staging: comedi: drivers: introduce comedi_dio_update_state()

The (*insn_bits) functions for DIO and DO subdevices typically use
the subdevice 's->state' to hold the current state of the output
channels. The 'insn' passed to these functions, INSN_BITS, specifies
two parameters passed in the 'data'.

  data[0] = 'mask', the channels to update
  data[1] = 'bits', the new state for the channels

Introduce a helper function to handle the boilerplate used to
update the internal state.

Note that the 'mask' is filtered by the 'chanmask' of the channels
actually supported by the subdevice. This is used to protect any
non-channel related bits that are stored in the subdevice state.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
index 2e19f659cd22ff828ceb056dc82bc644156e0913..1d8e61a822fdd25a71c98183098e1e363cec1813 100644 (file)
--- a/drivers/staging/comedi/comedidev.h
+++ b/drivers/staging/comedi/comedidev.h
@@ -345,6 +345,8 @@ void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
 int comedi_dio_insn_config(struct comedi_device *, struct comedi_subdevice *,
                           struct comedi_insn *, unsigned int *data,
                           unsigned int mask);
+unsigned int comedi_dio_update_state(struct comedi_subdevice *,
+                                    unsigned int *data);
 
 void *comedi_alloc_devpriv(struct comedi_device *, size_t);
 int comedi_alloc_subdevices(struct comedi_device *, int);

diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index aeef59492ba2e5ba4b87637394d0c06ebe3cce86..8f02bf66e20b2002b3b52655919a89f95c0fcad9 100644 (file)
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -190,6 +190,28 @@ int comedi_dio_insn_config(struct comedi_device *dev,
 }
 EXPORT_SYMBOL_GPL(comedi_dio_insn_config);
 
+/**
+ * comedi_dio_update_state() - update the internal state of DIO subdevices.
+ * @s: comedi_subdevice struct
+ * @data: the channel mask and bits to update
+ */
+unsigned int comedi_dio_update_state(struct comedi_subdevice *s,
+                                    unsigned int *data)
+{
+       unsigned int chanmask = (s->n_chan < 32) ? ((1 << s->n_chan) - 1)
+                                                : 0xffffffff;
+       unsigned int mask = data[0] & chanmask;
+       unsigned int bits = data[1];
+
+       if (mask) {
+               s->state &= ~mask;
+               s->state |= (bits & mask);
+       }
+
+       return mask;
+}
+EXPORT_SYMBOL_GPL(comedi_dio_update_state);
+
 static int insn_rw_emulate_bits(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn, unsigned int *data)