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Release 4.14 drivers/i2c/i2c-smbus.c

Directory: drivers/i2c
 * 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
 * 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/slab.h>
#include <linux/workqueue.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;
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; }


Jean Delvare11881.94%120.00%
Lars-Peter Clausen1913.19%120.00%
Benjamin Tissoires53.47%240.00%
Stephen Rothwell21.39%120.00%

/* * 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 addresses for future * use. We neither handle them, nor try to use PEC here. */ status = i2c_smbus_read_byte(ara); if (status < 0) break; = 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,; /* 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); }


Jean Delvare16994.94%133.33%
Benjamin Tissoires84.49%133.33%
Shailendra Verma10.56%133.33%

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; }


Jean Delvare44100.00%1100.00%

/* 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; }


Jean Delvare16394.22%133.33%
Julia Lawall63.47%133.33%
Jingoo Han42.31%133.33%

/* 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; }


Jean Delvare32100.00%1100.00%

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); }


Jean Delvare44100.00%1100.00%

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); }


Jean Delvare29100.00%1100.00%

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");

Overall Contributors

Jean Delvare73991.92%215.38%
Benjamin Tissoires202.49%215.38%
Lars-Peter Clausen192.36%17.69%
Wolfram Sang81.00%215.38%
Julia Lawall70.87%17.69%
Jingoo Han40.50%17.69%
Fabio Estevam20.25%17.69%
Tejun Heo20.25%17.69%
Stephen Rothwell20.25%17.69%
Shailendra Verma10.12%17.69%
Directory: drivers/i2c
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