queue-4.4/hwmon-smsc47b397-use-request_muxed_region-for-super-.patch

   1 From 056e4008ea95bfc4da7d8efab09fe2d779d9329f Mon Sep 17 00:00:00 2001
   2 From: Guenter Roeck <linux@roeck-us.net>
   3 Date: Thu, 4 Apr 2019 11:22:42 -0700
   4 Subject: hwmon: (smsc47b397) Use request_muxed_region for Super-IO accesses
   5
   6 [ Upstream commit 8c0826756744c0ac1df600a5e4cca1a341b13101 ]
   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: 8d5d45fb1468 ("I2C: Move hwmon drivers (2/3)")
  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/smsc47b397.c | 13 +++++++++++--
  26  1 file changed, 11 insertions(+), 2 deletions(-)
  27
  28 diff --git a/drivers/hwmon/smsc47b397.c b/drivers/hwmon/smsc47b397.c
  29 index 6bd2007565603..cbdb5c4991ae3 100644
  30 --- a/drivers/hwmon/smsc47b397.c
  31 +++ b/drivers/hwmon/smsc47b397.c
  32 @@ -72,14 +72,19 @@ static inline void superio_select(int ld)
  33         superio_outb(0x07, ld);
  34  }
  35
  36 -static inline void superio_enter(void)
  37 +static inline int superio_enter(void)
  38  {
  39 +       if (!request_muxed_region(REG, 2, DRVNAME))
  40 +               return -EBUSY;
  41 +
  42         outb(0x55, REG);
  43 +       return 0;
  44  }
  45
  46  static inline void superio_exit(void)
  47  {
  48         outb(0xAA, REG);
  49 +       release_region(REG, 2);
  50  }
  51
  52  #define SUPERIO_REG_DEVID      0x20
  53 @@ -300,8 +305,12 @@ static int __init smsc47b397_find(void)
  54         u8 id, rev;
  55         char *name;
  56         unsigned short addr;
  57 +       int err;
  58 +
  59 +       err = superio_enter();
  60 +       if (err)
  61 +               return err;
  62
  63 -       superio_enter();
  64         id = force_id ? force_id : superio_inb(SUPERIO_REG_DEVID);
  65
  66         switch (id) {
  67 --
  68 2.20.1
  69