1 // SPDX-License-Identifier: GPL-2.0-only
2 /* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
3 *
4 * Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be)
5 */
6
7 #include <linux/module.h>
8 #include <linux/types.h>
9 #include <linux/errno.h>
10 #include <linux/miscdevice.h>
11 #include <linux/fcntl.h>
12 #include <linux/poll.h>
13 #include <linux/mutex.h>
14 #include <linux/spinlock.h>
15 #include <linux/mm.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18
19 #include <linux/uaccess.h>
20 #include <asm/io.h>
21 #include <asm/upa.h>
22
23 static DEFINE_MUTEX(flash_mutex);
24 static DEFINE_SPINLOCK(flash_lock);
25 static 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 static int
flash_mmap(struct file * file,struct vm_area_struct * vma)34 flash_mmap(struct file *file, struct vm_area_struct *vma)
35 {
36 unsigned long addr;
37 unsigned long size;
38
39 spin_lock(&flash_lock);
40 if (flash.read_base == flash.write_base) {
41 addr = flash.read_base;
42 size = flash.read_size;
43 } else {
44 if ((vma->vm_flags & VM_READ) &&
45 (vma->vm_flags & VM_WRITE)) {
46 spin_unlock(&flash_lock);
47 return -EINVAL;
48 }
49 if (vma->vm_flags & VM_READ) {
50 addr = flash.read_base;
51 size = flash.read_size;
52 } else if (vma->vm_flags & VM_WRITE) {
53 addr = flash.write_base;
54 size = flash.write_size;
55 } else {
56 spin_unlock(&flash_lock);
57 return -ENXIO;
58 }
59 }
60 spin_unlock(&flash_lock);
61
62 if ((vma->vm_pgoff << PAGE_SHIFT) > size)
63 return -ENXIO;
64 addr = vma->vm_pgoff + (addr >> PAGE_SHIFT);
65
66 if (vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT)) > size)
67 size = vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT));
68
69 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
70
71 if (io_remap_pfn_range(vma, vma->vm_start, addr, size, vma->vm_page_prot))
72 return -EAGAIN;
73
74 return 0;
75 }
76
77 static long long
flash_llseek(struct file * file,long long offset,int origin)78 flash_llseek(struct file *file, long long offset, int origin)
79 {
80 mutex_lock(&flash_mutex);
81 switch (origin) {
82 case 0:
83 file->f_pos = offset;
84 break;
85 case 1:
86 file->f_pos += offset;
87 if (file->f_pos > flash.read_size)
88 file->f_pos = flash.read_size;
89 break;
90 case 2:
91 file->f_pos = flash.read_size;
92 break;
93 default:
94 mutex_unlock(&flash_mutex);
95 return -EINVAL;
96 }
97 mutex_unlock(&flash_mutex);
98 return file->f_pos;
99 }
100
101 static ssize_t
flash_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)102 flash_read(struct file * file, char __user * buf,
103 size_t count, loff_t *ppos)
104 {
105 loff_t p = *ppos;
106 int i;
107
108 if (count > flash.read_size - p)
109 count = flash.read_size - p;
110
111 for (i = 0; i < count; i++) {
112 u8 data = upa_readb(flash.read_base + p + i);
113 if (put_user(data, buf))
114 return -EFAULT;
115 buf++;
116 }
117
118 *ppos += count;
119 return count;
120 }
121
122 static int
flash_open(struct inode * inode,struct file * file)123 flash_open(struct inode *inode, struct file *file)
124 {
125 mutex_lock(&flash_mutex);
126 if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
127 mutex_unlock(&flash_mutex);
128 return -EBUSY;
129 }
130
131 mutex_unlock(&flash_mutex);
132 return 0;
133 }
134
135 static int
flash_release(struct inode * inode,struct file * file)136 flash_release(struct inode *inode, struct file *file)
137 {
138 spin_lock(&flash_lock);
139 flash.busy = 0;
140 spin_unlock(&flash_lock);
141
142 return 0;
143 }
144
145 static const struct file_operations flash_fops = {
146 /* no write to the Flash, use mmap
147 * and play flash dependent tricks.
148 */
149 .owner = THIS_MODULE,
150 .llseek = flash_llseek,
151 .read = flash_read,
152 .mmap = flash_mmap,
153 .open = flash_open,
154 .release = flash_release,
155 };
156
157 static struct miscdevice flash_dev = { SBUS_FLASH_MINOR, "flash", &flash_fops };
158
flash_probe(struct platform_device * op)159 static int flash_probe(struct platform_device *op)
160 {
161 struct device_node *dp = op->dev.of_node;
162 struct device_node *parent;
163
164 parent = dp->parent;
165
166 if (!of_node_name_eq(parent, "sbus") &&
167 !of_node_name_eq(parent, "sbi") &&
168 !of_node_name_eq(parent, "ebus"))
169 return -ENODEV;
170
171 flash.read_base = op->resource[0].start;
172 flash.read_size = resource_size(&op->resource[0]);
173 if (op->resource[1].flags) {
174 flash.write_base = op->resource[1].start;
175 flash.write_size = resource_size(&op->resource[1]);
176 } else {
177 flash.write_base = op->resource[0].start;
178 flash.write_size = resource_size(&op->resource[0]);
179 }
180 flash.busy = 0;
181
182 printk(KERN_INFO "%pOF: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
183 op->dev.of_node,
184 flash.read_base, flash.read_size,
185 flash.write_base, flash.write_size);
186
187 return misc_register(&flash_dev);
188 }
189
flash_remove(struct platform_device * op)190 static int flash_remove(struct platform_device *op)
191 {
192 misc_deregister(&flash_dev);
193
194 return 0;
195 }
196
197 static const struct of_device_id flash_match[] = {
198 {
199 .name = "flashprom",
200 },
201 {},
202 };
203 MODULE_DEVICE_TABLE(of, flash_match);
204
205 static struct platform_driver flash_driver = {
206 .driver = {
207 .name = "flash",
208 .of_match_table = flash_match,
209 },
210 .probe = flash_probe,
211 .remove = flash_remove,
212 };
213
214 module_platform_driver(flash_driver);
215
216 MODULE_LICENSE("GPL");
217
