devmap_default_access(9f)

1devmap_default_access(9F)Kernel Functions for Driversdevmap_default_access(9F)
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NAME

6       devmap_default_access - default driver memory access function
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SYNOPSIS

9       #include <sys/ddi.h>
10       #include <sys/sunddi.h>
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13       int devmap_default_access(devmap_cookie_t dhp, void *pvtp,
14            offset_t off, size_t len, uint_t type, uint_t rw);
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INTERFACE LEVEL

18       Solaris DDI specific (Solaris DDI).
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PARAMETERS

21       dhp      An  opaque mapping handle that the system uses to describe the
22                mapping.
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25       pvtp     Driver private mapping data.
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28       off      User offset within the logical  device  memory  at  which  the
29                access begins.
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32       len      Length (in bytes) of the memory being accessed.
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35       type     Type of access operation.
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38       rw       Type of access.
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DESCRIPTION

42       devmap_default_access()  is  a  function  providing  the  semantics  of
43       devmap_access(9E). The drivers call devmap_default_access()  to  handle
44       the  mappings that do not support context switching. The drivers should
45       call devmap_do_ctxmgt(9F) for the mappings that support context manage‐
46       ment.
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49       devmap_default_access()  can either be called from devmap_access(9E) or
50       be used as the devmap_access(9E) entry point. The arguments dhp,  pvtp,
51       off,   len,  type,   and rw are provided by the devmap_access(9E) entry
52       point and must not be modified.
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RETURN VALUES

55       0           Successful completion.
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58       Non-zero    An error occurred.
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CONTEXT

62       devmap_default_access()   must   be   called    from    the    driver's
63       devmap_access(9E) entry point.
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EXAMPLES

66       Example 1 Using devmap_default_access in devmap_access.
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69       The  following shows an example of using devmap_default_access() in the
70       devmap_access(9E) entry point.
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73         ...
74         #define OFF_DO_CTXMGT  0x40000000
75         #define OFF_NORMAL     0x40100000
76         #define CTXMGT_SIZE    0x100000
77         #define NORMAL_SIZE    0x100000
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79         /*
80          * Driver devmap_contextmgt(9E) callback function.
81          */
82         static int
83         xx_context_mgt(devmap_cookie_t dhp, void *pvtp, offset_t offset,
84             size_t length, uint_t type, uint_t rw)
85         {
86             ......
87             /*
88              * see devmap_contextmgt(9E) for an example
89              */
90         }
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92         /*
93          * Driver devmap_access(9E) entry point
94          */
95         static int
96         xxdevmap_access(devmap_cookie_t dhp, void *pvtp, offset_t off,
97             size_t len, uint_t type, uint_t rw)
98         {
99             offset_t diff;
100             int err;
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102             /*
103              * check if off is within the range that supports
104              * context management.
105              */
106             if ((diff = off - OFF_DO_CTXMG) >= 0 && diff < CTXMGT_SIZE) {
107                 /*
108                  * calculates the length for context switching
109                  */
110                 if ((len + off) > (OFF_DO_CTXMGT + CTXMGT_SIZE))
111                     return (-1);
112                 /*
113                  * perform context switching
114                  */
115                 err = devmap_do_ctxmgt(dhp, pvtp, off, len, type,
116                     rw,  xx_context_mgt);
117             /*
118              * check if off is within the range that does normal
119              * memory mapping.
120              */
121             } else if ((diff = off - OFF_NORMAL) >= 0 && diff < NORMAL_SIZE) {
122                 if ((len + off) > (OFF_NORMAL + NORMAL_SIZE))
123                     return (-1);
124                 err = devmap_default_access(dhp, pvtp, off, len, type, rw);
125             } else
126                 return (-1);
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128             return (err);
129         }
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