queue-4.4/hwmon-smsc47m1-use-request_muxed_region-for-super-io.patch

   1 From 396bccc5f60d886c07ad9d5e00347909367632f3 Mon Sep 17 00:00:00 2001
   2 From: Guenter Roeck <linux@roeck-us.net>
   3 Date: Thu, 4 Apr 2019 11:28:37 -0700
   4 Subject: hwmon: (smsc47m1) Use request_muxed_region for Super-IO accesses
   5
   6 [ Upstream commit d6410408ad2a798c4cc685252c1baa713be0ad69 ]
   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/smsc47m1.c | 28 +++++++++++++++++++---------
  26  1 file changed, 19 insertions(+), 9 deletions(-)
  27
  28 diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c
  29 index 5d323186d2c10..d24df0c50bea4 100644
  30 --- a/drivers/hwmon/smsc47m1.c
  31 +++ b/drivers/hwmon/smsc47m1.c
  32 @@ -73,16 +73,21 @@ superio_inb(int reg)
  33  /* logical device for fans is 0x0A */
  34  #define superio_select() superio_outb(0x07, 0x0A)
  35
  36 -static inline void
  37 +static inline int
  38  superio_enter(void)
  39  {
  40 +       if (!request_muxed_region(REG, 2, DRVNAME))
  41 +               return -EBUSY;
  42 +
  43         outb(0x55, REG);
  44 +       return 0;
  45  }
  46
  47  static inline void
  48  superio_exit(void)
  49  {
  50         outb(0xAA, REG);
  51 +       release_region(REG, 2);
  52  }
  53
  54  #define SUPERIO_REG_ACT                0x30
  55 @@ -531,8 +536,12 @@ static int __init smsc47m1_find(struct smsc47m1_sio_data *sio_data)
  56  {
  57         u8 val;
  58         unsigned short addr;
  59 +       int err;
  60 +
  61 +       err = superio_enter();
  62 +       if (err)
  63 +               return err;
  64
  65 -       superio_enter();
  66         val = force_id ? force_id : superio_inb(SUPERIO_REG_DEVID);
  67
  68         /*
  69 @@ -608,13 +617,14 @@ static int __init smsc47m1_find(struct smsc47m1_sio_data *sio_data)
  70  static void smsc47m1_restore(const struct smsc47m1_sio_data *sio_data)
  71  {
  72         if ((sio_data->activate & 0x01) == 0) {
  73 -               superio_enter();
  74 -               superio_select();
  75 -
  76 -               pr_info("Disabling device\n");
  77 -               superio_outb(SUPERIO_REG_ACT, sio_data->activate);
  78 -
  79 -               superio_exit();
  80 +               if (!superio_enter()) {
  81 +                       superio_select();
  82 +                       pr_info("Disabling device\n");
  83 +                       superio_outb(SUPERIO_REG_ACT, sio_data->activate);
  84 +                       superio_exit();
  85 +               } else {
  86 +                       pr_warn("Failed to disable device\n");
  87 +               }
  88         }
  89  }
  90
  91 --
  92 2.20.1
  93