Commit 72fd15c0 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet

eisa.txt: standardize document format

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- use ReST notation for titles;
- identify literal blocks;
- use :Author: for document authorship;
- use the proper notation for tables;
- adjust whitespaces where needed.
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent ef16bcc7
EISA bus support (Marc Zyngier <maz@wild-wind.fr.eu.org>)
================
EISA bus support
================
:Author: Marc Zyngier <maz@wild-wind.fr.eu.org>
This document groups random notes about porting EISA drivers to the
new EISA/sysfs API.
......@@ -14,168 +18,189 @@ detection code is generally also used to probe ISA cards). Moreover,
most EISA drivers are among the oldest Linux drivers so, as you can
imagine, some dust has settled here over the years.
The EISA infrastructure is made up of three parts :
The EISA infrastructure is made up of three parts:
- The bus code implements most of the generic code. It is shared
among all the architectures that the EISA code runs on. It
implements bus probing (detecting EISA cards available on the bus),
allocates I/O resources, allows fancy naming through sysfs, and
offers interfaces for driver to register.
among all the architectures that the EISA code runs on. It
implements bus probing (detecting EISA cards available on the bus),
allocates I/O resources, allows fancy naming through sysfs, and
offers interfaces for driver to register.
- The bus root driver implements the glue between the bus hardware
and the generic bus code. It is responsible for discovering the
device implementing the bus, and setting it up to be latter probed
by the bus code. This can go from something as simple as reserving
an I/O region on x86, to the rather more complex, like the hppa
EISA code. This is the part to implement in order to have EISA
running on an "new" platform.
and the generic bus code. It is responsible for discovering the
device implementing the bus, and setting it up to be latter probed
by the bus code. This can go from something as simple as reserving
an I/O region on x86, to the rather more complex, like the hppa
EISA code. This is the part to implement in order to have EISA
running on an "new" platform.
- The driver offers the bus a list of devices that it manages, and
implements the necessary callbacks to probe and release devices
whenever told to.
implements the necessary callbacks to probe and release devices
whenever told to.
Every function/structure below lives in <linux/eisa.h>, which depends
heavily on <linux/device.h>.
** Bus root driver :
Bus root driver
===============
::
int eisa_root_register (struct eisa_root_device *root);
int eisa_root_register (struct eisa_root_device *root);
The eisa_root_register function is used to declare a device as the
root of an EISA bus. The eisa_root_device structure holds a reference
to this device, as well as some parameters for probing purposes.
struct eisa_root_device {
struct device *dev; /* Pointer to bridge device */
struct resource *res;
unsigned long bus_base_addr;
int slots; /* Max slot number */
int force_probe; /* Probe even when no slot 0 */
u64 dma_mask; /* from bridge device */
int bus_nr; /* Set by eisa_root_register */
struct resource eisa_root_res; /* ditto */
};
node : used for eisa_root_register internal purpose
dev : pointer to the root device
res : root device I/O resource
bus_base_addr : slot 0 address on this bus
slots : max slot number to probe
force_probe : Probe even when slot 0 is empty (no EISA mainboard)
dma_mask : Default DMA mask. Usually the bridge device dma_mask.
bus_nr : unique bus id, set by eisa_root_register
** Driver :
int eisa_driver_register (struct eisa_driver *edrv);
void eisa_driver_unregister (struct eisa_driver *edrv);
to this device, as well as some parameters for probing purposes::
struct eisa_root_device {
struct device *dev; /* Pointer to bridge device */
struct resource *res;
unsigned long bus_base_addr;
int slots; /* Max slot number */
int force_probe; /* Probe even when no slot 0 */
u64 dma_mask; /* from bridge device */
int bus_nr; /* Set by eisa_root_register */
struct resource eisa_root_res; /* ditto */
};
============= ======================================================
node used for eisa_root_register internal purpose
dev pointer to the root device
res root device I/O resource
bus_base_addr slot 0 address on this bus
slots max slot number to probe
force_probe Probe even when slot 0 is empty (no EISA mainboard)
dma_mask Default DMA mask. Usually the bridge device dma_mask.
bus_nr unique bus id, set by eisa_root_register
============= ======================================================
Driver
======
::
int eisa_driver_register (struct eisa_driver *edrv);
void eisa_driver_unregister (struct eisa_driver *edrv);
Clear enough ?
struct eisa_device_id {
char sig[EISA_SIG_LEN];
unsigned long driver_data;
};
struct eisa_driver {
const struct eisa_device_id *id_table;
struct device_driver driver;
};
id_table : an array of NULL terminated EISA id strings,
followed by an empty string. Each string can
optionally be paired with a driver-dependent value
(driver_data).
driver : a generic driver, such as described in
Documentation/driver-model/driver.txt. Only .name,
.probe and .remove members are mandatory.
