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Commit d6410408 authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (smsc47m1) 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: 8d5d45fb ("I2C: Move hwmon drivers (2/3)")
Reported-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Reported-by: default avatarJohn Garry <john.garry@huawei.com>
Cc: John Garry <john.garry@huawei.com>
Acked-by: default avatarJohn Garry <john.garry@huawei.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 19f7b176

drivers/hwmon/smsc47m1.c

+19 −9
Original line number Diff line number Diff line
@@ -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();

		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");

		}

	}

}