gld(9E)
NAME
gld, gldm_reset, gldm_start, gldm_stop, gldm_set_mac_addr,
gldm_set_multicast, gldm_set_promiscuous, gldm_send,
gldm_intr, gldm_get_stats, gldm_ioctl - Generic LAN Driver
entry points
SYNOPSIS
#include <sys/gld.h>
int prefix_reset(gld_mac_info_t *macinfo);
int prefix_start(gld_mac_info_t *macinfo);
int prefix_stop(gld_mac_info_t *macinfo);
int prefix_set_mac_addr(gld_mac_info_t *macinfo, unsigned
char *macaddr);
int prefix_set_multicast(gld_mac_info_t *macinfo, unsigned
char *multicastaddr, int multiflag);
int prefix_set_promiscuous(gld_mac_info_t *macinfo, int
promiscflag);
int prefix_send(gld_mac_info_t *macinfo, mblk_t *mp);
uint_t prefix_intr(gld_mac_info_t *macinfo);
int prefix_get_stats(gld_mac_info_t *macinfo, struct
gld_stats *stats);
int prefix_ioctl(gld_mac_info_t *macinfo, queue_t *q, mblk_t
*mp);
INTERFACE LEVEL
Solaris architecture specific (Solaris DDI).
PARAMETERS
macinfo
Pointer to a gld_mac_info(9S) structure.
macaddr
Pointer to the beginning of a character array contain-
ing a valid MAC address. The array will be of the
length specified by the driver in the gldm_addrlen
element of the gld_mac_info(9S) structure.
multicastaddr
Pointer to the beginning of a character array contain-
ing a multicast, group, or functional address. The
array will be of the length specified by the driver in
the gldm_addrlen element of the gld_mac_info(9S)
structure.
multiflag
A flag indicating whether reception of the multicast
address is to be enabled or disabled. This argument is
specified as GLD_MULTI_ENABLE or GLD_MULTI_DISABLE.
promiscflag
A flag indicating what type of promiscuous mode, if
any, is to be enabled. This argument is specified as
GLD_MAC_PROMISC_PHYS, GLD_MAC_PROMISC_MULTI, or
GLD_MAC_PROMISC_NONE.
mp Pointer to a STREAMS message block containing the
packet to be transmitted or the ioctl to be executed.
stats Pointer to a gld_stats(9S) structure to be filled in
with the current values of statistics counters.
q Pointer to the queue(9S) structure to be used in the
reply to the ioctl.
DESCRIPTION
These entry points must be implemented by a device-specific
network driver designed to interface with the Generic LAN
Driver (GLD).
As described in gld(7D), the main data structure for commun-
ication between the device-specific driver and the GLD
module is the gld_mac_info(9S) structure. Some of the ele-
ments in that structure are function pointers to the entry
points described here. The device-specific driver must, in
its attach(9E) routine, initialize these function pointers
before calling gld_register().
gldm_reset() resets the hardware to its initial state.
gldm_start() enables the device to generate interrupts and
prepares the driver to call gld_recv() for delivering
received data packets to GLD.
gldm_stop() disables the device from generating any inter-
rupts and stops the driver from calling gld_recv() for
delivering data packets to GLD. GLD depends on the
gldm_stop() routine to ensure that the device will no longer
interrupt, and it must do so without fail.
gldm_set_mac_addr() sets the physical address that the
hardware is to use for receiving data. This function should
program the device to the passed MAC address macaddr.
gldm_set_multicast() enables and disables device-level
reception of specific multicast addresses. If the third
argument multiflag is set to GLD_MULTI_ENABLE, then the
function sets the interface to receive packets with the mul-
ticast address pointed to by the second argument; if multi-
flag is set to GLD_MULTI_DISABLE, the driver is allowed to
disable reception of the specified multicast address.
This function is called whenever GLD wants to enable or dis-
able reception of a multicast, group, or functional address.
GLD makes no assumptions about how the device does multicast
support and calls this function to enable or disable a
specific multicast address. Some devices may use a hash
algorithm and a bitmask to enable collections of multicast
addresses; this is allowed, and GLD will filter out any
superfluous packets that are not required. If disabling an
address could result in disabling more than one address at
the device level, it is the responsibility of the device
driver to keep whatever information it needs to avoid disa-
bling an address that GLD has enabled but not disabled.
gldm_set_multicast() will not be called to enable a particu-
lar multicast address that is already enabled, nor to dis-
able an address that is not currently enabled. GLD keeps
track of multiple requests for the same multicast address
and only calls the driver's entry point when the first
request to enable, or the last request to disable a particu-
lar multicast address is made.
gldm_set_promiscuous() enables and disables promiscuous
mode. This function is called whenever GLD wants to enable
or disable the reception of all packets on the medium, or
all multicast packets on the medium. If the second argument
promiscflag is set to the value of GLD_MAC_PROMISC_PHYS,
then the function enables physical-level promiscuous mode,
resulting in the reception of all packets on the medium. If
promiscflag is set to GLD_MAC_PROMISC_MULTI, then reception
of all multicast packets will be enabled. If promiscflag is
set to GLD_MAC_PROMISC_NONE, then promiscuous mode is dis-
abled.
In the case of a request for promiscuous multicast mode,
drivers for devices that have no multicast-only promiscuous
mode must set the device to physical promiscuous mode to
ensure that all multicast packets are received. In this case
the routine should return GLD_SUCCESS. The GLD software will
filter out any superfluous packets that are not required.
