i2c: Add SMBus alert support (b5527a77) · Commits · 戴 / test

Documentation/i2c/smbus-protocol

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		@@ -185,6 +185,22 @@ the protocol. All ARP communications use slave address 0x61 and
		require PEC checksums.


		SMBus Alert
		===========

		SMBus Alert was introduced in Revision 1.0 of the specification.

		The SMBus alert protocol allows several SMBus slave devices to share a
		single interrupt pin on the SMBus master, while still allowing the master
		to know which slave triggered the interrupt.

		This is implemented the following way in the Linux kernel:
		* I2C bus drivers which support SMBus alert should call
		i2c_setup_smbus_alert() to setup SMBus alert support.
		* I2C drivers for devices which can trigger SMBus alerts should implement
		the optional alert() callback.


		I2C Block Transactions
		======================

drivers/i2c/Makefile

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		@@ -3,7 +3,7 @@
		#

		obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
		obj-$(CONFIG_I2C) += i2c-core.o
		obj-$(CONFIG_I2C) += i2c-core.o i2c-smbus.o
		obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
		obj-y += busses/ chips/ algos/

drivers/i2c/i2c-smbus.c

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		/*
		* i2c-smbus.c - SMBus extensions to the I2C protocol
		*
		* Copyright (C) 2008 David Brownell
		* Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
		*
		* 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.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write to the Free Software
		* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
		*/

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

		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 client->driver won't change.
		*/
		down(&dev->sem);
		if (client->driver) {
		if (client->driver->alert)
		client->driver->alert(client, data->flag);
		else
		dev_warn(&client->dev, "no driver alert()!\n");
		} else
		dev_dbg(&client->dev, "alert with no driver\n");
		up(&dev->sem);

		/* 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 = ara->dev.platform_data;
		struct i2c_smbus_alert *alert;
		struct i2c_adapter *adapter = ara->adapter;
		int res;

		alert = kzalloc(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) {
		kfree(alert);
		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 resource is managed so it is freed automatically */
		static int smbalert_remove(struct i2c_client *ara)
		{
		struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);

		cancel_work_sync(&alert->alert);

		i2c_set_clientdata(ara, NULL);
		kfree(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);

		static int __init i2c_smbus_init(void)
		{
		return i2c_add_driver(&smbalert_driver);
		}

		static void __exit i2c_smbus_exit(void)
		{
		i2c_del_driver(&smbalert_driver);
		}

		module_init(i2c_smbus_init);
		module_exit(i2c_smbus_exit);

		MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
		MODULE_DESCRIPTION("SMBus protocol extensions support");
		MODULE_LICENSE("GPL");

include/linux/i2c-smbus.h

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		/*
		* i2c-smbus.h - SMBus extensions to the I2C protocol
		*
		* Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
		*
		* 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.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write to the Free Software
		* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
		*/

		#ifndef _LINUX_I2C_SMBUS_H
		#define _LINUX_I2C_SMBUS_H

		#include <linux/i2c.h>


		/**
		* i2c_smbus_alert_setup - platform data for the smbus_alert i2c client
		* @alert_edge_triggered: whether the alert interrupt is edge (1) or level (0)
		* triggered
		* @irq: IRQ number, if the smbus_alert driver should take care of interrupt
		* handling
		*
		* If irq is not specified, the smbus_alert driver doesn't take care of
		* interrupt handling. In that case it is up to the I2C bus driver to either
		* handle the interrupts or to poll for alerts.
		*
		* If irq is specified then it it crucial that alert_edge_triggered is
		* properly set.
		*/
		struct i2c_smbus_alert_setup {
		unsigned int alert_edge_triggered:1;
		int irq;
		};

		struct i2c_client i2c_setup_smbus_alert(struct i2c_adapter adapter,
		struct i2c_smbus_alert_setup *setup);
		int i2c_handle_smbus_alert(struct i2c_client *ara);

		#endif /* _LINUX_I2C_SMBUS_H */

include/linux/i2c.h

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		@@ -152,6 +152,13 @@ struct i2c_driver {
		int (suspend)(struct i2c_client , pm_message_t mesg);
		int (resume)(struct i2c_client );

		/* Alert callback, for example for the SMBus alert protocol.
		* The format and meaning of the data value depends on the protocol.
		* For the SMBus alert protocol, there is a single bit of data passed
		* as the alert response's low bit ("event flag").
		*/
		void (alert)(struct i2c_client , unsigned int data);

		/* a ioctl like command that can be used to perform specific functions
		* with the device.
		*/

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