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