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authorGuenter Roeck <linux@roeck-us.net>2019-04-04 11:22:42 -0700
committerGuenter Roeck <linux@roeck-us.net>2019-04-15 17:19:53 -0700
commit8c0826756744c0ac1df600a5e4cca1a341b13101 (patch)
tree2798eb6a92ce30f42c9517cc1d36f5fd2f74e0f9 /drivers/hwmon/smsc47b397.c
parent755a9b0f8aaa5639ba5671ca50080852babb89ce (diff)
hwmon: (smsc47b397) 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: 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>
Diffstat (limited to 'drivers/hwmon/smsc47b397.c')
-rw-r--r--drivers/hwmon/smsc47b397.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/hwmon/smsc47b397.c b/drivers/hwmon/smsc47b397.c
index c0775084dde0..60e193f2e970 100644
--- 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
@@ -300,8 +305,12 @@ 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) {