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path: root/drivers/hwmon/lm78.c
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Diffstat (limited to 'drivers/hwmon/lm78.c')
-rw-r--r--drivers/hwmon/lm78.c78
1 files changed, 65 insertions, 13 deletions
diff --git a/drivers/hwmon/lm78.c b/drivers/hwmon/lm78.c
index 2c96d8a548f7..ec601bbf91b9 100644
--- a/drivers/hwmon/lm78.c
+++ b/drivers/hwmon/lm78.c
@@ -120,10 +120,7 @@ static inline int TEMP_FROM_REG(s8 val)
LM78 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 LM78 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. */
@@ -457,12 +454,24 @@ static SENSOR_DEVICE_ATTR(temp1_alarm, S_IRUGO, show_alarm, NULL, 4);
/* This function is called when:
* lm78_driver is inserted (when this module is loaded), for each
available adapter
- * when a new adapter is inserted (and lm78_driver is still present) */
+ * when a new adapter is inserted (and lm78_driver is still present)
+ We block updates of the ISA device to minimize the risk of concurrent
+ access to the same LM78 chip through different interfaces. */
static int lm78_attach_adapter(struct i2c_adapter *adapter)
{
+ struct lm78_data *data;
+ int err;
+
if (!(adapter->class & I2C_CLASS_HWMON))
return 0;
- return i2c_probe(adapter, &addr_data, lm78_detect);
+
+ data = pdev ? platform_get_drvdata(pdev) : NULL;
+ if (data)
+ mutex_lock(&data->update_lock);
+ err = i2c_probe(adapter, &addr_data, lm78_detect);
+ if (data)
+ mutex_unlock(&data->update_lock);
+ return err;
}
static struct attribute *lm78_attributes[] = {
@@ -531,6 +540,40 @@ static ssize_t show_name(struct device *dev, struct device_attribute
}
static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+/* Returns 1 if the I2C chip appears to be an alias of the ISA chip */
+static int lm78_alias_detect(struct i2c_client *client, u8 chipid)
+{
+ struct lm78_data *i2c, *isa;
+ int i;
+
+ if (!pdev) /* No ISA chip */
+ return 0;
+
+ i2c = i2c_get_clientdata(client);
+ isa = platform_get_drvdata(pdev);
+
+ if (lm78_read_value(isa, LM78_REG_I2C_ADDR) != client->addr)
+ return 0; /* Address doesn't match */
+ if ((lm78_read_value(isa, LM78_REG_CHIPID) & 0xfe) != (chipid & 0xfe))
+ 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 (lm78_read_value(isa, i) != lm78_read_value(i2c, i))
+ return 0;
+ }
+ if (lm78_read_value(isa, LM78_REG_CONFIG) !=
+ lm78_read_value(i2c, LM78_REG_CONFIG))
+ return 0;
+ for (i = 0x43; i <= 0x46; i++) {
+ if (lm78_read_value(isa, i) != lm78_read_value(i2c, i))
+ return 0;
+ }
+
+ return 1;
+}
+
/* This function is called by i2c_probe */
static int lm78_detect(struct i2c_adapter *adapter, int address, int kind)
{
@@ -589,6 +632,13 @@ static int lm78_detect(struct i2c_adapter *adapter, int address, int kind)
err = -ENODEV;
goto ERROR2;
}
+
+ if (lm78_alias_detect(new_client, i)) {
+ dev_dbg(&adapter->dev, "Device at 0x%02x appears to "
+ "be the same as ISA device\n", address);
+ err = -ENODEV;
+ goto ERROR2;
+ }
}
if (kind == lm78) {
@@ -959,14 +1009,12 @@ static int __init sm_lm78_init(void)
{
int res;
- res = i2c_add_driver(&lm78_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 (lm78_isa_found(isa_address)) {
res = platform_driver_register(&lm78_isa_driver);
if (res)
- goto exit_unreg_i2c_driver;
+ goto exit;
/* Sets global pdev as a side effect */
res = lm78_isa_device_add(isa_address);
@@ -974,12 +1022,16 @@ static int __init sm_lm78_init(void)
goto exit_unreg_isa_driver;
}
+ res = i2c_add_driver(&lm78_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(&lm78_isa_driver);
- exit_unreg_i2c_driver:
- i2c_del_driver(&lm78_driver);
exit:
return res;
}