staging: comedi: dmm32at: introduce dmm32_ai_get_sample()

Introduce a helper function to read the two's complement analog input
sample from the hardware and munge it to the offset binary (unsigned)
format that comedi expects. Use the comedi_offset_munge() helper to
munge the data.

Use the new helper in the analog input (*insn_read) and in the interrupt
handler for the async command.

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/drivers/dmm32at.c b/drivers/staging/comedi/drivers/dmm32at.c
index fce3b855fdbd09050cab35ecc0b956b306f8a9ab..b90f61965396adde7ccbc745ea60be8783839ec1 100644 (file)
--- a/drivers/staging/comedi/drivers/dmm32at.c
+++ b/drivers/staging/comedi/drivers/dmm32at.c
@@ -156,6 +156,18 @@ struct dmm32at_private {
        unsigned char dio_config;
 };
 
+static unsigned int dmm32at_ai_get_sample(struct comedi_device *dev,
+                                         struct comedi_subdevice *s)
+{
+       unsigned int val;
+
+       val = inb(dev->iobase + DMM32AT_AILSB);
+       val |= (inb(dev->iobase + DMM32AT_AIMSB) << 8);
+
+       /* munge two's complement value to offset binary */
+       return comedi_offset_munge(s, val);
+}
+
 static int dmm32at_ai_status(struct comedi_device *dev,
                             struct comedi_subdevice *s,
                             struct comedi_insn *insn,
@@ -174,8 +186,6 @@ static int dmm32at_ai_rinsn(struct comedi_device *dev,
                            struct comedi_insn *insn, unsigned int *data)
 {
        int n;
-       unsigned int d;
-       unsigned short msb, lsb;
        unsigned char chan;
        int range;
        int ret;
@@ -210,19 +220,7 @@ static int dmm32at_ai_rinsn(struct comedi_device *dev,
                if (ret)
                        return ret;
 
-               /* read data */
-               lsb = inb(dev->iobase + DMM32AT_AILSB);
-               msb = inb(dev->iobase + DMM32AT_AIMSB);
-
-               /* invert sign bit to make range unsigned, this is an
-                  idiosyncrasy of the diamond board, it return
-                  conversions as a signed value, i.e. -32768 to
-                  32767, flipping the bit and interpreting it as
-                  signed gives you a range of 0 to 65535 which is
-                  used by comedi */
-               d = ((msb ^ 0x0080) << 8) + lsb;
-
-               data[n] = d;
+               data[n] = dmm32at_ai_get_sample(dev, s);
        }
 
        /* return the number of samples read/written */
@@ -465,8 +463,7 @@ static irqreturn_t dmm32at_isr(int irq, void *d)
 {
        struct comedi_device *dev = d;
        unsigned char intstat;
-       unsigned int samp;
-       unsigned short msb, lsb;
+       unsigned int val;
        int i;
 
        if (!dev->attached) {
@@ -481,13 +478,8 @@ static irqreturn_t dmm32at_isr(int irq, void *d)
                struct comedi_cmd *cmd = &s->async->cmd;
 
                for (i = 0; i < cmd->chanlist_len; i++) {
-                       /* read data */
-                       lsb = inb(dev->iobase + DMM32AT_AILSB);
-                       msb = inb(dev->iobase + DMM32AT_AIMSB);
-
-                       /* invert sign bit to make range unsigned */
-                       samp = ((msb ^ 0x0080) << 8) + lsb;
-                       comedi_buf_write_samples(s, &samp, 1);
+                       val = dmm32at_ai_get_sample(dev, s);
+                       comedi_buf_write_samples(s, &val, 1);
                }
 
                if (cmd->stop_src == TRIG_COUNT &&