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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 | |
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 | |
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 | |
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 | |
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 | |
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 | ||
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 | ||
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"); |