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 <asm/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