1// SPDX-License-Identifier: GPL-2.0-only
2/* linux/drivers/char/nsc_gpio.c
3
4   National Semiconductor common GPIO device-file/VFS methods.
5   Allows a user space process to control the GPIO pins.
6
7   Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
8   Copyright (c) 2005      Jim Cromie <jim.cromie@gmail.com>
9*/
10
11#include <linux/fs.h>
12#include <linux/module.h>
13#include <linux/errno.h>
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/nsc_gpio.h>
17#include <linux/platform_device.h>
18#include <linux/uaccess.h>
19#include <asm/io.h>
20
21#define NAME "nsc_gpio"
22
23void nsc_gpio_dump(struct nsc_gpio_ops *amp, unsigned index)
24{
25	/* retrieve current config w/o changing it */
26	u32 config = amp->gpio_config(index, ~0, 0);
27
28	/* user requested via 'v' command, so its INFO */
29	dev_info(amp->dev, "io%02u: 0x%04x %s %s %s %s %s %s %s\tio:%d/%d\n",
30		 index, config,
31		 (config & 1) ? "OE" : "TS",      /* output-enabled/tristate */
32		 (config & 2) ? "PP" : "OD",      /* push pull / open drain */
33		 (config & 4) ? "PUE" : "PUD",    /* pull up enabled/disabled */
34		 (config & 8) ? "LOCKED" : "",    /* locked / unlocked */
35		 (config & 16) ? "LEVEL" : "EDGE",/* level/edge input */
36		 (config & 32) ? "HI" : "LO",     /* trigger on rise/fall edge */
37		 (config & 64) ? "DEBOUNCE" : "", /* debounce */
38
39		 amp->gpio_get(index), amp->gpio_current(index));
40}
41
42ssize_t nsc_gpio_write(struct file *file, const char __user *data,
43		       size_t len, loff_t *ppos)
44{
45	unsigned m = iminor(file_inode(file));
46	struct nsc_gpio_ops *amp = file->private_data;
47	struct device *dev = amp->dev;
48	size_t i;
49	int err = 0;
50
51	for (i = 0; i < len; ++i) {
52		char c;
53		if (get_user(c, data + i))
54			return -EFAULT;
55		switch (c) {
56		case '0':
57			amp->gpio_set(m, 0);
58			break;
59		case '1':
60			amp->gpio_set(m, 1);
61			break;
62		case 'O':
63			dev_dbg(dev, "GPIO%d output enabled\n", m);
64			amp->gpio_config(m, ~1, 1);
65			break;
66		case 'o':
67			dev_dbg(dev, "GPIO%d output disabled\n", m);
68			amp->gpio_config(m, ~1, 0);
69			break;
70		case 'T':
71			dev_dbg(dev, "GPIO%d output is push pull\n", m);
72			amp->gpio_config(m, ~2, 2);
73			break;
74		case 't':
75			dev_dbg(dev, "GPIO%d output is open drain\n", m);
76			amp->gpio_config(m, ~2, 0);
77			break;
78		case 'P':
79			dev_dbg(dev, "GPIO%d pull up enabled\n", m);
80			amp->gpio_config(m, ~4, 4);
81			break;
82		case 'p':
83			dev_dbg(dev, "GPIO%d pull up disabled\n", m);
84			amp->gpio_config(m, ~4, 0);
85			break;
86		case 'v':
87			/* View Current pin settings */
88			amp->gpio_dump(amp, m);
89			break;
90		case '\n':
91			/* end of settings string, do nothing */
92			break;
93		default:
94			dev_err(dev, "io%2d bad setting: chr<0x%2x>\n",
95				m, (int)c);
96			err++;
97		}
98	}
99	if (err)
100		return -EINVAL;	/* full string handled, report error */
101
102	return len;
103}
104
105ssize_t nsc_gpio_read(struct file *file, char __user * buf,
106		      size_t len, loff_t * ppos)
107{
108	unsigned m = iminor(file_inode(file));
109	int value;
110	struct nsc_gpio_ops *amp = file->private_data;
111
112	value = amp->gpio_get(m);
113	if (put_user(value ? '1' : '0', buf))
114		return -EFAULT;
115
116	return 1;
117}
118
119/* common file-ops routines for both scx200_gpio and pc87360_gpio */
120EXPORT_SYMBOL(nsc_gpio_write);
121EXPORT_SYMBOL(nsc_gpio_read);
122EXPORT_SYMBOL(nsc_gpio_dump);
123
124static int __init nsc_gpio_init(void)
125{
126	printk(KERN_DEBUG NAME " initializing\n");
127	return 0;
128}
129
130static void __exit nsc_gpio_cleanup(void)
131{
132	printk(KERN_DEBUG NAME " cleanup\n");
133}
134
135module_init(nsc_gpio_init);
136module_exit(nsc_gpio_cleanup);
137
138MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
139MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
140MODULE_LICENSE("GPL");
141