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
27 static struct platform_device *pdev;
28
29 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
30 MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
31 MODULE_LICENSE("GPL");
32
33 static int major = 0; /* default to dynamic major */
34 module_param(major, int, 0);
35 MODULE_PARM_DESC(major, "Major device number");
36
37 #define MAX_PINS 32 /* 64 later, when known ok */
38
39 struct 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 };
48 EXPORT_SYMBOL_GPL(scx200_gpio_ops);
49
scx200_gpio_open(struct inode * inode,struct file * file)50 static 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, file);
58 }
59
scx200_gpio_release(struct inode * inode,struct file * file)60 static int scx200_gpio_release(struct inode *inode, struct file *file)
61 {
62 return 0;
63 }
64
65 static 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 };
72
73 static struct cdev scx200_gpio_cdev; /* use 1 cdev for all pins */
74
scx200_gpio_init(void)75 static int __init scx200_gpio_init(void)
76 {
77 int rc;
78 dev_t devid;
79
80 if (!scx200_gpio_present()) {
81 printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
82 return -ENODEV;
83 }
84
85 /* support dev_dbg() with pdev->dev */
86 pdev = platform_device_alloc(DRVNAME, 0);
87 if (!pdev)
88 return -ENOMEM;
89
90 rc = platform_device_add(pdev);
91 if (rc)
92 goto undo_malloc;
93
94 /* nsc_gpio uses dev_dbg(), so needs this */
95 scx200_gpio_ops.dev = &pdev->dev;
96
97 if (major) {
98 devid = MKDEV(major, 0);
99 rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
100 } else {
101 rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
102 major = MAJOR(devid);
103 }
104 if (rc < 0) {
105 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
106 goto undo_platform_device_add;
107 }
108
109 cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops);
110 cdev_add(&scx200_gpio_cdev, devid, MAX_PINS);
111
112 return 0; /* succeed */
113
114 undo_platform_device_add:
115 platform_device_del(pdev);
116 undo_malloc:
117 platform_device_put(pdev);
118
119 return rc;
120 }
121
scx200_gpio_cleanup(void)122 static void __exit scx200_gpio_cleanup(void)
123 {
124 cdev_del(&scx200_gpio_cdev);
125 /* cdev_put(&scx200_gpio_cdev); */
126
127 unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
128 platform_device_unregister(pdev);
129 }
130
131 module_init(scx200_gpio_init);
132 module_exit(scx200_gpio_cleanup);
133