio_read(struct file *file, char __user * buf,
105		      size_t len, loff_t * ppos)
106{
107	unsigned m = iminor(file_inode(file));
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' : '0', buf))
113		return -EFAULT;
114
115	return 1;
116}
117
118/* common file-ops routines for both scx200_gpio and pc87360_gpio */
119EXPORT_SYMBOL(nsc_gpio_write);
120EXPORT_SYMBOL(nsc_gpio_read);
121EXPORT_SYMBOL(nsc_gpio_dump);
122
123static int __init nsc_gpio_init(void)
124{
125	printk(KERN_DEBUG NAME " initializing\n");
126	return 0;
127}
128
129static void __exit nsc_gpio_cleanup(void)
130{
131	printk(KERN_DEBUG NAME " cleanup\n");
132}
133
134module_init(nsc_gpio_init);
135module_exit(nsc_gpio_cleanup);
136
137MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
138MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
139MODULE_LICENSE("GPL");
140