From f5fbccb9eea7354b7aaf41b10a1b44cf4c7b8d99 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Mon, 5 Oct 2015 17:33:32 -0700 Subject: [PATCH] staging: comedi: mpc624: introduce mpc624_ai_get_sample() Introduce a helper function to read the analog sample from the serially connected A/D converter and handle the munging of the data. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/mpc624.c | 172 +++++++++++++++----------------- 1 file changed, 83 insertions(+), 89 deletions(-) diff --git a/drivers/staging/comedi/drivers/mpc624.c b/drivers/staging/comedi/drivers/mpc624.c index 0e8976045bff..3763dc52e48e 100644 --- a/drivers/staging/comedi/drivers/mpc624.c +++ b/drivers/staging/comedi/drivers/mpc624.c @@ -115,6 +115,85 @@ static const struct comedi_lrange range_mpc624_bipolar10 = { } }; +static unsigned int mpc624_ai_get_sample(struct comedi_device *dev, + struct comedi_subdevice *s) +{ + struct mpc624_private *devpriv = dev->private; + unsigned int data_out = devpriv->ai_speed; + unsigned int data_in = 0; + unsigned int bit; + int i; + + /* Start reading data */ + udelay(1); + for (i = 0; i < 32; i++) { + /* Set the clock low */ + outb(0, dev->iobase + MPC624_ADC); + udelay(1); + + /* Set the ADSDI line for the next bit (send to MPC624) */ + bit = (data_out & BIT(31)) ? MPC624_ADSDI : 0; + outb(bit, dev->iobase + MPC624_ADC); + udelay(1); + + /* Set the clock high */ + outb(MPC624_ADSCK | bit, dev->iobase + MPC624_ADC); + udelay(1); + + /* Read ADSDO on high clock (receive from MPC624) */ + data_in <<= 1; + data_in |= (inb(dev->iobase + MPC624_ADC) & MPC624_ADSDO) >> 4; + udelay(1); + + data_out <<= 1; + } + + /* + * Received 32-bit long value consist of: + * 31: EOC - (End Of Transmission) bit - should be 0 + * 30: DMY - (Dummy) bit - should be 0 + * 29: SIG - (Sign) bit - 1 if positive, 0 if negative + * 28: MSB - (Most Significant Bit) - the first bit of the + * conversion result + * .... + * 05: LSB - (Least Significant Bit)- the last bit of the + * conversion result + * 04-00: sub-LSB - sub-LSBs are basically noise, but when + * averaged properly, they can increase + * conversion precision up to 29 bits; + * they can be discarded without loss of + * resolution. + */ + if (data_in & MPC624_EOC_BIT) + dev_dbg(dev->class_dev, "EOC bit is set!"); + if (data_in & MPC624_DMY_BIT) + dev_dbg(dev->class_dev, "DMY bit is set!"); + + if (data_in & MPC624_SGN_BIT) { + /* + * Voltage is positive + * + * comedi operates on unsigned numbers, so mask off EOC + * and DMY and don't clear the SGN bit + */ + data_in &= 0x3fffffff; + } else { + /* + * The voltage is negative + * + * data_in contains a number in 30-bit two's complement + * code and we must deal with it + */ + data_in |= MPC624_SGN_BIT; + data_in = ~data_in; + data_in += 1; + /* clear EOC and DMY bits */ + data_in &= ~(MPC624_EOC_BIT | MPC624_DMY_BIT); + data_in = 0x20000000 - data_in; + } + return data_in; +} + static int mpc624_ai_eoc(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_insn *insn, @@ -133,10 +212,8 @@ static int mpc624_ai_insn_read(struct comedi_device *dev, struct comedi_insn *insn, unsigned int *data) { - struct mpc624_private *devpriv = dev->private; - int n, i; - unsigned long int data_in, data_out; int ret; + int i; /* * WARNING: @@ -144,7 +221,7 @@ static int mpc624_ai_insn_read(struct comedi_device *dev, */ outb(insn->chanspec, dev->iobase + MPC624_GNMUXCH); - for (n = 0; n < insn->n; n++) { + for (i = 0; i < insn->n; i++) { /* Trigger the conversion */ outb(MPC624_ADSCK, dev->iobase + MPC624_ADC); udelay(1); @@ -158,93 +235,10 @@ static int mpc624_ai_insn_read(struct comedi_device *dev, if (ret) return ret; - /* Start reading data */ - data_in = 0; - data_out = devpriv->ai_speed; - udelay(1); - for (i = 0; i < 32; i++) { - /* Set the clock low */ - outb(0, dev->iobase + MPC624_ADC); - udelay(1); - - if (data_out & BIT(31)) { /* the next bit is a 1 */ - /* Set the ADSDI line (send to MPC624) */ - outb(MPC624_ADSDI, dev->iobase + MPC624_ADC); - udelay(1); - /* Set the clock high */ - outb(MPC624_ADSCK | MPC624_ADSDI, - dev->iobase + MPC624_ADC); - } else { /* the next bit is a 0 */ - - /* Set the ADSDI line (send to MPC624) */ - outb(0, dev->iobase + MPC624_ADC); - udelay(1); - /* Set the clock high */ - outb(MPC624_ADSCK, dev->iobase + MPC624_ADC); - } - /* Read ADSDO on high clock (receive from MPC624) */ - udelay(1); - data_in <<= 1; - data_in |= - (inb(dev->iobase + MPC624_ADC) & MPC624_ADSDO) >> 4; - udelay(1); - - data_out <<= 1; - } - - /* - * Received 32-bit long value consist of: - * 31: EOC - - * (End Of Transmission) bit - should be 0 - * 30: DMY - * (Dummy) bit - should be 0 - * 29: SIG - * (Sign) bit- 1 if the voltage is positive, - * 0 if negative - * 28: MSB - * (Most Significant Bit) - the first bit of - * the conversion result - * .... - * 05: LSB - * (Least Significant Bit)- the last bit of the - * conversion result - * 04-00: sub-LSB - * - sub-LSBs are basically noise, but when - * averaged properly, they can increase conversion - * precision up to 29 bits; they can be discarded - * without loss of resolution. - */ - - if (data_in & MPC624_EOC_BIT) - dev_dbg(dev->class_dev, - "EOC bit is set (data_in=%lu)!", data_in); - if (data_in & MPC624_DMY_BIT) - dev_dbg(dev->class_dev, - "DMY bit is set (data_in=%lu)!", data_in); - if (data_in & MPC624_SGN_BIT) { /* Volatge is positive */ - /* - * comedi operates on unsigned numbers, so mask off EOC - * and DMY and don't clear the SGN bit - */ - data_in &= 0x3FFFFFFF; - data[n] = data_in; - } else { /* The voltage is negative */ - /* - * data_in contains a number in 30-bit two's complement - * code and we must deal with it - */ - data_in |= MPC624_SGN_BIT; - data_in = ~data_in; - data_in += 1; - data_in &= ~(MPC624_EOC_BIT | MPC624_DMY_BIT); - /* clear EOC and DMY bits */ - data_in = 0x20000000 - data_in; - data[n] = data_in; - } + data[i] = mpc624_ai_get_sample(dev, s); } - /* Return the number of samples read/written */ - return n; + return insn->n; } static int mpc624_attach(struct comedi_device *dev, struct comedi_devconfig *it) -- 2.11.0