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
26static struct platform_device *pdev;
27
28MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
29MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
30MODULE_LICENSE("GPL");
31
32static int major = 0;		/* default to dynamic major */
33module_param(major, int, 0);
34MODULE_PARM_DESC(major, "Major device number");
35
36#define MAX_PINS 32		/* 64 later, when known ok */
37
38struct 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};
47EXPORT_SYMBOL_GPL(scx200_gpio_ops);
48
49static 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
59static int scx200_gpio_release(struct inode *inode, struct file *file)
60{
61	return 0;
62}
63
64static 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
73static struct cdev scx200_gpio_cdev;  /* use 1 cdev for all pins */
74
75static 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
114undo_platform_device_add:
115	platform_device_del(pdev);
116undo_malloc:
117	platform_device_put(pdev);
118
119	return rc;
120}
121
122static 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
131module_init(scx200_gpio_init);
132module_exit(scx200_gpio_cleanup);
133