releases/4.13.6/iio-ad_sigma_delta-implement-a-dedicated-reset-function.patch

   1 From 7fc10de8d49a748c476532c9d8e8fe19e548dd67 Mon Sep 17 00:00:00 2001
   2 From: Dragos Bogdan <dragos.bogdan@analog.com>
   3 Date: Tue, 5 Sep 2017 15:14:45 +0300
   4 Subject: iio: ad_sigma_delta: Implement a dedicated reset function
   5
   6 From: Dragos Bogdan <dragos.bogdan@analog.com>
   7
   8 commit 7fc10de8d49a748c476532c9d8e8fe19e548dd67 upstream.
   9
  10 Since most of the SD ADCs have the option of reseting the serial
  11 interface by sending a number of SCLKs with CS = 0 and DIN = 1,
  12 a dedicated function that can do this is usefull.
  13
  14 Needed for the patch:  iio: ad7793: Fix the serial interface reset
  15 Signed-off-by: Dragos Bogdan <dragos.bogdan@analog.com>
  16 Acked-by: Lars-Peter Clausen <lars@metafoo.de>
  17 Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
  18 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  19
  20 ---
  21  drivers/iio/adc/ad_sigma_delta.c       |   28 ++++++++++++++++++++++++++++
  22  include/linux/iio/adc/ad_sigma_delta.h |    3 +++
  23  2 files changed, 31 insertions(+)
  24
  25 --- a/drivers/iio/adc/ad_sigma_delta.c
  26 +++ b/drivers/iio/adc/ad_sigma_delta.c
  27 @@ -177,6 +177,34 @@ out:
  28  }
  29  EXPORT_SYMBOL_GPL(ad_sd_read_reg);
  30
  31 +/**
  32 + * ad_sd_reset() - Reset the serial interface
  33 + *
  34 + * @sigma_delta: The sigma delta device
  35 + * @reset_length: Number of SCLKs with DIN = 1
  36 + *
  37 + * Returns 0 on success, an error code otherwise.
  38 + **/
  39 +int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
  40 +       unsigned int reset_length)
  41 +{
  42 +       uint8_t *buf;
  43 +       unsigned int size;
  44 +       int ret;
  45 +
  46 +       size = DIV_ROUND_UP(reset_length, 8);
  47 +       buf = kcalloc(size, sizeof(*buf), GFP_KERNEL);
  48 +       if (!buf)
  49 +               return -ENOMEM;
  50 +
  51 +       memset(buf, 0xff, size);
  52 +       ret = spi_write(sigma_delta->spi, buf, size);
  53 +       kfree(buf);
  54 +
  55 +       return ret;
  56 +}
  57 +EXPORT_SYMBOL_GPL(ad_sd_reset);
  58 +
  59  static int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
  60         unsigned int mode, unsigned int channel)
  61  {
  62 --- a/include/linux/iio/adc/ad_sigma_delta.h
  63 +++ b/include/linux/iio/adc/ad_sigma_delta.h
  64 @@ -111,6 +111,9 @@ int ad_sd_write_reg(struct ad_sigma_delt
  65  int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
  66         unsigned int size, unsigned int *val);
  67
  68 +int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
  69 +       unsigned int reset_length);
  70 +
  71  int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
  72         const struct iio_chan_spec *chan, int *val);
  73  int ad_sd_calibrate_all(struct ad_sigma_delta *sigma_delta,