drivers/sbus/char/flash.c

   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
  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
  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
 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
 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
 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
 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
 190 static void flash_remove(struct platform_device *op)
 191 {
 192         misc_deregister(&flash_dev);
 193 }
 194
 195 static const struct of_device_id flash_match[] = {
 196         {
 197                 .name = "flashprom",
 198         },
 199         {},
 200 };
 201 MODULE_DEVICE_TABLE(of, flash_match);
 202
 203 static 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
 212 module_platform_driver(flash_driver);
 213
 214 MODULE_LICENSE("GPL");