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 
nsc_gpio_dump(struct nsc_gpio_ops * amp,unsigned index)23 void 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 
nsc_gpio_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)42 ssize_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 
nsc_gpio_read(struct file * file,char __user * buf,size_t len,loff_t * ppos)105 ssize_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 */
120 EXPORT_SYMBOL(nsc_gpio_write);
121 EXPORT_SYMBOL(nsc_gpio_read);
122 EXPORT_SYMBOL(nsc_gpio_dump);
123 
nsc_gpio_init(void)124 static int __init nsc_gpio_init(void)
125 {
126 	printk(KERN_DEBUG NAME " initializing\n");
127 	return 0;
128 }
129 
nsc_gpio_cleanup(void)130 static void __exit nsc_gpio_cleanup(void)
131 {
132 	printk(KERN_DEBUG NAME " cleanup\n");
133 }
134 
135 module_init(nsc_gpio_init);
136 module_exit(nsc_gpio_cleanup);
137 
138 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
139 MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
140 MODULE_LICENSE("GPL");
141