xref: /openbmc/linux/drivers/char/scx200_gpio.c (revision 09c434b8)
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 	.llseek  = no_llseek,
72 };
73 
74 static struct cdev scx200_gpio_cdev;  /* use 1 cdev for all pins */
75 
scx200_gpio_init(void)76 static int __init scx200_gpio_init(void)
77 {
78 	int rc;
79 	dev_t devid;
80 
81 	if (!scx200_gpio_present()) {
82 		printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
83 		return -ENODEV;
84 	}
85 
86 	/* support dev_dbg() with pdev->dev */
87 	pdev = platform_device_alloc(DRVNAME, 0);
88 	if (!pdev)
89 		return -ENOMEM;
90 
91 	rc = platform_device_add(pdev);
92 	if (rc)
93 		goto undo_malloc;
94 
95 	/* nsc_gpio uses dev_dbg(), so needs this */
96 	scx200_gpio_ops.dev = &pdev->dev;
97 
98 	if (major) {
99 		devid = MKDEV(major, 0);
100 		rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
101 	} else {
102 		rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
103 		major = MAJOR(devid);
104 	}
105 	if (rc < 0) {
106 		dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
107 		goto undo_platform_device_add;
108 	}
109 
110 	cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops);
111 	cdev_add(&scx200_gpio_cdev, devid, MAX_PINS);
112 
113 	return 0; /* succeed */
114 
115 undo_platform_device_add:
116 	platform_device_del(pdev);
117 undo_malloc:
118 	platform_device_put(pdev);
119 
120 	return rc;
121 }
122 
scx200_gpio_cleanup(void)123 static void __exit scx200_gpio_cleanup(void)
124 {
125 	cdev_del(&scx200_gpio_cdev);
126 	/* cdev_put(&scx200_gpio_cdev); */
127 
128 	unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
129 	platform_device_unregister(pdev);
130 }
131 
132 module_init(scx200_gpio_init);
133 module_exit(scx200_gpio_cleanup);
134