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
27static struct platform_device *pdev;
28
29MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
30MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
31MODULE_LICENSE("GPL");
32
33static int major = 0;		/* default to dynamic major */
34module_param(major, int, 0);
35MODULE_PARM_DESC(major, "Major device number");
36
37#define MAX_PINS 32		/* 64 later, when known ok */
38
39struct 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};
48EXPORT_SYMBOL_GPL(scx200_gpio_ops);
49
50static 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
60static int scx200_gpio_release(struct inode *inode, struct file *file)
61{
62	return 0;
63}
64
65static 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
74static struct cdev scx200_gpio_cdev;  /* use 1 cdev for all pins */
75
76static 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
115undo_platform_device_add:
116	platform_device_del(pdev);
117undo_malloc:
118	platform_device_put(pdev);
119
120	return rc;
121}
122
123static 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
132module_init(scx200_gpio_init);
133module_exit(scx200_gpio_cleanup);
134