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pciutils

    1: /*
    2:  *	The PCI Library -- Portable interface to pread() and pwrite()
    3:  *
    4:  *	Copyright (c) 1997--2003 Martin Mares <mj@ucw.cz>
    5:  *
    6:  *	Can be freely distributed and used under the terms of the GNU GPL.
    7:  */
    8: 
    9: /*
   10:  *  We'd like to use pread/pwrite for configuration space accesses, but
   11:  *  unfortunately it isn't simple at all since all libc's until glibc 2.1
   12:  *  don't define it.
   13:  */
   14: 
   15: #if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ > 0
   16: /* glibc 2.1 or newer -> pread/pwrite supported automatically */
   17: 
   18: #elif defined(i386) && defined(__GLIBC__)
   19: /* glibc 2.0 on i386 -> call syscalls directly */
   20: #include <asm/unistd.h>
   21: #include <syscall-list.h>
   22: #ifndef SYS_pread
   23: #define SYS_pread 180
   24: #endif
   25: static int pread(unsigned int fd, void *buf, size_t size, loff_t where)
   26: { return syscall(SYS_pread, fd, buf, size, where); }
   27: #ifndef SYS_pwrite
   28: #define SYS_pwrite 181
   29: #endif
   30: static int pwrite(unsigned int fd, void *buf, size_t size, loff_t where)
   31: { return syscall(SYS_pwrite, fd, buf, size, where); }
   32: 
   33: #elif defined(i386)
   34: /* old libc on i386 -> call syscalls directly the old way */
   35: #include <asm/unistd.h>
   36: static _syscall5(int, pread, unsigned int, fd, void *, buf, size_t, size, u32, where_lo, u32, where_hi);
   37: static _syscall5(int, pwrite, unsigned int, fd, void *, buf, size_t, size, u32, where_lo, u32, where_hi);
   38: static int do_read(struct pci_dev *d UNUSED, int fd, void *buf, size_t size, int where) { return pread(fd, buf, size, where, 0); }
   39: static int do_write(struct pci_dev *d UNUSED, int fd, void *buf, size_t size, int where) { return pwrite(fd, buf, size, where, 0); }
   40: #define PCI_HAVE_DO_READ
   41: 
   42: #else
   43: /* In all other cases we use lseek/read/write instead to be safe */
   44: #define make_rw_glue(op) \
   45: 	static int do_##op(struct pci_dev *d, int fd, void *buf, size_t size, int where)	\
   46: 	{											\
   47: 	  struct pci_access *a = d->access;							\
   48: 	  int r;										\
   49: 	  if (a->fd_pos != where && lseek(fd, where, SEEK_SET) < 0)				\
   50: 	    return -1;										\
   51: 	  r = op(fd, buf, size);								\
   52: 	  if (r < 0)										\
   53: 	    a->fd_pos = -1;									\
   54: 	  else											\
   55: 	    a->fd_pos = where + r;								\
   56: 	  return r;										\
   57: 	}
   58: make_rw_glue(read)
   59: make_rw_glue(write)
   60: #define PCI_HAVE_DO_READ
   61: #endif
   62: 
   63: #ifndef PCI_HAVE_DO_READ
   64: #define do_read(d,f,b,l,p) pread(f,b,l,p)
   65: #define do_write(d,f,b,l,p) pwrite(f,b,l,p)
   66: #endif