216 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/* 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 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 33static int34flash_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 77static long long78flash_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 101static ssize_t102flash_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 122static int123flash_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 135static int136flash_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 145static const struct file_operations flash_fops = {146 /* no write to the Flash, use mmap147 * 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 157static struct miscdevice flash_dev = { SBUS_FLASH_MINOR, "flash", &flash_fops };158 159static 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 190static void flash_remove(struct platform_device *op)191{192 misc_deregister(&flash_dev);193}194 195static const struct of_device_id flash_match[] = {196 {197 .name = "flashprom",198 },199 {},200};201MODULE_DEVICE_TABLE(of, flash_match);202 203static struct platform_driver flash_driver = {204 .driver = {205 .name = "flash",206 .of_match_table = flash_match,207 },208 .probe = flash_probe,209 .remove_new = flash_remove,210};211 212module_platform_driver(flash_driver);213 214MODULE_DESCRIPTION("OBP Flash Device driver");215MODULE_LICENSE("GPL");216