1 /* 2 * arc_hostlink.c: Pseudo-driver for Metaware provided "hostlink" facility 3 * 4 * Allows Linux userland access to host in absence of any peripherals. 5 * 6 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <linux/fs.h> /* file_operations */ 14 #include <linux/miscdevice.h> 15 #include <linux/mm.h> /* VM_IO */ 16 #include <linux/module.h> 17 #include <linux/uaccess.h> 18 19 static unsigned char __HOSTLINK__[4 * PAGE_SIZE] __aligned(PAGE_SIZE); 20 21 static int arc_hl_mmap(struct file *fp, struct vm_area_struct *vma) 22 { 23 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 24 25 if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, 26 vma->vm_end - vma->vm_start, 27 vma->vm_page_prot)) { 28 pr_warn("Hostlink buffer mmap ERROR\n"); 29 return -EAGAIN; 30 } 31 return 0; 32 } 33 34 static long arc_hl_ioctl(struct file *file, unsigned int cmd, 35 unsigned long arg) 36 { 37 /* we only support, returning the physical addr to mmap in user space */ 38 put_user((unsigned int)__HOSTLINK__, (int __user *)arg); 39 return 0; 40 } 41 42 static const struct file_operations arc_hl_fops = { 43 .unlocked_ioctl = arc_hl_ioctl, 44 .mmap = arc_hl_mmap, 45 }; 46 47 static struct miscdevice arc_hl_dev = { 48 .minor = MISC_DYNAMIC_MINOR, 49 .name = "hostlink", 50 .fops = &arc_hl_fops 51 }; 52 53 static int __init arc_hl_init(void) 54 { 55 pr_info("ARC Hostlink driver mmap at 0x%p\n", __HOSTLINK__); 56 return misc_register(&arc_hl_dev); 57 } 58 module_init(arc_hl_init); 59