An example is the 3c59x driver :
static struct eisa_device_id vortex_eisa_ids[] = {
{ "TCM5920", EISA_3C592_OFFSET },
{ "TCM5970", EISA_3C597_OFFSET },
{ "" }
};
static struct eisa_driver vortex_eisa_driver = {
.id_table = vortex_eisa_ids,
.driver = {
.name = "3c59x",
.probe = vortex_eisa_probe,
.remove = vortex_eisa_remove
}
};
** Device :
::
struct eisa_device_id {
char sig[EISA_SIG_LEN];
unsigned long driver_data;
};
struct eisa_driver {
const struct eisa_device_id *id_table;
struct device_driver driver;
};
=============== ====================================================
id_table an array of NULL terminated EISA id strings,
followed by an empty string. Each string can
optionally be paired with a driver-dependent value
(driver_data).
driver a generic driver, such as described in
Documentation/driver-model/driver.txt. Only .name,
.probe and .remove members are mandatory.
=============== ====================================================
An example is the 3c59x driver::
static struct eisa_device_id vortex_eisa_ids[] = {
{ "TCM5920", EISA_3C592_OFFSET },
{ "TCM5970", EISA_3C597_OFFSET },
{ "" }
};
static struct eisa_driver vortex_eisa_driver = {
.id_table = vortex_eisa_ids,
.driver = {
.name = "3c59x",
.probe = vortex_eisa_probe,
.remove = vortex_eisa_remove
}
};
Device
======
The sysfs framework calls .probe and .remove functions upon device
discovery and removal (note that the .remove function is only called
when driver is built as a module).
Both functions are passed a pointer to a 'struct device', which is
encapsulated in a 'struct eisa_device' described as follows :
struct eisa_device {
struct eisa_device_id id;
int slot;
int state;
unsigned long base_addr;
struct resource res[EISA_MAX_RESOURCES];
u64 dma_mask;
struct device dev; /* generic device */
};
id : EISA id, as read from device. id.driver_data is set from the
matching driver EISA id.
slot : slot number which the device was detected on
state : set of flags indicating the state of the device. Current
flags are EISA_CONFIG_ENABLED and EISA_CONFIG_FORCED.
res : set of four 256 bytes I/O regions allocated to this device
dma_mask: DMA mask set from the parent device.
dev : generic device (see Documentation/driver-model/device.txt)
encapsulated in a 'struct eisa_device' described as follows::
struct eisa_device {
struct eisa_device_id id;
int slot;
int state;
unsigned long base_addr;
struct resource res[EISA_MAX_RESOURCES];
u64 dma_mask;
struct device dev; /* generic device */
};
======== ============================================================
id EISA id, as read from device. id.driver_data is set from the
matching driver EISA id.
slot slot number which the device was detected on
state set of flags indicating the state of the device. Current
flags are EISA_CONFIG_ENABLED and EISA_CONFIG_FORCED.
res set of four 256 bytes I/O regions allocated to this device
dma_mask DMA mask set from the parent device.
dev generic device (see Documentation/driver-model/device.txt)
======== ============================================================
You can get the 'struct eisa_device' from 'struct device' using the
'to_eisa_device' macro.
** Misc stuff :
Misc stuff
==========
::
void eisa_set_drvdata (struct eisa_device *edev, void *data);
void eisa_set_drvdata (struct eisa_device *edev, void *data);
Stores data into the device's driver_data area.
void *eisa_get_drvdata (struct eisa_device *edev):
::
void *eisa_get_drvdata (struct eisa_device *edev):
Gets the pointer previously stored into the device's driver_data area.
int eisa_get_region_index (void *addr);
::
int eisa_get_region_index (void *addr);
Returns the region number (0 <= x < EISA_MAX_RESOURCES) of a given
address.
** Kernel parameters :
Kernel parameters
=================
eisa_bus.enable_dev :
eisa_bus.enable_dev
A comma-separated list of slots to be enabled, even if the firmware
set the card as disabled. The driver must be able to properly
initialize the device in such conditions.
A comma-separated list of slots to be enabled, even if the firmware
set the card as disabled. The driver must be able to properly
initialize the device in such conditions.
eisa_bus.disable_dev
A comma-separated list of slots to be enabled, even if the firmware
set the card as enabled. The driver won't be called to handle this
device.
eisa_bus.disable_dev :
virtual_root.force_probe
Force the probing code to probe EISA slots even when it cannot find an
EISA compliant mainboard (nothing appears on slot 0). Defaults to 0
(don't force), and set to 1 (force probing) when either
CONFIG_ALPHA_JENSEN or CONFIG_EISA_VLB_PRIMING are set.
A comma-separated list of slots to be enabled, even if the firmware
set the card as enabled. The driver won't be called to handle this
device.
virtual_root.force_probe :
Force the probing code to probe EISA slots even when it cannot find an
EISA compliant mainboard (nothing appears on slot 0). Defaults to 0
(don't force), and set to 1 (force probing) when either
CONFIG_ALPHA_JENSEN or CONFIG_EISA_VLB_PRIMING are set.
** Random notes :
Random notes
============
Converting an EISA driver to the new API mostly involves *deleting*
code (since probing is now in the core EISA code). Unfortunately, most
......@@ -194,9 +219,11 @@ routine.
For example, switching your favorite EISA SCSI card to the "hotplug"
model is "the right thing"(tm).
** Thanks :
Thanks
======
I'd like to thank the following people for their help:
I'd like to thank the following people for their help :
- Xavier Benigni for lending me a wonderful Alpha Jensen,
- James Bottomley, Jeff Garzik for getting this stuff into the kernel,
- Andries Brouwer for contributing numerous EISA ids,
......
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