diff options
Diffstat (limited to 'drivers/i2c/i2c-smbus.c')
| -rw-r--r-- | drivers/i2c/i2c-smbus.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c new file mode 100644 index 000000000..5a1dd7f13 --- /dev/null +++ b/drivers/i2c/i2c-smbus.c @@ -0,0 +1,217 @@ +/* + * i2c-smbus.c - SMBus extensions to the I2C protocol + * + * Copyright (C) 2008 David Brownell + * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de> + * + * 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 <linux/device.h> +#include <linux/i2c.h> +#include <linux/i2c-smbus.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_irq.h> +#include <linux/slab.h> +#include <linux/workqueue.h> + +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; + + 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) + driver->alert(client, data->type, data->data); + else + dev_warn(&client->dev, "no driver alert()!\n"); + } else + dev_dbg(&client->dev, "alert with no driver\n"); + device_unlock(dev); + + /* Stop iterating after we find the device */ + return -EBUSY; +} + +/* + * 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 = 0; /* 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; + + if (data.addr == prev_addr) { + dev_warn(&ara->dev, "Duplicate SMBALERT# from dev " + "0x%02x, skipping\n", data.addr); + break; + } + 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 */ + device_for_each_child(&ara->adapter->dev, &data, + smbus_do_alert); + 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 <jdelvare@suse.de>"); +MODULE_DESCRIPTION("SMBus protocol extensions support"); +MODULE_LICENSE("GPL"); |