i2c: Add driver suspend/resume/shutdown support

Driver model updates for the I2C core:

 - Add new suspend(), resume(), and shutdown() methods.  Use them in the
   standard driver model style; document them.

 - Minor doc updates to highlight zero-initialized fields in drivers, and
   the driver model accessors for "clientdata".

If any i2c drivers were previously using the old suspend/resume calls
in "struct driver", they were getting warning messages ... and will
now no longer work.  Other than that, this patch changes no behaviors;
and it lets I2C drivers use conventional PM and shutdown support.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
David Brownell 2007-02-13 22:09:00 +01:00 committed by Jean Delvare
parent b8d6f45b32
commit f37dd80ac2
4 changed files with 108 additions and 34 deletions

View file

@ -129,6 +129,12 @@ Technical changes:
structure, those name member should be initialized to a driver name
string. i2c_driver itself has no name member anymore.
* [Driver model] Instead of shutdown or reboot notifiers, provide a
shutdown() method in your driver.
* [Power management] Use the driver model suspend() and resume()
callbacks instead of the obsolete pm_register() calls.
Coding policy:
* [Copyright] Use (C), not (c), for copyright.

View file

@ -21,20 +21,26 @@ The driver structure
Usually, you will implement a single driver structure, and instantiate
all clients from it. Remember, a driver structure contains general access
routines, a client structure specific information like the actual I2C
address.
routines, and should be zero-initialized except for fields with data you
provide. A client structure holds device-specific information like the
driver model device node, and its I2C address.
static struct i2c_driver foo_driver = {
.driver = {
.name = "foo",
},
.attach_adapter = &foo_attach_adapter,
.detach_client = &foo_detach_client,
.command = &foo_command /* may be NULL */
.attach_adapter = foo_attach_adapter,
.detach_client = foo_detach_client,
.shutdown = foo_shutdown, /* optional */
.suspend = foo_suspend, /* optional */
.resume = foo_resume, /* optional */
.command = foo_command, /* optional */
}
The name field must match the driver name, including the case. It must not
contain spaces, and may be up to 31 characters long.
The name field is the driver name, and must not contain spaces. It
should match the module name (if the driver can be compiled as a module),
although you can use MODULE_ALIAS (passing "foo" in this example) to add
another name for the module.
All other fields are for call-back functions which will be explained
below.
@ -43,11 +49,18 @@ below.
Extra client data
=================
The client structure has a special `data' field that can point to any
structure at all. You can use this to keep client-specific data. You
Each client structure has a special `data' field that can point to any
structure at all. You should use this to keep device-specific data,
especially in drivers that handle multiple I2C or SMBUS devices. You
do not always need this, but especially for `sensors' drivers, it can
be very useful.
/* store the value */
void i2c_set_clientdata(struct i2c_client *client, void *data);
/* retrieve the value */
void *i2c_get_clientdata(struct i2c_client *client);
An example structure is below.
struct foo_data {
@ -493,6 +506,33 @@ by `__init_data'. Hose functions and structures can be removed after
kernel booting (or module loading) is completed.
Power Management
================
If your I2C device needs special handling when entering a system low
power state -- like putting a transceiver into a low power mode, or
activating a system wakeup mechanism -- do that in the suspend() method.
The resume() method should reverse what the suspend() method does.
These are standard driver model calls, and they work just like they
would for any other driver stack. The calls can sleep, and can use
I2C messaging to the device being suspended or resumed (since their
parent I2C adapter is active when these calls are issued, and IRQs
are still enabled).
System Shutdown
===============
If your I2C device needs special handling when the system shuts down
or reboots (including kexec) -- like turning something off -- use a
shutdown() method.
Again, this is a standard driver model call, working just like it
would for any other driver stack: the calls can sleep, and can use
I2C messaging.
Command function
================

View file

@ -41,30 +41,15 @@ static LIST_HEAD(drivers);
static DEFINE_MUTEX(core_lists);
static DEFINE_IDR(i2c_adapter_idr);
/* ------------------------------------------------------------------------- */
/* match always succeeds, as we want the probe() to tell if we really accept this match */
static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
return 1;
}
static int i2c_bus_suspend(struct device * dev, pm_message_t state)
{
int rc = 0;
if (dev->driver && dev->driver->suspend)
rc = dev->driver->suspend(dev, state);
return rc;
}
static int i2c_bus_resume(struct device * dev)
{
int rc = 0;
if (dev->driver && dev->driver->resume)
rc = dev->driver->resume(dev);
return rc;
}
static int i2c_device_probe(struct device *dev)
{
return -ENODEV;
@ -75,15 +60,53 @@ static int i2c_device_remove(struct device *dev)
return 0;
}
static void i2c_device_shutdown(struct device *dev)
{
struct i2c_driver *driver;
if (!dev->driver)
return;
driver = to_i2c_driver(dev->driver);
if (driver->shutdown)
driver->shutdown(to_i2c_client(dev));
}
static int i2c_device_suspend(struct device * dev, pm_message_t mesg)
{
struct i2c_driver *driver;
if (!dev->driver)
return 0;
driver = to_i2c_driver(dev->driver);
if (!driver->suspend)
return 0;
return driver->suspend(to_i2c_client(dev), mesg);
}
static int i2c_device_resume(struct device * dev)
{
struct i2c_driver *driver;
if (!dev->driver)
return 0;
driver = to_i2c_driver(dev->driver);
if (!driver->resume)
return 0;
return driver->resume(to_i2c_client(dev));
}
struct bus_type i2c_bus_type = {
.name = "i2c",
.match = i2c_device_match,
.probe = i2c_device_probe,
.remove = i2c_device_remove,
.suspend = i2c_bus_suspend,
.resume = i2c_bus_resume,
.name = "i2c",
.match = i2c_device_match,
.probe = i2c_device_probe,
.remove = i2c_device_remove,
.shutdown = i2c_device_shutdown,
.suspend = i2c_device_suspend,
.resume = i2c_device_resume,
};
/* ------------------------------------------------------------------------- */
void i2c_adapter_dev_release(struct device *dev)
{
struct i2c_adapter *adap = dev_to_i2c_adapter(dev);

View file

@ -125,7 +125,12 @@ struct i2c_driver {
* it must be freed here.
*/
int (*detach_client)(struct i2c_client *);
/* driver model interfaces that don't relate to enumeration */
void (*shutdown)(struct i2c_client *);
int (*suspend)(struct i2c_client *, pm_message_t mesg);
int (*resume)(struct i2c_client *);
/* a ioctl like command that can be used to perform specific functions
* with the device.
*/