DEVMAP_DO_CTXMGT(9F) | Kernel Functions for Drivers | DEVMAP_DO_CTXMGT(9F) |
#include <sys/ddi.h> #include <sys/sunddi.h> int devmap_do_ctxmgt(devmap_cookie_t dhp, void *pvtp, offset_t off, size_t len, uint_t type, uint_t rw, int (*devmap_contextmgt)devmap_cookie_t, void *, offset_t, size_t, uint_t, uint_t);
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devmap_do_ctxmgt() performs context switching on the mapping object identified by dhp and pvtp in the range specified by off and len. The arguments dhp, pvtp, type, and rw are provided by the devmap_access(9E) entry point and must not be modified. The range from off to off+len must support context switching.
The system will pass through dhp, pvtp, off, len, type, and rw to devmap_contextmgt(9E) in order to perform the actual device context switching. The return value from devmap_contextmgt(9E) will be returned directly to devmap_do_ctxmgt().
Non-zero
The following shows an example of using devmap_do_ctxmgt() in the devmap_access(9E) entry point.
... #define OFF_DO_CTXMGT 0x40000000 #define OFF_NORMAL 0x40100000 #define CTXMGT_SIZE 0x100000 #define NORMAL_SIZE 0x100000 /* * Driver devmap_contextmgt(9E) callback function. */ static int xx_context_mgt(devmap_cookie_t dhp, void *pvtp, offset_t offset, size_t length, uint_t type, uint_t rw) { ...... /* * see devmap_contextmgt(9E) for an example */ } /* * Driver devmap_access(9E) entry point */ static int xxdevmap_access(devmap_cookie_t dhp, void *pvtp, offset_t off, size_t len, uint_t type, uint_t rw) { offset_t diff; int err; /* * check if off is within the range that supports * context management. */ if ((diff = off - OFF_DO_CTXMG) >= 0 && diff < CTXMGT_SIZE) { /* * calculates the length for context switching */ if ((len + off) > (OFF_DO_CTXMGT + CTXMGT_SIZE)) return (-1); /* * perform context switching */ err = devmap_do_ctxmgt(dhp, pvtp, off, len, type, rw, xx_context_mgt); /* * check if off is within the range that does normal * memory mapping. */ } else if ((diff = off - OFF_NORMAL) >= 0 && diff < NORMAL_SIZE) { if ((len + off) > (OFF_NORMAL + NORMAL_SIZE)) return (-1); err = devmap_default_access(dhp, pvtp, off, len, type, rw); } else return (-1); return (err); }
Writing Device Drivers
January 22, 1997 | OmniOS |