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c65a0d84ee
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Notice that in this particular case, I replaced "...and fall through."
with the specific string "fall through", which is what GCC is
expecting to find thus supressing this false positive.
As Peter has observed this breaks the nice English flow, which is
less than ideal, but short of teaching GCC to read English, there
isn't a lot that we can do about it.
Addresses-Coverity-ID: 1462408 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
263 lines
6.1 KiB
C
263 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* IIO DAC emulation driver using a digital potentiometer
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*
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* Copyright (C) 2016 Axentia Technologies AB
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*
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* Author: Peter Rosin <peda@axentia.se>
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*/
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/*
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* It is assumed that the dpot is used as a voltage divider between the
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* current dpot wiper setting and the maximum resistance of the dpot. The
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* divided voltage is provided by a vref regulator.
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*
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* .------.
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* .-----------. | |
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* | vref |--' .---.
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* | regulator |--. | |
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* '-----------' | | d |
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* | | p |
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* | | o | wiper
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* | | t |<---------+
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* | | |
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* | '---' dac output voltage
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* | |
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* '------+------------+
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*/
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#include <linux/err.h>
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#include <linux/iio/consumer.h>
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#include <linux/iio/iio.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/regulator/consumer.h>
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struct dpot_dac {
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struct regulator *vref;
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struct iio_channel *dpot;
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u32 max_ohms;
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};
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static const struct iio_chan_spec dpot_dac_iio_channel = {
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
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| BIT(IIO_CHAN_INFO_SCALE),
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.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
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.output = 1,
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.indexed = 1,
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};
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static int dpot_dac_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct dpot_dac *dac = iio_priv(indio_dev);
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int ret;
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unsigned long long tmp;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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return iio_read_channel_raw(dac->dpot, val);
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case IIO_CHAN_INFO_SCALE:
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ret = iio_read_channel_scale(dac->dpot, val, val2);
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switch (ret) {
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case IIO_VAL_FRACTIONAL_LOG2:
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tmp = *val * 1000000000LL;
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do_div(tmp, dac->max_ohms);
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tmp *= regulator_get_voltage(dac->vref) / 1000;
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do_div(tmp, 1000000000LL);
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*val = tmp;
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return ret;
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case IIO_VAL_INT:
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/*
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* Convert integer scale to fractional scale by
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* setting the denominator (val2) to one, and...
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*/
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*val2 = 1;
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ret = IIO_VAL_FRACTIONAL;
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/* fall through */
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case IIO_VAL_FRACTIONAL:
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*val *= regulator_get_voltage(dac->vref) / 1000;
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*val2 *= dac->max_ohms;
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break;
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}
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return ret;
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}
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return -EINVAL;
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}
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static int dpot_dac_read_avail(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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const int **vals, int *type, int *length,
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long mask)
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{
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struct dpot_dac *dac = iio_priv(indio_dev);
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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*type = IIO_VAL_INT;
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return iio_read_avail_channel_raw(dac->dpot, vals, length);
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}
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return -EINVAL;
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}
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static int dpot_dac_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int val, int val2, long mask)
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{
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struct dpot_dac *dac = iio_priv(indio_dev);
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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return iio_write_channel_raw(dac->dpot, val);
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}
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return -EINVAL;
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}
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static const struct iio_info dpot_dac_info = {
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.read_raw = dpot_dac_read_raw,
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.read_avail = dpot_dac_read_avail,
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.write_raw = dpot_dac_write_raw,
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};
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static int dpot_dac_channel_max_ohms(struct iio_dev *indio_dev)
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{
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struct device *dev = &indio_dev->dev;
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struct dpot_dac *dac = iio_priv(indio_dev);
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unsigned long long tmp;
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int ret;
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int val;
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int val2;
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int max;
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ret = iio_read_max_channel_raw(dac->dpot, &max);
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if (ret < 0) {
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dev_err(dev, "dpot does not indicate its raw maximum value\n");
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return ret;
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}
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switch (iio_read_channel_scale(dac->dpot, &val, &val2)) {
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case IIO_VAL_INT:
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return max * val;
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case IIO_VAL_FRACTIONAL:
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tmp = (unsigned long long)max * val;
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do_div(tmp, val2);
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return tmp;
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case IIO_VAL_FRACTIONAL_LOG2:
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tmp = val * 1000000000LL * max >> val2;
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do_div(tmp, 1000000000LL);
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return tmp;
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default:
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dev_err(dev, "dpot has a scale that is too weird\n");
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}
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return -EINVAL;
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}
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static int dpot_dac_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct iio_dev *indio_dev;
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struct dpot_dac *dac;
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enum iio_chan_type type;
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int ret;
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indio_dev = devm_iio_device_alloc(dev, sizeof(*dac));
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if (!indio_dev)
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return -ENOMEM;
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platform_set_drvdata(pdev, indio_dev);
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dac = iio_priv(indio_dev);
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indio_dev->name = dev_name(dev);
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indio_dev->dev.parent = dev;
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indio_dev->info = &dpot_dac_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = &dpot_dac_iio_channel;
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indio_dev->num_channels = 1;
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dac->vref = devm_regulator_get(dev, "vref");
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if (IS_ERR(dac->vref)) {
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if (PTR_ERR(dac->vref) != -EPROBE_DEFER)
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dev_err(&pdev->dev, "failed to get vref regulator\n");
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return PTR_ERR(dac->vref);
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}
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dac->dpot = devm_iio_channel_get(dev, "dpot");
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if (IS_ERR(dac->dpot)) {
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if (PTR_ERR(dac->dpot) != -EPROBE_DEFER)
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dev_err(dev, "failed to get dpot input channel\n");
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return PTR_ERR(dac->dpot);
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}
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ret = iio_get_channel_type(dac->dpot, &type);
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if (ret < 0)
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return ret;
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if (type != IIO_RESISTANCE) {
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dev_err(dev, "dpot is of the wrong type\n");
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return -EINVAL;
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}
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ret = dpot_dac_channel_max_ohms(indio_dev);
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if (ret < 0)
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return ret;
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dac->max_ohms = ret;
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ret = regulator_enable(dac->vref);
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if (ret) {
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dev_err(dev, "failed to enable the vref regulator\n");
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return ret;
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}
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ret = iio_device_register(indio_dev);
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if (ret) {
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dev_err(dev, "failed to register iio device\n");
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goto disable_reg;
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}
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return 0;
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disable_reg:
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regulator_disable(dac->vref);
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return ret;
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}
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static int dpot_dac_remove(struct platform_device *pdev)
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{
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struct iio_dev *indio_dev = platform_get_drvdata(pdev);
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struct dpot_dac *dac = iio_priv(indio_dev);
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iio_device_unregister(indio_dev);
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regulator_disable(dac->vref);
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return 0;
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}
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static const struct of_device_id dpot_dac_match[] = {
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{ .compatible = "dpot-dac" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, dpot_dac_match);
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static struct platform_driver dpot_dac_driver = {
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.probe = dpot_dac_probe,
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.remove = dpot_dac_remove,
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.driver = {
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.name = "iio-dpot-dac",
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.of_match_table = dpot_dac_match,
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},
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};
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module_platform_driver(dpot_dac_driver);
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MODULE_DESCRIPTION("DAC emulation driver using a digital potentiometer");
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MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
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MODULE_LICENSE("GPL v2");
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