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. In addition, if a client have an irq line to trigger smbus alert, client driver register its irq with i2c_smbus_alert_add_irq() to the smbus alert driver to use the generic alert interrupt handler. On detach, the client must unregister its irq from the smbus alert driver with i2c_smbus_alert_free_irq(). Signed-off-by: Marc CAPDEVILLE <m.capdeville@xxxxxxxxxx> --- drivers/i2c/i2c-core-smbus.c | 42 +++++++++++ drivers/i2c/i2c-smbus.c | 171 +++++++++++++++++++++++++++++++++++++++++-- include/linux/i2c-smbus.h | 22 ++++++ include/linux/i2c.h | 2 + 4 files changed, 232 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 1238c94fe5a1..0d84ac9669e9 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -659,6 +659,48 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter, } EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert); +/** + * i2c_require_smbus_alert - Client discovered SMBus alert + * @client: client requiring ARA support + * + * 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. + * + * 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; + int ret; + + if (adapter->smbus_ara) { + /* + * ARA is already known and handled by the adapter (ideal case) + * or another client has specified ARA is needed + */ + ret = 0; + } else { + /* First client requesting alert and no adapter has + * has setup one + */ + setup.irq = 0; + ara = i2c_setup_smbus_alert(adapter, &setup); + if (!ara) + return -ENODEV; + ret = 1; + } + + return ret; +} +EXPORT_SYMBOL_GPL(i2c_require_smbus_alert); + #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF) int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter) { diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index 5a1dd7f13bac..1699333ac950 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -25,9 +25,16 @@ #include <linux/slab.h> #include <linux/workqueue.h> +struct i2c_smbus_irq_usage { + struct list_head list; + int irq; + int count; +}; + struct i2c_smbus_alert { struct work_struct alert; struct i2c_client *ara; /* Alert response address */ + struct list_head irq_usage; /* irq usage list */ }; struct alert_data { @@ -126,6 +133,124 @@ static void smbalert_work(struct work_struct *work) } +/** + * i2c_smbus_alert_add_irq - Add a new irq handler to ARA client + * @client: The client which want to add an smbus alert irq handler + * @irq: The irq number to be added to the smbus alert device + * return: 0 if irq handler already exist, 1 if a new handler has been + * registered, <0 on error + * + * This is used by the smbalert_probe and by smbus client to check if an + * irq handler already exist for that irq and if not register a new one + * Clients must free their irq with i2c_smbus_alert_free_irq() on driver + * detach. + */ +int i2c_smbus_alert_add_irq(struct i2c_client *client, int irq) +{ + int res; + struct i2c_smbus_irq_usage *irq_usage; + struct i2c_client *ara; + struct i2c_smbus_alert *alert; + + ara = client->adapter->smbus_ara; + if (!ara) + return -EINVAL; + + alert = i2c_get_clientdata(client->adapter->smbus_ara); + if (!alert) + return -EINVAL; + + if (!irq) + return 0; + + /* Check if handler exist for that irq */ + list_for_each_entry(irq_usage, &alert->irq_usage, list) + if (irq_usage->irq == irq) + break; + + if (irq_usage->irq == irq) { + irq_usage->count++; + } else { + /* setup a new handler for that irq */ + res = devm_request_threaded_irq(&ara->dev, irq, + NULL, smbus_alert, + IRQF_SHARED | IRQF_ONESHOT, + "smbus_alert", alert); + if (res) + return res; + + /* Add adapter irq number to used irq list with a count of 1 */ + irq_usage = devm_kmalloc(&ara->dev, + sizeof(struct i2c_smbus_irq_usage), + GFP_KERNEL); + INIT_LIST_HEAD(&irq_usage->list); + irq_usage->irq = irq; + irq_usage->count = 1; + list_add(&irq_usage->list, &alert->irq_usage); + + return 0; + } + + return 1; +} +EXPORT_SYMBOL_GPL(i2c_smbus_alert_add_irq); + +/** + * i2c_smbus_alert_free_irq - free irq added with i2c_smbus_alert_add_irq() + * @client: The client which want to free its smbus alert irq + * @irq: The irq number to be freed + * return: 0 if irq handler still exist for other client, + * 1 if client is the last one using this handler and handler have been + * removed, + * <0 on error. + * + * This is used by smbus clients to free their irq usage from smbus alert + * device. + */ +int i2c_smbus_alert_free_irq(struct i2c_client *client, int irq) +{ + struct i2c_smbus_irq_usage *irq_usage; + struct i2c_client *ara; + struct i2c_smbus_alert *alert; + + ara = client->adapter->smbus_ara; + if (!ara) + return -EINVAL; + + alert = i2c_get_clientdata(client->adapter->smbus_ara); + if (!alert) + return -EINVAL; + + if (!irq) + return 0; + + /* Check if handler exist for that irq */ + list_for_each_entry(irq_usage, &alert->irq_usage, list) + if (irq_usage->irq == irq) + break; + + if (irq_usage->irq == irq) { + irq_usage->count--; + if (!irq_usage->count) { + /* usage count goes to 0 + * so remove irq_usage from list + */ + list_del(&irq_usage->list); + devm_kfree(&ara->dev, irq_usage); + + /* remove irq handler */ + devm_free_irq(&ara->dev, irq, alert); + + return 1; + } + + return 0; + } + + return -EINVAL; +} +EXPORT_SYMBOL_GPL(i2c_smbus_alert_free_irq); + /* Setup SMBALERT# infrastructure */ static int smbalert_probe(struct i2c_client *ara, const struct i2c_device_id *id) @@ -151,16 +276,18 @@ static int smbalert_probe(struct i2c_client *ara, INIT_WORK(&alert->alert, smbalert_work); alert->ara = ara; + INIT_LIST_HEAD(&alert->irq_usage); + + i2c_set_clientdata(ara, alert); + + ara->adapter->smbus_ara = ara; + if (irq > 0) { - res = devm_request_threaded_irq(&ara->dev, irq, - NULL, smbus_alert, - IRQF_SHARED | IRQF_ONESHOT, - "smbus_alert", alert); + res = i2c_smbus_alert_add_irq(ara, irq); if (res) return res; } - i2c_set_clientdata(ara, alert); dev_info(&adapter->dev, "supports SMBALERT#\n"); return 0; @@ -172,6 +299,9 @@ 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 +340,37 @@ int i2c_handle_smbus_alert(struct i2c_client *ara) } EXPORT_SYMBOL_GPL(i2c_handle_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(). + * + * return: <0 on error + */ +int i2c_smbus_alert_event(struct i2c_client *client) +{ + struct i2c_client *ara; + struct i2c_smbus_alert *alert; + + ara = client->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..cf777f29cc79 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -47,6 +47,7 @@ struct i2c_smbus_alert_setup { struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter, struct i2c_smbus_alert_setup *setup); +int i2c_require_smbus_alert(struct i2c_client *client); int i2c_handle_smbus_alert(struct i2c_client *ara); #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF) @@ -58,4 +59,25 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap) } #endif +#if IS_ENABLED(CONFIG_I2C_SMBUS) +int i2c_smbus_alert_add_irq(struct i2c_client *client, int irq); +int i2c_smbus_alert_free_irq(struct i2c_client *client, int irq); +int i2c_smbus_alert_event(struct i2c_client *client); +#else +static inline int i2c_smbus_alert_add_irq(struct i2c_client *client, int irq) +{ + return -EINVAL; +} + +static inline int i2c_smbus_alert_free_irq(struct i2c_client *client, int irq) +{ + return -EINVAL; +} + +static inline int i2c_smbus_alert_event(struct i2c_client *client) +{ + return -EINVAL; +} +#endif + #endif /* _LINUX_I2C_SMBUS_H */ diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 5d7f3c1853ae..7592dce12923 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -652,6 +652,8 @@ struct i2c_adapter { const struct i2c_adapter_quirks *quirks; struct irq_domain *host_notify_domain; + + struct i2c_client *smbus_ara; /* ARA client address if any or NULL */ }; #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev) -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
