On 04/04/2019 19:33, Guenter Roeck wrote:
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: 8d5d45fb1468 ("I2C: Move hwmon drivers (2/3)") Reported-by: Kefeng Wang <[email protected]> Reported-by: John Garry <[email protected]> Cc: John Garry <[email protected]>
Acked-by: John Garry <[email protected]>
Signed-off-by: Guenter Roeck <[email protected]> --- drivers/hwmon/smsc47m1.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c index c7b6a425e2c0..0736ca6a3aee 100644 --- a/drivers/hwmon/smsc47m1.c +++ b/drivers/hwmon/smsc47m1.c @@ -73,16 +73,21 @@ superio_inb(int reg) /* logical device for fans is 0x0A */ #define superio_select() superio_outb(0x07, 0x0A) -static inline void +static inline int superio_enter(void) { + if (!request_muxed_region(REG, 2, DRVNAME)) + return -EBUSY; + outb(0x55, REG); + return 0; } static inline void superio_exit(void) { outb(0xAA, REG); + release_region(REG, 2); } #define SUPERIO_REG_ACT 0x30 @@ -531,8 +536,12 @@ static int __init smsc47m1_find(struct smsc47m1_sio_data *sio_data) { u8 val; unsigned short addr; + int err; + + err = superio_enter(); + if (err) + return err; - superio_enter(); val = force_id ? force_id : superio_inb(SUPERIO_REG_DEVID); /*
