mirror of
https://github.com/AetherDroid/android_kernel_samsung_on5xelte.git
synced 2025-09-05 16:07:46 -04:00
Fixed MTP to work with TWRP
This commit is contained in:
awab228
commit
f6dfaef42e
50820 changed files with 20846062 additions and 0 deletions
287
Documentation/s390/driver-model.txt
Normal file
287
Documentation/s390/driver-model.txt
Normal file
|
|
@ -0,0 +1,287 @@
|
|||
S/390 driver model interfaces
|
||||
-----------------------------
|
||||
|
||||
1. CCW devices
|
||||
--------------
|
||||
|
||||
All devices which can be addressed by means of ccws are called 'CCW devices' -
|
||||
even if they aren't actually driven by ccws.
|
||||
|
||||
All ccw devices are accessed via a subchannel, this is reflected in the
|
||||
structures under devices/:
|
||||
|
||||
devices/
|
||||
- system/
|
||||
- css0/
|
||||
- 0.0.0000/0.0.0815/
|
||||
- 0.0.0001/0.0.4711/
|
||||
- 0.0.0002/
|
||||
- 0.1.0000/0.1.1234/
|
||||
...
|
||||
- defunct/
|
||||
|
||||
In this example, device 0815 is accessed via subchannel 0 in subchannel set 0,
|
||||
device 4711 via subchannel 1 in subchannel set 0, and subchannel 2 is a non-I/O
|
||||
subchannel. Device 1234 is accessed via subchannel 0 in subchannel set 1.
|
||||
|
||||
The subchannel named 'defunct' does not represent any real subchannel on the
|
||||
system; it is a pseudo subchannel where disconnected ccw devices are moved to
|
||||
if they are displaced by another ccw device becoming operational on their
|
||||
former subchannel. The ccw devices will be moved again to a proper subchannel
|
||||
if they become operational again on that subchannel.
|
||||
|
||||
You should address a ccw device via its bus id (e.g. 0.0.4711); the device can
|
||||
be found under bus/ccw/devices/.
|
||||
|
||||
All ccw devices export some data via sysfs.
|
||||
|
||||
cutype: The control unit type / model.
|
||||
|
||||
devtype: The device type / model, if applicable.
|
||||
|
||||
availability: Can be 'good' or 'boxed'; 'no path' or 'no device' for
|
||||
disconnected devices.
|
||||
|
||||
online: An interface to set the device online and offline.
|
||||
In the special case of the device being disconnected (see the
|
||||
notify function under 1.2), piping 0 to online will forcibly delete
|
||||
the device.
|
||||
|
||||
The device drivers can add entries to export per-device data and interfaces.
|
||||
|
||||
There is also some data exported on a per-subchannel basis (see under
|
||||
bus/css/devices/):
|
||||
|
||||
chpids: Via which chpids the device is connected.
|
||||
|
||||
pimpampom: The path installed, path available and path operational masks.
|
||||
|
||||
There also might be additional data, for example for block devices.
|
||||
|
||||
|
||||
1.1 Bringing up a ccw device
|
||||
----------------------------
|
||||
|
||||
This is done in several steps.
|
||||
|
||||
a. Each driver can provide one or more parameter interfaces where parameters can
|
||||
be specified. These interfaces are also in the driver's responsibility.
|
||||
b. After a. has been performed, if necessary, the device is finally brought up
|
||||
via the 'online' interface.
|
||||
|
||||
|
||||
1.2 Writing a driver for ccw devices
|
||||
------------------------------------
|
||||
|
||||
The basic struct ccw_device and struct ccw_driver data structures can be found
|
||||
under include/asm/ccwdev.h.
|
||||
|
||||
struct ccw_device {
|
||||
spinlock_t *ccwlock;
|
||||
struct ccw_device_private *private;
|
||||
struct ccw_device_id id;
|
||||
|
||||
struct ccw_driver *drv;
|
||||
struct device dev;
|
||||
int online;
|
||||
|
||||
void (*handler) (struct ccw_device *dev, unsigned long intparm,
|
||||
struct irb *irb);
|
||||
};
|
||||
|
||||
struct ccw_driver {
|
||||
struct module *owner;
|
||||
struct ccw_device_id *ids;
|
||||
int (*probe) (struct ccw_device *);
|
||||
int (*remove) (struct ccw_device *);
|
||||
int (*set_online) (struct ccw_device *);
|
||||
int (*set_offline) (struct ccw_device *);
|
||||
int (*notify) (struct ccw_device *, int);
|
||||
struct device_driver driver;
|
||||
char *name;
|
||||
};
|
||||
|
||||
The 'private' field contains data needed for internal i/o operation only, and
|
||||
is not available to the device driver.
