ddi_copyout(9f)

1ddi_copyout(9F)          Kernel Functions for Drivers          ddi_copyout(9F)
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NAME

6       ddi_copyout - copy data from a driver
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SYNOPSIS

9       #include <sys/types.h>
10       #include <sys/ddi.h>
11       #include <sys/sunddi.h>
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13
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15       int ddi_copyout(const void *driverbuf, void *buf, size_t cn, int flags);
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17

INTERFACE LEVEL

19       Solaris DDI specific (Solaris DDI).
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PARAMETERS

22       driverbuf    Source address in the driver from which the data is trans‐
23                    ferred.
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26       buf          Destination address to which the data is transferred.
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29       cn           Number of bytes to copy.
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32       flags        Set of flag bits that provide  address  space  information
33                    about buf.
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DESCRIPTION

37       This routine is designed for use in driver ioctl(9E) routines for driv‐
38       ers that support layered  ioctls.  ddi_copyout()  copies  data  from  a
39       driver buffer to a destination address, buf.
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42       The  flags argument determines the address space information about buf.
43       If the FKIOCTL flag is  set,  this  indicates  that  buf  is  a  kernel
44       address,  and  ddi_copyout() behaves like bcopy(9F). Otherwise,  buf is
45       interpreted as a user buffer address, and  ddi_copyout()  behaves  like
46       copyout(9F).
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49       Addresses  that  are word-aligned are moved most efficiently.  However,
50       the driver developer is not obliged to ensure alignment.  This function
51       automatically  finds  the  most  efficient  move algorithm according to
52       address alignment.
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RETURN VALUES

55       Under normal conditions, 0 is returned to indicate a  successful  copy.
56       Otherwise, −1 is returned if one of the following occurs:
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58           o      Paging  fault;  the  driver tried to access a page of memory
59                  for which it did not have read or write access.
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61           o      Invalid user address, such as a user area or stack area.
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63           o      Invalid address that  would  have  resulted  in  data  being
64                  copied into the user block.
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66           o      Hardware  fault;  a  hardware  error prevented access to the
67                  specified user memory. For example, an uncorrectable  parity
68                  or ECC error occurred.
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71       If  −1  is  returned  to the caller, driver entry point routines should
72       return EFAULT.
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CONTEXT

75       ddi_copyout() can be called from user or kernel context only.
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EXAMPLES

78       Example 1 ddi_copyout() example
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81       A driver ioctl(9E) routine (line 12) can be used to get or  set  device
82       attributes  or  registers.  In  the XX_GETREGS condition (line 25), the
83       driver copies the current device register values to another data  area.
84       If the specified argument contains an invalid address, an error code is
85       returned.
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87
88         1  struct device  {        /* layout of physical device registers  */
89          2     int      control;    /* physical device control word  */
90          3     int      status;     /* physical device status word   */
91          4     short    recv_char;  /* receive character from device */
92          5     short    xmit_char;  /* transmit character to device  */
93          6  };
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95          7  struct device_state {
96          8     volatile struct device *regsp;   /* pointer to device registers */
97          9     kmutex_t reg_mutex;              /* protect device registers */
98                . . .
99         10  };
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101         11  static void *statep; /* for soft state routines */
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103         12  xxioctl(dev_t dev, int cmd, int arg, int mode,
104         13      cred_t *cred_p, int *rval_p)
105         14  {
106         15      struct device_state *sp;
107         16      volatile struct device *rp;
108         17      struct device reg_buf;     /* temporary buffer for registers */
109         18      int instance;
110
111         19      instance = getminor(dev);
112         20      sp = ddi_get_soft_state(statep, instance);
113         21      if (sp == NULL)
114         22          return (ENXIO);
115         23      rp = sp->regsp;
116                 . . .
117         24      switch (cmd)  {
118
119         25      case XX_GETREGS:   /* copy registers to arg */
120         26            mutex_enter(&sp->reg_mutex);
121         27            /*
122         28             * Copy data from device registers to
123         29             * temporary device register buffer
124         30             * e.g. reg_buf.control = rp->control;
125         31             */
126         32            mutex_exit(&sp->reg_mutex);
127         33            if (ddi_copyout(&reg_buf, arg,
128         34                sizeof (struct device), mode) != 0) {
129         35                    return (EFAULT);
130         36            }
131
132         37            break;
133         38      }
134         39  }
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NOTES

145       The  value  of  the  flags  argument  to ddi_copyout() should be passed
146       through directly from the mode argument of ioctl() untranslated.
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149       Driver defined locks should not be held across calls to this function.
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152       ddi_copyout() should not be used from a streams  driver.  See  M_COPYIN
153       and M_COPYOUT in STREAMS Programming Guide.
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157SunOS 5.11                        19 Apr 2000                  ddi_copyout(9F)