hwmon: (it87) Avoid registering the same chip on both SIO addresses

IT8705F is known to respond on both SIO addresses. Registering it twice
may result in system lockups.

Reported-by: Russell King <linux@armlinux.org.uk>
Fixes: e84bd9535e2b ("hwmon: (it87) Add support for second Super-IO chip")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index efb01c247e2d90680f02980af76148799f3823fc..4dfc7238313ebd393e0e4dc0e17bb4414d1e8b68 100644 (file)
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -3198,7 +3198,7 @@ static int __init sm_it87_init(void)
 {
        int sioaddr[2] = { REG_2E, REG_4E };
        struct it87_sio_data sio_data;
-       unsigned short isa_address;
+       unsigned short isa_address[2];
        bool found = false;
        int i, err;
 
@@ -3208,15 +3208,29 @@ static int __init sm_it87_init(void)
 
        for (i = 0; i < ARRAY_SIZE(sioaddr); i++) {
                memset(&sio_data, 0, sizeof(struct it87_sio_data));
-               isa_address = 0;
-               err = it87_find(sioaddr[i], &isa_address, &sio_data);
-               if (err || isa_address == 0)
+               isa_address[i] = 0;
+               err = it87_find(sioaddr[i], &isa_address[i], &sio_data);
+               if (err || isa_address[i] == 0)
                        continue;
+               /*
+                * Don't register second chip if its ISA address matches
+                * the first chip's ISA address.
+                */
+               if (i && isa_address[i] == isa_address[0])
+                       break;
 
-               err = it87_device_add(i, isa_address, &sio_data);
+               err = it87_device_add(i, isa_address[i], &sio_data);
                if (err)
                        goto exit_dev_unregister;
+
                found = true;
+
+               /*
+                * IT8705F may respond on both SIO addresses.
+                * Stop probing after finding one.
+                */
+               if (sio_data.type == it87)
+                       break;
        }
 
        if (!found) {