1 /* linux/drivers/char/scx200_gpio.c
2
3 National Semiconductor SCx200 GPIO driver. Allows a user space
4 process to play with the GPIO pins.
5
6 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */
7
8 #include <linux/device.h>
9 #include <linux/fs.h>
10 #include <linux/module.h>
11 #include <linux/errno.h>
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <linux/platform_device.h>
15 #include <linux/uaccess.h>
16 #include <asm/io.h>
17
18 #include <linux/types.h>
19 #include <linux/cdev.h>
20
21 #include <linux/scx200_gpio.h>
22 #include <linux/nsc_gpio.h>
23
24 #define DRVNAME "scx200_gpio"
25
26 static struct platform_device *pdev;
27
28 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
29 MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
30 MODULE_LICENSE("GPL");
31
32 static int major = 0; /* default to dynamic major */
33 module_param(major, int, 0);
34 MODULE_PARM_DESC(major, "Major device number");
35
36 #define MAX_PINS 32 /* 64 later, when known ok */
37
38 struct nsc_gpio_ops scx200_gpio_ops = {
39 .owner = THIS_MODULE,
40 .gpio_config = scx200_gpio_configure,
41 .gpio_dump = nsc_gpio_dump,
42 .gpio_get = scx200_gpio_get,
43 .gpio_set = scx200_gpio_set,
44 .gpio_change = scx200_gpio_change,
45 .gpio_current = scx200_gpio_current
46 };
47 EXPORT_SYMBOL_GPL(scx200_gpio_ops);
48
scx200_gpio_open(struct inode * inode,struct file * file)49 static int scx200_gpio_open(struct inode *inode, struct file *file)
50 {
51 unsigned m = iminor(inode);
52 file->private_data = &scx200_gpio_ops;
53
54 if (m >= MAX_PINS)
55 return -EINVAL;
56 return nonseekable_open(inode, file);
57 }
58
scx200_gpio_release(struct inode * inode,struct file * file)59 static int scx200_gpio_release(struct inode *inode, struct file *file)
60 {
61 return 0;
62 }
63
64 static const struct file_operations scx200_gpio_fileops = {
65 .owner = THIS_MODULE,
66 .write = nsc_gpio_write,
67 .read = nsc_gpio_read,
68 .open = scx200_gpio_open,
69 .release = scx200_gpio_release,
70 .llseek = no_llseek,
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
