1 files changed, 66 insertions, 13 deletions

diff --git a/drivers/hwmon/w83781d.c b/drivers/hwmon/w83781d.c
index 136bec3fd64..1c00d9f7c14 100644
--- a/drivers/hwmon/w83781d.c
+++ b/drivers/hwmon/w83781d.c
@@ -205,10 +205,7 @@ DIV_TO_REG(long val, enum chips type)
    W83781D chips available (well, actually, that is probably never done; but
    it is a clean illustration of how to handle a case like that). Finally,
    a specific chip may be attached to *both* ISA and SMBus, and we would
-   not like to detect it double. Fortunately, in the case of the W83781D at
-   least, a register tells us what SMBus address we are on, so that helps
-   a bit - except if there could be more than one SMBus. Groan. No solution
-   for this yet. */
+   not like to detect it double. */
 
 /* For ISA chips, we abuse the i2c_client addr and name fields. We also use
    the driver field to differentiate between I2C and ISA chips. */
@@ -852,13 +849,25 @@ static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 /* This function is called when:
      * w83781d_driver is inserted (when this module is loaded), for each
        available adapter
-     * when a new adapter is inserted (and w83781d_driver is still present) */
+     * when a new adapter is inserted (and w83781d_driver is still present)
+   We block updates of the ISA device to minimize the risk of concurrent
+   access to the same W83781D chip through different interfaces. */
 static int
 w83781d_attach_adapter(struct i2c_adapter *adapter)
 {
+	struct w83781d_data *data;
+	int err;
+
 	if (!(adapter->class & I2C_CLASS_HWMON))
 		return 0;
-	return i2c_probe(adapter, &addr_data, w83781d_detect);
+
+	data = pdev ? platform_get_drvdata(pdev) : NULL;
+	if (data)
+		mutex_lock(&data->update_lock);
+	err = i2c_probe(adapter, &addr_data, w83781d_detect);
+	if (data)
+		mutex_unlock(&data->update_lock);
+	return err;
 }
 
 /* Assumes that adapter is of I2C, not ISA variety.
@@ -1028,6 +1037,40 @@ static const struct attribute_group w83781d_group_opt = {
 	.attrs = w83781d_attributes_opt,
 };
 
+/* Returns 1 if the I2C chip appears to be an alias of the ISA chip */
+static int w83781d_alias_detect(struct i2c_client *client, u8 chipid)
+{
+	struct w83781d_data *i2c, *isa;
+	int i;
+
+	if (!pdev)	/* No ISA chip */
+		return 0;
+
+	i2c = i2c_get_clientdata(client);
+	isa = platform_get_drvdata(pdev);
+
+	if (w83781d_read_value(isa, W83781D_REG_I2C_ADDR) != client->addr)
+		return 0;	/* Address doesn't match */
+	if (w83781d_read_value(isa, W83781D_REG_WCHIPID) != chipid)
+		return 0;	/* Chip type doesn't match */
+
+	/* We compare all the limit registers, the config register and the
+	 * interrupt mask registers */
+	for (i = 0x2b; i <= 0x3d; i++) {
+		if (w83781d_read_value(isa, i) != w83781d_read_value(i2c, i))
+			return 0;
+	}
+	if (w83781d_read_value(isa, W83781D_REG_CONFIG) !=
+	    w83781d_read_value(i2c, W83781D_REG_CONFIG))
+		return 0;
+	for (i = 0x43; i <= 0x46; i++) {
+		if (w83781d_read_value(isa, i) != w83781d_read_value(i2c, i))
+			return 0;
+	}
+
+	return 1;
+}
+
 /* No clean up is done on error, it's up to the caller */
 static int
 w83781d_create_files(struct device *dev, int kind, int is_isa)
@@ -1242,6 +1285,14 @@ w83781d_detect(struct i2c_adapter *adapter, int address, int kind)
 			err = -EINVAL;
 			goto ERROR2;
 		}
+
+		if ((kind == w83781d || kind == w83782d)
+		 && w83781d_alias_detect(client, val1)) {
+			dev_dbg(&adapter->dev, "Device at 0x%02x appears to "
+				"be the same as ISA device\n", address);
+			err = -ENODEV;
+			goto ERROR2;
+		}
 	}
 
 	if (kind == w83781d) {
@@ -1904,14 +1955,12 @@ sensors_w83781d_init(void)
 {
 	int res;
 
-	res = i2c_add_driver(&w83781d_driver);
-	if (res)
-		goto exit;
-
+	/* We register the ISA device first, so that we can skip the
+	 * registration of an I2C interface to the same device. */
 	if (w83781d_isa_found(isa_address)) {
 		res = platform_driver_register(&w83781d_isa_driver);
 		if (res)
-			goto exit_unreg_i2c_driver;
+			goto exit;
 
 		/* Sets global pdev as a side effect */
 		res = w83781d_isa_device_add(isa_address);
@@ -1919,12 +1968,16 @@ sensors_w83781d_init(void)
 			goto exit_unreg_isa_driver;
 	}
 
+	res = i2c_add_driver(&w83781d_driver);
+	if (res)
+		goto exit_unreg_isa_device;
+
 	return 0;
 
+ exit_unreg_isa_device:
+	platform_device_unregister(pdev);
  exit_unreg_isa_driver:
 	platform_driver_unregister(&w83781d_isa_driver);
- exit_unreg_i2c_driver:
-	i2c_del_driver(&w83781d_driver);
  exit:
 	return res;
 }