[ Upstream commit d6410408ad2a798c4cc685252c1baa713be0ad69 ]
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 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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwmon/smsc47m1.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c index 5d323186d2c10..d24df0c50bea4 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);
/* @@ -608,13 +617,14 @@ static int __init smsc47m1_find(struct smsc47m1_sio_data *sio_data) static void smsc47m1_restore(const struct smsc47m1_sio_data *sio_data) { if ((sio_data->activate & 0x01) == 0) { - superio_enter(); - superio_select(); - - pr_info("Disabling device\n"); - superio_outb(SUPERIO_REG_ACT, sio_data->activate); - - superio_exit(); + if (!superio_enter()) { + superio_select(); + pr_info("Disabling device\n"); + superio_outb(SUPERIO_REG_ACT, sio_data->activate); + superio_exit(); + } else { + pr_warn("Failed to disable device\n"); + } } }