[ Upstream commit 14b97ba5c20056102b3dd22696bf17b057e60976 ]
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: 2219cd81a6cd ("hwmon/vt1211: Add probing of alternate config index port") Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwmon/vt1211.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/hwmon/vt1211.c b/drivers/hwmon/vt1211.c index 3a6bfa51cb94f..95d5e8ec8b7fc 100644 --- a/drivers/hwmon/vt1211.c +++ b/drivers/hwmon/vt1211.c @@ -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 @@ static int __init vt1211_device_add(unsigned short address)
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;