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hwmon: (vt1211) Use request_muxed_region for Super-IO accesses 

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: 2219cd81a6 ("hwmon/vt1211: Add probing of alternate config index port")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
hifive-unleashed-5.2
Guenter Roeck 2019-04-05 08:53:08 -07:00
parent e95fd518d0
commit 14b97ba5c2
1 changed files with 12 additions and 3 deletions
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15
drivers/hwmon/vt1211.c
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@ -226,15 +226,21 @@ static inline void superio_select(int sio_cip, int ldn)
outb(ldn, sio_cip + 1);
}
static inline void superio_enter(int sio_cip)
static inline int superio_enter(int sio_cip)
{
if (!request_muxed_region(sio_cip, 2, DRVNAME))
return -EBUSY;
outb(0x87, sio_cip);
outb(0x87, sio_cip);
return 0;
}
static inline void superio_exit(int sio_cip)
{
outb(0xaa, sio_cip);
release_region(sio_cip, 2);
}
/* ---------------------------------------------------------------------
@ -1282,11 +1288,14 @@ EXIT:
static int __init vt1211_find(int sio_cip, unsigned short *address)
{
int err = -ENODEV;
int err;
int devid;
superio_enter(sio_cip);
err = superio_enter(sio_cip);
if (err)
return err;
err = -ENODEV;
devid = force_id ? force_id : superio_inb(sio_cip, SIO_VT1211_DEVID);
if (devid != SIO_VT1211_ID)
goto EXIT;