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1// SPDX-License-Identifier: GPL-2.02/*3 * Generic sigma delta modulator driver4 *5 * Copyright (C) 2017, STMicroelectronics - All Rights Reserved6 * Author: Arnaud Pouliquen <arnaud.pouliquen@st.com>.7 */8 9#include <linux/iio/backend.h>10#include <linux/iio/iio.h>11#include <linux/iio/triggered_buffer.h>12#include <linux/module.h>13#include <linux/mod_devicetable.h>14#include <linux/platform_device.h>15#include <linux/property.h>16#include <linux/regulator/consumer.h>17 18static const struct iio_info iio_sd_mod_iio_info;19 20static const struct iio_chan_spec iio_sd_mod_ch = {21 .type = IIO_VOLTAGE,22 .indexed = 1,23 .scan_type = {24 .sign = 'u',25 .realbits = 1,26 .shift = 0,27 },28};29 30struct iio_sd_backend_priv {31 struct regulator *vref;32 int vref_mv;33};34 35static int iio_sd_mod_enable(struct iio_backend *backend)36{37 struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);38 39 if (priv->vref)40 return regulator_enable(priv->vref);41 42 return 0;43};44 45static void iio_sd_mod_disable(struct iio_backend *backend)46{47 struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);48 49 if (priv->vref)50 regulator_disable(priv->vref);51};52 53static int iio_sd_mod_read(struct iio_backend *backend, struct iio_chan_spec const *chan, int *val,54 int *val2, long mask)55{56 struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);57 58 switch (mask) {59 case IIO_CHAN_INFO_SCALE:60 *val = priv->vref_mv;61 return IIO_VAL_INT;62 63 case IIO_CHAN_INFO_OFFSET:64 *val = 0;65 return IIO_VAL_INT;66 }67 68 return -EOPNOTSUPP;69};70 71static const struct iio_backend_ops sd_backend_ops = {72 .enable = iio_sd_mod_enable,73 .disable = iio_sd_mod_disable,74 .read_raw = iio_sd_mod_read,75};76 77static const struct iio_backend_info sd_backend_info = {78 .name = "sd-modulator",79 .ops = &sd_backend_ops,80};81 82static int iio_sd_mod_register(struct platform_device *pdev)83{84 struct device *dev = &pdev->dev;85 struct iio_dev *iio;86 87 iio = devm_iio_device_alloc(dev, 0);88 if (!iio)89 return -ENOMEM;90 91 iio->name = dev_name(dev);92 iio->info = &iio_sd_mod_iio_info;93 iio->modes = INDIO_BUFFER_HARDWARE;94 95 iio->num_channels = 1;96 iio->channels = &iio_sd_mod_ch;97 98 platform_set_drvdata(pdev, iio);99 100 return devm_iio_device_register(&pdev->dev, iio);101}102 103static int iio_sd_mod_probe(struct platform_device *pdev)104{105 struct device *dev = &pdev->dev;106 struct regulator *vref;107 struct iio_sd_backend_priv *priv;108 int ret;109 110 /* If sd modulator is not defined as an IIO backend device, fallback to legacy */111 if (!device_property_present(dev, "#io-backend-cells"))112 return iio_sd_mod_register(pdev);113 114 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);115 if (!priv)116 return -ENOMEM;117 118 /*119 * Get regulator reference if any, but don't enable regulator right now.120 * Rely on enable and disable callbacks to manage regulator power.121 */122 vref = devm_regulator_get_optional(dev, "vref");123 if (IS_ERR(vref)) {124 if (PTR_ERR(vref) != -ENODEV)125 return dev_err_probe(dev, PTR_ERR(vref), "Failed to get vref\n");126 } else {127 /*128 * Retrieve voltage right now, as regulator_get_voltage() provides it whatever129 * the state of the regulator.130 */131 ret = regulator_get_voltage(vref);132 if (ret < 0)133 return ret;134 135 priv->vref = vref;136 priv->vref_mv = ret / 1000;137 }138 139 return devm_iio_backend_register(&pdev->dev, &sd_backend_info, priv);140};141 142static const struct of_device_id sd_adc_of_match[] = {143 { .compatible = "sd-modulator" },144 { .compatible = "ads1201" },145 { }146};147MODULE_DEVICE_TABLE(of, sd_adc_of_match);148 149static struct platform_driver iio_sd_mod_adc = {150 .driver = {151 .name = "iio_sd_adc_mod",152 .of_match_table = sd_adc_of_match,153 },154 .probe = iio_sd_mod_probe,155};156 157module_platform_driver(iio_sd_mod_adc);158 159MODULE_DESCRIPTION("Basic sigma delta modulator");160MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");161MODULE_LICENSE("GPL v2");162MODULE_IMPORT_NS(IIO_BACKEND);163