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[198.48.202.89]) by smtp.gmail.com with ESMTPSA id t125sm1932847qkf.41.2021.07.14.20.12.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jul 2021 20:12:42 -0700 (PDT) From: Liam Beguin To: liambeguin@gmail.com, peda@axentia.se, jic23@kernel.org, lars@metafoo.de, pmeerw@pmeerw.net Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, robh+dt@kernel.org Subject: [PATCH v5 06/10] iio: afe: rescale: add offset support Date: Wed, 14 Jul 2021 23:12:11 -0400 Message-Id: <20210715031215.1534938-7-liambeguin@gmail.com> X-Mailer: git-send-email 2.30.1.489.g328c10930387 In-Reply-To: <20210715031215.1534938-1-liambeguin@gmail.com> References: <20210715031215.1534938-1-liambeguin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Liam Beguin This is a preparatory change required for the addition of temperature sensing front ends. Signed-off-by: Liam Beguin --- drivers/iio/afe/iio-rescale.c | 72 +++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c index a2b220b5ba86..4d3b44884a89 100644 --- a/drivers/iio/afe/iio-rescale.c +++ b/drivers/iio/afe/iio-rescale.c @@ -32,6 +32,7 @@ struct rescale { bool chan_processed; s32 numerator; s32 denominator; + s32 offset; }; static int rescale_read_raw(struct iio_dev *indio_dev, @@ -39,6 +40,8 @@ static int rescale_read_raw(struct iio_dev *indio_dev, int *val, int *val2, long mask) { struct rescale *rescale = iio_priv(indio_dev); + int scale, scale2; + int schan_off = 0; s64 tmp, tmp2; u32 factor; int ret; @@ -110,6 +113,71 @@ static int rescale_read_raw(struct iio_dev *indio_dev, dev_err(&indio_dev->dev, "unsupported type %d\n", ret); return -EOPNOTSUPP; } + case IIO_CHAN_INFO_OFFSET: + /* + * Processed channels are scaled 1-to-1 and source offset is + * already taken into account. + * + * In other cases, real world measurement are expressed as: + * + * schan_scale * (raw + schan_offset) + * + * Given that the rescaler parameters are applied recursively: + * + * rescaler_scale * (schan_scale * (raw + schan_offset) + + * rescaler_offset) + * + * Or, + * + * (rescaler_scale * schan_scale) * (raw + + * (schan_offset + rescaler_offset / schan_scale) + * + * Thus, reusing the original expression the parameters exposed + * to userspace are: + * + * scale = schan_scale * rescaler_scale + * offset = schan_offset + rescaler_offset / schan_scale + */ + if (rescale->chan_processed) { + *val = rescale->offset; + return IIO_VAL_INT; + } + + if (iio_channel_has_info(rescale->source->channel, + IIO_CHAN_INFO_OFFSET)) { + ret = iio_read_channel_offset(rescale->source, + &schan_off, NULL); + if (ret != IIO_VAL_INT) + return ret < 0 ? ret : -EOPNOTSUPP; + } + + ret = iio_read_channel_scale(rescale->source, &scale, &scale2); + switch (ret) { + case IIO_VAL_FRACTIONAL: + tmp = (s64)rescale->offset * scale2; + *val = div_s64(tmp, scale) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT: + *val = div_s64(rescale->offset, scale) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_FRACTIONAL_LOG2: + tmp = (s64)rescale->offset * (1 << scale2); + *val = div_s64(tmp, scale) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT_PLUS_NANO: + tmp = (s64)rescale->offset * 1000000000UL; + tmp2 = ((s64)scale * 1000000000UL) + scale2; + *val = div_s64(tmp, tmp2) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT_PLUS_MICRO: + tmp = (s64)rescale->offset * 1000000UL; + tmp2 = ((s64)scale * 1000000UL) + scale2; + *val = div_s64(tmp, tmp2) + schan_off; + return IIO_VAL_INT; + default: + dev_err(&indio_dev->dev, "unsupported type %d\n", ret); + return -EOPNOTSUPP; + } default: return -EINVAL; } @@ -186,6 +254,9 @@ static int rescale_configure_channel(struct device *dev, chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE); + if (rescale->offset) + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET); + /* * Using .read_avail() is fringe to begin with and makes no sense * whatsoever for processed channels, so we make sure that this cannot @@ -350,6 +421,7 @@ static int rescale_probe(struct platform_device *pdev) rescale->cfg = of_device_get_match_data(dev); rescale->numerator = 1; rescale->denominator = 1; + rescale->offset = 0; ret = rescale->cfg->props(dev, rescale); if (ret) -- 2.30.1.489.g328c10930387