int a4l_check_cmddesc(struct a4l_device_context * cxt, struct a4l_cmd_desc * desc)
{
struct a4l_device *dev = a4l_get_dev(cxt);
struct a4l_subdevice *subd;
if (desc->idx_subd >= dev->transfer.nb_subd) {
__a4l_err("a4l_check_cmddesc: "
"subdevice index out of range (idx=%u)\n",
desc->idx_subd);
return -EINVAL;
}
subd = dev->transfer.subds[desc->idx_subd];
if ((subd->flags & A4L_SUBD_TYPES) == A4L_SUBD_UNUSED) {
__a4l_err("a4l_check_cmddesc: "
"subdevice type incoherent\n");
return -EIO;
}
if (!(subd->flags & A4L_SUBD_CMD)) {
__a4l_err("a4l_check_cmddesc: operation not supported, "
"synchronous only subdevice\n");
return -EIO;
}
if (test_bit(A4L_SUBD_BUSY, &subd->status)) {
__a4l_err("a4l_check_cmddesc: subdevice busy\n");
return -EBUSY;
}
return a4l_check_chanlist(dev->transfer.subds[desc->idx_subd],
desc->nb_chan, desc->chan_descs);
}
int a4l_do_insn(a4l_cxt_t * cxt, a4l_kinsn_t * dsc)
{
int ret;
a4l_subd_t *subd;
a4l_dev_t *dev = a4l_get_dev(cxt);
int (*hdlr) (a4l_subd_t *, a4l_kinsn_t *) = NULL;
/* Checks the subdevice index */
if (dsc->idx_subd >= dev->transfer.nb_subd) {
__a4l_err("a4l_do_insn: "
"subdevice index out of range (idx=%d)\n",
dsc->idx_subd);
return -EINVAL;
}
/* Recovers pointers on the proper subdevice */
subd = dev->transfer.subds[dsc->idx_subd];
/* Checks the subdevice's characteristics */
if ((subd->flags & A4L_SUBD_TYPES) == A4L_SUBD_UNUSED) {
__a4l_err("a4l_do_insn: wrong subdevice selected\n");
return -EINVAL;
}
/* Checks the channel descriptor */
ret = a4l_check_chanlist(dev->transfer.subds[dsc->idx_subd],
1, &dsc->chan_desc);
if (ret < 0)
return ret;
/* Choose the proper handler, we can check the pointer because
the subdevice was memset to 0 at allocation time */
switch (dsc->type) {
case A4L_INSN_READ:
hdlr = subd->insn_read;
break;
case A4L_INSN_WRITE:
hdlr = subd->insn_write;
break;
case A4L_INSN_BITS:
hdlr = subd->insn_bits;
break;
case A4L_INSN_CONFIG:
hdlr = subd->insn_config;
break;
default:
ret = -EINVAL;
}
/* We check the instruction type */
if (ret < 0)
return ret;
/* We check whether a handler is available */
if (hdlr == NULL)
return -ENOSYS;
/* Prevents the subdevice from being used during
the following operations */
ret = a4l_reserve_transfer(cxt, dsc->idx_subd);
if (ret < 0)
goto out_do_insn;
/* Let's the driver-specific code perform the instruction */
ret = hdlr(subd, dsc);
if (ret < 0)
__a4l_err("a4l_do_insn: "
"execution of the instruction failed (err=%d)\n",
ret);
out_do_insn:
/* Releases the subdevice from its reserved state */
a4l_cancel_transfer(cxt, dsc->idx_subd);
return ret;
}
