|GLD(9F)||Kernel Functions for Drivers||GLD(9F)|
#include <sys/gld.h> gld_mac_info_t *gld_mac_alloc(dev_info_t *dip);
void gld_mac_free(gld_mac_info_t *macinfo);
int gld_register(dev_info_t *dip, char *name, gld_mac_info_t *macinfo);
int gld_unregister(gld_mac_info_t *macinfo);
void gld_recv(gld_mac_info_t *macinfo, mblk_t *mp);
void gld_sched(gld_mac_info_t *macinfo);
void gld_linkstate(gld_mac_info_t *macinfo, int32_t newstate);
gld_mac_free() frees a gld_mac_info(9S) structure previously allocated by gld_mac_alloc().
gld_register() is called from the device driver's attach(9E) routine, and is used to link the GLD-based device driver with the GLD framework. Before calling gld_register() the device driver's attach(9E) routine must first use gld_mac_alloc() to allocate a gld_mac_info(9S) structure, and initialize several of its structure elements. See gld_mac_info(9S) for more information. A successful call to gld_register() performs the following actions:
The device interface name passed to gld_register() must exactly match the name of the driver module as it exists in the filesystem.
The driver's attach(9E) routine should return DDI_SUCCESS if gld_register() succeeds. If gld_register() returns DDI_FAILURE, the attach(9E) routine should deallocate any resources it allocated before calling gld_register() and then also return DDI_FAILURE.
gld_unregister() is called by the device driver's detach(9E) function, and if successful, performs the following tasks:
If gld_unregister() returns DDI_SUCCESS, the detach(9E) routine should deallocate any data structures allocated in the attach(9E) routine, using gld_mac_free() to deallocate the macinfo structure, and return DDI_SUCCESS. If gld_unregister() returns DDI_FAILURE, the driver's detach(9E) routine must leave the device operational and return DDI_FAILURE.
gld_recv() is called by the driver's interrupt handler to pass a received packet upstream. The driver must construct and pass a STREAMS M_DATA message containing the raw packet. gld_recv() determines which STREAMS queues, if any, should receive a copy of the packet, duplicating it if necessary. It then formats a DL_UNITDATA_IND message, if required, and passes the data up all appropriate streams.
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.
gld_sched() is called by the device driver to reschedule stalled outbound packets. Whenever the driver's gldm_send() routine has returned GLD_NORESOURCES, the driver must later call gld_sched() to inform the GLD framework that it should retry the packets that previously could not be sent. gld_sched() should be called as soon as possible after resources are again available, to ensure that GLD resumes passing outbound packets to the driver's gldm_send() routine in a timely way. (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.)
gld_intr() is GLD's main interrupt handler. Normally it is specified as the interrupt routine in the device driver's call to ddi_add_intr(9F). The argument to the interrupt handler (specified as int_handler_arg in the call to ddi_add_intr(9F)) must be a pointer to the gld_mac_info(9S) structure. gld_intr() will, when appropriate, call the device driver's gldm_intr() function, passing that pointer to the gld_mac_info(9S) structure. However, if the driver uses a high-level interrupt, it must provide its own high-level interrupt handler, and trigger a soft interrupt from within that. In this case, gld_intr() may be specified as the soft interrupt handler in the call to ddi_add_softintr().
gld_linkstate() is called by the device driver to notify GLD of changes in the media link state. The newstate argument should be set to one of the following:
If a driver calls gld_linkstate(), it must also set the GLD_CAP_LINKSTATE bit in the gldm_capabilities field of the gld_mac_info(9S) structure.
gld_register() and gld_unregister() return:
gld_intr() returns a value appropriate for an interrupt handler.
Writing Device Drivers
|February 15, 2020|