arch/powerpc/platforms/pseries/hvconsole.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * hvconsole.c
   4  * Copyright (C) 2004 Hollis Blanchard, IBM Corporation
   5  * Copyright (C) 2004 IBM Corporation
   6  *
   7  * Additional Author(s):
   8  *  Ryan S. Arnold <[email protected]>
   9  *
  10  * LPAR console support.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/export.h>
  15 #include <linux/errno.h>
  16 #include <asm/hvcall.h>
  17 #include <asm/hvconsole.h>
  18 #include <asm/plpar_wrappers.h>
  19
  20 /**
  21  * hvc_get_chars - retrieve characters from firmware for denoted vterm adapter
  22  * @vtermno: The vtermno or unit_address of the adapter from which to fetch the
  23  *      data.
  24  * @buf: The character buffer into which to put the character data fetched from
  25  *      firmware.
  26  * @count: not used?
  27  */
  28 ssize_t hvc_get_chars(uint32_t vtermno, u8 *buf, size_t count)
  29 {
  30         long ret;
  31         unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
  32         unsigned long *lbuf = (unsigned long *)buf;
  33
  34         ret = plpar_hcall(H_GET_TERM_CHAR, retbuf, vtermno);
  35         lbuf[0] = be64_to_cpu(retbuf[1]);
  36         lbuf[1] = be64_to_cpu(retbuf[2]);
  37
  38         if (ret == H_SUCCESS)
  39                 return retbuf[0];
  40
  41         return 0;
  42 }
  43
  44 EXPORT_SYMBOL(hvc_get_chars);
  45
  46
  47 /**
  48  * hvc_put_chars: send characters to firmware for denoted vterm adapter
  49  * @vtermno: The vtermno or unit_address of the adapter from which the data
  50  *      originated.
  51  * @buf: The character buffer that contains the character data to send to
  52  *      firmware. Must be at least 16 bytes, even if count is less than 16.
  53  * @count: Send this number of characters.
  54  */
  55 ssize_t hvc_put_chars(uint32_t vtermno, const u8 *buf, size_t count)
  56 {
  57         unsigned long *lbuf = (unsigned long *) buf;
  58         long ret;
  59
  60
  61         /* hcall will ret H_PARAMETER if 'count' exceeds firmware max.*/
  62         if (count > MAX_VIO_PUT_CHARS)
  63                 count = MAX_VIO_PUT_CHARS;
  64
  65         ret = plpar_hcall_norets(H_PUT_TERM_CHAR, vtermno, count,
  66                                  cpu_to_be64(lbuf[0]),
  67                                  cpu_to_be64(lbuf[1]));
  68         if (ret == H_SUCCESS)
  69                 return count;
  70         if (ret == H_BUSY)
  71                 return -EAGAIN;
  72         return -EIO;
  73 }
  74
  75 EXPORT_SYMBOL(hvc_put_chars);