/drivers/i2c/i2c-smbus.c
http://github.com/mirrors/linux · C · 201 lines · 127 code · 34 blank · 40 comment · 14 complexity · 2a80f1b972a10491302f710e13e3f472 MD5 · raw file
- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * i2c-smbus.c - SMBus extensions to the I2C protocol
- *
- * Copyright (C) 2008 David Brownell
- * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
- */
- #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;
- 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 */
- device_for_each_child(&ara->adapter->dev, &data,
- smbus_do_alert);
- }
- 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_new_smbus_alert_device().
- */
- 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");