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author | Ian Abbott <abbotti@mev.co.uk> | 2014-09-15 12:45:57 (GMT) |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-09-19 22:55:31 (GMT) |
commit | f146fe63416de7162090a48135d33a2b74a4efcc (patch) | |
tree | 844fdef5cda705052dcb5f206995225beabcb89a /drivers/staging/comedi/drivers.c | |
parent | 062fdcada9858859b4c8a73322c4b0b718c779ff (diff) | |
download | linux-f146fe63416de7162090a48135d33a2b74a4efcc.tar.xz |
staging: comedi: add comedi_bytes_per_scan()
The "comedi_fc" module contains a few functions useful to Comedi
drivers. Their functionality is being migrated to the core "comedi"
module and renamed to start with the prefix `comedi_`. As part of this
migration, move `cfc_bytes_per_scan()` into the core comedi module and
rename it to `comedi_bytes_per_scan()`. Change the external declaration
of `cfc_bytes_per_scan()` into an inline function that calls
`comedi_bytes_per_scan()`.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/drivers.c')
-rw-r--r-- | drivers/staging/comedi/drivers.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c index c4ed8fd..891c092 100644 --- a/drivers/staging/comedi/drivers.c +++ b/drivers/staging/comedi/drivers.c @@ -290,6 +290,43 @@ unsigned int comedi_dio_update_state(struct comedi_subdevice *s, } EXPORT_SYMBOL_GPL(comedi_dio_update_state); +/** + * comedi_bytes_per_scan - get length of asynchronous command "scan" in bytes + * @s: comedi_subdevice struct + * + * Determines the overall scan length according to the subdevice type and the + * number of channels in the scan. + * + * For digital input, output or input/output subdevices, samples for multiple + * channels are assumed to be packed into one or more unsigned short or + * unsigned int values according to the subdevice's SDF_LSAMPL flag. For other + * types of subdevice, samples are assumed to occupy a whole unsigned short or + * unsigned int according to the SDF_LSAMPL flag. + * + * Returns the overall scan length in bytes. + */ +unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s) +{ + struct comedi_cmd *cmd = &s->async->cmd; + unsigned int num_samples; + unsigned int bits_per_sample; + + switch (s->type) { + case COMEDI_SUBD_DI: + case COMEDI_SUBD_DO: + case COMEDI_SUBD_DIO: + bits_per_sample = 8 * bytes_per_sample(s); + num_samples = (cmd->chanlist_len + bits_per_sample - 1) / + bits_per_sample; + break; + default: + num_samples = cmd->chanlist_len; + break; + } + return num_samples * bytes_per_sample(s); +} +EXPORT_SYMBOL_GPL(comedi_bytes_per_scan); + static int insn_rw_emulate_bits(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_insn *insn, unsigned int *data) |