1 // SPDX-License-Identifier: GPL-2.0-only
2 /* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
4 * Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be)
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>
17 #include <linux/of_device.h>
19 #include <linux/uaccess.h>
23 static DEFINE_MUTEX(flash_mutex);
24 static DEFINE_SPINLOCK(flash_lock);
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? */
34 flash_mmap(struct file *file, struct vm_area_struct *vma)
39 spin_lock(&flash_lock);
40 if (flash.read_base == flash.write_base) {
41 addr = flash.read_base;
42 size = flash.read_size;
44 if ((vma->vm_flags & VM_READ) &&
45 (vma->vm_flags & VM_WRITE)) {
46 spin_unlock(&flash_lock);
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;
56 spin_unlock(&flash_lock);
60 spin_unlock(&flash_lock);
62 if ((vma->vm_pgoff << PAGE_SHIFT) > size)
64 addr = vma->vm_pgoff + (addr >> PAGE_SHIFT);
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));
69 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
71 if (io_remap_pfn_range(vma, vma->vm_start, addr, size, vma->vm_page_prot))
78 flash_llseek(struct file *file, long long offset, int origin)
80 mutex_lock(&flash_mutex);
86 file->f_pos += offset;
87 if (file->f_pos > flash.read_size)
88 file->f_pos = flash.read_size;
91 file->f_pos = flash.read_size;
94 mutex_unlock(&flash_mutex);
97 mutex_unlock(&flash_mutex);
102 flash_read(struct file * file, char __user * buf,
103 size_t count, loff_t *ppos)
108 if (count > flash.read_size - p)
109 count = flash.read_size - p;
111 for (i = 0; i < count; i++) {
112 u8 data = upa_readb(flash.read_base + p + i);
113 if (put_user(data, buf))
123 flash_open(struct inode *inode, struct file *file)
125 mutex_lock(&flash_mutex);
126 if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
127 mutex_unlock(&flash_mutex);
131 mutex_unlock(&flash_mutex);
136 flash_release(struct inode *inode, struct file *file)
138 spin_lock(&flash_lock);
140 spin_unlock(&flash_lock);
145 static const struct file_operations flash_fops = {
146 /* no write to the Flash, use mmap
147 * and play flash dependent tricks.
149 .owner = THIS_MODULE,
150 .llseek = flash_llseek,
154 .release = flash_release,
157 static struct miscdevice flash_dev = { SBUS_FLASH_MINOR, "flash", &flash_fops };
159 static int flash_probe(struct platform_device *op)
161 struct device_node *dp = op->dev.of_node;
162 struct device_node *parent;
166 if (!of_node_name_eq(parent, "sbus") &&
167 !of_node_name_eq(parent, "sbi") &&
168 !of_node_name_eq(parent, "ebus"))
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]);
177 flash.write_base = op->resource[0].start;
178 flash.write_size = resource_size(&op->resource[0]);
182 printk(KERN_INFO "%pOF: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
184 flash.read_base, flash.read_size,
185 flash.write_base, flash.write_size);
187 return misc_register(&flash_dev);
190 static int flash_remove(struct platform_device *op)
192 misc_deregister(&flash_dev);
197 static const struct of_device_id flash_match[] = {
203 MODULE_DEVICE_TABLE(of, flash_match);
205 static struct platform_driver flash_driver = {
208 .of_match_table = flash_match,
210 .probe = flash_probe,
211 .remove = flash_remove,
214 module_platform_driver(flash_driver);
216 MODULE_LICENSE("GPL");