1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * arch/um/drivers/mmapper_kern.c 4 * 5 * BRIEF MODULE DESCRIPTION 6 * 7 * Copyright (C) 2000 RidgeRun, Inc. 8 * Author: RidgeRun, Inc. 9 * Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com 10 * 11 */ 12 13 #include <linux/stddef.h> 14 #include <linux/types.h> 15 #include <linux/fs.h> 16 #include <linux/init.h> 17 #include <linux/miscdevice.h> 18 #include <linux/module.h> 19 #include <linux/mm.h> 20 21 #include <linux/uaccess.h> 22 #include <mem_user.h> 23 24 /* These are set in mmapper_init, which is called at boot time */ 25 static unsigned long mmapper_size; 26 static unsigned long p_buf; 27 static char *v_buf; 28 29 static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count, 30 loff_t *ppos) 31 { 32 return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size); 33 } 34 35 static ssize_t mmapper_write(struct file *file, const char __user *buf, 36 size_t count, loff_t *ppos) 37 { 38 if (*ppos > mmapper_size) 39 return -EINVAL; 40 41 return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count); 42 } 43 44 static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 45 { 46 return -ENOIOCTLCMD; 47 } 48 49 static int mmapper_mmap(struct file *file, struct vm_area_struct *vma) 50 { 51 int ret = -EINVAL; 52 int size; 53 54 if (vma->vm_pgoff != 0) 55 goto out; 56 57 size = vma->vm_end - vma->vm_start; 58 if (size > mmapper_size) 59 return -EFAULT; 60 61 /* 62 * XXX A comment above remap_pfn_range says it should only be 63 * called when the mm semaphore is held 64 */ 65 if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size, 66 vma->vm_page_prot)) 67 goto out; 68 ret = 0; 69 out: 70 return ret; 71 } 72 73 static int mmapper_open(struct inode *inode, struct file *file) 74 { 75 return 0; 76 } 77 78 static int mmapper_release(struct inode *inode, struct file *file) 79 { 80 return 0; 81 } 82 83 static const struct file_operations mmapper_fops = { 84 .owner = THIS_MODULE, 85 .read = mmapper_read, 86 .write = mmapper_write, 87 .unlocked_ioctl = mmapper_ioctl, 88 .mmap = mmapper_mmap, 89 .open = mmapper_open, 90 .release = mmapper_release, 91 .llseek = default_llseek, 92 }; 93 94 /* 95 * No locking needed - only used (and modified) by below initcall and exitcall. 96 */ 97 static struct miscdevice mmapper_dev = { 98 .minor = MISC_DYNAMIC_MINOR, 99 .name = "mmapper", 100 .fops = &mmapper_fops 101 }; 102 103 static int __init mmapper_init(void) 104 { 105 int err; 106 107 printk(KERN_INFO "Mapper v0.1\n"); 108 109 v_buf = (char *) find_iomem("mmapper", &mmapper_size); 110 if (mmapper_size == 0) { 111 printk(KERN_ERR "mmapper_init - find_iomem failed\n"); 112 return -ENODEV; 113 } 114 p_buf = __pa(v_buf); 115 116 err = misc_register(&mmapper_dev); 117 if (err) { 118 printk(KERN_ERR "mmapper - misc_register failed, err = %d\n", 119 err); 120 return err; 121 } 122 return 0; 123 } 124 125 static void __exit mmapper_exit(void) 126 { 127 misc_deregister(&mmapper_dev); 128 } 129 130 module_init(mmapper_init); 131 module_exit(mmapper_exit); 132 133 MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>"); 134 MODULE_DESCRIPTION("DSPLinux simulator mmapper driver"); 135 MODULE_LICENSE("GPL"); 136