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hwmon: (smsc47m1) Use request_muxed_region for Super-IO accesses

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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: 8d5d45fb14 ("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>
This commit is contained in:
Guenter Roeck 2019-04-04 11:28:37 -07:00
parent 19f7b17630
commit d6410408ad
1 changed files with 19 additions and 9 deletions
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28
drivers/hwmon/smsc47m1.c
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@ -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
@ -535,8 +540,12 @@ 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);
/*
@ -612,13 +621,14 @@ 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");
}
}
}