linux/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/interrupt.h>
#include <linux/workqueue.h>
#include <linux/i2c.h>
#include <linux/i2c-smbus.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#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");