releases/4.9.180/hwmon-vt1211-use-request_muxed_region-for-super-io-a.patch

   1 From 3bc527587a789c36f995437a91ae4d1f0363bfbf Mon Sep 17 00:00:00 2001
   2 From: Guenter Roeck <linux@roeck-us.net>
   3 Date: Fri, 5 Apr 2019 08:53:08 -0700
   4 Subject: hwmon: (vt1211) Use request_muxed_region for Super-IO accesses
   5
   6 [ Upstream commit 14b97ba5c20056102b3dd22696bf17b057e60976 ]
   7
   8 Super-IO accesses may fail on a system with no or unmapped LPC bus.
   9
  10 Also, other drivers may attempt to access the LPC bus at the same time,
  11 resulting in undefined behavior.
  12
  13 Use request_muxed_region() to ensure that IO access on the requested
  14 address space is supported, and to ensure that access by multiple drivers
  15 is synchronized.
  16
  17 Fixes: 2219cd81a6cd ("hwmon/vt1211: Add probing of alternate config index port")
  18 Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  19 Signed-off-by: Sasha Levin <sashal@kernel.org>
  20 ---
  21  drivers/hwmon/vt1211.c | 15 ++++++++++++---
  22  1 file changed, 12 insertions(+), 3 deletions(-)
  23
  24 diff --git a/drivers/hwmon/vt1211.c b/drivers/hwmon/vt1211.c
  25 index 3a6bfa51cb94f..95d5e8ec8b7fc 100644
  26 --- a/drivers/hwmon/vt1211.c
  27 +++ b/drivers/hwmon/vt1211.c
  28 @@ -226,15 +226,21 @@ static inline void superio_select(int sio_cip, int ldn)
  29         outb(ldn, sio_cip + 1);
  30  }
  31
  32 -static inline void superio_enter(int sio_cip)
  33 +static inline int superio_enter(int sio_cip)
  34  {
  35 +       if (!request_muxed_region(sio_cip, 2, DRVNAME))
  36 +               return -EBUSY;
  37 +
  38         outb(0x87, sio_cip);
  39         outb(0x87, sio_cip);
  40 +
  41 +       return 0;
  42  }
  43
  44  static inline void superio_exit(int sio_cip)
  45  {
  46         outb(0xaa, sio_cip);
  47 +       release_region(sio_cip, 2);
  48  }
  49
  50  /* ---------------------------------------------------------------------
  51 @@ -1282,11 +1288,14 @@ static int __init vt1211_device_add(unsigned short address)
  52
  53  static int __init vt1211_find(int sio_cip, unsigned short *address)
  54  {
  55 -       int err = -ENODEV;
  56 +       int err;
  57         int devid;
  58
  59 -       superio_enter(sio_cip);
  60 +       err = superio_enter(sio_cip);
  61 +       if (err)
  62 +               return err;
  63
  64 +       err = -ENODEV;
  65         devid = force_id ? force_id : superio_inb(sio_cip, SIO_VT1211_DEVID);
  66         if (devid != SIO_VT1211_ID)
  67                 goto EXIT;
  68 --
  69 2.20.1
  70