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hwmon: (pc87427) Use request_muxed_region for Super-IO accesses

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Super-IO accesses may fail on a system with no or unmapped LPC bus.

Also, other drivers may attempt to access the LPC bus at the same time,
resulting in undefined behavior.

Use request_muxed_region() to ensure that IO access on the requested
address space is supported, and to ensure that access by multiple drivers
is synchronized.

Fixes: ba224e2c4f0a7 ("hwmon: New PC87427 hardware monitoring driver")
Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reported-by: John Garry <john.garry@huawei.com>
Cc: John Garry <john.garry@huawei.com>
Acked-by: John Garry <john.garry@huawei.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Guenter Roeck 2019-04-04 11:16:20 -07:00
parent 73e6ff71a7
commit 755a9b0f8a
1 changed files with 13 additions and 1 deletions
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14
drivers/hwmon/pc87427.c
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@ -106,6 +106,13 @@ static const char *logdev_str[2] = { DRVNAME " FMC", DRVNAME " HMC" };
#define LD_IN 1
#define LD_TEMP 1
static inline int superio_enter(int sioaddr)
{
if (!request_muxed_region(sioaddr, 2, DRVNAME))
return -EBUSY;
return 0;
}
static inline void superio_outb(int sioaddr, int reg, int val)
{
outb(reg, sioaddr);
@ -122,6 +129,7 @@ static inline void superio_exit(int sioaddr)
{
outb(0x02, sioaddr);
outb(0x02, sioaddr + 1);
release_region(sioaddr, 2);
}
/*
@ -1195,7 +1203,11 @@ static int __init pc87427_find(int sioaddr, struct pc87427_sio_data *sio_data)
{
u16 val;
u8 cfg, cfg_b;
int i, err = 0;
int i, err;
err = superio_enter(sioaddr);
if (err)
return err;
/* Identify device */
val = force_id ? force_id : superio_inb(sioaddr, SIOREG_DEVID);