1// SPDX-License-Identifier: GPL-2.0-only
2/* linux/drivers/char/scx200_gpio.c
3
4 National Semiconductor SCx200 GPIO driver. Allows a user space
5 process to play with the GPIO pins.
6
7 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */
8
9#include <linux/device.h>
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/platform_device.h>
16#include <linux/uaccess.h>
17#include <asm/io.h>
18
19#include <linux/types.h>
20#include <linux/cdev.h>
21
22#include <linux/scx200_gpio.h>
23#include <linux/nsc_gpio.h>
24
25#define DRVNAME "scx200_gpio"
26
27static struct platform_device *pdev;
28
29MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
30MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
31MODULE_LICENSE("GPL");
32
33static int major = 0; /* default to dynamic major */
34module_param(major, int, 0);
35MODULE_PARM_DESC(major, "Major device number");
36
37#define MAX_PINS 32 /* 64 later, when known ok */
38
39struct nsc_gpio_ops scx200_gpio_ops = {
40 .owner = THIS_MODULE,
41 .gpio_config = scx200_gpio_configure,
42 .gpio_dump = nsc_gpio_dump,
43 .gpio_get = scx200_gpio_get,
44 .gpio_set = scx200_gpio_set,
45 .gpio_change = scx200_gpio_change,
46 .gpio_current = scx200_gpio_current
47};
48EXPORT_SYMBOL_GPL(scx200_gpio_ops);
49
50static int scx200_gpio_open(struct inode *inode, struct file *file)
51{
52 unsigned m = iminor(inode);
53 file->private_data = &scx200_gpio_ops;
54
55 if (m >= MAX_PINS)
56 return -EINVAL;
57 return nonseekable_open(inode, filp: file);
58}
59
60static int scx200_gpio_release(struct inode *inode, struct file *file)
61{
62 return 0;
63}
64
65static const struct file_operations scx200_gpio_fileops = {
66 .owner = THIS_MODULE,
67 .write = nsc_gpio_write,
68 .read = nsc_gpio_read,
69 .open = scx200_gpio_open,
70 .release = scx200_gpio_release,
71 .llseek = no_llseek,
72};
73
74static struct cdev scx200_gpio_cdev; /* use 1 cdev for all pins */
75
76static int __init scx200_gpio_init(void)
77{
78 int rc;
79 dev_t devid;
80
81 if (!scx200_gpio_present()) {
82 printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
83 return -ENODEV;
84 }
85
86 /* support dev_dbg() with pdev->dev */
87 pdev = platform_device_alloc(DRVNAME, id: 0);
88 if (!pdev)
89 return -ENOMEM;
90
91 rc = platform_device_add(pdev);
92 if (rc)
93 goto undo_malloc;
94
95 /* nsc_gpio uses dev_dbg(), so needs this */
96 scx200_gpio_ops.dev = &pdev->dev;
97
98 if (major) {
99 devid = MKDEV(major, 0);
100 rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
101 } else {
102 rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
103 major = MAJOR(devid);
104 }
105 if (rc < 0) {
106 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
107 goto undo_platform_device_add;
108 }
109
110 cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops);
111 cdev_add(&scx200_gpio_cdev, devid, MAX_PINS);
112
113 return 0; /* succeed */
114
115undo_platform_device_add:
116 platform_device_del(pdev);
117undo_malloc:
118 platform_device_put(pdev);
119
120 return rc;
121}
122
123static void __exit scx200_gpio_cleanup(void)
124{
125 cdev_del(&scx200_gpio_cdev);
126 /* cdev_put(&scx200_gpio_cdev); */
127
128 unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
129 platform_device_unregister(pdev);
130}
131
132module_init(scx200_gpio_init);
133module_exit(scx200_gpio_cleanup);
134

source code of linux/drivers/char/scx200_gpio.c