drivers/sbus/char/flash.c

   1 /* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
   2  *
   3  * Copyright (C) 1997  Eddie C. Dost  (ecd@skynet.be)
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/types.h>
   8 #include <linux/errno.h>
   9 #include <linux/miscdevice.h>
  10 #include <linux/fcntl.h>
  11 #include <linux/poll.h>
  12 #include <linux/mutex.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/mm.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17
  18 #include <linux/uaccess.h>
  19 #include <asm/pgtable.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 #define FLASH_MINOR     152
  34
  35 static int
  36 flash_mmap(struct file *file, struct vm_area_struct *vma)
  37 {
  38         unsigned long addr;
  39         unsigned long size;
  40
  41         spin_lock(&flash_lock);
  42         if (flash.read_base == flash.write_base) {
  43                 addr = flash.read_base;
  44                 size = flash.read_size;
  45         } else {
  46                 if ((vma->vm_flags & VM_READ) &&
  47                     (vma->vm_flags & VM_WRITE)) {
  48                         spin_unlock(&flash_lock);
  49                         return -EINVAL;
  50                 }
  51                 if (vma->vm_flags & VM_READ) {
  52                         addr = flash.read_base;
  53                         size = flash.read_size;
  54                 } else if (vma->vm_flags & VM_WRITE) {
  55                         addr = flash.write_base;
  56                         size = flash.write_size;
  57                 } else {
  58                         spin_unlock(&flash_lock);
  59                         return -ENXIO;
  60                 }
  61         }
  62         spin_unlock(&flash_lock);
  63
  64         if ((vma->vm_pgoff << PAGE_SHIFT) > size)
  65                 return -ENXIO;
  66         addr = vma->vm_pgoff + (addr >> PAGE_SHIFT);
  67
  68         if (vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT)) > size)
  69                 size = vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT));
  70
  71         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
  72
  73         if (io_remap_pfn_range(vma, vma->vm_start, addr, size, vma->vm_page_prot))
  74                 return -EAGAIN;
  75
  76         return 0;
  77 }
  78
  79 static long long
  80 flash_llseek(struct file *file, long long offset, int origin)
  81 {
  82         mutex_lock(&flash_mutex);
  83         switch (origin) {
  84                 case 0:
  85                         file->f_pos = offset;
  86                         break;
  87                 case 1:
  88                         file->f_pos += offset;
  89                         if (file->f_pos > flash.read_size)
  90                                 file->f_pos = flash.read_size;
  91                         break;
  92                 case 2:
  93                         file->f_pos = flash.read_size;
  94                         break;
  95                 default:
  96                         mutex_unlock(&flash_mutex);
  97                         return -EINVAL;
  98         }
  99         mutex_unlock(&flash_mutex);
 100         return file->f_pos;
 101 }
 102
 103 static ssize_t
 104 flash_read(struct file * file, char __user * buf,
 105            size_t count, loff_t *ppos)
 106 {
 107         loff_t p = *ppos;
 108         int i;
 109
 110         if (count > flash.read_size - p)
 111                 count = flash.read_size - p;
 112
 113         for (i = 0; i < count; i++) {
 114                 u8 data = upa_readb(flash.read_base + p + i);
 115                 if (put_user(data, buf))
 116                         return -EFAULT;
 117                 buf++;
 118         }
 119
 120         *ppos += count;
 121         return count;
 122 }
 123
 124 static int
 125 flash_open(struct inode *inode, struct file *file)
 126 {
 127         mutex_lock(&flash_mutex);
 128         if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
 129                 mutex_unlock(&flash_mutex);
 130                 return -EBUSY;
 131         }
 132
 133         mutex_unlock(&flash_mutex);
 134         return 0;
 135 }
 136
 137 static int
 138 flash_release(struct inode *inode, struct file *file)
 139 {
 140         spin_lock(&flash_lock);
 141         flash.busy = 0;
 142         spin_unlock(&flash_lock);
 143
 144         return 0;
 145 }
 146
 147 static const struct file_operations flash_fops = {
 148         /* no write to the Flash, use mmap
 149          * and play flash dependent tricks.
 150          */
 151         .owner =        THIS_MODULE,
 152         .llseek =       flash_llseek,
 153         .read =         flash_read,
 154         .mmap =         flash_mmap,
 155         .open =         flash_open,
 156         .release =      flash_release,
 157 };
 158
 159 static struct miscdevice flash_dev = { FLASH_MINOR, "flash", &flash_fops };
 160
 161 static int flash_probe(struct platform_device *op)
 162 {
 163         struct device_node *dp = op->dev.of_node;
 164         struct device_node *parent;
 165
 166         parent = dp->parent;
 167
 168         if (strcmp(parent->name, "sbus") &&
 169             strcmp(parent->name, "sbi") &&
 170             strcmp(parent->name, "ebus"))
 171                 return -ENODEV;
 172
 173         flash.read_base = op->resource[0].start;
 174         flash.read_size = resource_size(&op->resource[0]);
 175         if (op->resource[1].flags) {
 176                 flash.write_base = op->resource[1].start;
 177                 flash.write_size = resource_size(&op->resource[1]);
 178         } else {
 179                 flash.write_base = op->resource[0].start;
 180                 flash.write_size = resource_size(&op->resource[0]);
 181         }
 182         flash.busy = 0;
 183
 184         printk(KERN_INFO "%pOF: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
 185                op->dev.of_node,
 186                flash.read_base, flash.read_size,
 187                flash.write_base, flash.write_size);
 188
 189         return misc_register(&flash_dev);
 190 }
 191
 192 static int flash_remove(struct platform_device *op)
 193 {
 194         misc_deregister(&flash_dev);
 195
 196         return 0;
 197 }
 198
 199 static const struct of_device_id flash_match[] = {
 200         {
 201                 .name = "flashprom",
 202         },
 203         {},
 204 };
 205 MODULE_DEVICE_TABLE(of, flash_match);
 206
 207 static struct platform_driver flash_driver = {
 208         .driver = {
 209                 .name = "flash",
 210                 .of_match_table = flash_match,
 211         },
 212         .probe          = flash_probe,
 213         .remove         = flash_remove,
 214 };
 215
 216 module_platform_driver(flash_driver);
 217
 218 MODULE_LICENSE("GPL");