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