drivers/i2c/i2c-smbus.c - kernel/bruno - Git at Google

 /*
  * 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/kernel.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/interrupt.h>
 #include <linux/workqueue.h>
 #include <linux/i2c.h>
 #include <linux/i2c-smbus.h>
 #include <linux/slab.h>

 struct i2c_smbus_alert {
 	unsigned int		alert_edge_triggered:1;
 	int			irq;
 	struct work_struct	alert;
 	struct i2c_client	*ara;		/* Alert response address */
 };

 struct alert_data {
 	unsigned short		addr;
 	u8			flag:1;
 };

 /* 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->flag);
 		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 void smbus_alert(struct work_struct *work)
 {
 	struct i2c_smbus_alert *alert;
 	struct i2c_client *ara;
 	unsigned short prev_addr = 0;	/* Not a valid address */

 	alert = container_of(work, struct i2c_smbus_alert, alert);
 	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 addresess for future
 		 * use.  We neither handle them, nor try to use PEC here.
 		 */
 		status = i2c_smbus_read_byte(ara);
 		if (status < 0)
 			break;

 		data.flag = status & 1;
 		data.addr = status >> 1;

 		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.flag);

 		/* Notify driver for the device which issued the alert */
 		device_for_each_child(&ara->adapter->dev, &data,
 				      smbus_do_alert);
 		prev_addr = data.addr;
 	}

 	/* We handled all alerts; re-enable level-triggered IRQs */
 	if (!alert->alert_edge_triggered)
 		enable_irq(alert->irq);
 }

 static irqreturn_t smbalert_irq(int irq, void *d)
 {
 	struct i2c_smbus_alert *alert = d;

 	/* Disable level-triggered IRQs until we handle them */
 	if (!alert->alert_edge_triggered)
 		disable_irq_nosync(irq);

 	schedule_work(&alert->alert);
 	return IRQ_HANDLED;
 }

 /* 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;

 	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
 			     GFP_KERNEL);
 	if (!alert)
 		return -ENOMEM;

 	alert->alert_edge_triggered = setup->alert_edge_triggered;
 	alert->irq = setup->irq;
 	INIT_WORK(&alert->alert, smbus_alert);
 	alert->ara = ara;

 	if (setup->irq > 0) {
 		res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
 				       0, "smbus_alert", alert);
 		if (res)
 			return res;
 	}

 	i2c_set_clientdata(ara, alert);
 	dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
 		 setup->alert_edge_triggered ? "edge" : "level");

 	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_setup_smbus_alert - Setup SMBus alert support
  * @adapter: the target adapter
  * @setup: setup data for the SMBus alert handler
  * Context: can sleep
  *
  * Setup handling of the SMBus alert protocol on a given I2C bus segment.
  *
  * Handling can be done either through our IRQ handler, or by the
  * adapter (from its handler, periodic polling, or whatever).
  *
  * NOTE that if we manage the IRQ, we *MUST* know if it's level or
  * edge triggered in order to hand it to the workqueue correctly.
  * If triggering the alert seems to wedge the system, you probably
  * should have said it's level triggered.
  *
  * This returns the ara client, which should be saved for later use with
  * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
  * to indicate an error.
  */
 struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
 					 struct i2c_smbus_alert_setup *setup)
 {
 	struct i2c_board_info ara_board_info = {
 		I2C_BOARD_INFO("smbus_alert", 0x0c),
 		.platform_data = setup,
 	};

 	return i2c_new_device(adapter, &ara_board_info);
 }
 EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);

 /**
  * 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");
	/*
	* 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/kernel.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/interrupt.h>
	#include <linux/workqueue.h>
	#include <linux/i2c.h>
	#include <linux/i2c-smbus.h>
	#include <linux/slab.h>

	struct i2c_smbus_alert {
	unsigned int alert_edge_triggered:1;
	int irq;
	struct work_struct alert;
	struct i2c_client ara; / Alert response address */
	};

	struct alert_data {
	unsigned short addr;
	u8 flag:1;
	};

	/* 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->flag);
	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 void smbus_alert(struct work_struct *work)
	{
	struct i2c_smbus_alert *alert;
	struct i2c_client *ara;
	unsigned short prev_addr = 0; /* Not a valid address */

	alert = container_of(work, struct i2c_smbus_alert, alert);
	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 addresess for future
	* use. We neither handle them, nor try to use PEC here.
	*/
	status = i2c_smbus_read_byte(ara);
	if (status < 0)
	break;

	data.flag = status & 1;
	data.addr = status >> 1;

	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.flag);

	/* Notify driver for the device which issued the alert */
	device_for_each_child(&ara->adapter->dev, &data,
	smbus_do_alert);
	prev_addr = data.addr;
	}

	/* We handled all alerts; re-enable level-triggered IRQs */
	if (!alert->alert_edge_triggered)
	enable_irq(alert->irq);
	}

	static irqreturn_t smbalert_irq(int irq, void *d)
	{
	struct i2c_smbus_alert *alert = d;

	/* Disable level-triggered IRQs until we handle them */
	if (!alert->alert_edge_triggered)
	disable_irq_nosync(irq);

	schedule_work(&alert->alert);
	return IRQ_HANDLED;
	}

	/* 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;

	alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
	GFP_KERNEL);
	if (!alert)
	return -ENOMEM;

	alert->alert_edge_triggered = setup->alert_edge_triggered;
	alert->irq = setup->irq;
	INIT_WORK(&alert->alert, smbus_alert);
	alert->ara = ara;

	if (setup->irq > 0) {
	res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
	0, "smbus_alert", alert);
	if (res)
	return res;
	}

	i2c_set_clientdata(ara, alert);
	dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
	setup->alert_edge_triggered ? "edge" : "level");

	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_setup_smbus_alert - Setup SMBus alert support
	* @adapter: the target adapter
	* @setup: setup data for the SMBus alert handler
	* Context: can sleep
	*
	* Setup handling of the SMBus alert protocol on a given I2C bus segment.
	*
	* Handling can be done either through our IRQ handler, or by the
	* adapter (from its handler, periodic polling, or whatever).
	*
	* NOTE that if we manage the IRQ, we MUST know if it's level or
	* edge triggered in order to hand it to the workqueue correctly.
	* If triggering the alert seems to wedge the system, you probably
	* should have said it's level triggered.
	*
	* This returns the ara client, which should be saved for later use with
	* i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
	* to indicate an error.
	*/
	struct i2c_client i2c_setup_smbus_alert(struct i2c_adapter adapter,
	struct i2c_smbus_alert_setup *setup)
	{
	struct i2c_board_info ara_board_info = {
	I2C_BOARD_INFO("smbus_alert", 0x0c),
	.platform_data = setup,
	};

	return i2c_new_device(adapter, &ara_board_info);
	}
	EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);

	/**
	* 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");