| From | Ben Hutchings <> | Date | Fri, 20 Sep 2019 15:23:35 +0100 | Subject | [PATCH 3.16 030/132] hwmon: (smsc47b397) Use request_muxed_region for Super-IO accesses |
| |
3.16.74-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Guenter Roeck <linux@roeck-us.net>
commit 8c0826756744c0ac1df600a5e4cca1a341b13101 upstream.
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: Ben Hutchings <ben@decadent.org.uk> --- drivers/hwmon/smsc47b397.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/drivers/hwmon/smsc47b397.c +++ b/drivers/hwmon/smsc47b397.c @@ -72,14 +72,19 @@ static inline void superio_select(int ld superio_outb(0x07, ld); } -static inline void superio_enter(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_DEVID 0x20 @@ -338,8 +343,12 @@ static int __init smsc47b397_find(void) u8 id, rev; char *name; unsigned short addr; + int err; + + err = superio_enter(); + if (err) + return err; - superio_enter(); id = force_id ? force_id : superio_inb(SUPERIO_REG_DEVID); switch (id) {
|