Root/drivers/char/scx200_gpio.c

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

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