This is from rfc by Alan Cox : https://patchwork.ozlabs.org/patch/381773 The idea is as follows (extract from above rfc) : - If an adapter knows about its ARA and smbus alerts then the adapter creates its own interrupt handler as before - If a client knows it needs smbus alerts it calls i2c_require_smbus_alert(). This ensures that there is an ARA handler registered and tells the client whether the adapter is handling it anyway or not. - When the client learns that an ARA event has occurred it calls i2c_smbus_alert_event() which uses the existing ARA mechanism to kick things off. Suggested-by: Alan Cox <alan@xxxxxxxxxxxxxxx> Signed-off-by: Marc CAPDEVILLE <m.capdeville@xxxxxxxxxx> --- drivers/i2c/i2c-smbus.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/i2c-smbus.h | 15 +++++++++ 2 files changed, 98 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index 5a1dd7f13bac..e97fbafd10ef 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -161,6 +161,9 @@ static int smbalert_probe(struct i2c_client *ara, } i2c_set_clientdata(ara, alert); + + ara->adapter->smbus_ara = ara; + dev_info(&adapter->dev, "supports SMBALERT#\n"); return 0; @@ -172,6 +175,9 @@ static int smbalert_remove(struct i2c_client *ara) struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); cancel_work_sync(&alert->alert); + + ara->adapter->smbus_ara = NULL; + return 0; } @@ -210,6 +216,83 @@ int i2c_handle_smbus_alert(struct i2c_client *ara) } EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); +/* + * i2c_require_smbus_alert - Client discovered SMBus alert + * @c: client requiring ARA + * + * When a client needs an ARA it calls this method. If the bus adapter + * supports ARA and already knows how to do so then it will already have + * configured for ARA and this is a no-op. If not then we set up an ARA + * on the adapter. + * + * We *cannot* simply register a new IRQ handler for this because we might + * have multiple GPIO interrupts to devices all of which trigger an ARA. + * + * Return: + * 0 if ara support already registered + * 1 if call register a new smbus_alert device + * <0 on error + */ +int i2c_require_smbus_alert(struct i2c_client *client) +{ + struct i2c_adapter *adapter = client->adapter; + struct i2c_smbus_alert_setup setup; + struct i2c_client *ara; + + /* ARA is already known and handled by the adapter (ideal case) + * or another client has specified ARA is needed + */ + if (adapter->smbus_ara) + return 0; + + /* Client driven, do not set up a new IRQ handler */ + setup.irq = 0; + + ara = i2c_setup_smbus_alert(adapter, &setup); + if (!ara) + return -ENODEV; + + return 1; +} +EXPORT_SYMBOL_GPL(i2c_require_smbus_alert); + +/* + * i2c_smbus_alert_event + * @client: the client who known of a probable ara event + * Context: can't sleep + * + * Helper function to be called from an I2C device driver's interrupt + * handler. It will schedule the alert work, in turn calling the + * corresponding I2C device driver's alert function. + * + * It is assumed that client is an i2c client who previously call + * i2c_require_smbus_alert(). + */ +int i2c_smbus_alert_event(struct i2c_client *client) +{ + struct i2c_adapter *adapter; + struct i2c_client *ara; + struct i2c_smbus_alert *alert; + + if (!client) + return -EINVAL; + + adapter = client->adapter; + if (!adapter) + return -EINVAL; + + ara = adapter->smbus_ara; + if (!ara) + return -EINVAL; + + alert = i2c_get_clientdata(ara); + if (!alert) + return -EINVAL; + + return schedule_work(&alert->alert); +} +EXPORT_SYMBOL_GPL(i2c_smbus_alert_event); + module_i2c_driver(smbalert_driver); MODULE_AUTHOR("Jean Delvare <jdelvare@xxxxxxx>"); diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h index fb0e040b1abb..49f362fa6ac5 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -58,4 +58,19 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap) } #endif +#if IS_ENABLED(CONFIG_I2C_SMBUS) +int i2c_require_smbus_alert(struct i2c_client *client); +int i2c_smbus_alert_event(struct i2c_client *client); +#else +static inline int i2c_require_smbus_alert(struct i2c_client *client) +{ + return NULL; +} + +static inline int i2c_smbus_alert_event(struct i2c_client *client) +{ + return NULL; +} +#endif + #endif /* _LINUX_I2C_SMBUS_H */ -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
