264 lines
7.1 KiB
C
264 lines
7.1 KiB
C
/*
|
|
* 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/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;
|
|
|
|
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.
|
|
*/
|
|
device_lock(dev);
|
|
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");
|
|
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 = 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");
|