On Sat, 13 Jan 2018 14:37:02 +0100 Marc CAPDEVILLE <[email protected]> wrote:
> 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(). A trivial comment inline... Also, I think this whole thing could do with some documentation as it is a little 'unusual' :) Perhaps put a cover letter explaining how whole series has changed as well. Jonathan > > Signed-off-by: Marc CAPDEVILLE <[email protected]> > --- > 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 > + /* 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 <[email protected]>"); > 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) >