For forward compatibility, gldm_set_promiscuous() routines
should treat any unrecognized values for promiscflag as
though they were GLD_MAC_PROMISC_PHYS.
gldm_send() queues a packet to the device for transmission.
This routine is passed a STREAMS message containing the
packet to be sent. The message may comprise multiple mes-
sage blocks, and the send routine must chain through all the
message blocks in the message to access the entire packet to
be sent. The driver should be prepared to handle and skip
over any zero-length message continuation blocks in the
chain. The driver should check to ensure that the packet
does not exceed the maximum allowable packet size, and must
pad the packet, if necessary, to the minimum allowable
packet size. If the send routine successfully transmits or
queues the packet, it should return GLD_SUCCESS.
The send routine should return GLD_NORESOURCES if it cannot
immediately accept the packet for transmission; in this case
GLD will retry it later. If gldm_send() ever returns
GLD_NORESOURCES, the driver must, at a later time when
resources have become available, call gld_sched() to inform
GLD that it should retry packets that the driver previously
failed to queue for transmission. (If the driver's
gldm_stop() routine is called, the driver is absolved from
this obligation until it later again returns GLD_NORESOURCES
from its gldm_send() routine; however, extra calls to
gld_sched() will not cause incorrect operation.)
If the driver's send routine returns GLD_SUCCESS, then the
driver is responsible for freeing the message when the
driver and the hardware no longer need it. If the send rou-
tine copied the message into the device, or into a private
buffer, then the send routine may free the message after the
copy is made. If the hardware uses DMA to read the data
directly out of the message data blocks, then the driver
must not free the message until the hardware has completed
reading the data. In this case the driver will probably free
the message in the interrupt routine, or in a buffer-reclaim
operation at the beginning of a future send operation. If
the send routine returns anything other than GLD_SUCCESS,
then the driver must not free the message.
gldm_intr() is called when the device might have inter-
rupted. Since it is possible to share interrupts with other
devices, the driver must check the device status to deter-
mine whether it actually caused an interrupt. If the device
that the driver controls did not cause the interrupt, then
this routine must return DDI_INTR_UNCLAIMED. Otherwise it
must service the interrupt and should return
DDI_INTR_CLAIMED. If the interrupt was caused by successful
receipt of a packet, this routine should put the received
packet into a STREAMS message of type M_DATA and pass that
message to gld_recv().
gld_recv() will pass the inbound packet upstream to the
appropriate next layer of the network protocol stack. It is
important to correctly set the b_rptr and b_wptr members of
the STREAMS message before calling gld_recv().
The driver should avoid holding mutex or other locks during
the call to gld_recv(). In particular, locks that could be
taken by a transmit thread may not be held during a call to
gld_recv(): the interrupt thread that calls gld_recv() may
in some cases carry out processing that includes sending an
outgoing packet, resulting in a call to the driver's
gldm_send() routine. If the gldm_send() routine were to try
to acquire a mutex being held by the gldm_intr() routine at
the time it calls gld_recv(), this could result in a panic
due to recursive mutex entry.
The interrupt code should increment statistics counters for
any errors. This includes failure to allocate a buffer
needed for the received data and any hardware-specific
errors such as CRC errors or framing errors.
gldm_get_stats() gathers statistics from the hardware and/or
driver private counters, and updates the gld_stats(9S)
structure pointed to by stats. This routine is called by GLD
when it gets a request for statistics, and provides the
mechanism by which GLD acquires device dependent statistics
from the driver before composing its reply to the statistics
request. See gld_stats(9S) and gld(7D) for a description of
the defined statistics counters.
gldm_ioctl() implements any device-specific ioctl commands.
This element may be specified as NULL if the driver does not
implement any ioctl functions. The driver is responsible for
converting the message block into an ioctl reply message and
calling the qreply(9F) function before returning
GLD_SUCCESS. This function should always return GLD_SUCCESS;
any errors the driver may wish to report should be returned
via the message passed to qreply(9F). If the gldm_ioctl ele-
ment is specified as NULL, GLD will return a message of type
M_IOCNAK with an error of EINVAL.
RETURN VALUES
gldm_intr() must return:
DDI_INTR_CLAIMED
if and only if the device definitely interrupted.
DDI_INTR_UNCLAIMED
if the device did not interrupt.
The other functions must return:
GLD_SUCCESS
on success. gldm_stop() and gldm_ioctl() should always
return this value.
GLD_NORESOURCES
if there are insufficient resources to carry out the
request at this time. Only gldm_set_mac_addr(),
gldm_set_multicast(), gldm_set_promiscuous(), and
gldm_send() may return this value.
GLD_NOLINK
if gldm_send() is called when there is no physical
connection to a network or link partner.
GLD_NOTSUPPORTED
if the requested function is not supported. Only
gldm_set_mac_addr(), gldm_set_multicast(), and
gldm_set_promiscuous() may return this value.
GLD_BADARG
if the function detected an unsuitable argument, for
example, a bad multicast address, a bad MAC address,
or a bad packet or packet length.
GLD_FAILURE
on hardware failure.
SEE ALSO
gld(7D), gld(9F), gld_mac_info(9S), gld_stats(9S), dlpi(7P),
attach(9E), ddi_add_intr(9F)
Writing Device Drivers
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