|
||||
|
||||
Each driver should declare in a MODULE_DEVICE_TABLE into which CU types/models
|
||||
and/or device types/models it is interested. This information can later be found
|
||||
in the struct ccw_device_id fields:
|
||||
|
||||
struct ccw_device_id {
|
||||
__u16 match_flags;
|
||||
|
||||
__u16 cu_type;
|
||||
__u16 dev_type;
|
||||
__u8 cu_model;
|
||||
__u8 dev_model;
|
||||
|
||||
unsigned long driver_info;
|
||||
};
|
||||
|
||||
The functions in ccw_driver should be used in the following way:
|
||||
probe: This function is called by the device layer for each device the driver
|
||||
is interested in. The driver should only allocate private structures
|
||||
to put in dev->driver_data and create attributes (if needed). Also,
|
||||
the interrupt handler (see below) should be set here.
|
||||
|
||||
int (*probe) (struct ccw_device *cdev);
|
||||
|
||||
Parameters: cdev - the device to be probed.
|
||||
|
||||
|
||||
remove: This function is called by the device layer upon removal of the driver,
|
||||
the device or the module. The driver should perform cleanups here.
|
||||
|
||||
int (*remove) (struct ccw_device *cdev);
|
||||
|
||||
Parameters: cdev - the device to be removed.
|
||||
|
||||
|
||||
set_online: This function is called by the common I/O layer when the device is
|
||||
activated via the 'online' attribute. The driver should finally
|
||||
setup and activate the device here.
|
||||
|
||||
int (*set_online) (struct ccw_device *);
|
||||
|
||||
Parameters: cdev - the device to be activated. The common layer has
|
||||
verified that the device is not already online.
|
||||
|
||||
|
||||
set_offline: This function is called by the common I/O layer when the device is
|
||||
de-activated via the 'online' attribute. The driver should shut
|
||||
down the device, but not de-allocate its private data.
|
||||
|
||||
int (*set_offline) (struct ccw_device *);
|
||||
|
||||
Parameters: cdev - the device to be deactivated. The common layer has
|
||||
verified that the device is online.
|
||||
|
||||
|
||||
notify: This function is called by the common I/O layer for some state changes
|
||||
of the device.
|
||||
Signalled to the driver are:
|
||||
* In online state, device detached (CIO_GONE) or last path gone
|
||||
(CIO_NO_PATH). The driver must return !0 to keep the device; for
|
||||
return code 0, the device will be deleted as usual (also when no
|
||||
notify function is registered). If the driver wants to keep the
|
||||
device, it is moved into disconnected state.
|
||||
* In disconnected state, device operational again (CIO_OPER). The
|
||||
common I/O layer performs some sanity checks on device number and
|
||||
Device / CU to be reasonably sure if it is still the same device.
|
||||
If not, the old device is removed and a new one registered. By the
|
||||
return code of the notify function the device driver signals if it
|
||||
wants the device back: !0 for keeping, 0 to make the device being
|
||||
removed and re-registered.
|
||||
|
||||
int (*notify) (struct ccw_device *, int);
|
||||
|
||||
Parameters: cdev - the device whose state changed.
|
||||
event - the event that happened. This can be one of CIO_GONE,
|
||||
CIO_NO_PATH or CIO_OPER.
|
||||
|
||||
The handler field of the struct ccw_device is meant to be set to the interrupt
|
||||
handler for the device. In order to accommodate drivers which use several
|
||||
distinct handlers (e.g. multi subchannel devices), this is a member of ccw_device
|
||||
instead of ccw_driver.
|
||||
The handler is registered with the common layer during set_online() processing
|
||||
before the driver is called, and is deregistered during set_offline() after the
|
||||
driver has been called. Also, after registering / before deregistering, path
|
||||
grouping resp. disbanding of the path group (if applicable) are performed.
|
||||
|
||||
void (*handler) (struct ccw_device *dev, unsigned long intparm, struct irb *irb);
|
||||
|
||||
Parameters: dev - the device the handler is called for
|
||||
intparm - the intparm which allows the device driver to identify
|
||||
the i/o the interrupt is associated with, or to recognize
|
||||
the interrupt as unsolicited.
|
||||
irb - interruption response block which contains the accumulated
|
||||
status.
|
||||
|
||||
The device driver is called from the common ccw_device layer and can retrieve
|
||||
information about the interrupt from the irb parameter.
|
||||
|
||||
|
||||
1.3 ccwgroup devices
|
||||
--------------------
|
||||
|
||||
The ccwgroup mechanism is designed to handle devices consisting of multiple ccw
|
||||
devices, like lcs or ctc.
|
||||
|
||||
The ccw driver provides a 'group' attribute. Piping bus ids of ccw devices to
|
||||
this attributes creates a ccwgroup device consisting of these ccw devices (if
|
||||
possible). This ccwgroup device can be set online or offline just like a normal
|
||||
ccw device.
|
||||
|
||||
Each ccwgroup device also provides an 'ungroup' attribute to destroy the device
|
||||
again (only when offline). This is a generic ccwgroup mechanism (the driver does
|
||||
not need to implement anything beyond normal removal routines).
|
||||
|
||||
A ccw device which is a member of a ccwgroup device carries a pointer to the
|
||||
ccwgroup device in the driver_data of its device struct. This field must not be
|
||||
touched by the driver - it should use the ccwgroup device's driver_data for its
|
||||
private data.
|
||||
|
||||
To implement a ccwgroup driver, please refer to include/asm/ccwgroup.h. Keep in
|
||||
mind that most drivers will need to implement both a ccwgroup and a ccw
|
||||
driver.
|
||||
|
||||
|
||||
2. Channel paths
|
||||
-----------------
|
||||
|
||||
Channel paths show up, like subchannels, under the channel subsystem root (css0)
|
||||
and are called 'chp0.<chpid>'. They have no driver and do not belong to any bus.
|
||||
Please note, that unlike /proc/chpids in 2.4, the channel path objects reflect
|
||||
only the logical state and not the physical state, since we cannot track the
|
||||
latter consistently due to lacking machine support (we don't need to be aware
|
||||
of it anyway).
|
||||
|
||||
status - Can be 'online' or 'offline'.
|
||||
Piping 'on' or 'off' sets the chpid logically online/offline.
|
||||
Piping 'on' to an online chpid triggers path reprobing for all devices
|
||||
the chpid connects to. This can be used to force the kernel to re-use
|
||||
a channel path the user knows to be online, but the machine hasn't
|
||||
created a machine check for.
|
||||
|
||||
type - The physical type of the channel path.
|
||||
|
||||
shared - Whether the channel path is shared.
|
||||
|
||||
cmg - The channel measurement group.
|
||||
|
||||
3. System devices
|
||||
-----------------
|
||||
|
||||
3.1 xpram
|
||||
---------
|
||||
|
||||
xpram shows up under devices/system/ as 'xpram'.
|
||||
|
||||
3.2 cpus
|
||||
--------
|
||||
|
||||
For each cpu, a directory is created under devices/system/cpu/. Each cpu has an
|
||||
attribute 'online' which can be 0 or 1.
|
||||
|
||||
|
||||
4. Other devices
|
||||
----------------
|
||||
|
||||
4.1 Netiucv
|
||||
-----------
|
||||
|
||||
The netiucv driver creates an attribute 'connection' under
|
||||
bus/iucv/drivers/netiucv. Piping to this attribute creates a new netiucv
|
||||
connection to the specified host.
|
||||
|
||||
Netiucv connections show up under devices/iucv/ as "netiucv<ifnum>". The interface
|
||||
number is assigned sequentially to the connections defined via the 'connection'
|
||||
attribute.
|
||||
|
||||
user - shows the connection partner.
|
||||
|
||||
buffer - maximum buffer size.
|
||||
Pipe to it to change buffer size.
|
||||
|
||||
|
||||
Loading…
Add table
Add a link
Reference in a new issue