[go: nahoru, domu]
1/* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
2 *
3 * Copyright (C) 1997  Eddie C. Dost  (ecd@skynet.be)
4 */
5
6#include <linux/module.h>
7#include <linux/types.h>
8#include <linux/errno.h>
9#include <linux/miscdevice.h>
10#include <linux/fcntl.h>
11#include <linux/poll.h>
12#include <linux/mutex.h>
13#include <linux/spinlock.h>
14#include <linux/mm.h>
15#include <linux/of.h>
16#include <linux/of_device.h>
17
18#include <asm/uaccess.h>
19#include <asm/pgtable.h>
20#include <asm/io.h>
21#include <asm/upa.h>
22
23static DEFINE_MUTEX(flash_mutex);
24static DEFINE_SPINLOCK(flash_lock);
25static struct {
26	unsigned long read_base;	/* Physical read address */
27	unsigned long write_base;	/* Physical write address */
28	unsigned long read_size;	/* Size of read area */
29	unsigned long write_size;	/* Size of write area */
30	unsigned long busy;		/* In use? */
31} flash;
32
33#define FLASH_MINOR	152
34
35static int
36flash_mmap(struct file *file, struct vm_area_struct *vma)
37{
38	unsigned long addr;
39	unsigned long size;
40
41	spin_lock(&flash_lock);
42	if (flash.read_base == flash.write_base) {
43		addr = flash.read_base;
44		size = flash.read_size;
45	} else {
46		if ((vma->vm_flags & VM_READ) &&
47		    (vma->vm_flags & VM_WRITE)) {
48			spin_unlock(&flash_lock);
49			return -EINVAL;
50		}
51		if (vma->vm_flags & VM_READ) {
52			addr = flash.read_base;
53			size = flash.read_size;
54		} else if (vma->vm_flags & VM_WRITE) {
55			addr = flash.write_base;
56			size = flash.write_size;
57		} else {
58			spin_unlock(&flash_lock);
59			return -ENXIO;
60		}
61	}
62	spin_unlock(&flash_lock);
63
64	if ((vma->vm_pgoff << PAGE_SHIFT) > size)
65		return -ENXIO;
66	addr = vma->vm_pgoff + (addr >> PAGE_SHIFT);
67
68	if (vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT)) > size)
69		size = vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT));
70
71	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
72
73	if (io_remap_pfn_range(vma, vma->vm_start, addr, size, vma->vm_page_prot))
74		return -EAGAIN;
75
76	return 0;
77}
78
79static long long
80flash_llseek(struct file *file, long long offset, int origin)
81{
82	mutex_lock(&flash_mutex);
83	switch (origin) {
84		case 0:
85			file->f_pos = offset;
86			break;
87		case 1:
88			file->f_pos += offset;
89			if (file->f_pos > flash.read_size)
90				file->f_pos = flash.read_size;
91			break;
92		case 2:
93			file->f_pos = flash.read_size;
94			break;
95		default:
96			mutex_unlock(&flash_mutex);
97			return -EINVAL;
98	}
99	mutex_unlock(&flash_mutex);
100	return file->f_pos;
101}
102
103static ssize_t
104flash_read(struct file * file, char __user * buf,
105	   size_t count, loff_t *ppos)
106{
107	loff_t p = *ppos;
108	int i;
109
110	if (count > flash.read_size - p)
111		count = flash.read_size - p;
112
113	for (i = 0; i < count; i++) {
114		u8 data = upa_readb(flash.read_base + p + i);
115		if (put_user(data, buf))
116			return -EFAULT;
117		buf++;
118	}
119
120	*ppos += count;
121	return count;
122}
123
124static int
125flash_open(struct inode *inode, struct file *file)
126{
127	mutex_lock(&flash_mutex);
128	if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
129		mutex_unlock(&flash_mutex);
130		return -EBUSY;
131	}
132
133	mutex_unlock(&flash_mutex);
134	return 0;
135}
136
137static int
138flash_release(struct inode *inode, struct file *file)
139{
140	spin_lock(&flash_lock);
141	flash.busy = 0;
142	spin_unlock(&flash_lock);
143
144	return 0;
145}
146
147static const struct file_operations flash_fops = {
148	/* no write to the Flash, use mmap
149	 * and play flash dependent tricks.
150	 */
151	.owner =	THIS_MODULE,
152	.llseek =	flash_llseek,
153	.read =		flash_read,
154	.mmap =		flash_mmap,
155	.open =		flash_open,
156	.release =	flash_release,
157};
158
159static struct miscdevice flash_dev = { FLASH_MINOR, "flash", &flash_fops };
160
161static int flash_probe(struct platform_device *op)
162{
163	struct device_node *dp = op->dev.of_node;
164	struct device_node *parent;
165
166	parent = dp->parent;
167
168	if (strcmp(parent->name, "sbus") &&
169	    strcmp(parent->name, "sbi") &&
170	    strcmp(parent->name, "ebus"))
171		return -ENODEV;
172
173	flash.read_base = op->resource[0].start;
174	flash.read_size = resource_size(&op->resource[0]);
175	if (op->resource[1].flags) {
176		flash.write_base = op->resource[1].start;
177		flash.write_size = resource_size(&op->resource[1]);
178	} else {
179		flash.write_base = op->resource[0].start;
180		flash.write_size = resource_size(&op->resource[0]);
181	}
182	flash.busy = 0;
183
184	printk(KERN_INFO "%s: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
185	       op->dev.of_node->full_name,
186	       flash.read_base, flash.read_size,
187	       flash.write_base, flash.write_size);
188
189	return misc_register(&flash_dev);
190}
191
192static int flash_remove(struct platform_device *op)
193{
194	misc_deregister(&flash_dev);
195
196	return 0;
197}
198
199static const struct of_device_id flash_match[] = {
200	{
201		.name = "flashprom",
202	},
203	{},
204};
205MODULE_DEVICE_TABLE(of, flash_match);
206
207static struct platform_driver flash_driver = {
208	.driver = {
209		.name = "flash",
210		.owner = THIS_MODULE,
211		.of_match_table = flash_match,
212	},
213	.probe		= flash_probe,
214	.remove		= flash_remove,
215};
216
217module_platform_driver(flash_driver);
218
219MODULE_LICENSE("GPL");
220