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 This document groups random notes about porting EISA drivers to the
new EISA/sysfs API. new EISA/sysfs API.
...@@ -14,168 +18,189 @@ detection code is generally also used to probe ISA cards). Moreover, ...@@ -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 most EISA drivers are among the oldest Linux drivers so, as you can
imagine, some dust has settled here over the years. 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 - The bus code implements most of the generic code. It is shared
among all the architectures that the EISA code runs on. It among all the architectures that the EISA code runs on. It
implements bus probing (detecting EISA cards available on the bus), implements bus probing (detecting EISA cards available on the bus),
allocates I/O resources, allows fancy naming through sysfs, and allocates I/O resources, allows fancy naming through sysfs, and
offers interfaces for driver to register. offers interfaces for driver to register.
- The bus root driver implements the glue between the bus hardware - The bus root driver implements the glue between the bus hardware
and the generic bus code. It is responsible for discovering the and the generic bus code. It is responsible for discovering the
device implementing the bus, and setting it up to be latter probed 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 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 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 EISA code. This is the part to implement in order to have EISA
running on an "new" platform. running on an "new" platform.
- The driver offers the bus a list of devices that it manages, and - The driver offers the bus a list of devices that it manages, and
implements the necessary callbacks to probe and release devices implements the necessary callbacks to probe and release devices
whenever told to. whenever told to.
Every function/structure below lives in <linux/eisa.h>, which depends Every function/structure below lives in <linux/eisa.h>, which depends
heavily on <linux/device.h>. 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 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 root of an EISA bus. The eisa_root_device structure holds a reference
to this device, as well as some parameters for probing purposes. to this device, as well as some parameters for probing purposes::
struct eisa_root_device { struct eisa_root_device {
struct device *dev; /* Pointer to bridge device */ struct device *dev; /* Pointer to bridge device */
struct resource *res; struct resource *res;
unsigned long bus_base_addr; unsigned long bus_base_addr;
int slots; /* Max slot number */ int slots; /* Max slot number */
int force_probe; /* Probe even when no slot 0 */ int force_probe; /* Probe even when no slot 0 */
u64 dma_mask; /* from bridge device */ u64 dma_mask; /* from bridge device */
int bus_nr; /* Set by eisa_root_register */ int bus_nr; /* Set by eisa_root_register */
struct resource eisa_root_res; /* ditto */ struct resource eisa_root_res; /* ditto */
}; };
node : used for eisa_root_register internal purpose ============= ======================================================
dev : pointer to the root device node used for eisa_root_register internal purpose
res : root device I/O resource dev pointer to the root device
bus_base_addr : slot 0 address on this bus res root device I/O resource
slots : max slot number to probe bus_base_addr slot 0 address on this bus
force_probe : Probe even when slot 0 is empty (no EISA mainboard) slots max slot number to probe
dma_mask : Default DMA mask. Usually the bridge device dma_mask. force_probe Probe even when slot 0 is empty (no EISA mainboard)
bus_nr : unique bus id, set by eisa_root_register 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); Driver
void eisa_driver_unregister (struct eisa_driver *edrv); ======
::
int eisa_driver_register (struct eisa_driver *edrv);
void eisa_driver_unregister (struct eisa_driver *edrv);
Clear enough ? Clear enough ?
struct eisa_device_id { ::
char sig[EISA_SIG_LEN];
unsigned long driver_data; 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; 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). id_table an array of NULL terminated EISA id strings,
followed by an empty string. Each string can
driver : a generic driver, such as described in optionally be paired with a driver-dependent value
Documentation/driver-model/driver.txt. Only .name, (driver_data).
.probe and .remove members are mandatory.
driver a generic driver, such as described in
An example is the 3c59x driver : Documentation/driver-model/driver.txt. Only .name,
.probe and .remove members are mandatory.
static struct eisa_device_id vortex_eisa_ids[] = { =============== ====================================================
{ "TCM5920", EISA_3C592_OFFSET },
{ "TCM5970", EISA_3C597_OFFSET }, An example is the 3c59x driver::
{ "" }
}; static struct eisa_device_id vortex_eisa_ids[] = {
{ "TCM5920", EISA_3C592_OFFSET },
static struct eisa_driver vortex_eisa_driver = { { "TCM5970", EISA_3C597_OFFSET },
.id_table = vortex_eisa_ids, { "" }
.driver = { };
.name = "3c59x",
.probe = vortex_eisa_probe, static struct eisa_driver vortex_eisa_driver = {
.remove = vortex_eisa_remove .id_table = vortex_eisa_ids,
} .driver = {
}; .name = "3c59x",
.probe = vortex_eisa_probe,
** Device : .remove = vortex_eisa_remove
}
};
Device
======
The sysfs framework calls .probe and .remove functions upon device The sysfs framework calls .probe and .remove functions upon device
discovery and removal (note that the .remove function is only called discovery and removal (note that the .remove function is only called
when driver is built as a module). when driver is built as a module).
Both functions are passed a pointer to a 'struct device', which is Both functions are passed a pointer to a 'struct device', which is
encapsulated in a 'struct eisa_device' described as follows : encapsulated in a 'struct eisa_device' described as follows::
struct eisa_device { struct eisa_device {
struct eisa_device_id id; struct eisa_device_id id;
int slot; int slot;
int state; int state;
unsigned long base_addr; unsigned long base_addr;
struct resource res[EISA_MAX_RESOURCES]; struct resource res[EISA_MAX_RESOURCES];
u64 dma_mask; u64 dma_mask;
struct device dev; /* generic device */ struct device dev; /* generic device */
}; };
id : EISA id, as read from device. id.driver_data is set from the ======== ============================================================
matching driver EISA id. id EISA id, as read from device. id.driver_data is set from the
slot : slot number which the device was detected on matching driver EISA id.
state : set of flags indicating the state of the device. Current slot slot number which the device was detected on
flags are EISA_CONFIG_ENABLED and EISA_CONFIG_FORCED. state set of flags indicating the state of the device. Current
res : set of four 256 bytes I/O regions allocated to this device flags are EISA_CONFIG_ENABLED and EISA_CONFIG_FORCED.
dma_mask: DMA mask set from the parent device. res set of four 256 bytes I/O regions allocated to this device
dev : generic device (see Documentation/driver-model/device.txt) 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 You can get the 'struct eisa_device' from 'struct device' using the
'to_eisa_device' macro. '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. 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. 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 Returns the region number (0 <= x < EISA_MAX_RESOURCES) of a given
address. 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 eisa_bus.disable_dev
set the card as disabled. The driver must be able to properly A comma-separated list of slots to be enabled, even if the firmware
initialize the device in such conditions. 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 Random notes
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 :
Converting an EISA driver to the new API mostly involves *deleting* Converting an EISA driver to the new API mostly involves *deleting*
code (since probing is now in the core EISA code). Unfortunately, most code (since probing is now in the core EISA code). Unfortunately, most
...@@ -194,9 +219,11 @@ routine. ...@@ -194,9 +219,11 @@ routine.
For example, switching your favorite EISA SCSI card to the "hotplug" For example, switching your favorite EISA SCSI card to the "hotplug"
model is "the right thing"(tm). 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, - Xavier Benigni for lending me a wonderful Alpha Jensen,
- James Bottomley, Jeff Garzik for getting this stuff into the kernel, - James Bottomley, Jeff Garzik for getting this stuff into the kernel,
- Andries Brouwer for contributing numerous EISA ids, - Andries Brouwer for contributing numerous EISA ids,
......
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