Some ACPI devices report multiple ids for a single i2c_client, while not
really implementing the hw-interface asociated with some of these ids.
For some of these devices calling probe and having probe fail with
-ENODEV is a problem in itself as this causes the device to be
powered-up and down again (causes its PS0 and PS3 ACPI methods to be
executed) which puts some devices in an unusable state.
This commit adds a match callback to i2c_driver, allowing drivers to
override the default i2c_bus match behavior and tell the core they
are not the right driver for the device, avoiding i2c_bus_type.probe
getting called, avoiding the undesirable power up / down cycle.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/i2c/i2c-core-base.c | 12 +++++++++---
include/linux/i2c.h | 6 ++++++
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index c89dac7fd2e7..2c6702f2347b 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -98,8 +98,16 @@ EXPORT_SYMBOL_GPL(i2c_match_id);
static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
struct i2c_client *client = i2c_verify_client(dev);
- struct i2c_driver *driver;
+ struct i2c_driver *driver = to_i2c_driver(drv);
+ int ret;
+ if (driver->match && client) {
+ ret = driver->match(client);
+ if (ret < 0)
+ return 0;
+ if (ret > 0)
+ return 1;
+ }
/* Attempt an OF style match */
if (i2c_of_match_device(drv->of_match_table, client))
@@ -109,8 +117,6 @@ static int i2c_device_match(struct device *dev, struct device_driver *drv)
if (acpi_driver_match_device(dev, drv))
return 1;
- driver = to_i2c_driver(drv);
-
/* Finally an I2C match */
if (i2c_match_id(driver->id_table, client))
return 1;
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 00ca5b86a753..670577c82bc3 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -139,6 +139,9 @@ enum i2c_alert_protocol {
* struct i2c_driver - represent an I2C device driver
* @class: What kind of i2c device we instantiate (for detect)
* @attach_adapter: Callback for bus addition (deprecated)
+ * @match: Allows the driver to override the default i2c_bus match behavior
+ * return < 0 to fail the match, > 0 to force a match, 0 to fallback
+ * to default id matching
* @probe: Callback for device binding - soon to be deprecated
* @probe_new: New callback for device binding
* @remove: Callback for device unbinding
@@ -180,6 +183,9 @@ struct i2c_driver {
*/
int (*attach_adapter)(struct i2c_adapter *) __deprecated;
+ /* Set this to override standard i2c_bus match behavior */
+ int (*match)(struct i2c_client *);
+
/* Standard driver model interfaces */
int (*probe)(struct i2c_client *, const struct i2c_device_id *);
int (*remove)(struct i2c_client *);
--
2.13.0
--
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