misc questions about the device&driver arch

[M. Warner Losh]

In message: <87ab37ab0606040823k73cf27b1q787d544ce19a9687 at mail.gmail.com>
            "william wallace" <avalonwallace at gmail.com> writes:
:       now i am dealing with the pciexpress resource release and allocation
: i found it hard to distinguish between the bus_alloc_resource
: familiy(type rid and flag) and the rman_get/set_***** family(struct
: rman and resource ) ,i have heard that memory resource which alloc by
: the  bus_alloc_resource should not be refer to by rid ,
:  "  SYS_RES_MEMORY
:  Memory-access is done with the bus_space_(read,write)_(1,2,3,4)
: functions (depends on how many bytes you want to read/write).
: u_int8_t old;
: old = bus_space_read_1(sc->bst, sc->bsh, 0);
: bus_space_write_1(sc->bst, sc->bsh, 0, old); "
: is that true?

bus_alloc_resources is how you get resources from your parent device.
It will return a struct resource * that the rman* rouintes can access
the insides of (let's call it r).
	bus_space_read_1(rman_get_bustag(r), rman_get_bushandle(r), 0);
or the newer
	bus_read_1(r, 0);

: the second question ,if i do hot swap and donot release the hot remove
: card 's resource ,how can i attach it to the newly add-in card ?

You must release the resource whent he card exits the system.

: shall i do a
: pci_write_config(child, rle->rid, rle->start, 4);to pin the resource
: to the pci space ?

No.  The pci code should already handle things correctly.

: i wonder if there 's a find document for the freebsd resource topology,

There's not a centralized document outside of the source.

Warner


:                                  thank you ,sir .
: On 6/4/06, M. Warner Losh <imp at bsdimp.com> wrote:
: > In message: <87ab37ab0606040029u67edc35ende0b34e39e80bd37 at mail.gmail.com>
: >            "william wallace" <avalonwallace at gmail.com> writes:
: > : On 5/20/06, Warner Losh <imp at bsdimp.com> wrote:
: > : > From: "william wallace" <avalonwallace at gmail.com>
: > : > Subject: Re: misc questions about the device&driver arch
: > : > Date: Sat, 20 May 2006 13:39:08 +0800
: > : >
: > : > > comparing the method array of pci_pci and cardbusbridge:
: > : > > what losts in pci bridge but exist in cardbusbridge:
: > : > > 1 card interface
: > : > > 2 power interface
: > : > > 3 some functions :
: > : > >   3ain bus interface
: > : > >       (bus_driver_added,              cbb_driver_added),
: > : > >       (bus_child_detached,            cbb_child_detached),
: > : > >       (bus_child_present,             cbb_child_present),
: > : > >  3b in device interface
: > : > >       (device_detach,         cbb_detach),
: > : > > what exists in pci bridge but losts in cardbusbridge:
: > : > >  (pcib_route_interrupt,       pcib_route_interrupt),
: > : > >
: > : > > not only that ,functions r very different eventhough they realize the
: > : > > same interface function template
: > : > > wooo，so long to go to hotplug pci
: > : >
: > : > Yes.  The hardest part would be to create a pci hot swap bridge
: > : > driver.  The interface for them tend to be underdocumented.
: > : >
: > : > The bus_child_present is important for detaching.
: > : >
: > : > Also, I think that we may need to start implementing a quiess method
: > : > to tell the drivers they are about to be removed.   For hot plug PCI,
: > : > the model is that you quess the driver, the os tells you somehow it is
: > : > safe, and then you remove the card.  The details vary (some system are
: > : > all in software, while others have a complicated interlock and LEDs),
: > : > but they are similar.  Cardbus is harder in some ways because cards
: > : > leave unannounced (in fact, there's not a good way to announce a card
: > : > leaving, but there should be).
: > : >
: > : > Warner
: > : >
: > : > > On 5/20/06, Warner Losh <imp at bsdimp.com> wrote:
: > : > >
: > : > > > Busses create devices to represent hardware in the system.  The bus
: > : > > > then causes these devices to be probed and attached.  This latter
: > : > > > usage is for those cases.  As drivers are loaded these devices are
: > : > > > offered to the new (and old) drivers in the system.
: > : > > >
: > : > > > FreeBSD inherently dynamic in its device system.  The hardest part of
: > : > > > adding hotplug support is programming the bridge.  Adding new devices
: > : > > > to the tree is easy, but knowing when to add them is hard since you
: > : > > > have to write a bridge driver...
: > : > > >
: > : > > > Warner
: > : Prior to removing a card from the system, two things must occur:
: > :
: > : The device's driver must cease accessing the card.
: > :
: > : The card must cease generation transaction and interrupts.
: > :
: > : How this is accomplished is OS-specific, but the following must take place:
: > :
: > : The OS must stop issuing new requests to the device's driver or must
: > : instruct the driver to stop accepting new requests.
: > :
: > : The driver must terminate or complete all outstanding requests.
: > :
: > : The card must be disabled from generating interrupts or transactions.
: > :
: > : When the OS commands the driver to quiesce itself and its device, the
: > : OS must not expect the device to remain in the system (in other words,
: > : it could be removed and not replaced with a similar card).
: > :
: > : How to design and implement quiescing in freebsd?
: >
: > device_quiesce?  I have it in a p4 tree right now.  Specifically, it
: > hooks up to the MOD_UNLOAD with a QUIESCE flag.  The driver's
: > device_quiesce routine gets called, the driver sleeps there until it
: > knows that it is good, then returns to the caller.  Then the driver's
: > detach routine can be called.
: >
: > Warner
: >
: 
: 
: -- 
: we who r about to die,salute u!
: 
: