queue-4.4/hwmon-pc87427-use-request_muxed_region-for-super-io-.patch

   1 From 85770069abc314bc8c98380d9851da23b3857a46 Mon Sep 17 00:00:00 2001
   2 From: Guenter Roeck <linux@roeck-us.net>
   3 Date: Thu, 4 Apr 2019 11:16:20 -0700
   4 Subject: hwmon: (pc87427) Use request_muxed_region for Super-IO accesses
   5
   6 [ Upstream commit 755a9b0f8aaa5639ba5671ca50080852babb89ce ]
   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: ba224e2c4f0a7 ("hwmon: New PC87427 hardware monitoring driver")
  18 Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
  19 Reported-by: John Garry <john.garry@huawei.com>
  20 Cc: John Garry <john.garry@huawei.com>
  21 Acked-by: John Garry <john.garry@huawei.com>
  22 Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  23 Signed-off-by: Sasha Levin <sashal@kernel.org>
  24 ---
  25  drivers/hwmon/pc87427.c | 14 +++++++++++++-
  26  1 file changed, 13 insertions(+), 1 deletion(-)
  27
  28 diff --git a/drivers/hwmon/pc87427.c b/drivers/hwmon/pc87427.c
  29 index cb9fdd37bd0d9..2b5b8c3de8fce 100644
  30 --- a/drivers/hwmon/pc87427.c
  31 +++ b/drivers/hwmon/pc87427.c
  32 @@ -106,6 +106,13 @@ static const char *logdev_str[2] = { DRVNAME " FMC", DRVNAME " HMC" };
  33  #define LD_IN          1
  34  #define LD_TEMP                1
  35
  36 +static inline int superio_enter(int sioaddr)
  37 +{
  38 +       if (!request_muxed_region(sioaddr, 2, DRVNAME))
  39 +               return -EBUSY;
  40 +       return 0;
  41 +}
  42 +
  43  static inline void superio_outb(int sioaddr, int reg, int val)
  44  {
  45         outb(reg, sioaddr);
  46 @@ -122,6 +129,7 @@ static inline void superio_exit(int sioaddr)
  47  {
  48         outb(0x02, sioaddr);
  49         outb(0x02, sioaddr + 1);
  50 +       release_region(sioaddr, 2);
  51  }
  52
  53  /*
  54 @@ -1220,7 +1228,11 @@ static int __init pc87427_find(int sioaddr, struct pc87427_sio_data *sio_data)
  55  {
  56         u16 val;
  57         u8 cfg, cfg_b;
  58 -       int i, err = 0;
  59 +       int i, err;
  60 +
  61 +       err = superio_enter(sioaddr);
  62 +       if (err)
  63 +               return err;
  64
  65         /* Identify device */
  66         val = force_id ? force_id : superio_inb(sioaddr, SIOREG_DEVID);
  67 --
  68 2.20.1
  69