/* * i2c-smbus.c - SMBus extensions to the I2C protocol * * Copyright (C) 2008 David Brownell * Copyright (C) 2010 Jean Delvare * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include #include #include #include #include #include #include #include #include struct i2c_smbus_alert { struct work_struct alert; struct i2c_client *ara; /* Alert response address */ }; struct alert_data { unsigned short addr; enum i2c_alert_protocol type; unsigned int data; }; /* If this is the alerting device, notify its driver */ static int smbus_do_alert(struct device *dev, void *addrp) { struct i2c_client *client = i2c_verify_client(dev); struct alert_data *data = addrp; struct i2c_driver *driver; int ret; if (!client || client->addr != data->addr) return 0; if (client->flags & I2C_CLIENT_TEN) return 0; /* * Drivers should either disable alerts, or provide at least * a minimal handler. Lock so the driver won't change. */ device_lock(dev); if (client->dev.driver) { driver = to_i2c_driver(client->dev.driver); if (driver->alert) { /* Stop iterating after we find the device */ driver->alert(client, data->type, data->data); ret = -EBUSY; } else { dev_warn(&client->dev, "no driver alert()!\n"); ret = -EOPNOTSUPP; } } else { dev_dbg(&client->dev, "alert with no driver\n"); ret = -ENODEV; } device_unlock(dev); return ret; } /* Same as above, but call back all drivers with alert handler */ static int smbus_do_alert_force(struct device *dev, void *addrp) { struct i2c_client *client = i2c_verify_client(dev); struct alert_data *data = addrp; struct i2c_driver *driver; if (!client || (client->flags & I2C_CLIENT_TEN)) return 0; /* * Drivers should either disable alerts, or provide at least * a minimal handler. Lock so the driver won't change. */ device_lock(dev); if (client->dev.driver) { driver = to_i2c_driver(client->dev.driver); if (driver->alert) driver->alert(client, data->type, data->data); } device_unlock(dev); return 0; } /* * The alert IRQ handler needs to hand work off to a task which can issue * SMBus calls, because those sleeping calls can't be made in IRQ context. */ static irqreturn_t smbus_alert(int irq, void *d) { struct i2c_smbus_alert *alert = d; struct i2c_client *ara; unsigned short prev_addr = I2C_CLIENT_END; /* Not a valid address */ ara = alert->ara; for (;;) { s32 status; struct alert_data data; /* * Devices with pending alerts reply in address order, low * to high, because of slave transmit arbitration. After * responding, an SMBus device stops asserting SMBALERT#. * * Note that SMBus 2.0 reserves 10-bit addresses for future * use. We neither handle them, nor try to use PEC here. */ status = i2c_smbus_read_byte(ara); if (status < 0) break; data.data = status & 1; data.addr = status >> 1; data.type = I2C_PROTOCOL_SMBUS_ALERT; dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n", data.addr, data.data); /* Notify driver for the device which issued the alert */ status = device_for_each_child(&ara->adapter->dev, &data, smbus_do_alert); /* * If we read the same address more than once, and the alert * was not handled by a driver, it won't do any good to repeat * the loop because it will never terminate. Try again, this * time calling the alert handlers of all devices connected to * the bus, and abort the loop afterwards. If this helps, we * are all set. If it doesn't, there is nothing else we can do, * so we might as well abort the loop. * Note: This assumes that a driver with alert handler handles * the alert properly and clears it if necessary. */ if (data.addr == prev_addr && status != -EBUSY) { device_for_each_child(&ara->adapter->dev, &data, smbus_do_alert_force); break; } prev_addr = data.addr; } return IRQ_HANDLED; } static void smbalert_work(struct work_struct *work) { struct i2c_smbus_alert *alert; alert = container_of(work, struct i2c_smbus_alert, alert); smbus_alert(0, alert); } /* Setup SMBALERT# infrastructure */ static int smbalert_probe(struct i2c_client *ara, const struct i2c_device_id *id) { struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev); struct i2c_smbus_alert *alert; struct i2c_adapter *adapter = ara->adapter; int res, irq; alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert), GFP_KERNEL); if (!alert) return -ENOMEM; if (setup) { irq = setup->irq; } else { irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert"); if (irq <= 0) return irq; } INIT_WORK(&alert->alert, smbalert_work); alert->ara = ara; if (irq > 0) { res = devm_request_threaded_irq(&ara->dev, irq, NULL, smbus_alert, IRQF_SHARED | IRQF_ONESHOT, "smbus_alert", alert); if (res) return res; } i2c_set_clientdata(ara, alert); dev_info(&adapter->dev, "supports SMBALERT#\n"); return 0; } /* IRQ and memory resources are managed so they are freed automatically */ static int smbalert_remove(struct i2c_client *ara) { struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); cancel_work_sync(&alert->alert); return 0; } static const struct i2c_device_id smbalert_ids[] = { { "smbus_alert", 0 }, { /* LIST END */ } }; MODULE_DEVICE_TABLE(i2c, smbalert_ids); static struct i2c_driver smbalert_driver = { .driver = { .name = "smbus_alert", }, .probe = smbalert_probe, .remove = smbalert_remove, .id_table = smbalert_ids, }; /** * i2c_handle_smbus_alert - Handle an SMBus alert * @ara: the ARA client on the relevant adapter * Context: can't sleep * * Helper function to be called from an I2C bus 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 ara is a valid i2c client previously returned by * i2c_setup_smbus_alert(). */ int i2c_handle_smbus_alert(struct i2c_client *ara) { struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); return schedule_work(&alert->alert); } EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); module_i2c_driver(smbalert_driver); MODULE_AUTHOR("Jean Delvare "); MODULE_DESCRIPTION("SMBus protocol extensions support"); MODULE_LICENSE("GPL");